Sample records for glaciology

  1. The spatial glaciological data infrastructure

    T. Y. Khromova


    Full Text Available Substantial and rapid environmental changes require developing methods which could be able to manage huge information flows, to optimize processes of the data acquisition, storage, analysis, and exchange. Such facilities can be provided by the newly developed GIS technologies. Digital data bases are used as the key component of the GIS methods. We present the system of glaciological data management, developed in the Institute of Geography of Russian Academy of Sciences (IGRAS. Digital Atlas «Snow and Ice on the Earth», glacier inventories and digital library are the basic structures making possible objective presentation of the glaciological knowledge and data. The system provides the data integration, access to the data base, and makes possible using the GIS techniques for analysis. Data integration technologies are designed to form the united information space of subject areas of the spatial data. The objects of integration in our study are the information resources of glaciology, accumulated in a distributed system of data on the IGRAS web servers and geoportals in forms of data and metadata bases, structured (in a particular format data files, object data files (plain text, documents, images, etc., and electronic atlases. The best option for formation of a large-scale distributed environment, integration of many information resources of glaciology is to provide the so-called interoperability of data. This refers to compliance with certain rules or usage of additional software tools that allows interaction between various spatial data. These are standards to which the integrated information resources of glaciology should satisfy. The result of integration of the glaciological data technology application is the series of software and technology solutions. The main result of this work is creation of geoportals «Electronic Earth» (, «The Nature and Resources of the Russian North» (, «IPY-IGRAS» (www

  2. A Classification Scheme for Glaciological AVA Responses

    Booth, A.; Emir, E.


    A classification scheme is proposed for amplitude vs. angle (AVA) responses as an aid to the interpretation of seismic reflectivity in glaciological research campaigns. AVA responses are a powerful tool in characterising the material properties of glacier ice and its substrate. However, before interpreting AVA data, careful true amplitude processing is required to constrain basal reflectivity and compensate amplitude decay mechanisms, including anelastic attenuation and spherical divergence. These fundamental processing steps can be difficult to design in cases of noisy data, e.g. where a target reflection is contaminated by surface wave energy (in the case of shallow glaciers) or by energy reflected from out of the survey plane. AVA methods have equally powerful usage in estimating the fluid fill of potential hydrocarbon reservoirs. However, such applications seldom use true amplitude data and instead consider qualitative AVA responses using a well-defined classification scheme. Such schemes are often defined in terms of the characteristics of best-fit responses to the observed reflectivity, e.g. the intercept (I) and gradient (G) of a linear approximation to the AVA data. The position of the response on a cross-plot of I and G then offers a diagnostic attribute for certain fluid types. We investigate the advantages in glaciology of emulating this practice, and develop a cross-plot based on the 3-term Shuey AVA approximation (using I, G, and a curvature term C). Model AVA curves define a clear lithification trend: AVA responses to stiff (lithified) substrates fall discretely into one quadrant of the cross-plot, with positive I and negative G, whereas those to fluid-rich substrates plot diagonally opposite (in the negative I and positive G quadrant). The remaining quadrants are unoccupied by plausible single-layer responses and may therefore be diagnostic of complex thin-layer reflectivity, and the magnitude and polarity of the C term serves as a further indicator

  3. Building expertise in glaciology through intense international summer schools

    Hock, R.


    As the field of glaciology grows in response to recent rapid glacier changes and their potential socio-environmental consequences, the need for well-trained scientists possessing a high level expertise in physical glaciology has increased. Opportunities necessary to cultivate these efforts have not kept pace with the need for increased proficiency in this field. To our knowledge there is no academic degree in glaciology anywhere, but glaciology education, if offered at all, is generally restricted to one or a few individual classes. Glaciology graduate students tend to come from a wide range of background education and often pursue their degree at institutes without any glaciology classes. To cater to this demand we have organized four intense 11-day International Summer Schools in Glaciology which have provided an opportunity for a total of 119 students from around the world to obtain a comprehensive insight into a wide range of topics in glaciology and a more holistic view beyond the scope of their graduate thesis topic. The summer schools were held bi-annually (2010 - 2016) in the tiny village of McCarthy in central Alaska in the immediate vicinity of easily accessible glaciers. The unique setting facilitated close interaction among all participants. The courses included daily lectures, computational exercises, a poster-session and two glacier excursions. In addition, students worked in small teams on a glaciology computer project mentored by one of the 7-9 instructors from several US and foreign institutions, and presented their results in a `mini' student conference at the end of the course. All instructors were required to stay for the entire period. Thus the courses provided a valuable platform for international networking between students and instructors and among the students themselves, thereby fostering future collaborations. This was generally perceived as a major asset of our summer schools.

  4. Methodological synergies for glaciological constraints to find Oldest Ice

    Eisen, Olaf


    The Beyond EPICA - Oldest Ice (BE-OI) consortium and its international partners unite a globally unique concentration of scientific expertise and infrastructure for ice-core investigations. It delivers the technical, scientific and financial basis for a comprehensive plan to retrieve an ice core up to 1.5 million years old. The consortium takes care of the pre-site surveys for site selection around Dome C and Dome Fuji, both potentially appropriate regions in East Antarctica. Other science consortia will investigate other regions under the umbrella of the International Partnerships in Ice Core Sciences (IPICS). Of major importance to obtain reliable estimates of the age of the ice in the basal layers of the ice sheet are the physical boundary conditions and ice-flow dynamics: geothermal heat flux, advection and layer integrity to avoid layer overturning and the formation of folds. The project completed the first field season at both regions of interest. This contribution will give an overview how the combined application of various geophysical, geodetical and glaciological methods applied in the field in combination with ice-flow modelling can constrain the glaciological boundary conditions and thus age at depth.

  5. Glaciological and hydrological sensitivities in the Hindu Kush - Himalaya

    Shea, Joseph; Immerzeel, Walter


    Glacier responses to future climate change will affect hydrology at subbasin-scales. The main goal of this study is to assess glaciological and hydrological sensitivities of sub-basins throughout the Hindu Kush - Himalaya (HKH) region. We use a simple geometrical analysis based on a full glacier inventory and digital elevation model (DEM) to estimate sub-basin equilibrium line altitudes (ELA) from assumptions of steady-state accumulation area ratios (AARs). The ELA response to an increase in temperature is expressed as a function of mean annual precipitation, derived from a range of high-altitude studies. Changes in glacier contributions to streamflow in response to increased temperatures are examined for scenarios of both static and adjusted glacier geometries. On average, glacier contributions to streamflow increase by approximately 50% for a +1K warming based on a static geometry. Large decreases (-60% on average) occur in all basins when glacier geometries are instantaneously adjusted to reflect the new ELA. Finally, we provide estimates of sub-basin glacier response times that suggest a majority of basins will experience declining glacier contributions by the year 2100.

  6. Coastal-change and glaciological map of the Saunders Coast area, Antarctica: 1972-97

    Ferrigno, J.G.; Williams, R.S.; Foley, K.M.


    Satellite images from 1972 to 1997 have been used to prepare a map showing glaciological features of the Saunders Coast area, Antarctica. Analysis of the imagery shows a trend toward ice-front retreat that may be a result of changing environmental conditions.

  7. Glaciological and geodetic mass balance of ten long-term glaciers in Norway

    L. M. Andreassen


    Full Text Available The glaciological and geodetic methods provide independent observations of glacier mass balance. The glaciological method measures the surface mass balance, on a seasonal or annual basis, whereas the geodetic method measures surface, internal and basal mass balances, over a period of years or decades. In this paper, we reanalyse the 10 glaciers with long-term mass balance series in Norway. The reanalysis includes (i homogenisation of both glaciological and geodetic observation series, (ii uncertainty assessment, (iii estimates of generic differences including estimates of internal and basal melt, (iv validation, and (v partly calibration of mass balance series. This study comprises an extensive set of data (454 mass balance years, 34 geodetic surveys and large volumes of supporting data, such as metadata and field notes. In total, 21 periods of data were compared and the results show discrepancies between the glaciological and geodetic methods for some glaciers, which in part are attributed to internal and basal ablation and in part to inhomogeneity in the data processing. Deviations were smaller than 0.2 m w.e. a−1 for 12 out of 21 periods. Calibration was applied to seven out of 21 periods, as the deviations were larger than the uncertainty. The reanalysed glaciological series shows a more consistent signal of glacier change over the period of observations than previously reported: six glaciers had a significant mass loss (14–22 m w.e. and four glaciers were nearly in balance. All glaciers have lost mass after year 2000. More research is needed on the sources of uncertainty, to reduce uncertainties and adjust the observation programmes accordingly. The study confirms the value of carrying out independent high-quality geodetic surveys to check and correct field observations.

  8. Evaluating digital elevation models for glaciologic applications: An example from Nevado Coropuna, Peruvian Andes

    A. E. Racoviteanu; Manley, W.F; Arnaud, Yves; Williams, M.W.


    This paper evaluates the suitability of readily available elevation data derived from recent sensors - the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and the Shuttle Radar Topography Mission (SRTM) - for glaciological applications. The study area is Nevado Coropuna (6426 m), situated in Cordillera Ampato of Southern Peru. The glaciated area was 82.6 km(2) in 1962, based on aerial photography. We estimate the glacier area to be ca. 60.8 km(2) in 2000, based on analy...

  9. Low-cost, on-demand aerial photogrammetry for glaciological measurement

    K. Whitehead


    Full Text Available Remotely-sensed glaciological measurements can be expensive, and often involve a trade-off between resolution, scale, and frequency. In an attempt to overcome these issues we report on a case study in which two low-cost techniques were used to generate orthomosaic images and digital elevation models (DEMs of an arctic glacier in two consecutive ablation seasons. In the first aerial survey we used an unmanned aerial vehicle (UAV and acquired images autonomously, while in the second we used a piloted helicopter and acquired images manually. We present a preliminary assessment of accuracy and apply these data to measure glacier thinning and motion.

  10. Progress of Glaciology and Geocryology Incubation Program of the National Natural Science Foundation of China

    Cheng Guodong; Zhang Yaonan; Wang Zhengwen


    The 10th 5-year Plan for National Natural Science Foundation of China (NSFC) for fostering competent research teams and highly qualified scholars in fundamental research in glaciology and geocryology was based on the strategy of incubating "competitive, problem-solving oriented and motivated fledgling scientists, who can effectively lead and greatly advance the aimed subjects and conduct the cutting edge research". This principle has been playing crucial roles in restructuring the team aiming at world-first-class research projects and at solving critical problems in national key projects. It was under the guidance of this strategy that the key research team for mitigating the challenging and differential frost and thaw hazards along the Qinghai-Tibet Railway (QTR) had been formed, that a strong group focused on the cryosphere (snow, ice and permafrost ) research was re-established and enhanced. These accomplishments have facilitated the formation and growth of highly motivated competitive research teams on comprehensive and integrated fundamental research, which promoted, intensified, and expanded the research programs in glaciology and geocryology.

  11. 中国冰川研究进展%Recent progress of glaciological studies in China

    刘时银; 王宁练; 段克勤


    Glacier inventory compilation during the past 20 years and modifications of that for the Eastern Pamir and Banggong Lake indicate that there are 46,342 modern glaciers with a total area and volume of 59415 km2 and 5601 km3 respectively in China. These glaciers can be classified into maritime and continental (including sub-continental and extremely continental) types. Researches show that glaciers in China have been retreating since the Little Ice Age and the mass wastage was accelerated during the past 30 to 40 years. Being an important part of glaciological studies in China,ice core climatic and environmental studies on Tibetan Plateau and in the Antarctica have provided abundant, high resolution information about past climatic and environmental evolution over the Tibetan Plateau and Antarctica. Except for different parameters recorded in ice cores relating to climate and environment changes on Tibetan Plateau, records from ice cores extracted from different glaciers show that the discrepancies in climatic and environmental changes on the north and south parts of the plateau may be the consequence of different influencing effects from terrestrial and solar sources.Glaciological and meteorological phenomena imply that Lambert Glacier valley is an important boundary of climate in the east Antarctica, which is thought to be connected with cyclonic activities and Circum-polar Waves over the Antarctica.

  12. Which DEM is the best for glaciology? -Evaluation of global-scale DEM products-

    Nagai, Hiroto; Tadono, Takeo


    Digital elevation models (DEMs) are fundamental geospatial data to study glacier distribution, changes, dynamics, mass balance and various geomorphological conditions. This study evaluates latest global-scale free DEMs in order to clarify their superiority and inferiority in glaciological uses. Three DEMs are now available; the 1-arcsec. product obtained from the Shuttle Radar Topographic Mission (SRTM1), the second version of Global Digital Elevation Model of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER GDEM2), and the first resampled dataset acquired by the Advanced Land observing Satellite, namely ALOS World 3D-30m (AW3D30). These DEMs have common specifications of global coverage (B>C). In the Tone river basin, SRTM1 has equivalent accuracy to AW3D30. High resolution (2.5 m) of the original stereo-pair images for AW3D30 (i.e. ALOS PRISM imagery) contributes for the best absolute accuracy. Glaciers on rather flat terrains are usually distributed in higher latitude (e.g. Antarctica and Greenland), where SRTM1 is unable. Glaciers at mid-to-low latitudes glaciers are usually distributed in high and steep mountains, where SRTM1 has lower accuracy than AW3D30. AW3D30 would contributes as a preferable option for glaciology in a global scale. At the tops of high mountains in the Nepal Himalaya, however, AW3D30 has a large area of data missing due to snow cover. This inferiority should be improved by filling with other datasets in the next version. ASTER GDEM2 has less area of data missing in the Nepal Himalaya, which would contribute for coarse uses such as generation of river basin, brief drawing of a topographic map, etc.

  13. Palaeoclimatic conditions during the last tree centuries in the tropical Andes inferred from two glaciological models

    Jomelli, V.; Blard, P.; Favier, V.; Pavlova, I.; Brunstein, D.; Soruco, A.; Grancher, D.


    Tropical glaciers are considered to be especially sensitive to climate change and thus offer an attractive proxy for palaeoclimatic conditions. Here we present temperature and precipitation changes during the last three centuries inferred from two different glaciological models applied on three glaciers selected in Bolivia and in Ecuador. Both models used glaciological parameters such as Equilibrium line Altitude, length, surface- area, and volume variations that were estimated from paleo glaciers documented with moraine records. Moraines were mapped with a GPS field survey and dated by lichenometry using the already published generalized extreme value approach. Climate changes were analyzed for different dates such as 1730, 1800, 1880 and 1956. Climatic reconstructions were firstly based on the modelling of past glacier extensions using a coupling of an ice melt model (to calculate the glacier mass balance) with an ice flow model. The second alternative approach was based on Area-Altitude balance ratio model. Once the models are adequately calibrated, starting from the present conditions, temperature and precipitation have just to be simultaneously changed in order to make the glaciers grow and advance until their past positions are documented by the successive old moraines. Both models revealed cool (about 0.8-1°C colder than today) and wet conditions during the 18th century (about 30% higher accumulation than today) followed by a short drier but colder period at the beginning of the 19th century. The observed reduction of Andean glaciers from the middle of the 19th century is due to a combination of increasingly warmer and drier conditions than before.

  14. Climate Past and Present: A Study on Glaciology of Himalayas in India

    Shanmuganandan, S.


    Glaciers are moving bodies of ice and snow, which are normally present above the snow line. Glaciers and ice sheets are hundreds to more than one thousand meters thick and change significantly only over decades. On these longer time scales they can influence atmospheric circulation and global sea levels. Glaciers play an important role in maintaining ecosystem stability as they act as buffers and regulate the runoff water supply from high mountains to the plains during both dry and wet spells. The present study is an attempt to analyze the Climate of the Past and Present of the Himalayas with reference to study the glaciology. The study also attempted to use the remote sensed data to explore the past and present situation of glaciology of the Himalayas. Since mountain glaciology of Himalayas played a vital role and stand as an example to explore the possibility of the climate change that occurred from the past to the present and also to determine the status in the future. The Study was based on the secondary and primary data collected from available sources and also collected from various published records to document the evidences for the same. It was observed that the Himalayan glaciers account for about 70% of the world’s non-polar glaciers and affect the lives of millions of people in several countries: China, India, Pakistan, Afghanistan, Nepal and Bangladesh. Their runoff feeds two of the oldest rivers in the world, the Indus and the Ganges, whose tributaries carry precious water for 500 million people on the northern Indian plains. Most of the glaciers in the Himalayas are of a summer-accumulation type, that is major accumulation and ablation take place simultaneously during summer (Fujita et. al, 1997). The glaciers of the Himalayas include some of the longest outside the Polar Regions and reached their largest extent during the end of the last ice age (more than 20,000 years ago). The evidence of these large ice masses can be seen in 'U' shaped valleys

  15. Coastal-change and glaciological map of the Ross Island area, Antarctica

    Ferrigno, Jane G.; Foley, Kevin M.; Swithinbank, Charles; Williams, Richard S.


    Reduction in the area and volume of Earth?s two polar ice sheets is intricately linked to changes in global climate and to the resulting rise in sea level. Measurement of changes in area and mass balance of the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council. On the basis of these recommendations, the U.S. Geological Survey used its archive of satellite images to document changes in the cryospheric coastline of Antarctica and analyze the glaciological features of the coastal regions. The Ross Island area map is bounded by long 141? E. and 175? E. and by lat 76? S. and 81? S. The map covers the part of southern Victoria Land that includes the northwestern Ross Ice Shelf, the McMurdo Ice Shelf, part of the polar plateau and Transantarctic Mountains, the McMurdo Dry Valleys, northernmost Shackleton Coast, Hillary Coast, the southern part of Scott Coast, and Ross Island. Little noticeable change has occurred in the ice fronts on the map, so the focus is on glaciological features. In the western part of the map area, the polar plateau of East Antarctica, once thought to be a featureless region, has subtle wavelike surface forms (megadunes) and flow traces of glaciers that originate far inland and extend to the coast or into the Ross Ice Shelf. There are numerous outlet glaciers. Glaciers drain into the McMurdo Dry Valleys, through the Transantarctic Mountains into the Ross Sea, or into the Ross Ice Shelf. Byrd Glacier is the largest. West of the Transantarctic Mountains are areas of blue ice, readily identifiable on Landsat images, that have been determined to be prime areas for finding meteorites. Three subglacial lakes have been identified in the map area. Because McMurdo Station, the main U.S. scientific research station in Antarctica, is located on Ross Island in the map area, many of these and other features in the area have been studied extensively. The paper version of this map is

  16. Glaciological and hydrological sensitivities to climate change in the Hindu-Kush Himalayas

    Shea, J. M.; Immerzeel, W.


    The impact of climate change on glaciers will affect the timing and magnitude of water availability from high-altitude catchments in the Hindu-Kush Himalaya (HKH) region. In this study, we quantify the current sensitivity of glacier systems to climatic change and the associated sub-basin hydrological sensitivity throughout the HKH region using glacier inventory data and high-resolution dynamically downscaled climate fields. We first estimate the glaciological sensitivity, or change in glacierized area with change in equilibrium line altitude (ELA), for each sub-basin using a glacier inventory and SRTM DEM. We assign a climatic sensitivity of the ELA to temperature changes (dELA/dT) based on published values for tropical and sub-tropical glaciers and a high-resolution annual precipitation field. To assess the change in glacier meltwater contribution as a result of warming, we first estimate baseline glacier meltwater contributions using a mass balance gradient and estimated current ELA. Future climate warming scenarios of +1K and +2K are then used to examine the change in glacier meltwater contributions based on the increased ELA and ablation area. Finally, we calculate a glacier significance index that examines the relative importance of melt within each sub-basin, and discuss regional variations in glacier sensitivity and significance.

  17. Coastal-change and glaciological map of the Amery Ice Shelf area, Antarctica: 1961–2004

    Foley, Kevin M.; Ferrigno, Jane G.; Swithinbank, Charles; Williams, Richard S.; Orndorff, Audrey L.


    Reduction in the area and volume of Earth’s two polar ice sheets is intricately linked to changes in global climate and to the resulting rise in sea level. Measurement of changes in area and mass balance of the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council. On the basis of these recommendations, the U.S. Geological Survey used its archive of satellite images to document changes in the cryospheric coastline of Antarctica and analyze the glaciological features of the coastal regions. Amery Ice Shelf, lying between 67.5° and 75° East longitude and 68.5° and 73.2° South latitude, is the largest ice shelf in East Antarctica. The latest measurements of the area of the ice shelf range between 62,620 and 71,260 square kilometers. The ice shelf is fed primarily by Lambert, Mellor, and Fisher Glaciers; its thickness ranges from 3,000 meters in the center of the grounding line to less than 300 meters at the ice front. Lambert Glacier is considered to be the largest glacier in the world, and its drainage basin is more than 1 million square kilometers in area. It is possible to see some coastal change on the outlet glaciers along the coast, but most of the noticeable change occurs on the Amery Ice Shelf front.

  18. Beryllium-10 in the Taylor Dome ice core: Applications to Antarctic glaciology and paleoclimatology

    Steig, E.J.


    An ice core was drilled at Taylor dome, East Antarctica, reaching to bedrock at 554 meters. Oxygen-isotope measurements reveal climatic fluctuations through the last interglacial period. To facilitate comparison of the Taylor Dome paleoclimate record with geologic data and results from other deep ice cores, several glaciological issues need to be addressed. In particular, accumulation data are necessary as input for numerical ice-flow-models, for determining the flux of chemical constituents from measured concentrations, and for calculation of the offset in age between ice and trapped air in the core. The analysis of cosmogenic beryllium-10 provides a geochemical method for constraining the accumulation-rate history at Taylor Dome. High-resolution measurements were made in shallow firn cores and snow pits to determine the relationship among beryllium-10 concentrations, wet and dry deposition mechanisms, and snow-accumulation rates. Comparison between theoretical and measured variations in deposition over the last 75 years constrains the relationship between beryllium-10 deposition and global average production rates. The results indicate that variations in geomagnetically-modulated production-rate do not strongly influence beryllium-10 deposition at Taylor Dome. Although solar modulation of production rate is important for time scales of years to centuries, snow-accumulation rate is the dominant control on ice-core beryllium-10 concentrations for longer periods. Results show that the Taylor Dome core can be used to provide new constraints on regional climate over the last 130,000 years, complementing the terrestrial and marine geological record from the Dry Valley, Transantarctic Mountains and western Ross Sea.

  19. Glaciological measurements and mass balances from Sperry Glacier, Montana, USA, years 2005-2015

    Clark, Adam M.; Fagre, Daniel B.; Peitzsch, Erich H.; Reardon, Blase A.; Harper, Joel T.


    Glacier mass balance measurements help to provide an understanding of the behavior of glaciers and their response to local and regional climate. In 2005 the United States Geological Survey established a surface mass balance monitoring program on Sperry Glacier, Montana, USA. This project is the first quantitative study of mass changes of a glacier in the US northern Rocky Mountains and continues to the present. The following paper describes the methods used during the first 11 years of measurements and reports the associated results. From 2005 to 2015, Sperry Glacier had a cumulative mean mass balance loss of 4.37 m w.e. (water equivalent). The mean winter, summer, and annual glacier-wide mass balances were 2.92, -3.41, and -0.40 m w.e. yr-1 respectively. We derive these cumulative and mean results from an expansive data set of snow depth, snow density, and ablation measurements taken at selected points on the glacier. These data allow for the determination of mass balance point values and a time series of seasonal and annual glacier-wide mass balances for all 11 measurement years. We also provide measurements of glacier extent and accumulation areas for select years. All data have been submitted to the World Glacier Monitoring Service and are available at doi:10.5904/wgms-fog-2016-08. This foundational work provides valuable insight about Sperry Glacier and supplies additional data to the worldwide record of glaciers measured using the glaciological method. Future research will focus on the processes that control accumulation and ablation patterns across the glacier. Also we plan to examine the uncertainties related to our methods and eventually quantify a more robust estimate of error associated with our results.

  20. Glaciological measurements and mass balances from Sperry Glacier, Montana, USA, years 2005–2015

    Clark, Adam; Fagre, Daniel B.; Peitzsch, Erich H.; Reardon, Blase A.; Harper, Joel T.


    Glacier mass balance measurements help to provide an understanding of the behavior of glaciers and their response to local and regional climate. In 2005 the United States Geological Survey established a surface mass balance monitoring program on Sperry Glacier, Montana, USA. This project is the first quantitative study of mass changes of a glacier in the US northern Rocky Mountains and continues to the present. The following paper describes the methods used during the first 11 years of measurements and reports the associated results. From 2005 to 2015, Sperry Glacier had a cumulative mean mass balance loss of 4.37 m w.e. (water equivalent). The mean winter, summer, and annual glacier-wide mass balances were 2.92, −3.41, and −0.40 m w.e. yr−1 respectively. We derive these cumulative and mean results from an expansive data set of snow depth, snow density, and ablation measurements taken at selected points on the glacier. These data allow for the determination of mass balance point values and a time series of seasonal and annual glacier-wide mass balances for all 11 measurement years. We also provide measurements of glacier extent and accumulation areas for select years. All data have been submitted to the World Glacier Monitoring Service and are available at doi:10.5904/wgms-fog-2016-08. This foundational work provides valuable insight about Sperry Glacier and supplies additional data to the worldwide record of glaciers measured using the glaciological method. Future research will focus on the processes that control accumulation and ablation patterns across the glacier. Also we plan to examine the uncertainties related to our methods and eventually quantify a more robust estimate of error associated with our results.

  1. Possibility of using remote sensing data for glaciological calculations and monitoring

    V. G. Konovalov


    Full Text Available Altitude and areal characteristics of glaciation of the Earth, as well as annual ELA and AAR values for a limited number of glaciers can be found in references [10, 15, 16, 18, 29]. According to these data, the analysis of the relations between ELA, AAR, annual mass balance of glaciers and its components was performed for use in the remote monitoring of glaciation. Appropriate sample included 45 to 66 glaciers located mainly in Eurasia, at mean weighted altitudes Zmed from 520 m to 4253 m above sea level. The existence of close and stable spatial relations AAR = f (Bn and AAR = f (ELA (see Table 1 allows, ultimately obtain local or regional estimates of glacier mass balance. In 1957, the area of the moraine on the glaciers of the Pamir was 320 km 2 , or 4.8% of the total area of glaciers in the region, and after ~ 20 years it has increased to 644 km2 or 10.7% [10]. In this paper we used photos of glaciers Medvezhiy and Bivachny in late August 2007 and 2012 from the ISS. Ground resolution is of 3–5 meters. Photos were transformed into WGS projection and tied to a topographic map 1:50 000. Altitudinal interval of moraines propagation on glaciers Medvezhiy and Bivachny in 2007–2012 was equal to, respectively: 3000–5000 and 3400–4800 m above sea level. It was revealed increase of total area of the moraine on these glaciers for the years 1975– 2007. Analysis of the content and quality of the main sources of global and regional information about modern glaciation of the Earth shows that without additional thematic processing they are not suitable for monitoring the dynamics of glaciers in the major river basins and use on a par with the existing data on precipitation, temperature, humidity, cloud cover and other climatic characteristics. Additional processing should be provided to exclude asynchronies in morphometric parameters. This will reduce errors in glaciological interpretation of satellite images and improve the quality of spatial

  2. A glaciological baseline for the upper Olivares basin, Chilean Central Andes

    Loriaux, T.; Bown, F.; Burger, F.; Cisternas, S.; Gacitúa, G.; Hernández, J.; Malmros, J.; Muñoz, C.; Oberreuter, J.; Rivera, A.; Silva, R.


    Santiago de Chile, with near 6.7 million of inhabitants, is located at the foot of the Andes, in the Maipo river basin, where there are approximately 424 km2 of ice, being the biggest glaciers, those located at the upper Olivares basin. Very little has been researched in recent years about the ongoing changes taking place in the area or about the glacier meltwater contribution or about the human impact on the glaciers. In order to tackle this deficiency, we began a research program in 2012, aiming to complete a glaciological baseline for this area, including glacier mass, energy and hydrological studies. For this purpose, we have established a detailed monitoring program on two glaciers where we installed 3 automatic weather stations, two arrays of stakes for mass balance studies, two automatic photographic cameras for monitoring albedo changes and two runoff stations, among several other instruments. Also, we have surveyed 5 glaciers with our airborne radar and lidar systems, allowing mapping their surface topographies at different seasons and the bedrocks underneath the ice. Analysis of satellite images shows generalized glacier area shrinkage, with a mean area lost of 25.5% since 1967 (total of 68.6 km2 in 1967 among 6 studied glaciers). The collected radar ice thickness data (maximum ice thickness of 223 m), allowed calculating a total volume of water equivalent of 3 km3 storage in 5 main glaciers of the basin. The GPS surveys of several stakes resulted in surface ice velocities between 1 and 5 m/yr. The mass balance studies showed high summer ablation rates, with an important role of sublimation, expressed as penitentes with heights of up to 1.5 m. Runoff contributed by Olivares Alfa glacier averaged 461 l/s between January and April 2013 with peaks of up to 2000 l/s, confirming the importance of glacier meltwater for the basin during summer months (January-March). The above numbers are some of the results obtained in the area, illustrating the importance of

  3. Alpine ice cores and ground penetrating radar: combined investigations for glaciological and climatic interpretations of a cold Alpine ice body

    Eisen, Olaf; Nixdorf, Uwe [Alfred-Wegener-Inst. fuer Polar- und Meeresforschung, Bremerhaven (Germany); Keck, Lothar; Wagenbach, Dietmar [Univ. Heidelberg (Germany). Inst. fuer Umweltphysik


    Accurate interpretation of ice cores as climate archives requires detailed knowledge of their past and present geophysical environment. Different techniques facilitate the determination and reconstruction of glaciological settings surrounding the drilling location. During the ALPCLIM1 project, two ice cores containing long-term climate information were retrieved from Colle Gnifetti, Swiss-Italian Alps. Here, we investigate the potential of ground penetrating radar (GPR) surveys, in conjunction with ice core data, to obtain information about the internal structure of the cold Alpine ice body to improve climatic interpretations. Three drill sites are connected by GPR profiles, running parallel and perpendicular to the flow line, thus yielding a three-dimensional picture of the subsurface and enabling the tracking of internal reflection horizons between the locations. As the observed reflections are of isochronic origin, they permit the transfer of age-depth relations between the ice cores. The accuracy of the GPR results is estimated by comparison of transferred timescales with original core datings, independent information from an older ice core, and, based on glaciological surface data, findings from flow modeling. Our study demonstrates that GPR is a mandatory tool for Alpine ice core studies, as it permits mapping of major transitions in physical-chemical properties, transfer of age-depth relations between sites, correlate signals in core records for interpretation, and establish a detailed picture of the flow regime surrounding the climate archive.

  4. Analysis of a website used to communicate glaciology by an academic (Invited)

    Davies, B. J.


    Research into polar science is driven by humanity's pressing concerns about environmental issues and climate change. The effective communication of this science is vital for it to realise its societal and political relevance. However, effective science communication has proved challenging for many reasons, including biased media presentation, lack of time and funds, lack of training, fear of attack by denialists, and poor career credit given for outreach and education work. A key question is how time-poor researchers, whilst working in full-time academic positions, can implement effective outreach strategies with little budget and few resources, that satisfies not only their personal desire to publicise and communicate their work, but also the demands of their research funder. Science websites and blogs offer one possibility, but there is little critical evaluation as to their effectiveness. The aim of this work is to evaluate a website and social medial tools written by an academic that was established to communicate peer-reviewed science. The goal of is to communicate key scientific concepts and to deliver new research findings via a professional, attractive, website and blog, supported by a strong social media presence. The objectives were to 1) to clearly explain and illustrate key concepts in glaciology as well as the latest developments in Antarctic research; 2) to be well aligned with national school curriculums, and to support school and university learning; 3) to include interactive features and social networking tools to encourage engagement and discourse; 4) to be aware of and well aligned with the website's intended audience. One year after website launch, the website was evaluated using a combination of an online feedback form, Google Analytics and analysis of Twitter followers. Our analysis shows that just one year after launch the website is a useful information resource, with some aspects that do challenge the knowledge

  5. Quaternary glaciation history and glaciology of Jakobshavn Isbræ and the Disko Bugt region,

    Bennike, Ole


    Full Text Available The Disko Bugt region in central West Greenland is characterised by permanent ice streams, of which Jakobshavn Isbræ is by far the most important. The first thorough studies on the glaciology of the region were conducted over 150 years ago by H.J. Rink, who introduced the terms ‘ice streams’ and ‘Inland Ice’. Rink’s work inspired new field work, which has continued to the present, and the long series of observations are unique for an Arctic region.Cooling during the Cenozoic led to ice-sheet growth in Greenland. A number of interglacial occurrences have been reported from the Disko Bugt region, and during the penultimate glacial stage, the Greenland ice-sheet margin extended to the shelf break. During the last glacial maximum, the ice margin probably extended only to the inner part of the banks on the continental shelf, and large floating glaciers may have been present at this time. During the Younger Dryas cold period, the ice margin may have been located at a marked basalt escarpment west of Disko Bugt.Disko Bugt was deglaciated rapidly in the early Holocene, around 10 500 – 10 000 years before present (10.5–10 ka B.P., but when the ice margin reached the eastern shore of the bay, recession paused, and major moraine systems were formed. With renewed recession, the present ice-margin position was attained around 8–6 ka B.P., and by c. 5 ka B.P. the ice margin was located east of its present position. The subsequent Neoglacial readvance generally reached a maximum during the Little Ice Age, around AD 1850. This was followed by recession that has continued to the present day.The relative sea-level history shows a rapid sea-level fall in the early Holocene, and a slow rise in the late Holocene. This development mainly reflects a direct isostatic response to the ice-margin history.Jakobshavn Isbræ is the main outlet from the Greenland ice sheet. It drains c. 6.5% of the present Inland Ice, and produces c. 35–50 km3 of icebergs

  6. Coastal-change and glaciological map of the Ronne Ice Shelf area, Antarctica, 1974-2002

    Ferrigno, Jane G.; Foley, K.M.; Swithinbank, C.; Williams, R.S.; Dalide, L.M.


    (MSS) images of Ant-arctica and the subsequent repeat coverage made possible with Landsat and other satellite images provided an excellent means of documenting changes in the coastline of Antarctica (Ferrigno and Gould, 1987). The availability of this information provided the impetus for carrying out a comprehensive analysis of the glaciological features of the coastal regions and changes in ice fronts of Antarctica (Swithinbank, 1988; Williams and Ferrigno, 1988). The project was later modified to include Landsat 4 and 5 MSS and Thematic Mapper (TM) (and in some areas Landsat 7 Enhanced Thematic Mapper Plus (ETM+)), RADARSAT images, and other data where available, to compare changes during a 20- to 25- or 30-year time interval (or longer where data were available, as in the Antarctic Peninsula). The results of the analysis are being used to produce a digital database and a series of USGS Geologic Investigations Series Maps (I-2600) consisting of 23 maps at 1:1,000,000 scale and 1 map at 1:5,000,000 scale, in both paper and digital format (Williams and others, 1995; Williams and Ferrigno, 1998; Ferrigno and others, 2002) (available online at

  7. Coastal-Change and Glaciological Map of the Larsen Ice Shelf Area, Antarctica, 1940-2005

    Ferrigno, Jane G.; Cook, Alison J.; Mathie, Amy M.; Williams, Richard S.; Swithinbank, Charles; Foley, Kevin M.; Fox, Adrian J.; Thomson, Janet W.; Sievers, Jorn


    comprehensive analysis of the glaciological features of the coastal regions and changes in ice fronts of Antarctica (Swithinbank, 1988; Williams and Ferrigno, 1988). The project was later modified to include Landsat 4 and 5 MSS and Thematic Mapper (TM) images [and in some areas Landsat 7 Enhanced Thematic Mapper Plus (ETM+) images], RADARSAT images, aerial photography, and other data where available, to compare changes that occurred during a 20- to 25- or 30-year time interval (or longer where data were available, as in the Antarctic Peninsula). The results of the analysis are being used to produce a digital database and a series of USGS Geologic Investigations Series Maps (I-2600) (Williams and others, 1995; Ferrigno and others, 2002; and Williams and Ferrigno, 2005) (available online at

  8. Coastal-Change and Glaciological Map of the Palmer Land Area, Antarctica: 1947-2009

    Ferrigno, Jane G.; Cook, Alison J.; Mathie, Amy M.; Williams, Richard S.; Swithinbank, Charles; Foley, Kevin M.; Fox, Adrian J.; Thomson, Janet W.; Sievers, Jorn


    out a comprehensive analysis of the glaciological features of the coastal regions and changes in ice fronts of Antarctica (Swithinbank, 1988; Williams and Ferrigno, 1988). The project was later modified to include Landsat 4 and 5 MSS and Thematic Mapper (TM) images (and in some areas Landsat 7 Enhanced Thematic Mapper Plus (ETM+) images), RADARSAT images, aerial photography, and other data where available, to compare changes that occurred during a 20- to 25- or 30-year time interval (or longer where data were available, as in the Antarctic Peninsula). The results of the analysis are being used to produce a digital database and a series of USGS Geologic Investigations Series Maps (I-2600) (Williams and others, 1995; Swithinbank and others, 2003a,b, 2004; Ferrigno and others, 2002, 2005, 2006, 2007, 2008, and in press; and Williams and Ferrigno, 2005) (available online at

  9. A preliminary application GIS in glaciological research along the traverse route from Zhongshan Station to Dome A, Antarctica

    温家洪; 孙波; 康建成; 李院生


    GIS is applied in glaciological research along the traverse route from Zhongshan Station to Dome A, one of the key routes in ITASE project, to display, process, manage and analyze the data obtained mainly by the 3rd Chinese Inland Expedition, together with Antarctic databases provided by ADD and BEDMAP project.The ways of ADD data merging and clipping, and coordinate projection transformation of field data and BEDMAP data are introduced.Elevation data derived by GPS navigator are corrected using ADD and ArcView's contour interpolation.Sub-ice topography and ice thickness along the route are extracted from BEDMAP database.Slope and aspect data are derived at each positioning station.GIS is a convenient and useful tool for us to record, query and display a variety of data in detail along the traverse route.

  10. Glaciological and geophysical investigations aimed at organization of a new airfield at the Station Mirny (East Antarctica

    S. V. Popov


    Full Text Available Main results of glaciological and geophysical engineering surveys, conducted during three summer field seasons of 2013– 2016 (59–61st Russian Antarctic Expeditions  – RAE near the Russian Station Mirny (East Antarctica, are discussed in the paper. Objective of these works was to site and then to organize a new airfield for landing of medium-range aircrafts with ski landing gears. Investigations included aerial photography, GPR surveys (georadar profiling, ice core drilling, and installation of landmarks to measure velocity of the glacier motion. The GSSI ground-penetrating radars with the main frequencies of 270 MHz and 900 MHz were used. In addition, special explorations were conducted for detecting the englacial crevasses by means of remote-sensing methods. The GPR data allowed a revealing the boundary between snow-andfirn thickness and atmospheric ice. In the course of processing of 252 travel-time curves of the diffracted waves a kinematic model of the sub-surface part of the glacier has been constructed. It was found that the dielectric permittivity of the snowfirn thickness averages 2.43; similar value for the atmospheric ice amounts to 3.0. The GPR data made it possible to determine intraglacial (englacial crevasses and to choose the most favorable field for the landing. On February 10, 2016, the first middle-range aircraft DC-3T (BT-67 had landed onto the new run-way near the station Mirny.

  11. Coastal-change and glaciological map of the Trinity Peninsula area and south Shetland Islands, Antarctica: 1843-2001: Chapter A in Coastal-change and glaciological maps of Antarctica

    Ferrigno, Jane G.; Cook, Alison J.; Foley, Kevin M.; Williams, Richard S.; Swithinbank, Charles; Fox, Adrian J.; Thomson, Janet W.; Sievers, Jorn


    Foundation's (1990) Division of Polar Programs. On the basis of these recommendations, the U.S. Geological Survey (USGS) decided that the archive of early 1970s Landsat 1, 2, and 3 Multispectral Scanner (MSS) images of Antarctica and the subsequent repeat coverage made possible with Landsat and other satellite images provided an excellent means of documenting changes in the coastline of Antarctica (Ferrigno and Gould, 1987). The availability of this information provided the impetus for carrying out a comprehensive analysis of the glaciological features of the coastal regions and changes in ice fronts of Antarctica (Swithinbank, 1988; Williams and Ferrigno, 1988). The project was later modified to include Landsat 4 and 5 MSS and Thematic Mapper (TM) [and in some areas Landsat 7 Enhanced Thematic Mapper Plus (ETM+)], RADARSAT images, and other data where available, to compare changes that occurred during a 20- to 25- or 30-year time interval (or longer where data were available, as in the Antarctic Peninsula). The results of the analysis are being used to produce a digital database and a series of USGS Geologic Investigations Series Maps (I–2600) consisting of 23 maps at 1:1,000,000 scale and 1 map at 1:5,000,000 scale, in both paper and digital format (Williams and others, 1995; Williams and Ferrigno, 1998; Ferrigno and others, 2002).

  12. Coastal-Change and Glaciological Map of the Northern Ross Ice Shelf Area, Antarctica: 1962-2004

    Ferrigno, Jane G.; Foley, Kevin M.; Swithinbank, Charles; Williams, Richard S.


    Programs. On the basis of these recommendations, the U.S. Geological Survey (USGS) decided that the archive of early 1970s Landsat 1, 2, and 3 Multispectral Scanner (MSS) images of Antarctica and the subsequent repeat coverage made possible with Landsat and other satellite images provided an excellent means of documenting changes in the coastline of Antarctica (Ferrigno and Gould, 1987). The availability of this information provided the impetus for carrying out a comprehensive analysis of the glaciological features of the coastal regions and changes in ice fronts of Antarctica (Swithinbank, 1988; Williams and Ferrigno, 1988). The project was later modified to include Landsat 4 and 5 MSS and Thematic Mapper (TM) images (and in some areas Landsat 7 Enhanced Thematic Mapper Plus [ETM+] images), RADARSAT images, and other data where available, in order to compare changes that occurred during a 20- to 25- or 30-year time interval (or longer where data were available, as in the Antarctic Peninsula). The results of the analysis are being used to produce a digital database and a series of USGS Geologic Investigations Series Maps (I?2600) (Williams and others, 1995; Williams and Ferrigno, 1998; Ferrigno and others, 2002) (available online at

  13. IGY to IPY, the U.S. Antarctic oversnow and airborne geophysical-glaciological research program from 1957 to 1964 from the view of a young graduate student

    Behrendt, John C.


    When 12 countries established scientific stations in Antarctica for the 1957-58 (IGY), the Cold War was at its height, seven countries had made claims in Antarctica, and the Antarctic Treaty was in the future. The only major field project of the U.S. IGY Antarctic program was series of oversnow traverses, starting in 1957, making seismic reflection ice soundings (and other geophysical measurements) and glaciological studies. The U.S.S.R. and France made similar traverses coordinated through the IGY. Although geology and topographic mapping were not part of the IGY program because of the claims issue and the possibility of mineral resources, the oversnow traverse parties did geologic work, during which unknown mountains were discovered. The oversnow traverses continued through 1966 and resulted in an excellent first approximation of the snow surface elevation, ice thickness and bed topography of Antarctica, as well as the mean annual temperature of that era and snow accumulation.

  14. Holocene glacier chronology of the Southern Alps/New Zealand - a critical re-assessment based on geomorphological and glaciological principles

    Winkler, Stefan


    first to be calibrated to modern standards (non-calibrated radiocarbon ages), these raw data has in general not been put into question and taken as presented. The geomorphological interpretation has, however, been carefully reviewed alongside all potential consequences for the subsequent relation to the underlying glacier dynamics. Different glacier response times have been considered as well as a more conservative approach to the precision and accuracy of certain dating methods. The latter was seen as more appropriate due to the highly dynamic geomorphological process-systems, strong neotectonic activity, and specific regional glaciological properties like for example frequent extensive supraglacial debris-covers complicating every chronological approach in the Southern Alps. The preliminary results of this critical re-assessment presented here reveal that too optimistic judgement of achieved accuracy lead to an overestimation of the true number of regional glacier advances during the Late Holocene. More conservative error margins and application of the neoglacial event concept instead of displaying 'glacier pulses' in form of advances at individual glaciers would create a better albeit less accurate correspondence between chronologies developed at different localities. This more critical evaluation would in the end be beneficial to any subsequent attempts of intra-hemispheric and global correlation of glacier chronologies.

  15. Review and Prospect on the Study of Antarctic Glaciology in China during the Last 10 Years%中国南极冰川学研究10 a回顾与展望

    秦大河; 任贾文; 康世昌


    The study of Antarctic glaciology in China is reviewed with the emphasis on the past decade. Much progress has been achieved in the physical characteristics of the Antarctic ice sheet and caps and in the study of climatic and environmental records in Antarctic snow and ice. Through observations of snow profiles of numerous snow-pits and shallow cores in the Wilkes Land and Lambert Glacier basin and along the route of the 1990 International Trans-Antarctica Science Expedition (ITASE), the regional features of snow deposition and densification in Antarctica were revealed. The Nelson Island ice cap in South Shetland Islands was investigated in detail that greatly enriched the knowledge of glaciers under a sub-Antarctic maritime climate. From the analyses of shallow ice cores and surface snow samples, in particular those taken along the ITASE route, the systematic data of stable isotopes, soluble impurities and heavy metal Pb in present precipitation in Antarctica has been obtained. Some suggestions are proposed through discussing the present hot points in the above fields.

  16. Glaciological Applications of Terrestrial Radar Interferometry

    Voytenko, D.; Dixon, T. H.


    Terrestrial Radar Interferometry (TRI) is a relatively new ground-based technique that combines the precision and spatial resolution of InSAR with the temporal resolution of GPS. Although TRI can be applied to a variety of fields including bridge and landslide monitoring, it is ideal for studies of the highly dynamic terminal zones of marine-terminating glaciers. Our TRI instrument is the Gamma Portable Radar Interferometer, which operates at 17.2 GHz (1.74 cm wavelength), has two receiving antennas for DEM generation, and generates amplitude and phase images at minute-scale sampling rates. Here we review preliminary results from Breiðamerkurjökull in Iceland and Helheim and Jakobshavn in Greenland. We show that the high sampling rate of the TRI can be used to observe velocity variations at the glacier terminus associated with calving, and the spatial distribution of tidal forcing. Velocity uncertainties, mainly due to atmospheric effects, are typically less than 0.05 m/d. Additionally, iceberg tracking using the amplitude imagery may provide insight into ocean currents near the terminus when fjord or lagoon conditions permit.

  17. Analysis of Control Sites: Limnology and Glaciology


    you for your cc:ments and cuestions concerning our draft report on "Analysis of Control Sites," a study performed for the Environmental Evaluation Work...seconcd cuestion , a =aired site azroach to water qualitv monitoring during a Demonstration progra w.ould have an efficiency for detecting ship-induce

  18. Glaciological parameters of disruptive event analysis

    Bull, C.


    The possibility of complete glaciation of the earth is small and probably need not be considered in the consequence analysis by the Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program. However, within a few thousand years an ice sheet may well cover proposed waste disposal sites in Michigan. Those in the Gulf Coast region and New Mexico are unlikely to be ice covered. The probability of ice cover at Hanford in the next million years is finite, perhaps about 0.5. Sea level will fluctuate as a result of climatic changes. As ice sheets grow, sea level will fall. Melting of ice sheets will be accompanied by a rise in sea level. Within the present interglacial period there is a definite chance that the West Antarctic ice sheet will melt. Ice sheets are agents of erosion, and some estimates of the amount of material they erode have been made. As an average over the area glaciated by late Quaternary ice sheets, only a few tens of meters of erosion is indicated. There were perhaps 3 meters of erosion per glaciation cycle. Under glacial conditions the surface boundary conditions for ground water recharge will be appreciably changed. In future glaciations melt-water rivers generally will follow pre-existing river courses. Some salt dome sites in the Gulf Coast region could be susceptible to changes in the course of the Mississippi River. The New Mexico site, which is on a high plateau, seems to be immune from this type of problem. The Hanford Site is only a few miles from the Columbia River, and in the future, lateral erosion by the Columbia River could cause changes in its course. A prudent assumption in the AEGIS study is that the present interglacial will continue for only a limited period and that subsequently an ice sheet will form over North America. Other factors being equal, it seems unwise to site a nuclear waste repository (even at great depth) in an area likely to be glaciated.

  19. The U.S. Antarctic Oversnow and Airborne Geophysical-Glaciological Research Program of the International Geophysical Year (IGY) 1957-58 Period from the View of a Research Scientist Participant

    Behrendt, J. C.


    When 12 countries established scientific stations in Antarctica for the 1957-58 International Geophysical Year (IGY), the Cold War was at its height, seven countries had made claims in Antarctica, and the Antarctic Treaty was a few years in the future. The U.S. program was operated by the Navy and territorial claims were secretly made at several locations during the IGY; these were never officially announced and the U.S. remains a non-claimant state. I was a graduate student geophysicist (assistant seismologist) on the unexplored Filchner-Ronne Ice Shelf as part of the only large scale field project of the U.S. program. Starting in 1956, the U.S. began a series of oversnow traverses making seismic reflection ice soundings (and other geophysical measurements) and glaciological studies to determine the thickness and budget of the Antarctic Ice Sheet. The USSR and France made similar traverses coordinated through the IGY. Although geology and topographic mapping were not part of the IGY program because of the claims issue, and the possibility of mineral resources discoveries, the oversnow traverse parties did geologic work where unknown mountains were discovered. The oversnow traverses continued through 1966, and resulted in an excellent first approximation of the snow surface elevation, ice thickness and bed topography of Antarctica, as well as mean annual temperature of that era and snow accumulation. The vacuum tube dictated the logistics of the oversnow traverse program. Seismic equipment including heavy batteries weighed about 500 kg. Therefore a Sno-Cat tracked vehicle was needed to carry this load. Usually three such vehicles were needed for safety. Because about 3-4 l/km of Sno-Cat fuel was consumed, as much as 120 kg/day of fuel was required. A resupply flight could only carry only about 600 kg/flight (varying greatly as to range and type of aircraft), the major air logistic program of the U.S. IGY program were the three oversnow traverses (other than the

  20. From IGY to IPY, the U.S. Antarctic Oversnow and Airborne Geophysical-Glaciological Research Program from 1957 to 1964 from the View of a Young Graduate Student

    Behrendt, J. C.


    When 12 countries established scientific stations in Antarctica for the 1957-58 International Geophysical Year (IGY), the Cold War was at its height, seven countries had made claims in Antarctica, and the Antarctic Treaty was a few years in the future. I was a graduate student assistant seismologist, on the unexplored Filchner- Ronne Ice Shelf as part of the only major field project of the U.S. Antarctic program. Starting in 1957, the U.S. began a series of oversnow traverses making seismic reflection ice soundings (and other geophysical measurements) and glaciological studies to determine the thickness and budget of the Antarctic Ice Sheet. The U.S.S.R. and France made similar traverses coordinated through the IGY. Although geology and topographic mapping were not part of the IGY program because of the claims issue and the possibility of mineral resources, the oversnow traverse parties did geologic work, where unknown mountains were discovered. The oversnow traverses continued through 1966 and resulted in an excellent first approximation of the snow surface elevation, ice thickness and bed topography of Antarctica, as well as the mean annual temperature of that era and snow accumulation. The vacuum tube dictated the logistics of the oversnow traverse program. Seismic equipment including heavy batteries weighed about 500 kg. Therefore a Sno-Cat tracked vehicle was needed to carry this load. Usually three such vehicles were needed for safety. Because about 3 l/km of fuel were consumed by each Sno-Cat, about 100 kg/day of fuel per vehicle was required. A resupply flight could carry only ~600 kg/flight (varying greatly as to range and type of aircraft).The Filchner Ice Shelf Traverse, 1957-58, in which I participated, encountered many crevasses. Vehicles broke through thin snow bridges and one man fell deep into a crevasse. Fortunately there were no deaths and only one serious injury resulting from crevasse accidents on the U.S. oversnow traverse program. Starting in

  1. On the morphological characteristics of overdeepenings in high-mountain glacier beds W. Haeberli1, A. Cochachin2, U.H. Fischer3, A. Linsbauer1, C. Salazar2 1Geography Department, University of Zurich, Switzerland 2Glaciology and Water Resources Unit, Huaraz, Peru 3Nagra, Wettingen, Switzerland

    Haeberli, W.; Cochachin, A.; Fischer, U. H.; Linsbauer, A.; Salazar Checa, C. J.


    Overdeepenings, i.e. closed topographic depressions with adverse slopes in the flow direction, are characteristic for glacier beds and glacially sculpted landscapes. Besides their importance as geomorphological landforms, groundwater bodies and sedimentary archives, they are of increasing interest in relation to climate-induced lake formation in de-glaciating landscapes and depth erosion under ice age conditions in connection with the long-term safety of radioactive waste repositories in some mid-latitude countries. Quantitative predictions of their shape, distribution and conditions of occurrence remain difficult. One major problem thereby relates to the still unsatisfactory treatment in glacier erosion theory of sediment evacuation at glacier beds, especially by subglacial meltwater. An alternative way of searching for realistic/empirical quantitative estimates is, therefore, to analyse the geometry of well-documented overdeepenings. The present study attempts to do this by combining statistical analyses of (a) detailed bathymetries from recently exposed lakes in the Peruvian Andes, (b) numerous bed overdeepenigs below still existing glaciers of the Swiss Alps modelled with a robust shear stress approximation linking surface slope to ice thickness at high resolution, and (c, for comparison) reconstructed overdeepenings produced by ice age glaciers in the Swiss Plateau. The sample of (a) has the advantage that geometries are exactly measured and are only subject to young/small sedimentation effects. Sample (b) allows for a comparison with a modern model calculation and with known glacier characteristics. Sample (c) may provide some insights into the question how safely results from high mountain topography can be transferred to sites with markedly different topographic, climatic and glaciological controls (cold-arid lowland). Where possible, mean and maximum values of the parameters surface area, length, width, depth, volume, adverse slope and their statistical

  2. The glaciology of IRD events: warming and ice dynamics

    Hindmarsh, R. C. A.


    Heinrich events, the enormous glacial-period ice-rafting episodeshave been posited to be due to large-scale surges of the Laurentide ice-sheet (3). However, more frequent events such as the Bond events are difficult to explain this way. Recently acquired geological evidence (2,4) suggests that climatic perturbations are correlated with some N. Atlantic IRD events. A model (1) which show how climate perturbations can lead to IRD events is reviewed. The model shows how 20-50km retreats induced by ablation rates of 2 m/yr provide sufficient debris flux through the grounding line to produce large sedimentation events. Such ablation would reduce ice-shelf extent markedly, permitting debris to reach the calving front and be transported by icebergs leading to ice-rafted debris (IRD) events. Surges are not necessary conditions for the production of large IRD events. The glacial dynamics of this climate perturbation model is compared with the surge theory, with particular emphasis on the amount of sediment that either method can deliver to the oceans. Consideration of the non-exclusivety and consistency of the two mechanisms is emphasised. (1) R.C.A. Hindmarsh and A. Jenkins, Centurial-millenial ice-rafted debris pulses from ablating marine ice sheets, Geophys Res. Lett 22(12), 2477-2480, 2001; (2) Paul C. Knutz et al. G3 Multidecadal ocean variability and NW European ice sheet surges during the last deglaciation G3 3(12) 17 December 2002 1077, doi:10.1029/2002GC000351; (3) MacAyeal,D.R. Binge/purge oscillations of the Laurentide ice-sheet as a cause of the North-Atlantic's Heinrich events, Paleoceanography, 8(6), p.775-784, (1993); (4) M. Moros, et. al. Were glacial iceberg surges in the North Atlantic triggered by climatic warming?, Marine Geology, 192(4), 2002, p.393-417

  3. Kinects as sensors in earth science: glaciological, geomorphological, and hydrological applications

    Mankoff, K. D.; Russo, T. A.; Norris, B. K.; Hossainzadeh, S.; Beem, L.; Walter, J. I.; Tulaczyk, S. M.


    The $150 Kinect (a video game input device used with the Microsoft Xbox system) can be used by earth scientists as a sensor. The device contains a visual wavelength camera, a depth-sensing camera, and three accelerometers. Because of the efforts of the hacking community it is now easy to communicate with a Kinect from a standard personal computer. We present initial results from two test sites: 1) On the surface of a glacier in Alaska where we tracked ice, water, and debris, and 2) From a lake and stream in New Jersey, where we evaluated device capabilities to image below the water surface in lentic and lotic environments.

  4. Morphological characteristics, formation and glaciological significance of Rogen moraine in northern Scotland

    Finlayson, Andrew G.; Bradwell, Tom


    Rogen moraine are enigmatic landforms whose exact origin is still debated. We use NEXTMap digital surface models and aerial photographs to map the distribution of previously unreported fields of Rogen moraine in the vicinity of Loch Shin, northern Scotland. Existing models of formation are tested against detailed morphological Rogen moraine characteristics obtained from the remote sensing data and field observations. Detailed morphometric analyses combined with their geographical setting lead us to postulate a likely mechanism of formation. Rogen moraine appear to have formed in areas where there were strong basal ice-flow velocity gradients. Thrusting by compression, or fracturing by extension of preexisting partially frozen sediment probably occurred in these areas, resulting in Rogen moraine formation. A general down-ice increase in ridge crest spacing suggests that the latter process may have been dominant, and is consistent with the location of Rogen moraine in the lee of topographic obstructions, in areas that experienced overall extensional ice flow. We also suggest that at least one field of Rogen moraine formed where lateral basal ice-flow velocity gradients were strongest — possibly in a subglacial shear margin setting. Given their location, the landforms may be consistent with formation during headward scavenging of the Moray Firth palaeo-ice stream into a shrinking core of cold-based ice.

  5. Glaciological and chemical studies on ice cores from Hans Tausen ice cap, Greenland

    Clausen, H.B.; Stampe, Mia; Hammer, C.U.


    The paper presents studies of various chemical and isotopical parameters from ice cores drilled in the northernmost located ice cap, Hans Tausen Iskappe, Pearyland, Greenland (HT). The 346 m main core (MC95) was drilled to bedrock in 1995 as well as a 35 m shallow core (SC95). A 60 m shallow core...... exist along the 1995 cores (MC95 and SC95) and finally detailed records of dust and water soluble ion concentrations exist on selected parts of MC95. To determine a time scale for the ice core is an important prerequisite for the interpretation of other records. The age scale is based on acid layers......, caused by known volcanic eruptions, and by comparison of the chemical composition of these layers to that found in ice cores from other arctic locations. The total b-activity data from SC75 and SC76 provide fixed points to the time scale because a pronounced increase in total b-activity is related...

  6. Optimisation of glaciological parameters for ice core chronology by implementing counted layers between identified depth levels

    Bazin, L.; Lemieux-Dudon, B.; Landais, A.; Guillevic, M.; Kindler, P.; Parrenin, F.; Martinerie, P.


    A~recent coherent chronology has been built for 4 Antarctic ice cores and the NorthGRIP (NGRIP) Greenland ice core (Antarctic Ice Core Chronology 2012, AICC2012) using a bayesian approach for ice core dating (Datice). When building the AICC2012 chronology, and in order to prevent any confusion with official ice cores chronology, it has been imposed that the AICC2012 chronology for NGRIP should respect exactly the GICC05 chronology based on layer counting. However, such a strong tuning did not satisfy the hypothesis of independence of background parameters and observations for the NGRIP core as required by Datice. We present here the implementation in Datice of a new type of markers that is better suited to constraints deduced from layer counting: the markers of age-difference. Using this type of markers for NGRIP in a 5 cores dating exercise with Datice, we have performed several sensitivity tests and show that the new ice core chronologies obtained with these new markers do not differ by more than 400 years from AICC2012 for Antarctic ice cores and by more than 130 years from GICC05 for NGRIP over the last 60 000 years. With this new parameterization, the accumulation rate and lock-in depth associated with NGRIP are more coherent with independent estimates than those obtained in AICC2012. While these new chronologies should not be used yet as new ice core chronologies, the improved methodology presented here should be considered in the next coherent ice core dating exercise.

  7. Bridging Glaciological and Hydrological Trends in the Pamir Mountains, Central Asia

    Malte Knoche; Ralf Merz; Martin Lindner; Stephan M. Weise


    With respect to meteorological changes and glacier evolution, the southern Pamir Mountains are a transition zone between the Pamirs, Hindu Kush and Karakoram, which are water towers of Central Asia...

  8. Model calibration for ice sheets and glaciers dynamics: a general theory of inverse problems in glaciology

    M. Giudici


    Full Text Available Numerical modelling of the dynamic evolution of ice sheets and glaciers requires the solution of discrete equations which are based on physical principles (e.g. conservation of mass, linear momentum and energy and phenomenological constitutive laws (e.g. Glen's and Fourier's laws. These equations must be accompanied by information on the forcing term and by initial and boundary conditions (IBCs on ice velocity, stress and temperature; on the other hand the constitutive laws involve many physical parameters, some of which depend on the ice thermodynamical state. The proper forecast of the dynamics of ice sheets and glaciers requires a precise knowledge of several quantities which appear in the IBCs, in the forcing terms and in the phenomenological laws. As these quantities cannot be easily measured at the study scale in the field, they are often obtained through model calibration by solving an inverse problem (IP. The objective of this paper is to provide a thorough and rigorous conceptual framework for IPs in cryospheric studies and in particular: to clarify the role of experimental and monitoring data to determine the calibration targets and the values of the parameters that can be considered to be fixed; to define and characterise identifiability, a property related to the solution to the forward problem; to study well-posedness in a correct way, without confusing instability with ill-conditioning or with the properties of the method applied to compute a solution; to cast sensitivity analysis in a general framework and to differentiate between the computation of local sensitivity indicators with a one-at-a-time approach and first-order sensitivity indicators that consider the whole possible variability of the model parameters. The conceptual framework and the relevant properties are illustrated by means of a simple numerical example of isothermal ice flow, based on the shallow-ice approximation.

  9. An optimized treatment for algorithmic differentiation of an important glaciological fixed-point problem

    Goldberg, Daniel N.; Krishna Narayanan, Sri Hari; Hascoet, Laurent; Utke, Jean


    We apply an optimized method to the adjoint generation of a time-evolving land ice model through algorithmic differentiation (AD). The optimization involves a special treatment of the fixed-point iteration required to solve the nonlinear stress balance, which differs from a straightforward application of AD software, and leads to smaller memory requirements and in some cases shorter computation times of the adjoint. The optimization is done via implementation of the algorithm of Christianson (1994) for reverse accumulation of fixed-point problems, with the AD tool OpenAD. For test problems, the optimized adjoint is shown to have far lower memory requirements, potentially enabling larger problem sizes on memory-limited machines. In the case of the land ice model, implementation of the algorithm allows further optimization by having the adjoint model solve a sequence of linear systems with identical (as opposed to varying) matrices, greatly improving performance. The methods introduced here will be of value to other efforts applying AD tools to ice models, particularly ones which solve a hybrid shallow ice/shallow shelf approximation to the Stokes equations.

  10. A dynamic and generic cloud computing model for glaciological image processing

    Ranisavljević, Élisabeth; Devin, Florent; Laffly, Dominique; Le Nir, Yannick


    As satellite imaging is quite expensive, and because of poor weather conditions including common heavy cloud cover at polar latitudes, daily satellite imaging is not always accessible or suitable to observe fast temporal evolutions. We complement satellite imagery with a set of ground based autonomous automated digital cameras which take three pictures a day. With these pictures we build a mosaic with their projection and apply a classification to define the temporal evolution of the snow cover. As the pictures are subject to heavy disturbance, some processing is needed to build the mosaic. Once the processes are defined, we present our model. This model is built upon a cloud computing environment using Web services workflow. Then we present how the processes are dynamically organized using a scheduler. This scheduler chooses the order and the processes to apply to every picture to build the mosaic. Once we obtain a mosaic we can study the variation of the snow cover.

  11. Glaciological and marine geological controls on terminus dynamics of Hubbard Glacier, southeast Alaska

    Stearns, Leigh A.; Hamilton, Gordon S.; van der Veen, C. J.; Finnegan, D. C.; O'Neel, Shad; Scheick, J. B.; Lawson, D. E.


    Hubbard Glacier, located in southeast Alaska, is the world's largest non-polar tidewater glacier. It has been steadily advancing since it was first mapped in 1895; occasionally, the advance creates an ice or sediment dam that blocks a tributary fjord (Russell Fiord). The sustained advance raises the probability of long-term closure in the near-future, which will strongly impact the ecosystem of Russell Fiord and the nearby community of Yakutat. Here, we examine a 43-year record of flow speeds and terminus position to understand the large-scale dynamics of Hubbard Glacier. Our long-term record shows that the rate of terminus advance has increased slightly since 1895, with the exception of a slowed advance between approximately 1972 and 1984. The short-lived closure events in 1986 and 2002 were not initiated by perturbations in ice velocity or environmental forcings, but were likely due to fluctuations in sedimentation patterns at the terminus. This study points to the significance of a coupled system where short-term velocity fluctuations and morainal shoal development control tidewater glacier terminus position.

  12. geoPebble: Combined Seismic, Acoustic, and GPS Sensor with Wireless Communications for Glaciological Applications

    Anandakrishnan, S.; Burkett, P. G.; Long, B.


    Glaciologist and geophysicists study many dynamic processes in glaciated environments such as sliding, crevasse formation, and water flow. These processes generate signals that can be interpreted for fundamental parameters needed for numerical models of glacier and ice sheet flow. These signals include microearthquakes beneath glaciers and ice streams during stick-slip processes; seismically identifiable harmonic tremors associated with subglacial water flow; supraglacial lake drainage which can produce rapid uplift of the 1 m/hr. In addition, researchers use active seismic experiments to determine bed properties such as roughness and lubrication. Currently, each process requires different instrumentation and/or different field equipment to collect the data such as a GPS receiver for displacement, a passive seismic instrument for microearthquakes, and a multichannel seismic recorder for active seismic experiments. We report on the development of an instrument specifically designed for observing dynamic glaciated environments in a single platform, reducing the need for multiple field systems and reducing the cost considerably. The geoPebble wireless seismic acquisition system, designed and built at the Pennsylvania State University, comprises 4 channels of 24-bit seismic and acoustic digitizing, an L1 GPS engine, onboard data storage and an 802.15 ZigBee radio. Three of the four ADC channels are intended to be used with a 3 component seismic sensor. The fourth channel is a dedicated to an audio frequency microphone. The 1 Hz L1 GPS system is capable of horizontal position accuracy to better than 10 cm when post-processed against L1/L2 stations within 10 km. Onboard storage is achieved with a Secure Digital card where volumes now exceed 32 GB. The ZigBee radio is capable of forming a mesh network which reduces transmit and receive power requirements while maintaing communication throughout the array and provides state-of-health information as well as sufficient data to determine proper functionality of the unit. This single platform is flexible enough to be used for deployments where sample rates are low (~500 Hz) but continuous data is required such as basal seismicity or stick-slip experiments, as well as active source experiments where sampling rates are higher (>10 Khz) but recording is triggered rather than continuous. In addition to being a single platform capable of high sample rate acquisition, as needed in active source experiments, this system has the advantage of being wireless, which makes deployment and configuration of the array much simpler. In either mode, the L1 GPS data are collected so that surveying the station location is not necessary. We report on the field testing of the instrument in Greenland where the data were compared to commercial instruments.

  13. Geodetic observations of ice flow velocities over the southern part of subglacial Lake Vostok, Antarctica, and their glaciological implications

    Wendt, Jens; Dietrich, Reinhard; Fritsche, Mathias; Wendt, Anja; Yuskevich, Alexander; Kokhanov, Andrey; Senatorov, Anton; Lukin, Valery; Shibuya, Kazuo; Doi, Koichiro


    In the austral summer seasons 2001/02 and 2002/03, Global Positioning System (GPS) data were collected in the vicinity of Vostok Station to determine ice flow velocities over Lake Vostok. Ten GPS sites are located within a radius of 30km around Vostok Station on floating ice as well as on grounded ice to the east and to the west of the lake. Additionally, a local deformation network around the ice core drilling site 5G-1 was installed. The derived ice flow velocity for Vostok Station is 2.00ma-1 +/- 0.01ma-1. Along the flowline of Vostok Station an extension rate of about 10-5a-1 (equivalent to 1cm km-1 a-1) was determined. This significant velocity gradient results in a new estimate of 28700 years for the transit time of an ice particle along the Vostok flowline from the bedrock ridge in the southwest of the lake to the eastern shoreline. With these lower velocities compared to earlier studies and, hence, larger transit times the basal accretion rate is estimated to be 4mma-1 along a portion of the Vostok flowline. An assessment of the local accretion rate at Vostok Station using the observed geodetic quantities yields an accretion rate in the same order of magnitude. Furthermore, the comparison of our geodetic observations with results inferred from ice-penetrating radar data indicates that the ice flow may not have changed significantly for several thousand years.

  14. Water isotope diffusion rates from the NorthGRIP ice core for the last 16,000 years - glaciological and paleoclimatic implications

    Gkinis, Vasileios; Buchardt, Susanne L; White, James W; Vinther, Bo M


    A high resolution (0.05 m) water isotopic record $\\delta^{18}\\mathrm{O}$ is available from the NorthGRIP ice core. In this study we look into the water isotope diffusion history as estimated by the spectral characteristics of the $\\delta^{18}\\mathrm{O}$ time series covering the last 16,000 years. Based on it we infer a temperature history signal for the site. We use a water isotope diffusion model coupled to a steady-state densification model in order to infer the temperature signal from the site, assuming the accumulation and strain rate history as estimated using the GICC05 layer counted chronology and a Dansgaard--Johnsen ice flow model. The necessary corrections regarding ice diffusion and the discretized sampling of the dataset are also described. The temperature reconstruction accurately captures the timing and magnitude of the B{\\o}lling--Aller{\\o}d and Younger Dryas transitions. A Holocene climatic optimum is seen between 7 and 9 ky b2k with an apparent cooling trend thereafter. Our temperature estima...

  15. Water isotope diffusion rates from the NorthGRIP ice core for the last 16,000 years – Glaciological and paleoclimatic implications

    Gkinis, V.; Simonsen, Sebastian Bjerregaard; Buchardt, S. L.


    millennial and centennial scales with a profound cooling occurring at approximately 4000 years b2k. The new reconstruction technique is able to provide past temperature estimates by overcoming the issues apparent in the use of the classical δ18Oslope method. It can at the same time resolve temperature...

  16. From enzymes and viruses to clouds, snow, sea-glaciers, and green icebergs: How a protein crystallographer got into glaciology and atmospheric radiation

    Warren, S. G.


    Through a series of lucky breaks beginning five years after my Ph.D., I was able to change careers from molecular biology to earth science, via a postdoc at NCAR in 1978, leading to a job at the University of Washington (UW) in 1982. Steve Schneider, Warren Wiscombe, Julius London, Gary Thomas, and Ed LaChapelle helped me make the transition. At UW, a collaboration with Tom Grenfell got me started in Antarctic fieldwork. Long-term dedicated coworkers Carole Hahn (cloud climatology) and Rich Brandt (radiative and thermal properties of snow and sea ice) kept our funded projects going. Conversations with UW colleagues Bob Charlson on dimethyl sulfide (DMS) and Qiang Fu on the microwave sounding unit (MSU) enticed me into unfunded projects (biological influence on cloud albedo; satellite-derived tropospheric temperatures). Several other key collaborators I first met when they were students at UW: Tony Clarke and Sarah Doherty (black carbon in snow), Bonnie Light (laboratory experiments for Snowball Earth), and Von Walden (longwave radiation spectra). Ian Allison of the Australian Antarctic Division sponsored my first sabbatical, to learn about sea ice. Most of our work, of course, is on projects that are proposed, then funded, then completed (or not completed). But at least as much fun are projects that were completed but not proposed. Some of these were inspired by listening to seminars (particularly by Charlson), or were developed from student term-papers in my snow-and-ice class (Jon Rhodes's report on suncups, and Steve Hudson's on Antarctic bacteria). There is not much cross-cultural connection between my former life and my current life, but there is some, now institutionalized in UW's Astrobiology Program. My enthusiasm for the CLAW project was partly motivated by my background in biology and the knowledge that DMS originates from the amino acid methionine. I was happy to accept oceanic biota as the explanation for the color of green icebergs. And my motivation for Snowball Earth research is its role in biological evolution: If the ocean froze all the way to the equator, where did surface life survive?

  17. Thin-layer effects in glaciological seismic amplitude-versus-angle (AVA analysis: implications for characterising a subglacial till unit, Russell Glacier, West Greenland

    A. D. Booth


    Full Text Available Seismic amplitude-versus-angle (AVA methods are a powerful means of quantifying the physical properties of subglacial material, but serious interpretative errors can arise when AVA is measured over a thinly-layered substrate. A substrate layer with a thickness less than 1/4 of the seismic wavelength, λ, is considered "thin", and reflections from its bounding interfaces superpose and appear in seismic data as a single reflection event. AVA interpretation of subglacial till can be vulnerable to such thin-layer effects, since a lodged (non-deforming till can be overlain by a thin (metre-scale cap of dilatant (deforming till. We assess the potential for misinterpretation by simulating seismic data for a stratified subglacial till unit, with an upper dilatant layer between 0.1–5.0 m thick (λ / 120 to > λ / 4, with λ = 12 m. For dilatant layers less than λ / 6 thick, conventional AVA analysis yields acoustic impedance and Poisson's ratio that indicate contradictory water saturation. A thin-layer interpretation strategy is proposed, that accurately characterises the model properties of the till unit. The method is applied to example seismic AVA data from Russell Glacier, West Greenland, in which characteristics of thin-layer responses are evident. A subglacial till deposit is interpreted, having lodged till (acoustic impedance = 4.26±0.59 × 106 kg m−2 s−1 underlying a water-saturated dilatant till layer (thickness < 2 m, Poisson's ratio ~ 0.5. Since thin-layer considerations offer a greater degree of complexity in an AVA interpretation, and potentially avoid misinterpretations, they are a valuable aspect of quantitative seismic analysis, particularly for characterising till units.

  18. Paleo-Climate and Glaciological Reconstruction in Central Asia through the Collection and Analysis of Ice Cores and Instrumental Data from the Tien Shan

    Vladimir Aizen; Donald Bren; Karl Kreutz; Cameron Wake


    While the majority of ice core investigations have been undertaken in the polar regions, a few ice cores recovered from carefully selected high altitude/mid-to-low latitude glaciers have also provided valuable records of climate variability in these regions. A regional array of high resolution, multi-parameter ice core records developed from temperate and tropical regions of the globe can be used to document regional climate and environmental change in the latitudes which are home to the vase majority of the Earth's human population. In addition, these records can be directly compared with ice core records available from the polar regions and can therefore expand our understanding of inter-hemispheric dynamics of past climate changes. The main objectives of our paleoclimate research in the Tien Shan mountains of middle Asia combine the development of detailed paleoenvironmental records via the physical and chemical analysis of ice cores with the analysis of modern meteorological and hydrological data. The first step in this research was the collection of ice cores from the accumulation zone of the Inylchek Glacier and the collection of meteorological data from a variety of stations throughout the Tien Shan. The research effort described in this report was part of a collaborative effort with the United State Geological Survey's (USGS) Global Environmental Research Program which began studying radionuclide deposition in mid-latitude glaciers in 1995.

  19. Water isotope diffusion rates from the NorthGRIP ice core for the last 16,000 years - Glaciological and paleoclimatic implications

    Gkinis, V.; Simonsen, S. B.; Buchardt, S. L.; White, J. W. C.; Vinther, B. M.


    A high resolution (0.05 m) water isotopic record (δO18) is available from the NorthGRIP ice core. In this study we look into the water isotope diffusion history as estimated by the spectral characteristics of the δO18 time series covering the last 16,000 years. The diffusion of water vapor in the porous medium of the firn pack attenuates the initial isotopic signal, predominantly having an impact on the high frequency components of the power spectrum. Higher temperatures induce higher rates of smoothing and thus the signal can be used as a firn paleothermometer. We use a water isotope diffusion model coupled to a steady-state densification model in order to infer the temperature signal from the site, assuming the accumulation and strain rate history as estimated using the GICC05 layer counted chronology and a Dansgaard-Johnsen ice flow model. The temperature reconstruction accurately captures the timing and magnitude of the Bølling-Allerød and Younger Dryas transitions. A Holocene climatic optimum is seen between 7 and 9 ky b2k with an apparent cooling trend thereafter. Our temperature estimate for the Holocene climatic optimum, points to a necessary adjustment of the ice thinning function indicating that the ice flow model overestimates past accumulation rates by about 10% at 8 ky b2k. This result, is supported by recent gas isotopic fractionation studies proposing a similar reduction for glacial conditions. Finally, the record presents a climatic variability over the Holocene spanning millennial and centennial scales with a profound cooling occurring at approximately 4000 years b2k. The new reconstruction technique is able to provide past temperature estimates by overcoming the issues apparent in the use of the classical δO18 slope method. It can at the same time resolve temperature signals at low and high frequencies.

  20. Dynamically coupling the non-linear Stokes equations with the Shallow Ice Approximation in glaciology: Description and first applications of the ISCAL method

    Ahlkrona, Josefin; Kirchner, Nina; Zwinger, Thomas


    We propose and implement a new method, called the Ice Sheet Coupled Approximation Levels (ISCAL) method, for simulation of ice sheet flow in large domains under long time-intervals. The method couples the exact, full Stokes (FS) equations with the Shallow Ice Approximation (SIA). The part of the domain where SIA is applied is determined automatically and dynamically based on estimates of the modeling error. For a three dimensional model problem where the number of degrees of freedom is comparable to a real world application, ISCAL performs almost an order of magnitude faster with a low reduction in accuracy compared to a monolithic FS. Furthermore, ISCAL is shown to be able to detect rapid dynamic changes in the flow. Three different error estimations are applied and compared. Finally, ISCAL is applied to the Greenland Ice Sheet, proving ISCAL to be a potential valuable tool for the ice sheet modeling community.

  1. Calibrating a glaciological model of the Greenland ice sheet from the Last Glacial Maximum to present-day using field observations of relative sea level and ice extent

    Simpson, Matthew J. R.; Milne, Glenn A.; Huybrechts, Philippe; Long, Antony J.


    We constrain a three-dimensional thermomechanical model of Greenland ice sheet (GrIS) evolution from the Last Glacial Maximum (LGM, 21 ka BP) to the present-day using, primarily, observations of relative sea level (RSL) as well as field data on past ice extent. Our new model (Huy2) fits a majority of the observations and is characterised by a number of key features: (i) the ice sheet had an excess volume (relative to present) of 4.1 m ice-equivalent sea level at the LGM, which increased to reach a maximum value of 4.6 m at 16.5 ka BP; (ii) retreat from the continental shelf was not continuous around the entire margin, as there was a Younger Dryas readvance in some areas. The final episode of marine retreat was rapid and relatively late (c. 12 ka BP), leaving the ice sheet land based by 10 ka BP; (iii) in response to the Holocene Thermal Maximum (HTM) the ice margin retreated behind its present-day position by up to 80 km in the southwest, 20 km in the south and 80 km in a small area of the northeast. As a result of this retreat the modelled ice sheet reaches a minimum extent between 5 and 4 ka BP, which corresponds to a deficit volume (relative to present) of 0.17 m ice-equivalent sea level. Our results suggest that remaining discrepancies between the model and the observations are likely associated with non-Greenland ice load, differences between modelled and observed present-day ice elevation around the margin, lateral variations in Earth structure and/or the pattern of ice margin retreat.

  2. Dynamically coupling the non-linear Stokes equations with the shallow ice approximation in glaciology: Description and first applications of the ISCAL method

    Ahlkrona, Josefin; Lötstedt, Per; Kirchner, Nina; Zwinger, Thomas


    We propose and implement a new method, called the Ice Sheet Coupled Approximation Levels (ISCAL) method, for simulation of ice sheet flow in large domains during long time-intervals. The method couples the full Stokes (FS) equations with the Shallow Ice Approximation (SIA). The part of the domain where SIA is applied is determined automatically and dynamically based on estimates of the modeling error. For a three dimensional model problem, ISCAL computes the solution substantially faster with a low reduction in accuracy compared to a monolithic FS. Furthermore, ISCAL is shown to be able to detect rapid dynamic changes in the flow. Three different error estimations are applied and compared. Finally, ISCAL is applied to the Greenland Ice Sheet on a quasi-uniform grid, proving ISCAL to be a potential valuable tool for the ice sheet modeling community.

  3. Modeling the runoff regime of the glacierised upper Aconcagua River Basin using a physically-based distributed hydrological model: the value of short term glaciological observations

    Ragettli, S.; Pellicciotti, F.; Molnar, D.; Rimkus, S.; Helbing, J.; Escobar, F.; Burlando, P.


    In the Central Andes of Chile the interactions between snow, glaciers and water resources are governed by a distinct climatological forcing. Summers are dry and stable, with precipitation close to zero, low relative humidity and intense solar radiation. During the summer months, water originates almost exclusively from snow and ice melt. Evidence of glaciers retreat and changes in the seasonal snow cover suggests that climate change might have an impact on the water resources in the area. We use the physically-based, spatially-distributed hydrological model TOPKAPI to study the processes governing the exchange between the climate, snow and ice in the upper Aconcagua River Basin. The model incorporates the melting of snow and ice based on a simplified energy-balance approach (ETI model) and the routing of melt water through the glacial system. The model has numerous empirical parameters used in the computation of the single components of the hydrological cycle, the determination of which might lead to problems of equifinality. To address this issue we set up a rigorous calibration procedure that allows calibration of the main model parameters in three different steps by separating parameters governing distinct processes. We evaluate the parameters’ transferability in time and investigate the differences in model parameters and performance that result from applying the model at different spatial scales. The model ability to simulate the relevant processes is tested against a data set of meteorological data, measurements of surface ablation and glacier runoff at the snout of the Juncal Norte Glacier during two ablation seasons. Modeled snow height is compared to snow maps derived from terrestrial photos and MODIS images. Results show that the magnitude of snow and icemelt rates on the glacier tongue is correctly reproduced, but simulations at higher elevation have a larger uncertainty. Crucial factors affecting model performance are the model ability to simulate the redistribution of the winter snow cover due to wind and gravity, the correct modeling of the temperature fields; and the model ability to reproduce the melt onset. The model was found to be most sensitive to the parameters governing snow and glacier processes, and in particular the parameters governing the extrapolation of air temperature from point measurements to the glacier and basin wide scale. The parameters of the ETI melt model are transferable from one season to the other, despite important differences in terms of meteorological and surface conditions. The parameters governing the extrapolation of the meteorological input data and the routing of glacier melt water, on the contrary, need recalibration.

  4. Advancing Glaciological Applications of Remote Sensing with EO-1: (1) Mapping Snow Grain Size and Albedo on the Greenland Ice Sheet Using an Imaging Spectrometer, and (2) ALI Evaluation for Subtle Surface Topographic Mapping via Shape-from Shading


    The Hyperion sensor, onboard NASA's Earth Observing-1 (EO-1) satellite,is an imaging spectroradiometer with 220 spectral bands over the spectral range from 0.4 - 2.5 microns. Over the course of summer 2001, the instrument acquired numerous images over the Greenland ice sheet. Our main motivation is to develop an accurate and robust approach for measuring the broadband albedo of snow from satellites. Satellite-derived estimates of broadband have typically been plagued with three problems: errors resulting from inaccurate atmospheric correction, particularly in the visible wavelengths from the conversion of reflectance to albedo (accounting for snow BRDE); and errors resulting from regression-based approaches used to convert narrowband albedo to broadband albedo. A typerspectral method has been developed that substantially reduces these three main sources of error and produces highly accurate estimates of snow albedo. This technique uses hyperspectral data from 0.98 - 1.06 microns, spanning a spectral absorption feature centered at 1.03 microns. A key aspect of this work is that this spectral range is within an atmospheric transmission window and reflectances are largely unaffected by atmospheric aerosols, water vapor, or ozone. In this investigation, we make broadband albedo measurements at four sites on the Greenland ice sheet: Summit, a high altitude station in central Greenland; the ETH/CU camp, a camp on the equilibrium line in western Greenland; Crawford Point, a site located between Summit and the ETH/CU camp; and Tunu, a site located in northeastern Greenland at 2000 m. altitude. Each of these sites has an automated weather station (AWS) that continually measures broadband albedo thereby providing validation data.

  5. Terrain Analysis Procedural Guide for Soil. Report Number 6 in the ETL Series on Guides for Army Terrain Analysts


    gabbro porphyry, gabbro , pyroxenite porphyry, pyroxenite, periodotite. 554.~.4 I_ TAL 2---- (CNINE) LADOM AN COMMONL ASSCITE SOILS...Archives and Records Service Washington, D.C. 20A08 Telephone: (202) 523-3062 U.S. GEOLOGICAL SURVEY Glaciologic World Data Center - A: Glaciology NtData...Scientific Pub. Co., Amsterdam, New York, 1 76. Eyre, S., Vegetation and Soils, A World Picture, Aldine Publishing Co., Chicago, IL, 1963. Food and Agriculture

  6. New advances in the study of Alpine glaciations

    ShangZhe Zhou


    The European Alps is the birthplace of glaciology and in particular Quaternary glaciology and for over one hundred years has been a model region for studying mountain glaciations. In this paper, we review the achievements from this region, which will benefit glaciological studies of the Tibetan Plateau, China. According to new evidences of glaciofluvial de-posits discovered in valleys and forelands of the Alps, researchers have progressed from an original four Pleistocene gla-ciations to seven glaciations:Biber, Donua, Günz, Haslach, Mindel, Riss and Würm. The earliest one Biber possibly oc-curred between the Pliocene and Pleistocene, but the chronology before Riss is still in doubt. Recent years, Riss and Würm glaciations have been supported by a large numbers of cosmogenic exposure dating. In particular, cosmogenic nuclide exposure dating has been carried out for different moraine boulders in numerous valleys, which reveals a series of climatic change events, and they are comparable to post-glacial age records of northern Europe. The advancement of glaciological studies in the Alps is important in promoting glaciological research in the Tibetan Plateau.

  7. Firn Model Intercomparison Experiment (FirnMICE)

    Lundin, Jessica M.D.; Stevens, C. Max; Arthern, Robert


    Evolution of cold dry snow and firn plays important roles in glaciology; however, the physical formulation of a densification law is still an active research topic. We forced eight firn-densification models and one seasonal-snow model in six different experiments by imposing step changes in tempe......Evolution of cold dry snow and firn plays important roles in glaciology; however, the physical formulation of a densification law is still an active research topic. We forced eight firn-densification models and one seasonal-snow model in six different experiments by imposing step changes...

  8. The Statistical Physics of Iceberg Calving and the Emergence of Universal Calving Laws

    Bassis, J. N.


    Determining a calving law valid for all glaciological regimes has proven to be a difficult problem in glaciology. For this reason, most models of the calving process are semi-empirical, with little connection to the underlying fracture processes. In this study, I introduce methods rooted in statistical physics to show how calving laws, valid for any glaciological domain, can emerge naturally as a large spatial-scale/long temporal-scale limit of an underlying continuous or discrete fracture process. An important element of the method developed here is that iceberg calving is treated as a stochastic process and that the probability that an iceberg will detach in a given interval of time can be described by a probability distribution function. Using limiting assumptions about the underlying probability distribution, the theory is shown to be able to simulate a range of calving styles including the sporadic detachment of large, tabular icebergs from ice tongues and ice shelves and the more steady detachment of smaller sized bergs from tidewater/outlet glaciers. The method developed has the potential to provide a physical basis to include iceberg calving into numerical ice sheet models that can be used to produce more realistic estimates of the glaciological contribution to sea level rise.

  9. Profile of Chief Editor of Sciences in Cold and Arid Regions


    @@ 1.Biographical information GuoDong Cheng, born on 11 July, 1943, in Shanghai, China, received his Bachelor of Science in 1965, from the Department of Hydrogeology and Engineering Geology at Beijing Geology College (now China University of Geosciences).In the same year, he started his research career at the Lanzhou Institute of Glaciology, Geocryology, and Desert Research, Chinese Academy of Sciences (CAS).

  10. Recommended Books


    Book 1: (Editor-in-Chief: Shi Yafeng; Published by Elsevier and Science Press Beijing in 2008, 539 pages) Glaciers and Related Environments in China Since the professional institution for glaciology attached to the Chinese Academy of Sciences was established in 1958, studies of glaciers in alpine regions, and of Quaternary glaciations throughout

  11. CUDA GPU based full-Stokes finite difference modelling of glaciers

    Brædstrup, Christian; Egholm, D.L.

    pre- form well in glaciological flow probems. The Gauss-Seidel iterator is known to be robust but several other linear solvers have a much faster convergence. To aid convergence, the solver uses a multigrid approach where values are interpolated and extrapolated between different grid resolutions...

  12. A decade of ERS satellite orbits and altimetry

    Scharroo, R.


    The First European Remote Sensing Satellite, ERS-1, was launched in July 1991, fol- lowed by ERS-2 in April 1995. Both satellites carry a radar altimeter to serve oper- ational applications and scientific research in the fields of geodesy, oceanography, glaciology and meteorology. Together, the sate

  13. The thickness of glaciers

    Faraoni, Valerio; Vokey, Marshall W.


    Basic formulae and results of glacier physics appearing in glaciology textbooks can be derived from first principles introduced in algebra-based first year physics courses. We discuss the maximum thickness of alpine glaciers and ice sheets and the relation between maximum thickness and length of an ice sheet. Knowledge of ordinary differential equations allows one to derive also the local ice thickness.

  14. Glaciers and Climate Change

    Oerlemans, J.


    Although my book focuses on valley glaciers, it is not intended to provide a basic course in glaciology, nor does it claim to give a state-of-the-art picture of glacier research. It consists mainly of the personal reflections of a meteorologist who gradually became interested in glaciers and is writ

  15. A model of the Antarctic Ice Sheet

    Oerlemans, J.


    Numerical modelling of ice sheets and glaciers has become a useful tool in glaciological research. A model described here deals with the vertical mean ice velocity, is time dependent, computes bedrock adjustment and uses an empirical diagnostic relationship to derive the distribution of ice thicknes

  16. Elevation Change Measurements of the Greenland Ice Sheet

    Forsberg, R.; Keller, K.; Nielsen, C. S.


    Repeated GPS measurements have been performed at the centre of the Greenland Ice Sheet since 1992. Results have shown that the ice sheet is essentially stable at this location, with GPS-determined strain and elevation change rates in good accordance with yearly snow accumulation and glaciological...

  17. Beyond the Classroom: Finding the First Cornerstone

    Garran, Daniella K.


    What could two dozen middle school students, two teachers, land surveyors, journalists, divers, college professors, lawyers, archaeologists, an author, and an 85-year old retiree possibly have in common? The answer is their insatiable quest to redefine colonial American history. From geodesy to glaciology, from geology to hydrology, from…

  18. Mass balance of the Amitsulôg ice cap, West Greenland

    Ahlstrøm, Andreas P.; Bøggild, Carl Egede; Olesen, Ole B.


    Includes bibliographical references and index Proceedings of a workshop on Andean Glaciology and a symposium on the Contribution from Glaciers and Snow Cover to Runoff from Mountains in Different Climates held during the 7th Scientific Assembly of the International Association of Hydrological...

  19. 15 CFR 950.5 - National Geophysical and Solar-Terrestrial Data Center (NGSDC).


    ... COMMERCE GENERAL REGULATIONS OF THE ENVIRONMENTAL DATA SERVICE ENVIRONMENTAL DATA AND INFORMATION § 950.5...-A (Solid-Earth Geophysics, Solar Terrestrial Physics, and Glaciology). (a) Geophysical and solar... geological data, including data on heat flow, cores, samples, and sediments. (2) Solar-Terrestrial physics...

  20. Mass balance of the Amitsulôg ice cap, West Greenland

    Ahlstrøm, Andreas P.; Bøggild, Carl Egede; Olesen, Ole B.


    Includes bibliographical references and index Proceedings of a workshop on Andean Glaciology and a symposium on the Contribution from Glaciers and Snow Cover to Runoff from Mountains in Different Climates held during the 7th Scientific Assembly of the International Association of Hydrological Sci...

  1. Supporting Ice Seismology

    Parker, T.; Beaudoin, B. C.; Fowler, J. C.


    Climate change research, and glaciology in particular, has increasingly embraced seismology in recent years. The NSF supported IRIS/PASSCAL Instrument Center is working with researchers to develop the unique instruments and techniques for collecting data in this challenging environment. Global concern with sea level change along with strategic interests of the US government and other nations is driving a large investment in glaciological climate research. A number of groups have demonstrated new seismologically-derived constraints on glaciological conditions and processes. Environmental challenges include remote and precarious locations, necessitating robust yet quickly deployable seismic stations and long periods of autonomous operation. Temperature extremes and the possibility of immersion from large annual snow loads, resulting in a deployment surface that can vary from 50 feet of snow cover to bare ice with large melt pools in a single season are additional major challenges. There is also an urgency created by studies indicating that the high latitude continental ice sheets are metastable and that behavior is changing now. Scientists are presently commonly utilizing adaptations of available instrumentation designed for low latitude and milder field conditions as appropriate, but seek better, more capable, and more flexible solutions, including integration of environmental sensors and real-time data telemetry and station control as some of these experiments evolve into a monitoring effort. Seismic instrumentation is only produced by a small number of companies and, innovation for new instruments takes time and requires substantial investment. While pursuing longer-term innovation funding strategies, we are also adapting current instrumentation paradigms to glaciological use (e.g., by leveraging the cold instrument development for research in Antarctica during the IPY). We are also encouraging industrial partners to respond to these demands and challenges with

  2. Informal STEM Education in Antarctica

    Chell, K.


    Tourism in Antarctica has increased dramatically with tens of thousands of tourists visiting the White Continent each year. Tourism cruises to Antarctica offer a unique educational experience for lay people through informal science-technology-engineering-mathematics (STEM) education. Passengers attend numerous scientific lectures that cover topics such as the geology of Antarctica, plate tectonics, glaciology, and climate change. Furthermore, tourists experience the geology and glaciology first hand during shore excursions. Currently, the grand challenges facing our global society are closely connected to the Earth sciences. Issues such as energy, climate change, water security, and natural hazards, are consistently on the legislative docket of policymakers around the world. However, the majority of the world’s population is uninformed about the role Earth sciences play in their everyday lives. Tourism in Antarctica provides opportunities for informal STEM learning and, as a result, tourists leave with a better understanding and greater appreciation for both Antarctica and Earth sciences.

  3. Adjoint accuracy for the full-Stokes ice flow model: limits to the transmission of basal friction variability to the surface

    Martin, Nathan


    This work focuses on the numerical assessment of the accuracy of an adjoint-based gradient in the perspective of variational data assimilation and parameter identification in glaciology. Using noisy synthetic data, we quantify the ability to identify the friction coefficient for such methods with a non-linear friction law. The exact adjoint problem is solved, based on second order numerical schemes, and a comparison with the so called "self-adjoint" approximation, neglecting the viscosity dependency to the velocity (leading to an incorrect gradient), common in glaciology, is carried out. For data with a noise of $1\\%$, a lower bound of identifiable wavelengths of $10$ ice thicknesses in the friction coefficient is established, when using the exact adjoint method, while the "self-adjoint" method is limited, even for lower noise, to a minimum of $20$ ice thicknesses wavelengths. The second order exact gradient method therefore provides robustness and reliability for the parameter identification process. In othe...

  4. Altitudinal Levels and Altitudinal Limits in High Mountains

    Matthias Kuhle


    In lowlands climate-specific processes due to weathering and erosion are dominant, whilst the geomorphology of mountains is dependent on the geologic-tectonic structure, i.e., the energy of erosion that increases according to the vertical. The expression "extremely high mountains" has been established as the extreme of a continuous mountain classification. It has to be understood in terms of geomorphology, glaciology and vegetation.Correspondence of the planetary and hypsometric change of forms is of great value as synthetic explanation. It is confirmed with regard to vegetation,periglacial geomorphology and glaciology. Due to the world-wide reconstruction of the snowline its paleoclimatic importance increases, too. Apart from lower limits the periglacial and glacial altitudinal levels also show zones of optimum development and climatic upper limits in the highest mountains of the earth. According to the proportion of the altitudinal levels a classification as to arid, temperate and humid high mountains has been carried out.

  5. Firn Model Intercomparison Experiment (FirnMICE)

    Lundin, Jessica M.D.; Stevens, C. Max; Arthern, Robert


    Evolution of cold dry snow and firn plays important roles in glaciology; however, the physical formulation of a densification law is still an active research topic. We forced eight firn-densification models and one seasonal-snow model in six different experiments by imposing step changes in tempe......Evolution of cold dry snow and firn plays important roles in glaciology; however, the physical formulation of a densification law is still an active research topic. We forced eight firn-densification models and one seasonal-snow model in six different experiments by imposing step changes...... rate and temperature. Firn Model Intercomparison Experiment can provide a benchmark of results for future models, provide a basis to quantify model uncertainties and guide future directions of firn-densification modeling....

  6. Estimating the avalanche contribution to the mass balance of debris covered glaciers

    A. Banerjee


    Full Text Available Avalanche from high head walls dominates the net accumulation in many debris covered glaciers in the Himalaya. These avalanche contributions are difficult to directly measure and may cause a systematic bias in glaciological mass balance measurements. In this paper we develop a method to estimate the avalanche contribution using available data, within the context of an idealised flowline model of the glacier. We focus on Hamtah glacier in Western Himalaya and estimate the magnitude of the avalanche accumulation to its specific mass balance profile. Our estimate explains the reported discrepancy between values of recent glaciological and geodetic net mass balance for this glacier. Model estimate of accumulation area ratio (AAR for this glacier is small (0.1 even at a steady state. This shows that empirical mass balance–AAR relationships derived from glaciers which do not have a significant avalanche contribution will not apply to a large region containing a significant fraction avalanche fed ones.

  7. Rock avalanches on glaciers

    Shugar, Daniel


    This thesis examines relations between rock avalanches and the glaciers on which they are deposited. I have attempted to understand a geophysical phenomenon from two viewpoints: sedimentology and glaciology. The contributions are both methodological, and practical. I have used a GIS to quantify debris sheet geomorphology. A thorough characterization of rock avalanche debris is a necessary step in understanding the flow mechanics of large landslide. I have also developed a technique for solvin...


    T. M. Manevich


    Full Text Available The paper presents main glaciological characteristics of present-day glaciers located on the Koryaksky volcano. The results of fieldwork (2008–2009 and high-resolution satellite image analysis let us to specify and complete information on modern glacial complex of Koryaksky volcano. Now there are seven glaciers with total area 8.36 km2. Three of them advance, two are in stationary state and one degrades. Moreover, the paper describes the new crater glacier.

  9. The Antartic Ice Borehole Probe

    Behar, A.; Carsey, F.; Lane, A.; Engelhardt, H.


    The Antartic Ice Borehole Probe mission is a glaciological investigation, scheduled for November 2000-2001, that will place a probe in a hot-water drilled hole in the West Antartic ice sheet. The objectives of the probe are to observe ice-bed interactions with a downward looking camera, and ice inclusions and structure, including hypothesized ice accretion, with a side-looking camera.

  10. Deriving glacier surface velocities from repeat optical images

    Heid, Torborg


    The velocity of glaciers is important for many aspects in glaciology. Mass accumulated in the accumulation area is transported down to the ablation area by deformation and sliding due to the gravitational force, and hence gla­cier velocity is connected to the mass balance of glaciers. It also contributes directly to the mass balance of calving glaciers because it is an important control of the ice discharge rate for such glaciers. Changing glacier velocities is an indicator of instable glacie...

  11. Revealing glacier flow and surge dynamics from animated satellite image sequences: examples from the Karakoram

    Paul, F


    Although animated images are very popular on the internet, they have so far found only limited use for glaciological applications. With long time series of satellite images becoming increasingly available and glaciers being well recognized for their rapid changes and variable flow dynamics, animated sequences of multiple satellite images reveal glacier dynamics in a time-lapse mode, making the otherwise slow changes of glacier movement visible and understandable to the wider...

  12. Georadar technique application to the civil engineering; Aplicacion de la tecnica georradar a la ingenieria civil

    Jimenez Sanchez, J.; Diaz Medina, F. J.


    The georadar technique or GPR (Ground Penetrating Radar) has been gone developing and employing since fifties in superficial investigations of high resolution of the underground or of certain subjects in Geology, Mining and Glaciology. From seventies, this technic begins to appear in the environment of the Civil Engineering. This method, not destructive reproduces in a better way the possible problems to resolve, even the first 40 m-50 m of depth, that any another geophysical technique. (Author)

  13. Airborne Geophysics and Remote Sensing Applied to Study Greenland Ice Dynamics

    Csatho, Beata M.


    Overview of project: we combined and jointly analysed geophysical, remote sensing and glaciological data for investigating the temporal changes in ice flow and the role of geologic control on glacial drainage. The project included two different studies, the investigation of recent changes of the Kangerlussuaq glacier and the study of geologic control of ice flow in NW Greenland, around the Humboldt, Petermann and Ryder glaciers.

  14. Supraglacial dust and debris characterization via in situ and optical remote sensing methods

    Casey, Kimberly Ann


    Supraglacial dust and debris affects many glaciologic variables, including radiative absorption, ablation, generation of supraglacial melt as well as mass flux. Earth observing satellite technology has advanced greatly in recent decades and allows for unprecedented spatial, temporal and spectral imaging of Earth’s glaciers. While remote sensing of ‘clean’ glacier ice can be done quite successfully, strategies for satellite mapping of supraglacial debris remain in development. This work provid...

  15. Surface elevation change and mass balance of Icelandic ice caps derived from swath mode CryoSat-2 altimetry

    Foresta, L.; Gourmelen, N.; Pálsson, F.; Nienow, P.; Björnsson, H.; Shepherd, A.


    We apply swath processing to CryoSat-2 interferometric mode data acquired over the Icelandic ice caps to generate maps of rates of surface elevation change at 0.5 km postings. This high-resolution mapping reveals complex surface elevation changes in the region, related to climate, ice dynamics, and subglacial geothermal and magmatic processes. We estimate rates of volume and mass change independently for the six major Icelandic ice caps, 90% of Iceland's permanent ice cover, for five glaciological years between October 2010 and September 2015. Annual mass balance is highly variable; during the 2014/2015 glaciological year, the Vatnajökull ice cap ( 70% of the glaciated area) experienced positive mass balance for the first time since 1992/1993. Our results indicate that between glaciological years 2010/2011and 2014/2015 Icelandic ice caps have lost 5.8 ± 0.7 Gt a-1 on average, 40% less than the preceding 15 years, contributing 0.016 ± 0.002 mm a-1 to sea level rise.

  16. Comparison of Satellite-Derived with Ground-Based Measurements of the Fluctuations of the Margins of Vatnajokull, Iceland 1973-1992

    Williams, Richard S., Jr.; Hall, Dorothy K.; Sigurdsson, Oddur; Chien, Janet Y. L.


    Vatnajokull, Iceland, is the Earth's most studied ice cap and represents a classical glaciological field site on the basis of S. Palsson's seminal glaciological field research in the late 18th century. Since the 19th century, Vatnajokull has been the focus of an array of glaciological studies by scientists from many nations, including many remote-sensing investigations since 1951. Landsat-derived positions of the termini of 11 outlet glaciers of Vatnajokull were compared with frontal positions of six of these 11 outlet glaciers determined by field observations during the period 1973-92. The largest changes during the 19 year period (1973-92) occurred in the large lobate, surge-type outlet glaciers along the southwestern, western, and northern margins of Vatnajokull, Tungnaarjokull receded - 1413 +/- 112 m (1380 +/- 1 m from ground observations), and Bruarjokull receded -1975 +/- 191 m (-2096 +/- 5 m from extrapolated ground observations) between 1973 and 1992. Satellite images can be used to delineate glacier margin changes on a time-lapse basis, if the glacier margin can be spectrally discriminated from terminal moraines and sandur deposits and if the advance/recession is larger than maximum image pixel size. "Local knowledge" of glaciers is critically important, however, in the accurate delineation of glacier margins on Landsat images.

  17. Comparison of satellite-derived with ground-based measurements of the fluctuations of the margins of Vatnajokull, Iceland, 1973-92

    Williams, R.S.; Hall, D.K.; Sigurbsson, O.; Chien, J.Y.L.


    Vatnajo??kull, Iceland, is the Earth's most studied ice cap and represents a classical glaciological field site on the basis of S. Pa??lsson's seminal glaciological field research in the late 18th century. Since the 19th century, Vatnajo??kull has been the focus of an array of glaciological studies by scientists from many nations, including many remotesensing investigations since 1951. Landsat-derived positions of the termini of 11 outlet glaciers of Vatnajo??kull were compared with frontal positions of six of these 11 outlet glaciers determined by field observations during the period 1973-92. The largest changes during the 19 year period (1973-92) occurred in the large lobate, surge-type outlet glaciers along the southwestern, western, and northern margins of Vatnajo??kull. Tungnaa??rjo??kull receded - 1413 ?? 112 m (-1380 ?? l m from ground observations), and Bru??arjo??kull receded -1975 ?? 191 m (-2096 ?? 5 m from extrapolated ground observations) between 1973 and 1992. Satellite images can be used to delineate glacier margin changes on a time-lapse basis, if the glacier margin can be spectrally discriminated from terminal moraines and sandur deposits and if the advance/recession is larger than maximum image pixel size. "Local knowledge" of glaciers is critically important, however, in the accurate delineation of glacier margins on Landsat images.



    The aim of the international project “Global Land Ice Measurements from Space (GLIMS)" headed by the US Geological Survey is to establish a world wide glacier inventory based on satellite imagery.This data set will form a first digital baseline study for future glacier monitoring.The presented GIS_based glacier inventory for King George Island is a case study for the area of the Antarctic Peninsula.In the database of the glacier inventory topographic information,specific glaciological parameters as well as metadata will be included.The topographic data consists of drainage basin limits,basin areas,altitudinal ranges,perimeters and mean lengths.Glaciological data sets should comprise information on glacier retreat in different periods,glacier velocities,ice thickness and bedrock topography as well as derived parameters.Modelled and measured mass balance parameters could be included as additional data layers.In particular,these metadata records must comprise background information on data accuracy and data sources and should be compatible with a future data model for the King George Island GIS (KGIS).Three examples illustrate that the GLIMS database will not only contain information valuable for glaciological applications,but also other environmental studies on the island will benefit from this standardised remote sensing data sets.Therefore,a very close link between the data models of KGIS and GLIMS has to be established to enable these synergisms.Finally,better access to historic aerial photography would enable a continuous record of glacier retreat from the beginning of the 1950's onward.

  19. Early Miocene basement clasts in ANDRILL AND-2A core and their implications for paleoenvironmental changes in the McMurdo Sound region (western Ross Sea, Antarctica)

    Talarico, Franco M.; Sandroni, Sonia


    A detailed provenance study of gravel-size clasts in the lowermost 438 m of the ANDRILL AND-2A core reveals a pattern of dynamic provenance variations which can be discussed for its implications for Early Miocene paleogeographical reconstructions and glaciological models in the McMurdo Sound region (Ross Sea). Clast distribution patterns and distribution of diagnostic basement clast assemblages indicative of three different provenance areas (Mulock-Skelton glacier, Carlyon-Darwin glacier and Koettlitz-Blue glacier regions) can be interpreted in terms of two distinctive ice dynamic scenarios: i) local fluctuations of outlet Transantarctic Mountains glaciers with dominant flows from W to E to the coast (documented in the lowermost core section, at ca. 20.2-20.1 Ma), and ii) larger volume of ice grounded at the regional scale in the Ross Embayment with flow lines running N-S close to the TAM front (in two periods, at ca. 19.7-19.7 Ma and at ca. 17.8-17.4 Ma). Moreover, in core sections including facies typical of open-marine to iceberg-influenced depositional environments, ice-rafted debris compositions reveal that during periods of glacial-minima setting sites of active calving processes dominantly occurred in areas including the present-day Blue-Koettlitz glacier coast, and subordinately in glacier tongues located further south in the Skelton-Mulock glacier area. Consistently with results of numerical modelling the reconstructed glaciological scenarios provide further constraints to paleogeographical reconstructions and glaciological models at the south-western tip of the Ross Sea during significant steps in Antarctic ice sheet evolution through the Early Miocene climatic events.

  20. Local glaciers and the marginal sector of the Inland Ice with respect to utilization of hydropower in basins near urban areas. Location and ice cover. [Greenland

    Weidick, A.; Hoejmark Thomsen, H.


    A review is made of glaciers connected with a research programme for hydropower potential connected to Greenland towns. The inventory covers the basins with varying ice cover consisting of 257 local glaciers and 29 lobes from the Inland Ice. Location; exposition, size, altitude and description of type and morphology are given in tabular form for the individual glaciers. To ensure homogeneity and clearness, the descriptions are given in code, and the meaning of the individual values are listed. For each basin an outline of morphology and geology connected to the former and present glaciation is given and the source material (topographical, geological and glaciological maps, aerial photo routes) is listed. The general description of the basins also contains reviews of the character of the ice cover, occurrence of glacier hazards (avalanches, rockfalls, ice-dammed lakes) and documented glacier changes in the basins or in the neighbouring areas. Glaciation limit and snow line are only described within the restrictions of the available maps and aerial photos. An update review of measurements of mass balance is made. Such measurements are performed in four basins covered by the project (Taseq, Buksefjord, Qapiarfiup sermia and Jakobshavn) and in a regional context these measurements can be supplemented with mass measurements on four other glaciers namely Johan Dahl Land , Qamanarssup sermia and Tasersiaq. The optimal utilization of the present glaciological information is primarily restricted by the lack of detailed maps of the selected basins. Also the quality of a regional glaciological evaluation of glacier runoff in the individual basins is dependent on the length of time for which the mass balance measurements have been made in the selected areas. Measurements for glaciers in the basins will cover at the most three years at the end of the 1982/83 season.

  1. Making geodetic glacier mass balances available to the community - Progress and challenges in modifying the WGMS database

    Machguth, Horst; Landmann, Johannes; Zemp, Michael; Paul, Frank


    The recent years have seen a sharp increase in the publication of geodetically derived glacier mass balances. Internationally coordinated glacier monitoring, however, has so far focused mainly on direct glaciological mass balance measurements. There is thus a need to collect geodetic glacier mass balance data in a standardized format and make the data available to the scientific community. This would allow easy access and data use for, e.g., assessment of regional to global scale glacier changes, re-analysis of glaciological mass balance series, evaluation of and comparison to, other data or model results. It appears logical to build such a data archive where glaciological data are already routinely collected. In the framework of the ESA project Glaciers_cci, the World Glacier Monitoring Service (WGMS) has started an initiative to establish the expertise, the strategy and the infrastructure to make the increasing amount of geodetic glacier mass balance available to the scientific community. The focus is (i) on geodetic (glacier wide) changes as obtained from differencing digital elevation models from two epochs, and (ii) on point elevation change from altimetry. Here we outline the chosen strategy to include gridded data of surface elevation change into the WGMS database. We describe the basic strategy using the netCDF4 data format, summarize the data handling as well as the standardization and discuss major challenges in efficient inclusion of geodetic glacier changes into the WGMS database. Finally, we discuss the potential use of the data and thereby highlight how the added geodetic data influence the calculation of regional to global averages of glacier mass balance.

  2. A Multifrequency Radiometer System

    Skou, Niels


    A radiometer system having four channels: 5 GHz, l7 GHz, 34 GHz, all vertical polarization, and a 34 GHz sky horn, will be described. The system which is designed for collecting glaciological and oceanographic data is intended for airborne use and imaging is achieved by means of a multifrequency ...... elaborate processing later, using ground facilities. In conjunction with a side looking radar which is under development at present, the radiometers are intended as the remote sensing basis for an all-weather ice reconnaissance service in the Greenland seas....

  3. GPR and GPS data integration: examples of application in Antarctica

    S. Gandolfi


    Full Text Available Ground Penetrating Radar (GPR and Global Positioning System (GPS techniques were employed in snow accumulation studies during the Italian leg of the International Trans-Antarctic Scientific Expedition (ITASE. The acquired data were useful both for glaciological and climatological studies. This paper presents some results obtained by GPR and GPS data integration employed to determine accumulation/ablation processes along the profile of the traverse that show how the snow-sublayer thickness can vary quickly in just a few kilometres. Some examples of data integration employed in detection and characterisation of buried crevasses are also presented.

  4. Profile of Chief Editor of Sciences in Cold and Arid Regions


    @@ 1. Biographical information GuoDong Cheng, born on 11 July, 1943, in Shanghai, China, received his Bachelor of Science in 1965, from the Department of Hydrogeology and Engineering Geology at Beijing Geology College (now China University of Gensciences). In the same year, he started his research career at the Lanzbou Institute of Glaciology, Geocryology, and Desert Research, Chinese Academy of Sciences (CAS). Over the past 45 years, Professor Cheng has published more than 200 papers in peer-reviewed professional journals and books.

  5. Brief Communication: 2014 velocity and flux for five major Greenland outlet glaciers using ImGRAFT and Landsat-8

    A. Messerli


    Full Text Available This study presents average velocity fields, mass flux estimates and central flowline profiles for five major Greenland outlet glaciers; Jakobshavn Isbræ, Nioghalvfjerdsbræ, Kangerdlugssuaq, Helheim and Petermann glaciers, spanning the period (August 2013–(September 2014. The results are produced by the feature tracking toolbox, ImGRAFT using Landsat-8, panchromatic data. The resulting velocity fields agree with the findings of existing studies. Furthermore, our results show an unprecedented speed of over 50 m day−1 at Jakobshavn Isbræ as it continues to retreat. All the processed data will be freely available for download at

  6. The forgotten component of sub-glacial heat flow: Upper crustal heat production and resultant total heat flux on the Antarctic Peninsula

    Burton-Johnson, Alex; Halpin, Jacqueline; Whittaker, Joanne; Watson, Sally


    Seismic and magnetic geophysical methods have both been employed to produce estimates of heat flux beneath the Antarctic ice sheet. However, both methods use a homogeneous upper crustal model despite the variable concentration of heat producing elements within its composite lithologies. Using geological and geochemical datasets from the Antarctic Peninsula we have developed a new methodology for incorporating upper crustal heat production in heat flux models and have shown the greater variability this introduces in to estimates of crustal heat flux, with implications for glaciological modelling.

  7. GPR and GPS data integration. Examples of application in Antarctica

    Urbini, S. [Genoa Univ., Genoa (Italy). Istituto Nazionale di Geofisica e Vulcanologia, Dipartimento per lo studio del Territorio e delle sue Risorse


    Ground Penetrating Radar (GPR) and Global Positioning System (GPS) techniques were employed in snow accumulation studies during the Italian leg of the International Trans-Antarctic Scientific Expedition (ITASE). The acquired data were useful both for glaciological and climatological studies. This paper presents some results obtained by GPR and GPS data integration employed to determine accumulation/ablation processes along the profile of the traverse that show how the snow-sublayer thickness can vary quickly in just a few kilometres. Some examples of data integration employed in detection and characterisation of buried crevasses are also presented.

  8. Radio-frequency Attenuation Length, Basal-Reflectivity, Depth, and Polarization Measurements from Moore's Bay in the Ross Ice-Shelf

    Barwick, S W; Besson, D; Duffin, T; Hanson, J C; Klein, S R; Kleinfelder, S A; Reed, C; Roumi, M; Stezelberger, T; Tatar, J; Walker, J; Zou, L


    Radio-glaciological parameters from Moore's Bay, in the Ross Ice Shelf, have been measured. The thickness of the ice shelf in Moore's Bay was measured from reflection times of radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean. The average depth obtained is $576\\pm8$ m. The temperature-averaged attenuation length of the ice column, $\\langle L \\rangle$, is derived from the returned power assuming 100\\% reflection. A linear fit to the data yields $\\langle L(\

  9. Application and validation of long-range terrestrial laser scanning to monitor the mass balance of very small glaciers in the Swiss Alps

    Fischer, Mauro; Huss, Matthias; Kummert, Mario; Hoelzle, Martin


    Due to the relative lack of empirical field data, the response of very small glaciers (here defined as being smaller than 0.5 km2) to current atmospheric warming is not fully understood yet. Investigating their mass balance, e.g. using the direct glaciological method, is a prerequisite to fill this knowledge gap. Terrestrial laser scanning (TLS) techniques operating in the near infrared range can be applied for the creation of repeated high-resolution digital elevation models and consecutive derivation of annual geodetic mass balances of very small glaciers. This method is promising, as laborious and potentially dangerous field measurements as well as the inter- and extrapolation of point measurements can be circumvented. However, it still needs to be validated. Here, we present TLS-derived annual surface elevation and geodetic mass changes for five very small glaciers in Switzerland (Glacier de Prapio, Glacier du Sex Rouge, St. Annafirn, Schwarzbachfirn, and Pizolgletscher) and two consecutive years (2013/14-2014/15). The scans were acquired with a long-range Riegl -6000 especially designed for surveying snow- and ice-covered terrain. Zonally variable conversion factors for firn and bare ice surfaces were applied to convert geodetic volume to mass changes. We compare the geodetic results to direct glaciological mass balance measurements coinciding with the TLS surveys and assess the uncertainties and errors included in both methods. Average glacier-wide mass balances were negative in both years, showing stronger mass losses in 2014/15 (-1.65 m w.e.) compared to 2013/14 (-0.59 m w.e.). Geodetic mass balances were slightly less negative but in close agreement with the direct glaciological ones (R2 = 0.91). Due to the dense in situ measurements, the uncertainties in the direct glaciological mass balances were small compared to the majority of measured glaciers worldwide (±0.09 m w.e. yr-1 on average), and similar to uncertainties in the TLS-derived geodetic mass

  10. Runoff, precipitation, mass balance, and ice velocity measurements at South Cascade Glacier, Washington, 1993 balance year

    Krimmel, R.M.


    Winter snow accumulation and summer snow, firn, and ice ablation were measured at South Cascade Glacier, Wash., to determine the winter and net balance for the 1993 balance year. The 1993 winter balance, averaged over the glacier, was 1.98 meters, and the net balance was -1.23 meters. This negative valance continued a trend of negative balance years beginning in 1977. Air temperature, barometric pressure, and runoff from this glacier basin and an adjacent non-glacierized basin were also continuously measured. Surface ice velocity was measured over an annual period. This report makes all these data available to users throughout the glaciological and climato1ogical community.

  11. Direction-of-Arrival Estimation for Radar Ice Sounding Surface Clutter Suppression

    Nielsen, Ulrik; Dall, Jørgen


    Ice sounding radars are able to measure ice sheets by profiling their glaciological features from the surface to the bedrock. The current airborne and, in particular, future space-based systems are suffering from off-nadir surface clutter, which can mask the depth signal of interest. The most...... estimation for surface clutter signals, which includes a formulation of the mathematical foundation of spatial aliasing. DOA estimation is applied to data acquired with the P-band POLarimetric Airborne Radar Ice Sounder at the Jutulstraumen Glacier, Antarctica. The effects of spatial aliasing related...

  12. Comparison of a UAV-derived point-cloud to Lidar data at Haig Glacier, Alberta, Canada

    Bash, E. A.; Moorman, B.; Montaghi, A.; Menounos, B.; Marshall, S. J.


    The use of unmanned aerial vehicles (UAVs) is expanding rapidly in glaciological research as a result of technological improvements that make UAVs a cost-effective solution for collecting high resolution datasets with relative ease. The cost and difficult access traditionally associated with performing fieldwork in glacial environments makes UAVs a particularly attractive tool. In the small, but growing, body of literature using UAVs in glaciology the accuracy of UAV data is tested through the comparison of a UAV-derived DEM to measured control points. A field campaign combining simultaneous lidar and UAV flights over Haig Glacier in April 2015, provided the unique opportunity to directly compare UAV data to lidar. The UAV was a six-propeller Mikrokopter carrying a Panasonic Lumix DMC-GF1 camera with a 12 Megapixel Live MOS sensor and Lumix G 20 mm lens flown at a height of 90 m, resulting in sub-centimetre ground resolution per image pixel. Lidar data collection took place April 20, while UAV flights were conducted April 20-21. A set of 65 control points were laid out and surveyed on the glacier surface on April 19 and 21 using a RTK GPS with a vertical uncertainty of 5 cm. A direct comparison of lidar points to these control points revealed a 9 cm offset between the control points and the lidar points on average, but the difference changed distinctly from points collected on April 19 versus those collected April 21 (7 cm and 12 cm). Agisoft Photoscan was used to create a point-cloud from imagery collected with the UAV and CloudCompare was used to calculate the difference between this and the lidar point cloud, revealing an average difference of less than 17 cm. This field campaign also highlighted some of the benefits and drawbacks of using a rotary UAV for glaciological research. The vertical takeoff and landing capabilities, combined with quick responsiveness and higher carrying capacity, make the rotary vehicle favourable for high-resolution photos when

  13. Drifting snow and its sublimation in turbulent boundary layer

    Li, Guang; Huang, Ning; Wang, Zhengshi


    Drifting snow is a special process of mass-energy transport in hydrological cycle especially in alpine region. It can not only change the snow distribution, but also result in phase change of ice crystal into water vapour, which is so called drifting snow sublimation. Thus drifting snow is of glaciological and hydrological importance in cold regions. In this paper, recent research on drifting snow and its sublimation is reviewed, and some new progresses by our research team in Lanzhou University are also introduced.

  14. Multispectral imaging contributions to global land ice measurements from space

    Kargel, J.S.; Abrams, M.J.; Bishop, M.P.; Bush, A.; Hamilton, G.; Jiskoot, H.; Kääb, Andreas; Kieffer, H.H.; Lee, E.M.; Paul, F.; Rau, F.; Raup, B.; Shroder, J.F.; Soltesz, D.; Stainforth, D.; Stearns, L.; Wessels, R.


    Global Land Ice Measurements from Space (GLIMS) is an international consortium established to acquire satellite images of the world's glaciers, analyse them for glacier extent and changes, and assess change data for causes and implications for people and the environment. Although GLIMS is making use of multiple remote-sensing systems, ASTER (Advanced Spaceborne Thermal Emission and reflection Radiometer) is optimized for many needed observations, including mapping of glacier boundaries and material facies, and tracking of surface dynamics, such as flow vector fields and supraglacial lake development. Software development by GLIMS is geared toward mapping clean-ice and debris-covered glaciers; terrain classification emphasizing snow, ice, water, and admixtures of ice with rock debris; multitemporal change analysis; visualization of images and derived data; and interpretation and archiving of derived data. A global glacier database has been designed at the National Snow and Ice Data Center (NSIDC, Boulder, Colorado); parameters are compatible with and expanded from those of the World Glacier Inventory (WGI). These technology efforts are summarized here, but will be presented in detail elsewhere. Our presentation here pertains to one broad question: How can ASTER and other satellite multispectral data be used to map, monitor, and characterize the state and dynamics of glaciers and to understand their responses to 20th and 21st century climate change? Our sampled results are not yet glaciologically or climatically representative. Our early results, while indicating complexity, are generally consistent with the glaciology community's conclusion that climate change is spurring glacier responses around the world (mainly retreat). Whether individual glaciers are advancing or retreating, the aggregate average of glacier change must be climatic in origin, as nonclimatic variations average out. We have discerned regional spatial patterns in glaciological response behavior

  15. Journey to the centre of the ice: narrating ice-core drillings in northern Greenland

    Hvenegård-Lassen, Kirsten


    to the Eemian period. This time travel ultimately aims at predicting the climate of the future. While the heroic polar expeditions of the past ventured into unknown spaces horizontally, the secrets of the frontier are now vertically stored in the ice cores. In Secrets of the Ice, five videos produced for public...... dissemination, Greenland is displayed as an empty, frozen space, waiting to be conquered by scientists. Resonating with classical Arctic explorer myths, this conquest has to overcome the difficulties presented by a harsh wilderness landscape. The article situates the glaciological project in Greenland within...

  16. Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978-1987

    Korsgaard, Niels J.; Nuth, Christopher; Khan, Shfaqat Abbas


    Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling...... and a 2 m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision...

  17. Geostatistical approaches to interpolation and classification of remote-sensing data from ice surfaces

    Herzfeld, Ute Christina; Mayer, Helmut; Higginson, Chris A.; Matassa, Michael


    Geostatistical methods for interpolation and extrapolation techniques are used in glaciological data analysis. The results of a program involving the mapping of the Antarctica from satellite radar altimeter data are discussed. A combination of high and low resolution techniques was applied in the analysis of the Bering Glacier (Alaska). The global positioning system (GPS) located video data collected from small aircraft and the ERS-1 synthetic aperture radar (SAR) images were used. From the perspective of SAR data analysis, the Bering Glacier surge was the opportunity to characterize the surface of fast flowing ice and the rapid changes in the surface roughness.

  18. Modern Radar Techniques for Geophysical Applications: Two Examples

    Arokiasamy, B. J.; Bianchi, C.; Sciacca, U.; Tutone, G.; Zirizzotti, A.; Zuccheretti, E.


    The last decade of the evolution of radar was heavily influenced by the rapid increase in the information processing capabilities. Advances in solid state radio HF devices, digital technology, computing architectures and software offered the designers to develop very efficient radars. In designing modern radars the emphasis goes towards the simplification of the system hardware, reduction of overall power, which is compensated by coding and real time signal processing techniques. Radars are commonly employed in geophysical radio soundings like probing the ionosphere; stratosphere-mesosphere measurement, weather forecast, GPR and radio-glaciology etc. In the laboratorio di Geofisica Ambientale of the Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy, we developed two pulse compression radars. The first is a HF radar called AIS-INGV; Advanced Ionospheric Sounder designed both for the purpose of research and for routine service of the HF radio wave propagation forecast. The second is a VHF radar called GLACIORADAR, which will be substituting the high power envelope radar used by the Italian Glaciological group. This will be employed in studying the sub glacial structures of Antarctica, giving information about layering, the bed rock and sub glacial lakes if present. These are low power radars, which heavily rely on advanced hardware and powerful real time signal processing. Additional information is included in the original extended abstract.

  19. Spatial and temporal variability of snow accumulation in Dronning Maud Land, East Antarctica, including two deep ice coring sites at Dome Fuji and EPICA DML

    S. Fujita


    Full Text Available To better understand the spatio-temporal variability of the glaciological environment in Dronning Maud Land (DML, East Antarctica, investigations were carried out along the 2800-km-long Japanese-Swedish IPY 2007/2008 traverse. The route covers ice sheet ridges and two deep ice coring sites at Dome Fuji and EPICA DML. The surface mass balance (SMB distribution was derived based on analysis of isochrones within snow pits, firn cores and subsurface radar signals. The SMB averaged over various time scales in the Holocene was determined. This was then compared with various glaciological data. We find that the large-scale distribution of the SMB depends on the surface elevation, continentality and interactions between ice sheet ridges and the prevailing counterclockwise windfield in DML. A different SMB is found for the windward and leeward sides of the ridges. Local-scale variability in the SMB is essentially governed by bedrock topography which determines the local surface topography. In the eastern part of DML, the accumulation rate in the second half of the 20th century is found to be higher by 15 % compared to averages over longer periods of 722 a or 7.9 ka before AD 2008. A similar trend has been reported for many inland plateau sites in East Antarctica.

  20. Explicit Numerical Modeling of Heat Transfer in Glacial Channels

    Jarosch, A. H.; Zwinger, T.


    Turbulent flow and heat transfer of water in englacial channels is explicitly modelelled and the numerical results are compared to the most commonly used heat transfer parameterization in glaciology, i.e. the Dittus-Boelter equation. The three-dimensional flow is simulated by solving the incompressible Navier-Stokes equations utilizing a variational multiscale method (VMS) turbulence model and the finite-element method (i.e. Elmer-FEM software), which also solves the heat equation. By studying a wide range of key parameters of the system, e.g. channel diameter, Reynolds number, water flux, water temperature and Darcy-Weisbach wall roughness (which is explicitly represented on the wall geometry), it is found that the Dittus-Boelter equation is inadequate for glaciological applications and a new, highly suitable heat transfer parameterization for englacial/subglacial channels will be presented. This new parameterization utilizes a standard combination of dimensionless numbers describing the flow and channel (i.e. Reynolds number, Prandtl number and Darcy-Weisbach roughness) to predict a suitable Nusselt number describing the effective heat transfer and thus can be readily used in existing englacial/subglacial hydrology models.

  1. Recent changes in area and thickness of Torngat Mountain glaciers (northern Labrador, Canada)

    Barrand, Nicholas E.; Way, Robert G.; Bell, Trevor; Sharp, Martin J.


    The Torngat Mountains National Park, northern Labrador, Canada, contains more than 120 small glaciers: the only remaining glaciers in continental northeast North America. These small cirque glaciers exist in a unique topo-climatic setting, experiencing temperate maritime summer conditions yet very cold and dry winters, and may provide insights into the deglaciation dynamics of similar small glaciers in temperate mountain settings. Due to their size and remote location, very little information exists regarding the health of these glaciers. Just a single study has been published on the contemporary glaciology of the Torngat Mountains, focusing on net mass balances from 1981 to 1984. This paper addresses the extent to which glaciologically relevant climate variables have changed in northern Labrador in concert with 20th-century Arctic warming, and how these changes have affected Torngat Mountain glaciers. Field surveys and remote-sensing analyses were used to measure regional glacier area loss of 27 % from 1950 to 2005, substantial rates of ice surface thinning (up to 6 m yr-1) and volume losses at Abraham, Hidden, and Minaret glaciers, between 2005 and 2011. Glacier mass balances appear to be controlled by variations in winter precipitation and, increasingly, by strong summer and autumn atmospheric warming since the early 1990s, though further observations are required to fully understand mass balance sensitivities. This study provides the first comprehensive contemporary assessment of Labrador glaciers and will inform both regional impact assessments and syntheses of global glacier mass balance.

  2. An improved technique for the reconstruction of former glacier mass-balance and dynamics

    Carr, Simon; Coleman, Christopher


    The recognition of past glacier extent and dynamics is a fundamental aspect of investigations of the climatic sensitivity of glaciers, especially when examining short-lived climate events such as the Younger Dryas or Little Ice Age. Existing approaches to the reconstruction of glacier form and dynamics depend on speculative reasoning of key glacier dynamic parameters, including the role of basal slip and subglacial deformation in glacier mass-transfer. This study reviews approaches to glacier reconstruction, derivation of former glacier equilibrium line altitudes (ELA's) and estimation of mass-balance and dynamics, concluding that most reconstructions of glacier mass-balance are compromised by a lack of glaciological considerations. An alternative approach to glacier reconstruction is presented, demonstrated and discussed, by which an empirical relationship between ablation gradient and mass loss at the ELA is used to derive mass-balance, mass-flux through the ELA and average balance velocity at the ELA. This 'glaciological' approach is applied to four reconstructed glaciers to test previous interpretations that each reflects Younger Dryas glaciation in the UK. The study concludes that this approach provides a more robust technique for reconstructing former glacier dynamics, and may be applied to test geomorphological interpretations of former mountain glaciation.

  3. Surface mass balance reanalysis of Taku and Lemon Creek glaciers, Alaska: 1946-2015

    McNeil, Christopher

    We reanalyzed geodetic and glaciological surface mass balance records of Taku and Lemon Creek glaciers for the period 1946--2015 to determine what has driven the contradictory behavior of these glaciers. During the past century, Taku Glacier has been increasing in area and mass, while Lemon Creek Glacier has simultaneously shrunk in area and mass. Between 1948 and 1999 geodetic mass balance rates are +0.33+/-0.34 m w.e. a--1 for Taku Glacier and 0.61+/-0.34 m w.e. a--1 for Lemon Creek Glacier. Geodetic mass balance rates decreased to +0.01+/-0.23 m w.e. a--1 and --0.65 +/-0.23 m w.e. a--1 for Taku and Lemon Creek glaciers respectively, between 1999 and 2013. We updated the glaciological analysis of annual field data, and found no significant difference between updated and previous annual mass balance solutions (p--value Lemon Creek Glacier record. Comparing mass balance anomalies we determined inter--annual variability of surface mass balance is the same for Taku and Lemon Creek glaciers. However, differences in glacier specific hypsometry and mass balance profile drive systematic differences in both annual and long--term glacier mass balance rates.

  4. Spatial and temporal variation of isotope levels in the firn of Dronnig-Maud-Land (DML) in the Antarctic; Raum-zeitliche Variation von Isotopengehalten im Firn von Dronning-Maud-Land, Antarktis

    Graf, W. [GSF - Forschungszentrum fuer Umwelt und Gesundheit GmbH, Neuherberg (Germany). Inst. fuer Hydrologie; Oerter, H. [Alfred-Wegener-Inst. fuer Polar- und Meeresforschung, Bremerhaven (Germany); Reinwarth, O. [Kommission fuer Glaziologie der BAW, Muenchen (Germany)


    This paper reports on isotope-glaciological studies carried out by the IfH in close cooperation with the Foundation of the Alfred-Wegner Institute for Polar and Marine Research in Bremerhaven (AWI), a member of the HGF, in contribution to the preexploration programme in DML. The goal of our joint work was to determine the spatial and temporal distribution of glaciologically and climatically relevant parameters in the target area of the deep drilling operations (accumulation rates, snow constituents: {sup 2}H,{sup 18}O, main ions, MSA). [German] Im Folgenden soll ueber isotopenglaziologische Arbeiten des IfH als Beitrag zu dem Vorerkundungsprogramm in DML berichtet werden, die in enger Zusammenarbeit mit der Stiftung Alfred-Wegner-Institut fuer Polar- und Meeresforschung, Bremerhaven (AWI), einem Mitglied der HGF, durchgefuehrt wurden. Ziel unserer gemeinsamen Arbeiten war, die raum-zeitliche Verteilung von glaziologisch und klimatisch relevanten Parametern im Zielgebiet der Tiefbohrung zu ermitteln (Akkumulationsraten, Schneeinhaltsstoffe: {sup 2}H, {sup 18}O, Hauptionen, MSA). (orig.)

  5. A Simple Laboratory Scale Model of Iceberg Dynamics and its Role in Undergraduate Education

    Burton, J. C.; MacAyeal, D. R.; Nakamura, N.


    Lab-scale models of geophysical phenomena have a long history in research and education. For example, at the University of Chicago, Dave Fultz developed laboratory-scale models of atmospheric flows. The results from his laboratory were so stimulating that similar laboratories were subsequently established at a number of other institutions. Today, the Dave Fultz Memorial Laboratory for Hydrodynamics ( teaches general circulation of the atmosphere and oceans to hundreds of students each year. Following this tradition, we have constructed a lab model of iceberg-capsize dynamics for use in the Fultz Laboratory, which focuses on the interface between glaciology and physical oceanography. The experiment consists of a 2.5 meter long wave tank containing water and plastic "icebergs". The motion of the icebergs is tracked using digital video. Movies can be found at: We have had 3 successful undergraduate interns with backgrounds in mathematics, engineering, and geosciences perform experiments, analyze data, and interpret results. In addition to iceberg dynamics, the wave-tank has served as a teaching tool in undergraduate classes studying dam-breaking and tsunami run-up. Motivated by the relatively inexpensive cost of our apparatus (~1K-2K dollars) and positive experiences of undergraduate students, we hope to serve as a model for undergraduate research and education that other universities may follow.

  6. Theoretical Foundations of Remote Sensing for Glacier Assessment and Mapping

    Bishop, Michael P.; Bush, Andrew B. G.; Furfaro, Roberto; Gillespie, Alan R.; Hall, Dorothy K.; Haritashya, Umesh K.; Shroder, John F., Jr.


    The international scientific community is actively engaged in assessing ice sheet and alpine glacier fluctuations at a variety of scales. The availability of stereoscopic, multitemporal, and multispectral satellite imagery from the optical wavelength regions of the electromagnetic spectrum has greatly increased our ability to assess glaciological conditions and map the cryosphere. There are, however, important issues and limitations associated with accurate satellite information extraction and mapping, as well as new opportunities for assessment and mapping that are all rooted in understanding the fundamentals of the radiation transfer cascade. We address the primary radiation transfer components, relate them to glacier dynamics and mapping, and summarize the analytical approaches that permit transformation of spectral variation into thematic and quantitative parameters. We also discuss the integration of satellite-derived information into numerical modeling approaches to facilitate understandings of glacier dynamics and causal mechanisms.

  7. Secret Science: Exploring Cold War Greenland

    Harper, K.


    During the early Cold War - from the immediate postwar period through the 1960s - the United States military carried out extensive scientific studies and pursued technological developments in Greenland. With few exceptions, most of these were classified - sometimes because new scientific knowledge was born classified, but mostly because the reasons behind the scientific explorations were. Meteorological and climatological, ionospheric, glaciological, seismological, and geological studies were among the geophysical undertakings carried out by military and civilian scientists--some in collaboration with the Danish government, and some carried out without their knowledge. This poster will present some of the results of the Exploring Greenland Project that is coming to a conclusion at Denmark's Aarhus University.

  8. Recent fluctuations of the Argentinian glaciers

    Leiva, Juan Carlos


    Some of the results obtained in the glaciological research carried out since 1979 at the Argentinian Andes are shown in this paper. The research covers a wide latitudinal gap extending from the Agua Negra glacier in the province of San Juan to the Frı´as glacier situated at Mount Tronador. Agua Negra and Piloto glaciers show a very similar behavior of almost continuous retreat since 1965 while at the Plomo region a small advance period, starting in 1982, is observed in five of the 10 glaciers studied. Finally, the Frı´as glacier fluctuations record shows a very strong recession since 1850 only interrupted by the 1976 advance that continued in 1977.

  9. Expedition to the Antarctic Peninsula in the 2012-2013 campaign with participation of the CIEMAT; Expedicion a la Peninsula Antartica en la campana 2012-2013 con participacion del CIEMAT

    Schmid, T.; Lopez Martinez, J.; Duran Valsero, J. J.; O' Neill, T.


    Antarctica is the most remote, hostile and uninhabited continent on Earth. It is key to understand how our planet works and the impact we have on it. The Antarctic has many unique geological, glaciological and biological features. Its environment and its biological communities have a limited natural capacity for recovery from the alterations they undergo and therefore can be easily and irreversibly damaged. This is why the Antarctic Treaty and, in particular, the Protocol on Environmental Protection of the Antarctic Treaty (the Madrid Protocol) pay special attention to these matters. In this context, the effects of climate change and also the growing pressure of human activities, including scientific research and tourist visits, are reason for this attention. (Author)

  10. Participation of Employees and Students of the Faculty of Geodesy and Cartography in Polar Research

    Pasik, Mariusz; Adamek, Artur; Rajner, Marcin; Kurczyński, Zdzisław; Pachuta, Andrzej; Woźniak, Marek; Bylina, Paweł; Próchniewicz, Dominik


    This year the Faculty of Geodesy and Cartography, Warsaw University of Technology celebrates its 95th jubilee, which provides an opportunity to present the Faculty's rich traditions in polar research. Employees and students of the faculty for almost 60 years have taken part in research expeditions to the polar circle. The article presents various studies typical of geodesy and cartography, as well as miscellany of possible measurement applications and geodetic techniques used to support interdisciplinary research. Wide range of geodetic techniques used in polar studies includes classic angular and linear surveys, photogrammetric techniques, gravimetric measurements, GNSS satellite techniques and satellite imaging. Those measurements were applied in glaciological, geological, geodynamic, botanical researches as well as in cartographic studies. Often they were used in activities aiming to ensure continuous functioning of Polish research stations on both hemispheres. This study is a short overview of thematic scope and selected research results conducted by our employees and students.

  11. The Hans Tausen drill

    Johnsen, Sigfus Johann; Dahl-Jensen, Dorthe; Steffensen, Jørgen Peder


    In the mid-1990s, excellent results from the GRIP and GISP2 deep drilling projects in Greenland opened up funding for continued ice-coring efforts in Antarctica (EPICA) and Greenland (NorthGRIP). The Glaciology Group of the Niels Bohr Institute, University of Copenhagen, was assigned the task...... of providing drilling capability for these projects, as it had done for the GRIP project. The group decided to further simplify existing deep drill designs for better reliability and ease of handling. The drill design decided upon was successfully tested on Hans Tausen Ice Cap, Peary Land, Greenland, in 1995....... The 5.0 m long Hans Tausen (HT) drill was a prototype for the ~11 m long EPICA and NorthGRIP versions of the drill which were mechanically identical to the HT drill except for a much longer core barrel and chips chamber. These drills could deliver up to 4 m long ice cores after some design improvements...

  12. SPOT satellite mapping of Ice Stream B

    Merry, Carolyn J.


    Numerous features of glaciological significance appear on two adjoining SPOT High Resolution Visible (HRV) images that cover the onset region of ice stream B. Many small-scale features, such as crevasses and drift plumes, have been previously observed in aerial photography. Subtle features, such as long flow traces that have not been mapped previously, are also clear in the satellite imagery. Newly discovered features include ladder-like runners and rungs within certain shear margins, flow traces that are parallel to ice flow, unusual crevasse patterns, and flow traces originating within shear margins. An objective of our work is to contribute to an understanding of the genesis of the features observed in satellite imagery. The genetic possibilities for flow traces, other lineations, bands of transverse crevasses, shear margins, mottles, and lumps and warps are described.

  13. Global Maps from Interferometeric TanDEM-X Data: Applications and Potentials

    Rizzoli, Paola; Martone, Michele; Brautigam, Benjamin; Zink, Manfred


    TanDEM-X is a spaceborne Synthetic Aperture Radar (SAR) mission, whose goal is the generation of a global Digital Elevation Model (DEM) with unprecedented accuracy, by using interferometric SAR (InSAR) techniques (InSAR). TanDEM-X offers a huge global data set of bistatic InSAR acquisitions, each of them supplemented by quick look images of different SAR quantities, such as amplitude, coherence, and DEM. Global quick look mosaics of the interferometric coherence and of the relative height error can be considered for mission performance monitoring and acquisition strategy optimization. The aim of this paper is to present the use of such mosaics within the TanDEM-X mission and to show their potentials for future scientific applications for example in the fields of glaciology and forestry.

  14. International glacier monitoring and data archiving, from a national perspective

    Andreassen, Liss M.


    The Global Terrestrial Network for Glaciers (GTN-G) is a framework for internationally coordinated monitoring of glaciers and ice caps and run by three operational bodies: the World Glacier Monitoring Service (WGMS), the US National Snow and Ice Data Center (NSIDC), and the Global Land Ice Measurements from Space (GLIMS) initiative. In this talk, I will present recent progresses by GTN-G in efforts to store and provide extensive glaciological data to the community. I will also discuss some of the challenges in monitoring and data archiving, illustrated with examples from my own experiences as a data provider. Finally, I would like to discuss how we as a community could enrich and complete existing databases.

  15. Importance of ice for the «White Olympics»

    A. F. Renkel


    Full Text Available Organization of any winter Olympic game, often called as «White Olympics», requires interfacing between sports, technology and glaciology. History of the Olympic winter games and the Norwegian figure skater Sonia Henie, first and the only three-time Olympic champion (1928, 1932, 1936 in ladies figure skating, is presented in the article. Leaving the amateurish sport, Henie became a Hollywood star of the ballet on ice. She was introduced to the inventor Frank Zamboni, who created the ice re-surfacer (the ice-cleaning combine to restore the ice on skating rinks. Using the combine by Henie during her tours in the United States served to advertise this machine, and the name Zamboni had become a trademark for machines «Zamboni».

  16. Firn Model Inter-Comparison Experiment (FirnMICE) (Invited)

    Lundin, J.; Arthern, R. J.; Buizert, C.; Cummings, E.; Essery, R.; Ligtenberg, S.; Orsi, A. J.; Simonsen, S. B.; Brook, E.; Leahy, W.; Stevens, C.; Harris, P.; Waddington, E. D.


    Firn evolution plays important roles in glaciology; however, the physical formulation of the compaction law, including sensitivities to temperature and accumulation rate, is an active research topic. We forced 10 firn-densification models in 6 different experiments by altering temperature and accumulation-rate boundary conditions and compared the steady-state and transient behavior of the models. We find that the models produce different results in both steady-state and transient modes for a suite of metrics, including depth-density and depth-age profiles. We use this study to quantitatively characterize the differences between firn models; to provide a benchmark of results for future models; to provide a basis to quantify model uncertainties; and to guide future directions of firn-densification modeling.

  17. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 1997 balance year

    Krimmel, Robert M.


    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington to determine the winter and net balances for the 1997 balance year. The 1997 winter balance, averaged over the glacier, was 3.71 meters, and the net balance was 0.63 meter. The winter balance was the greatest since 1972 (4.27 meters), and the second largest since the record began in 1959. The net balance, which was positive for the second year in a row, was 1.57 meters greater than the 1977-96 average (-0.94 meter). Runoff was measured from the glacier and an adjacent non-glacierized basin. Air temperature and precipitation were measured nearby. This report makes these data available to the glaciological and climatological community.

  18. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 1996 balance year

    Krimmel, Robert M.


    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington to determine the winter and net balances for the 1996 balance year. The 1996 winter balance, averaged over the glacier, was 2.94 meters, and the net balance was 0.10meter. The winter balance was approximately 0.6 meter greater than the 1977-95 average winter balance (2.30 meters). The net balance, which was positive for the first time since 1984, was more than a meter greater than the 1977-95 average net balance (-0.96 meter). The glacier retreated about 15 meters from its 1995 position. Runoff was measured from the glacier and an adjacent non-glacierized basin. Air temperature, precipitation, and barometric pressure were measured nearby. This report makes these data available to the glaciological and climatological community

  19. Water, ice, meteorological, and speed measurements at South Cascade Glacier, Washington, 1999 balance year

    Krimmel, Robert M.


    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington, to determine the winter and net balances for the 1999 balance year. The 1999 winter snow balance, averaged over the glacier, was 3.59 meters, and the net balance was 1.02 meters. Since the winter balance record began in 1959, only three winters have had a higher winter balance. Since the net balance record began in 1953, only 2 years have had a greater positive net balance than 1999. Runoff was measured from the glacier and an adjacent non-glacierized basin. Air temperature, precipitation, and humidity were measured nearby, and ice speed was measured. This report makes these data available to the glaciological and climatological community.

  20. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 1994 balance year

    Krimmel, R.M.


    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington to determine the winter and net balances for the 1994 balance year. The 1994 winter balance, averaged over the glacier, was 2.39 meters, and the net balance was -1.60 meters. The winter balance was approximately that of the 1977-94 average winter balance. The net balance was more negative than the 1977-94 average net balance of -1.02 meters. Runoff was measured from the glacier and an adjacent non- glacierized basin. Air temperature, precipitation, barometric pressure, solar radiation, and wind speed were measured nearby. This report makes these data available to the glaciological and climatological community.

  1. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 1995 balance year

    Krimmel, R.M.


    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington to determine the winter and net balances for the 1995 balance year. The 1995 winter balance, averaged over the glacier, was 2.86 meters, and the net balance was -0.69 meter. The winter balance was approximately 0.5 meter greater than the 1977-94 average winter balance. The net balance was approximately 0.3 meter less negative than the 1977-94 average net balance. Runoff was measured from the glacier and an adjacent non-glacierized basin. Air temperature, precipitation, barometric pressure, solar radiation, and wind speed were measured adjacent to the glacier. This report makes these data available to the glaciological and climatological community.

  2. The archives of the glacier survey of the Austrian Alpine Club

    Fischer, Andrea; Bendler, Gebhard


    The archive of the Austrian Alpine Club holds masses of material on glaciers and their former extent. The material includes descriptions and sketches of the summits conquered by early mountaineers, mapping campaigns and data from early scientific expeditions as well as data on glacier length change. To date a large proportion of the glaciological information in the material has not been catalogued or analysed. As cold ice, containing relevant climate information, might still exist at the highest peaks of Austria, a pilot project was started to collect some of the data of two test sites in Tyrol, in Silvretta and Ötztal Alps, to reveal former summit shapes and glacier tongue positions. Additional information on the number and position of crevasses as well as firn extent is often evident from the material. Challenging tasks not yet tackled are compiling a catalogue of the material and defining an analysis scheme.

  3. TANGR2015 Heidelberg. Second international workshop on tracer applications of noble gas radionuclides in the geosciences



    TANGR2015 is a workshop on the progress in the technique and application of Atom Trap Trace Analyis (ATTA). It is a follow-up to the first TANGR workshop, TANGR2012, which was held at the Argonne National Laboratory, Argonne, USA, in June 2012. It is organized in response to recent technical advances and new applications of Atom Trap Trace Analysis (ATTA), an analytical method for measuring the isotopes {sup 81}Kr, {sup 85}Kr, and {sup 39}Ar. The primary aim of the workshop is to discuss the technical progress of ATTA and thereby enable innovative and timely applications of the noble gas radionuclides to important scientific problems in earth and environmental sciences, e.g. in the fields of groundwater hydrology, glaciology, oceanography, and paleoclimatology.

  4. A Journalist's View From the Bottom of the Earth

    Harris, R.


    Each year, a few journalists travel to Antarctica under the aegis of the National Science Foundation, to report about research at the ends of the earth. National Public Radio science correspondent Richard Harris took that trip in November, 2000. Listeners, readers and viewers are fascinated by exotic locales, so a trip to the ice provides an ideal backdrop to report on topics such as limnology and glaciology, which are otherwise unlikely to make the news. Journalists have to be flexible and creative - just as the researchers do - to overcome constraints imposed by weather and logistics. In this case, a trip to the West Antarctic Ice Sheet was canceled at the last minute and replaced with a trip to study the chemistry of an icebound lake in the McMurdo Dry Valleys. But the essential ingredient for a compelling story remained the same: Scientists, willing to endure hardship to pursue their passion.

  5. A conceptual glacio-hydrological model for high mountainous catchments

    B. Schaefli


    Full Text Available In high mountainous catchments, the spatial precipitation and therefore the overall water balance is generally difficult to estimate. The present paper describes the structure and calibration of a semi-lumped conceptual glacio-hydrological model for the joint simulation of daily discharge and annual glacier mass balance that represents a better integrator of the water balance. The model has been developed for climate change impact studies and has therefore a parsimonious structure; it requires three input times series – precipitation, temperature and potential evapotranspiration – and has 7 parameters to calibrate. A multi-signal approach considering daily discharge and – if available – annual glacier mass balance has been developed for the calibration of these parameters. The model has been calibrated for three different catchments in the Swiss Alps having glaciation rates between 37% and 52%. It simulates well the observed daily discharge, the hydrological regime and some basic glaciological features, such as the annual mass balance.

  6. Comparison of the glacial chronology of Eastern Baffin Island, East Greenland and Camp century accumulation record

    Andrews, John; Funder, Svend Visby; Hjort, Chritian;


    level between 120,000 and 70,000 B.P. may well be related to glacierization of high arctic land masses under conditions of heavy snowfall. The subsequent reduction of accumulation in these high arctic areas then leads to a reduction of ice volume with a dry, cold interstadial correlative in time......Independently derived glacial chronologies from eastern Baffin Island, Canadian Arctic, and from East Greenland show essentially similar glaciologic trends that arc notably different from the response of the southern margins of the Laurentide and FCllnoscandia Ice Sheets. The critical aspe......~ts of both chronologies and the related extcn t of the ice sheets are (1) an early and maximum glacial stade, during the early phase of the last glaciation, reaching its peak abqut 100,000 to 75,000 yr ago; (2) an in terstadial about .70,000 n.p.; (3) an ice advance peaking about 45,000 yr ago; (4...

  7. On the potential of very high-resolution repeat DEMs in glacial and periglacial environments

    J. Abermann


    Full Text Available The potential of high-resolution repeat DEMs was investigated for glaciological applications including periglacial features (e.g. rock glaciers. It was shown that glacier boundaries can be delineated using airborne LIDAR-DEMs as a primary data source and that information on debris cover extent could be extracted using multi-temporal DEMs. Problems and limitations are discussed, and accuracies quantified. Absolute deviations of airborne laser scanning (ALS derived glacier boundaries from ground-truthed ones were below 4 m for 80% of the ground-truthed values. Overall, we estimated an accuracy of +/−1.5% of the glacier area for glaciers larger than 1 km2. The errors in the case of smaller glaciers did not exceed +/−5% of the glacier area. The use of repeat DEMs in order to obtain information on the extent, characteristics and activity of rock glaciers was investigated and discussed based on examples.

  8. Radar measurements of melt zones on the Greenland Ice Sheet

    Jezek, Kenneth C.; Gogineni, Prasad; Shanableh, M.


    Surface-based microwave radar measurements were performed at a location on the western flank of the Greenland Ice Sheet. Here, firn metamorphasis is dominated by seasonal melt, which leads to marked contrasts in the vertical structure of winter and summer firn. This snow regime is also one of the brightest radar targets on Earth with an average backscatter coefficient of 0 dB at 5.3 GHz and an incidence angle of 25 deg. By combining detailed observations of firn physical properties with ranging radar measurements we find that the glaciological mechanism associated with this strong electromagnetic response is summer ice lens formation within the previous winter's snow pack. This observation has important implications for monitoring and understanding changes in ice sheet volume using spaceborne microwave sensors.

  9. Ocean heat drives rapid basal melt of the Totten Ice Shelf.

    Rintoul, Stephen Rich; Silvano, Alessandro; Pena-Molino, Beatriz; van Wijk, Esmee; Rosenberg, Mark; Greenbaum, Jamin Stevens; Blankenship, Donald D


    Mass loss from the West Antarctic ice shelves and glaciers has been linked to basal melt by ocean heat flux. The Totten Ice Shelf in East Antarctica, which buttresses a marine-based ice sheet with a volume equivalent to at least 3.5 m of global sea-level rise, also experiences rapid basal melt, but the role of ocean forcing was not known because of a lack of observations near the ice shelf. Observations from the Totten calving front confirm that (0.22 ± 0.07) × 10(6) m(3) s(-1) of warm water enters the cavity through a newly discovered deep channel. The ocean heat transport into the cavity is sufficient to support the large basal melt rates inferred from glaciological observations. Change in ocean heat flux is a plausible physical mechanism to explain past and projected changes in this sector of the East Antarctic Ice Sheet and its contribution to sea level.

  10. Modeling, simulation and optimization for science and technology

    Kuznetsov, Yuri; Neittaanmäki, Pekka; Pironneau, Olivier


    This volume contains thirteen articles on advances in applied mathematics and computing methods for engineering problems. Six papers are on optimization methods and algorithms with emphasis on problems with multiple criteria; four articles are on numerical methods for applied problems modeled with nonlinear PDEs; two contributions are on abstract estimates for error analysis; finally one paper deals with rare events in the context of uncertainty quantification. Applications include aerospace, glaciology and nonlinear elasticity. Herein is a selection of contributions from speakers at two conferences on applied mathematics held in June 2012 at the University of Jyväskylä, Finland. The first conference, “Optimization and PDEs with Industrial Applications” celebrated the seventieth birthday of Professor Jacques Périaux of the University of Jyväskylä and Polytechnic University of Catalonia (Barcelona Tech), and the second conference, “Optimization and PDEs with Applications” celebrated the seventy-fi...

  11. Raman spectroscopy on ice cores from Greenland and Antarctica

    Weikusat, C.; Kipfstuhl, S.


    Ice cores are invaluable archives for the reconstruction of the climatic history of the earth. Besides the analysis of various climatic processes from isotopes and chemical signatures they offer the unique possibility of directly extracting the past atmosphere from gaseous inclusions in the ice. Many aspects of the formation and alterations of these inclusions, e.g. the entrapment of air at the firn-ice-transition, the formation of crystalline gas hydrates (clathrates) from the bubbles or the structural relaxation during storage of the cores, need to be better understood to enable reliable interpretations of the obtained data. Modern micro Raman spectroscopy is an excellent tool to obtain high-quality data for all of these aspects. It has been productively used for phase identification of solid inclusions [1], investigation of air clathrates [2] and high-resolution measurements of N2/O2 mixing ratios inside individual air bubbles [3,4]. Detailed examples of the various uses of Raman spectroscopy will be presented along with practical information about the techniques required to obtain high-quality spectra. Retrieval and interpretation of quantitative data from the spectra will be explained. Future possibilities for advanced uses of Raman spectroscopy for ice core research will be discussed. [1] T. Sakurai et al., 2009, Direct observation of salts as micro-inclusions in the Greenland GRIP ice core. Journal of Glaciology, 55, 777-783. [2] F. Pauer et al., 1995, Raman spectroscopic study of nitrogen/oxygen ratio in natural ice clathrates in the GRIP ice core. Geophysical Research Letters, 22, 969-971. [3] T. Ikeda-Fukazawa et al., 2001, Variation in N2/O2 ratio of occluded air in Dome Fuji antarctic ice. Journal of Geophysical Research, 106, 17799-17810. [4] C. Weikusat et al., Raman spectroscopy of gaseous inclusions in EDML ice core: First results - microbubbles. Journal of Glaciology, accepted.

  12. Reanalysis of multi-temporal aerial images of Storglaciären, Sweden (1959–99 – Part 1: Determination of length, area, and volume changes

    W. Haeberli


    Full Text Available Storglaciären, located in the Kebnekaise massif in northern Sweden, has a long history of glaciological research. Early photo documentations date back to the late 19th century. Measurements of front position variations and distributed mass balance have been carried out since 1910 and 1945/46, respectively. In addition to these in-situ measurements, aerial photographs have been taken at decadal intervals since the beginning of the mass balance monitoring program and were used to produce topographic glacier maps. Inaccuracies in the maps were a challenge to early attempts to derive glacier volume changes and resulted in major differences when compared to the direct glaciological mass balances. In this study, we reanalyzed dia-positives of the original aerial photographs of 1959, -69, -80, -90 and -99 based on consistent photogrammetric processing. From the resulting digital elevation models and orthophotos, changes in length, area, and volume of Storglaciären were computed between the survey years, including an assessment of related errors. Between 1959 and 1999, Storglaciären lost an ice volume of 19×106 m3, which corresponds to a cumulative ice thickness loss of 5.69 m and a mean annual loss of 0.14 m. This ice loss resulted largely from a strong volume loss during the period 1959–80 and was partly compensated during the period 1980–99. As a consequence, the glacier shows a strong retreat in the 1960s, a slowing in the 1970s, and pseudo-stationary conditions in the 1980s and 1990s.

  13. In-situ glacier monitoring in Zackenberg (NE Greenland): Freya Glacier and A.P. Olsen Ice Cap

    Hynek, Bernhard; Hillerup Larsen, Signe; Binder, Daniel; Weyss, Gernot; Citterio, Michele; Schöner, Wolfgang; Ahlstrøm, Andreas Peter


    Due to the scarceness of glacier mass balance measurements from glaciers and local ice caps in East Greenland and the strong impact that local glaciers and ice caps outside the Ice Sheet are expected to exert on sea level rise in the present century, in 2007 and 2008 two glaciological monitoring programmes of peripheral Greenlandic glaciers started to operate near the Zackenberg Research Station in NE Greenland (74° N, 21° W). Freya (Fröya) Glacier is a 6 km long valley glacier situated on Clavering Island 10 km southeast of the Zackenberg research station with a surface area of 5.3 km2 (2013), reaching from 1305 m to 273 m a.s.l. The glacier is mainly oriented to NW and surrounded by high mountain ridges on both sides. A.P. Olsen Ice Cap is a 295 km2 peripheral ice cap located 35 km northeast of Zackenberg. The mass balance monitoring network is situated on the SE outlet glacier reaching from 1425 m to 525 m which drains into the hydrological basin of Zackenberg. This outlet glacier dams a lake which caused several glacial outburst floods within the period of investigation. The two studied glaciers are very close to each other (35 km), but they are complementary in many ways. Apart from the difference in size, which requires different monitoring strategies, Freya Glacier is nearer to the coast and therefore exposed to a more maritime climate with higher winter accumulation. The different area-altitude distribution of both glaciers is one of the main reason for the significantly more positive mean specific mass balance of A.P. Olsen Ice Cap compared to Freya Glacier. In this talk we present the glaciological monitoring on both glaciers and the main results of the first seven years of data.

  14. Friction distribution at the base of a surging glacier inferred from an inverse method

    Gagliardini, O.; Jay-Allemand, M.; Gillet-Chaulet, F.


    The main objectives of this study is to investigate the basal conditions of a surging glacier. For that, we apply the inverse method proposed by Arthern and Gudmundsson (Journal of Glaciology, 2010). This method is based on an iterative descent algorithm numerically implemented in the finite element code Elmer/Ice. Neumann and Dirichlet problems are solved successively in order to minimize the cost function constructed as the norm of the difference between the basal velocities solutions of both problems. The method is applied to the Variegated glacier, a surge type glacier located in Alaska. We use measurements on this glacier carried out by Raymond and Harrison (Journal of Glaciology, 1988) during the quiescent stage of 1966-81 and the surge of 1982-83. Data contain surface velocities as well as the bed and surface topography along the central flow-line. In a first step, for each set of data obtained at different dates, we run the model diagnostically to solve for the basal drag coefficient in order to match the modelled horizontal surface velocities and the observed velocities. In a second step, inferred basal drag coefficient are analysed and then integrated in a transient simulation which cover the whole period of the data set, i.e. both quiescent and surge stages. Results show the contribution of basal sliding in the surge phenomenon and the modification of the basal condition from the quiescent to the surge stages. These modifications can be interpreted in term of changes in sub-glacial water pressure and runoff.

  15. Reanalysis of a 10-year record (2004-2013) of seasonal mass balances at Langenferner/Vedretta Lunga, Ortler Alps, Italy

    Galos, Stephan Peter; Klug, Christoph; Maussion, Fabien; Covi, Federico; Nicholson, Lindsey; Rieg, Lorenzo; Gurgiser, Wolfgang; Mölg, Thomas; Kaser, Georg


    Records of glacier mass balance represent important data in climate science and their uncertainties affect calculations of sea level rise and other societally relevant environmental projections. In order to reduce and quantify uncertainties in mass balance series obtained by direct glaciological measurements, we present a detailed reanalysis workflow which was applied to the 10-year record (2004 to 2013) of seasonal mass balance of Langenferner, a small glacier in the European Eastern Alps. The approach involves a methodological homogenization of available point values and the creation of pseudo-observations of point mass balance for years and locations without measurements by the application of a process-based model constrained by snow line observations. We examine the uncertainties related to the extrapolation of point data using a variety of methods and consequently present a more rigorous uncertainty assessment than is usually reported in the literature. Results reveal that the reanalyzed balance record considerably differs from the original one mainly for the first half of the observation period. For annual balances these misfits reach the order of > 300 kg m-2 and could primarily be attributed to a lack of measurements in the upper glacier part and to the use of outdated glacier outlines. For winter balances respective differences are smaller (up to 233 kg m-2) and they originate primarily from methodological inhomogeneities in the original series. Remaining random uncertainties in the reanalyzed series are mainly determined by the extrapolation of point data to the glacier scale and are on the order of ±79 kg m-2 for annual and ±52 kg m-2 for winter balances with values for single years/seasons reaching ±136 kg m-2. A comparison of the glaciological results to those obtained by the geodetic method for the period 2005 to 2013 based on airborne laser-scanning data reveals that no significant bias of the reanalyzed record is detectable.

  16. Summer-time Mass Balance of Wolverine Glacier, Alaska, Derived from Ground-based Time-lapse Microgravity Measurements

    Young, E. V.; Muto, A.; Babcock, E.


    Monitoring the mass balance of alpine glaciers is important because alpine glaciers presently account for about half of the cryospheric contribution to the global sea-level rise. Mass balance measurements of alpine glaciers have predominantly relied upon glaciological and hydrological methods. However, these methods can be logistically costly and have potential extrapolation errors. Remote sensing approaches, such as gravimetric methods using data from GRACE satellite missions, have provided monthly mass-balance estimates of aggregates of alpine glaciers but their spatial resolution is far too large for studying a single glacier. On the other hand, ground-based time-lapse microgravity geophysical measurements can potentially circumvent some of the disadvantages of the glaciological and hydrological methods. It may detect the change in a single glacier's mass and its spatial distribution. We conducted ground-based time-lapse microgravity surveys on Wolverine Glacier, Alaska, in May and August of 2016, using a Scintrex CG-5 Autograv gravimeter. We collected data at seventy-nine individual stations on the glacier, roughly five stations per square kilometer. We included repeat-station and base-station measurements made at least twice a day for instrumental drift control. The uncertainty of our gravity measurements is better than 0.03 mGal, which is about 0.7 meters water equivalent of surface mass balance. Our summer-time mass balance of Wolverine Glacier determined from the time-lapse gravity measurements is independent of that derived from the stake-network or stream-gauge measurements, and could provide spatial insight into the mass balance process on Wolverine Glacier and similar glaciers.

  17. "Hot ice and wondrous strange snow": three-phase mixtures or something more?

    Morris, E. M.


    Over the 40 years since John Nye and his colleagues studied regelation and the thermodynamics of water inclusions in polycrystalline ice, physics-based models of mixtures of ice, water and water vapour have become widely-used in glaciology. Such models have been developed, for example, to predict snowmelt and avalanches, to understand the movement of impurities in snow and ice cores, to estimate densification at the surface of polar ice sheets and to help interpret satellite data. The basis for mixture theory models is the concept that each volume of the mixture contains an abundance of all the constituents dispersed within it. In other words the model equations describe properties averaged over a scale which is many times larger than the size of each constituent - the grain size in snow, the inclusion size in temperate ice and so on. All thermo-mechanical models developed so far make simplifying assumptions, sometimes simply to limit the time required for computation, as for example in the snow models used in climate models, but also because all the necessary constitutive relations required for a full thermo-mechanical treatment are not available. Deriving suitable constitutive laws for such a complex, sensitive material has vexed experimentalists and challenged the most determined of mathematical physicists. Nevertheless progress has been made. New measurement techniques, for example the non-destructive measurement of snow density using neutron-scattering and the determination of glacier ice water content using radar, provide better validation data, which can expose weaknesses in the model equations. In the future, we can hope that scaling-up from models of processes on the microstructure scale will provide a solid theoretical foundation for new mixture-scale constitutive relations. For many glaciological problems the mixture-theory approach is the only practical option. The challenge is to ensure that the complex behaviour of the material is well-represented and

  18. Dramatic mass loss in extreme high-elevation areas of a western Himalayan glacier: observations and modeling

    Zhao, Huabiao; Yang, Wei; Yao, Tandong; Tian, Lide; Xu, Baiqing


    Rapid climate change at high elevations has accelerated glacier retreat in the Himalayas and Tibetan Plateau. However, due to the lack of long-term glaciological measurements, there are still uncertainties regarding when the mass loss began and what the magnitude of mass loss is at such high elevations. Based on in situ glaciological observations during the past 9 years and a temperature-index mass balance model, this study investigates recent mass loss of the Naimona’nyi Glacier in the western Himalayas and reconstructs a 41-year (1973/74–2013/14) equilibrium line altitude (ELA) and glacier-wide mass loss. The result indicates that even at 6000 m above sea level (a.s.l.), the annual mass loss reaches ~0.73 m water equivalent (w.e.) during the past 9 years. Concordant with the abrupt climate shift in the end of 1980s, the ELA has dramatically risen from ~5969 ± 73 m a.s.l. during 1973/74–1988/89 to ~6193 ± 75 m a.s.l. during 1989/90–2013/14, suggesting that future ice cores containing uninterrupted climate records could only be recovered at least above 6200 m a.s.l. in the Naimona’nyi region. The glacier-wide mass balance over the past 41 years is averaged to be approximately ‑0.40 ± 0.17 m w.e., exhibiting a significant increase in the decadal average from ‑0.01 ± 0.15 to ‑0.69 ± 0.21 m w.e.

  19. Surface water hydrology and the Greenland Ice Sheet

    Smith, L. C.; Yang, K.; Pitcher, L. H.; Overstreet, B. T.; Chu, V. W.; Rennermalm, A. K.; Cooper, M. G.; Gleason, C. J.; Ryan, J.; Hubbard, A.; Tedesco, M.; Behar, A.


    Mass loss from the Greenland Ice Sheet now exceeds 260 Gt/year, raising global sea level by >0.7 mm annually. Approximately two-thirds of this total mass loss is now driven by negative ice sheet surface mass balance (SMB), attributed mainly to production and runoff of meltwater from the ice sheet surface. This new dominance of runoff as a driver of GrIS total mass loss will likely persist owing to anticipated further increases in surface melting, reduced meltwater storage in firn, and the waning importance of dynamical mass losses (ice calving) as the ice sheets retreat from their marine-terminating margins. It also creates the need and opportunity for integrative research pairing traditional surface water hydrology approaches with glaciology. As one example, we present a way to measure supraglacial "runoff" (i.e. specific discharge) at the supraglacial catchment scale ( 101-102 km2), using in situ measurements of supraglacial river discharge and high-resolution satellite/drone mapping of upstream catchment area. This approach, which is standard in terrestrial hydrology but novel for ice sheet science, enables independent verification and improvement of modeled SMB runoff estimates used to project sea level rise. Furthermore, because current SMB models do not consider the role of fluvial watershed processes operating on the ice surface, inclusion of even a simple surface routing model materially improves simulations of runoff delivered to moulins, the critical pathways for meltwater entry into the ice sheet. Incorporating principles of surface water hydrology and fluvial geomorphology and into glaciological models will thus aid estimates of Greenland meltwater runoff to the global ocean as well as connections to subglacial hydrology and ice sheet dynamics.

  20. Heinrich events driven by feedback between ocean forcing and glacial isostatic adjustment

    Bassis, J. N.; Petersen, S. V.; Cathles, L. M. M., IV


    One of the most puzzling glaciological features of the past ice age is the episodic discharge of large volumes of icebergs from the Laurentide Ice Sheet, known as Heinrich events. It has been suggested that Heinrich events are caused by internal instabilities in the ice sheet (e.g. the binge-purge oscillation). A purely ice dynamic cycle, however, is at odds with the fact that every Heinrich event occurs during the cold phase of a DO cycle, implying some regional climate connection. Recent work has pointed to subsurface water warming as a trigger for Heinrich events through increased basal melting of an ice shelf extending across the Hudson Strait and connecting with the Greenland Ice Sheet. Such a large ice shelf, spanning the deepest part of the Labrador Sea, has no modern analog and limited proxy evidence. Here we use a width averaged "flowline" model of the Hudson Strait ice stream to show that Heinrich events can be triggered by ocean forcing of a grounded terminus without the need for an ice shelf. At maximum ice extent, bed topography is depressed and the terminus is more sensitive to a subsurface thermal forcing. Once triggered, the retreat is rapid, and continues until isostatic rebound of the bed causes local sea level to drop sufficiently to arrest retreat. Topography slowly rebounds, decreasing the sensitivity to ocean forcing and the ice stream re-advances at a rate that is an order of magnitude slower than collapse. This simple feedback cycle between a short-lived ocean trigger and slower isostatic adjustment can reproduce the periodicity and timing of observed Heinrich events under a range of glaciological and solid earth parameters. Our results suggest that not only does the solid Earth play an important role in regulating ice sheet stability, but that grounded marine terminating portions of ice sheets may be more sensitive to ocean forcing than previously thought.

  1. A new glacier monitoring site in West Greenland

    Abermann, J.; van As, D.; Petersen, D.; Nauta, M.


    Greenland's mountain glaciers and ice caps have recently been shown to significantly contribute to current and future sea-level rise. Despite their importance in this respect they are heavily undersampled with only about 5 currently monitored glaciers out of more than 20000 distributed over complexly varying climatic regions. In 2012, Asiaq, Greenland Survey initiated therefore a glacier mass balance program at Qassinnguit glacier (64°9'N, 51°17'W), approx. 18 km East of Nuuk, Greenland's capital. The glacier is a representative example for mountain glaciers in South-West Greenland both in terms of size (ca 1 km2) and orientation (N). A dense stake network gives the basis for the determination of the surface mass balance with the glaciological method as well as flow velocity measurements and the first two complete years are presented. An automated camera is used to monitor ablation patterns and the evolution of the snow line. In early 2014, a ground-penetrating radar campaign was performed to determine the glacier volume. Ice thicknesses up to 50 m were measured with a 100 MHz antenna and the glacier was found to be largely cold-based with some minor temperate parts. In addition to direct glaciological measurements at the site, the monitoring program complements a 7 year long time series of runoff, which allows for quantifying Qassinnguit glacier's cryospheric contribution to the total catchment. In summer 2014 an on-glacier automated weather station was installed that measures parameters to determine the surface energy balance. Preliminary results will be presented and put into a larger spatial context by relating them to measurements with the same setup at an outlet glacier of the Greenland ice sheet approximately 100 km further East. Climate between these sites differs considerably with a marked negative West - East precipitation gradient.

  2. The LARsen Ice Shelf System, Antarctica, LARISSA a Model for Antarctic Integrated System Science (AISS) Investigations using Marine Platforms

    Domack, E. W.; Huber, B. A.; Vernet, M.; Leventer, A.; Scambos, T. A.; Mosley-Thompson, E. S.; Smith, C. R.; de Batist, M. A.; Yoon, H.; Larissa


    The LARISSA program is the first interdisciplinary project funded in the AISS program of the NSF Office of Polar Programs and was officially launched in the closing days of the IPY. This program brings together investigators, students, and media to address the rapid and fundamental changes taking place in the region of the Larsen Ice Shelf and surrounding areas. Scientific foci include: glaciologic and oceanographic interactions, the response of pelagic and benthic ecosystems to ice shelf decay, sedimentary record of ice shelf break disintegration, the geologic evolution of ice shelf systems over the last 100,000 years, paleoclimate/environmental records from marine sediment and ice cores, and the crustal response to ice mass loss at decade to millennial time scales. The first major field season took place this past austral summer aboard the NB Palmer (cruise NBP10-01) which deployed with a multi-layered logistical infrastructure that included: two Bell 220 aircraft, a multifunctional deep water ROV, video guided sediment corer, jumbo piston core, and an array of oceanographic and biological sensors and instruments. In tandem with this ship based operation Twin Otter aircraft supported an ice core team upon the crest of the Bruce Plateau with logistic support provided by the BAS at Rothera Station. Although unusually heavy sea ice prevented much of the original work from being completed in the Larsen Embayment the interdisciplinary approach proved useful. Further the logistical model of ship based aircraft to support interdisciplinary work proved viable, again despite an unusually severe summer meterologic pattern across the northern Antarctic Peninsula. As the program moves forward other vessels will come into play and the model can be applied to interdisciplinary objectives in other regions of Antarctica which are remote and lack land based infrastructure to support coastal field programs in glaciology, geology, or meteorology. This work could then be completed

  3. The Antarctic ice core chronology (AICC2012: an optimized multi-parameter and multi-site dating approach for the last 120 thousand years

    D. Veres


    Full Text Available The deep polar ice cores provide reference records commonly employed in global correlation of past climate events. However, temporal divergences reaching up to several thousand years (ka exist between ice cores over the last climatic cycle. In this context, we are hereby introducing the Antarctic Ice Core Chronology 2012 (AICC2012, a new and coherent timescale developed for four Antarctic ice cores, namely Vostok, EPICA Dome C (EDC, EPICA Dronning Maud Land (EDML and Talos Dome (TALDICE, alongside the Greenlandic NGRIP record. The AICC2012 time scale has been constructed using the Bayesian tool Datice (Lemieux-Dudon et al., 2010 that combines glaciological inputs and data constraints, including a wide range of relative and absolute gas and ice stratigraphic markers. We focus here on the last 120 ka, whereas the companion paper by Bazin et al., (2012 focuses on the interval 120–800 ka.

    Compared to previous timescales, AICC2012 presents an improved timing for the last glacial inception respecting the glaciological constraints of all analyzed records. Moreover, with the addition of numerous new stratigraphic markers and improved calculation of the lock-in depth (LID based on δ15N data employed as the Datice background scenario, the AICC2012 presents a new timing for the bipolar sequence of events over Marine Isotope Stage 3 associated with the see-saw mechanism, with maximum differences of about 500 yr with respect to the previous Datice-derived chronology of Lemieux-Dudon et al. (2010, hereafter denoted LD2010. Our improved scenario confirms the regional differences for the millennial scale variability over the last glacial period: while the EDC isotopic record (events of triangular shape displays peaks roughly at the same time as the NGRIP abrupt isotopic increases, the EDML isotopic record (events characterized by broader peaks or even extended periods of high isotope values reached the isotopic maximum several centuries

  4. Late Quaternary glaciation of the Upper Soca River Region (Southern Julian Alps, NW Slovenia)

    Bavec, Milos; Tulaczyk, Slawek M.; Mahan, Shannon; Stock, Gregory M.


    Extent of Late Quaternary glaciers in the Upper Soc??a River Region (Southern Julian Alps, SE Europe) has been analyzed using a combination of geological mapping, glaciological modeling, and sediment dating (radiocarbon, U/Th series and Infrared Stimulated Luminescence-IRSL). Field investigations focused mainly on relatively well preserved Quaternary sequences in the Bovec Basin, an intramontane basin located SW of the Mediterranean/Black Sea divide and surrounded by mountain peaks reaching from approximately 2100 up to 2587 m a.s.l. Within the Basin we recognized two Late Quaternary sedimentary assemblages, which consist of the same facies association of diamictons, laminated lacustrine deposits and sorted fluvial sediments. Radiocarbon dating of the upper part of the lake sediments sequence (between 12790??85 and 5885??60 14C years b.p.) indicates that the younger sedimentary assemblage was deposited during the last glacial maximum and through early Holocene (Marine Isotope Stage 21, MIS 2-1). Sediment ages obtained for the older assemblage with U/Th and IRSL techniques (between 154.74??22.88 and 129.93??7.90 ka b.p. for selected samples) have large errors but both methods yield results consistent with deposition during the penultimate glacial-interglacial transition (MIS 6-5). Based on analyses of field data combined with glaciological modeling, we argue that both sediment complexes formed due to high sediment productivity spurred by paraglacial conditions with glaciers present in the uplands around the Bovec Basin but not extending down to the basin floor. Our study shows that the extent and intensity of direct glacial sedimentation by Late Quaternary glaciers in the region was previously significantly overestimated. ?? 2004 Elsevier B.V. All rights reserved.

  5. Sensitivity of glacier mass balance and equilibrium line altitude to climatic change on King George Island, Antarctic Peninsula.

    Falk, Ulrike; Lopez, Damian; Silva-Busso, Adrian


    The South Shetland Islands are located at the northern tip of the Antarctic Peninsula which is among the fastest warming regions on Earth. Surface air temperature increases (ca. 3 K in 50 years) are concurrent with retreating glacier fronts, an increase in melt areas, ice surface lowering and rapid break-up and disintegration of ice shelves. Observed surface air temperature lapse rates show a high variability during winter months (standard deviations up to ±1.0 K/100 m), and a distinct spatial heterogeneity reflecting the impact of synoptic weather patterns especially during winter glacial mass accumulation periods. The increased mesocyclonic activity during the winter time in the study area results in intensified advection of warm, moist air with high temperatures and rain, and leads to melt conditions on the ice cap, fixating surface air temperatures to the melting point. The impact on winter accumulation results in even more negative mass balance estimates. Six years of glaciological measurements on mass balance stake transects are used with a glacier melt model to assess changes in melt water input to the coastal waters, glacier surface mass balance and the equilibrium line altitude. The average equilibrium line altitude (ELA) calculated from own glaciological observations for KGI over the time period 2010 - 2015 amounts to ELA=330±100 m. Published studies suggest rather stable condition slightly negative glacier mass balance until the mid 80's with an ELA of approx. 150 m. The calculated accumulation area ratio suggests rather dramatic changes in extension of the inland ice cap for the South Shetland Islands until an equilibrium with concurrent climate conditions is reached.

  6. Establishing mass balance observation at Austre Grønfjordbreen, Nordenskjöld land, Svalbard

    Elagina, Nelly; Kutuzov, Stanislav; Chernov, Robert; Lavrentiev, Ivan; Vasilyeva, Tatiana; Mavlyudov, Bulat; Kudikov, Arseny


    The Arctic archipelago Svalbard consists of a vast glacierized area which contributes significantly to the sea level rise outside of Greenland and Antarctica due to recent warming. The glaciers of Svalbard have already experienced an unprecedented increase in average summer temperatures, melt periods, and rainfall in late autumn and early summer. Glaciers of the Nordenskjöld land were the subject of glaciological studies conducted through the Soviet scientific program at the Institute of Geography RAS, Moscow starting in the 1960s. However, with the collapse of the Soviet Union glaciological monitoring was stopped in the late 1980s. It was resumed in 2003 with direct observations of winter accumulation and summer melt at a number of glaciers in Nordenskjöld land. However, until now snow pit and stake data were inconsistent and were reported randomly. Recent efforts by the Institute of Geography RAS have been aimed at establishing mass balance observation at Austre Grønfjordbreen (7 km2) located 16 km south of Barentsburg. Starting from 2014 observations have included a new ablation stake network of 15 stakes measured biannually, two automatic weather stations located at the glacier tongue and at the accumulation area, and annual high resolution GPR surveys of snow thickness together with snow pit measurements repeated every spring. Special attention has been paid to the evaluation of refreezing ice and superimposed ice distribution. Active layer (10 m) borehole temperatures are measured annually at stake locations. The obtained mass balance gradients are compared with the geodetic mass balance changes in 1990-2005 and recent Arctic DEM data. Additionally glacier bedrock, polythermal structure and surface topography maps have been completed using GPR data and DGPS measurements. All available satellite imagery has been used to reconstruct the snowline elevation changes from 1986 to 2016. Remarkably almost a total absence of accumulation area has been registered in

  7. Islands of the Arctic

    Dowdeswell, Julian; Hambrey, Michael


    The Arctic islands are characterized by beautiful mountains and glaciers, in which the wildlife lives in delicate balance with its environment. It is a fragile region with a long history of exploration and exploitation that is now experiencing rapid environmental change. All of these themes are explored in Islands of the Arctic, a richly illustrated volume with superb photographs from the Canadian Arctic archipelago, Greenland, Svalbard and the Russian Arctic. It begins with the various processes shaping the landscape: glaciers, rivers and coastal processes, the role of ice in the oceans and the weather and climate. Julian Dowdeswell and Michael Hambrey describe the flora and fauna in addition to the human influences on the environment, from the sustainable approach of the Inuit, to the devastating damage inflicted by hunters and issues arising from the presence of military security installations. Finally, they consider the future prospects of the Arctic islands Julian Dowdeswell is Director of the Scott Polar Research Institute and Professor of Physical Geography at 0he University of Cambridge. He received the Polar Medal from Queen Elizabeth for his contributions to the study of glacier geophysics and the Gill Memorial Award from the Royal Geographical Society. He is chair of the Publications Committee of the International Glaciological Society and head of the Glaciers and Ice Sheets Division of the International Commission for Snow and Ice. Michael Hambrey is Director of the Centre for Glaciology at the University of Wales, Aberystwyth. A past recipient of the Polar Medal, he was also given the Earth Science Editors' Outstanding Publication Award for Glaciers (Cambridge University Press). Hambrey is also the author of Glacial Environments (British Columbia, 1994).

  8. Variability of back carbon in Northwest Greenland during the past 350 years

    Goto-Azuma, Kumiko; Ogawa-Tsukagawa, Yoshimi; Kondo, Yutaka; Dallmayr, Remi; Hirabayashi, Motohiro; Ogata, Jun; Kitamura, Kyotaro; Kawamura, Kenji; Motoyama, Hideaki; Matoba, Sumito; Aoki, Teruo; Moteki, Nobuhiro; Ohata, Sho; Mori, Tatsuhiro; Koike, Makoto; Komuro, Yuki; Tsushima, Akane; Nagatsuka, Naoko


    An ice core to the depth of 225 m was drilled at the SIGMA-D site, Northwest Greenland, in 2014 under the SIGMA (Snow Impurity and Glacial Microbe Effects on Abrupt Warming in the Arctic) project (Matoba et al., 2015). The ice core was analyzed to the depth of 113 m with a Continuous Flow Analysis (CFA) system, which was recently built at the National Institute of Polar Research, Japan. The CFA system allowed high resolution analyses of black carbon (BC), stable isotopes of water, microparticles, electric conductivity, and trace elements (Na, K, Mg, Ca, Fe, and Al). BC was analyzed with a Wide Range SP2, which was recently developed by University of Tokyo (Mori et al., 2016). The Wide Range SP2 enabled us to measure BC particles with the size range between 40 and 4000 nm. Here we report the variability of BC concentrations and size distributions during the past 350 years. Anthropogenic impacts on concentrations, size distributions, and their seasonal variations were clearly seen during the first half of the 20th Century. References Matoba, S., H. Motoyama, K. Fujita. T. Yamasaki, M. Minowa, Y. Onuma Y. Komuro, T. Aoki, S. Yamaguchi, S. Sugiyama and H. Enomoto, Glaciological and meteorological observations at the SIGMA-D site, northwestern Greenland Ice Sheet. Bulletin of Glaciological Research 33, 7-10, 2015. Mori, T., N. Moteki, S. Ohata, M. Koike, K. Goto-Azuma, Y. Miyazaki and Y. Kondo, Improved technique for measuring the size distribution of black carbon particles in liquid water, Aerosol Science & Technology, 50, 3, 242-254, DOI: 10.1080/02786826.2016.1147644, 2016.

  9. ASTER Imaging and Analysis of Glacier Hazards

    Kargel, Jeffrey; Furfaro, Roberto; Kaser, Georg; Leonard, Gregory; Fink, Wolfgang; Huggel, Christian; Kääb, Andreas; Raup, Bruce; Reynolds, John; Wolfe, David; Zapata, Marco

    Most scientific attention to glaciers, including ASTER and other satellite-derived applications in glacier science, pertains to their roles in the following seven functions: (1) as signposts of climate change (Kaser et al. 1990; Williams and Ferrigno 1999, 2002; Williams et al. 2008; Kargel et al. 2005; Oerlemans 2005), (2) as natural reservoirs of fresh water (Yamada and Motoyama 1988; Yang and Hu 1992; Shiyin et al. 2003; Juen et al. 2007), (3) as contributors to sea-level change (Arendt et al. 2002), (4) as sources of hydropower (Reynolds 1993); much work also relates to the basic science of glaciology, especially (5) the physical phenomeno­logy of glacier flow processes and glacier change (DeAngelis and Skvarca 2003; Berthier et al. 2007; Rivera et al. 2007), (6) glacial geomorphology (Bishop et al. 1999, 2003), and (7) the technology required to acquire and analyze satellite images of glaciers (Bishop et al. 1999, 2000, 2003, 2004; Quincey et al. 2005, 2007; Raup et al. 2000, 2006ab; Khalsa et al. 2004; Paul et al. 2004a, b). These seven functions define the important areas of glaciological science and technology, yet a more pressing issue in parts of the world is the direct danger to people and infrastructure posed by some glaciers (Trask 2005; Morales 1969; Lliboutry et al. 1977; Evans and Clague 1988; Xu and Feng 1989; Reynolds 1993, 1998, 1999; Yamada and Sharma 1993; Hastenrath and Ames 1995; Mool 1995; Ames 1998; Chikita et al. 1999; Williams and Ferrigno 1999; Richardson and Reynolds 2000a, b; Zapata 2002; Huggel et al. 2002, 2004; Xiangsong 1992; Kääb et al. 2003, 2005, 2005c; Salzmann et al. 2004; Noetzli et al. 2006).

  10. Seismic signals associated with basal processes of the Greenland Ice Sheet

    Röösli, Claudia; Walter, Fabian; Kisslin, Edi; Helmstetter, Agnes; Lüthi, Martin


    Understanding ice sheet and glacier dynamics is crucial for modeling of ice mass balance and resulting sea level changes. Ice dynamics is strongly influenced by surface melt water accumulating at the glacier base and its effect on basal sliding. The relationship between surface melt and ice flow depends on hydraulic processes in the subglacial drainage system. However, both subglacial and englacial drainage systems are inherently difficult to investigate due to their remoteness, and basal processes to date remain poorly understood. Borrowing concepts from volcano studies, recent glacier studies are employing passive seismology as a supplement to traditional glaciological techniques. When monitoring the seismic activity of a glacier or an ice sheet, several different types of so-called 'icequakes' and some times even 'tremor' may be detected in the seismic records that is dominated by the large number of surficial icequakes. Deep icequakes may provide information about englacial water flow and basal motion in response to hydraulic events over a region whose size is only limited by seismic background noise and the aperture of the monitoring network. Here, we present results from a passive seismic deployment on western Greenland's ablation zone during summer 2011. The high-density seismometer network consisted of 17 three-component stations installed at the ice surface or in boreholes. We recorded a large variety of seismic signals, including thousands of near-surface crevasse events as well as dislocation events deep within the ice sheet and near its bed. We discuss these 'deep icequakes' in view of hydraulic processes and basal motion. Furthermore, the seismic deployment was part of larger field campaign including a deep drilling project and glaciological surface observations. This provides the unique opportunity to interpret the seismic monitoring results within the variety of observations including subglacial water pressures and other borehole measurements.

  11. Automated modelling of spatially-distributed glacier ice thickness and volume

    James, William H. M.; Carrivick, Jonathan L.


    Ice thickness distribution and volume are both key parameters for glaciological and hydrological applications. This study presents VOLTA (Volume and Topography Automation), which is a Python script tool for ArcGISTM that requires just a digital elevation model (DEM) and glacier outline(s) to model distributed ice thickness, volume and bed topography. Ice thickness is initially estimated at points along an automatically generated centreline network based on the perfect-plasticity rheology assumption, taking into account a valley side drag component of the force balance equation. Distributed ice thickness is subsequently interpolated using a glaciologically correct algorithm. For five glaciers with independent field-measured bed topography, VOLTA modelled volumes were between 26.5% (underestimate) and 16.6% (overestimate) of that derived from field observations. Greatest differences were where an asymmetric valley cross section shape was present or where significant valley infill had occurred. Compared with other methods of modelling ice thickness and volume, key advantages of VOLTA are: a fully automated approach and a user friendly graphical user interface (GUI), GIS consistent geometry, fully automated centreline generation, inclusion of a side drag component in the force balance equation, estimation of glacier basal shear stress for each individual glacier, fully distributed ice thickness output and the ability to process multiple glaciers rapidly. VOLTA is capable of regional scale ice volume assessment, which is a key parameter for exploring glacier response to climate change. VOLTA also permits subtraction of modelled ice thickness from the input surface elevation to produce an ice-free DEM, which is a key input for reconstruction of former glaciers. VOLTA could assist with prediction of future glacier geometry changes and hence in projection of future meltwater fluxes.

  12. Conditions of the alimentation and the variability of glaciers of the Severnaya Zemlya Archipelago from observations of 2014–2015

    D. Yu. Bolshiyanov


    Full Text Available Glaciological investigations on the Severnaya Zemlya archipelago were resumed in 2013 when a new research station «Ice base Cape Baranova» had been organized by Arctic and Antarctic Research Institute in the North-West of the Island Bolshevik. In 2014–2015, the glaciological polygon named after Leonid Govorukha was established on glaciers Mushketov and Semenov-Tyan-Shanskiy. Two years of observations on the glaciers allowed us to estimate the mass balance of the Mushketov Glacier, which was positive in the 2013–2015. By the end of the melting periods, a superimposed ice was formed on the glacier with thickness of 4 cm in 2014 and 17 cm in 2015, on the average. A snow-firn mass with its vertical thickness exceeding 3 m had been found on the upper part of the Semenov-Tyan-Shansky Glacier. Based on analyses of summer air temperatures and precipitation at the meteorological station «The Golomyanny Island», we assumed that in 2013–2015 the mass balance was also positive on the other glaciers of the archipelago, located to the North of the studied glaciers on the Island of Bolshevik. Data of remote sensing of the catastrophic advancing of the outlet glacier from the Vavilov Ice Cap, obtained in 2013–2016, testify that for much longer period, i.e. during 25 years, conditions for the ice mass accumulation were favorable on the southern and eastern slopes of the Vavilov Ice Cap.

  13. A half century perspective on the International Geophysical Year (IGY) - A Template for the International Polar Year 2007 (IPY 2007)?

    Behrendt, J. C.


    In 1956 I sailed for Antarctica to spend 18 months as a graduate student participating in geophysical-glaciological investigations, as part of the 18-month IGY. This led to a career in geophysics, which has taken me to all of the continents and oceans. As we approach the IPY 2007, the changes in technology and our understanding of the earth over the past half century are breathtaking to contemplate. Although 70 countries participated in IGY, the disciplines were restricted to geophysics. Originally the Third Polar Year, the name was changed to IGY in 1952, at the suggestion of Sydney Chapman. The geographical area comprised the entire earth. The highest priority was given to "problems requiring concurrent synoptic observations at many points involving cooperative observations by many stations." One category was reserved for research on topics such as ocean levels, weather patterns, and the distribution of glacier ice "to establish basic information for subsequent comparison at later epochs." IPY 2007 seems such an epoch. A major international efforts was concentrated in Antarctica, although only 12 counties participated. Glaciology, seismology, auroral studies, ionospheric soundings, magnetic field measurements, and other solar-terrestrial, and meteorological observations comprised the scientific station activities. The only major field activities away from the stations were the oversnow geophysical-glaciological traverses, which made seismic measurements of ice thickness and other ice properties; gravity and magnetic anomaly profiles; and determination of snow accumulation and mean annual temperature. The most intensive of the oversnow traverse programs were those of the U.S. and USSR. Geology and topographic mapping were excluded from the Antarctica because of potential complications due to territorial claims and the possibility of mineral resource discoveries. Despite this, significant geologic findings, such as the discovery of the Dufek intrusion, were made by

  14. Dasuopu ice core record of atmospheric methane over the past 2000 years

    XU; Baiqing


    [1]Barnola, J. M., Raynaud, D., Korotkevich, Y. S. et al., Vostok ice core provides 160,000-year record of atmospheric CO2, Nature, 1987, 329: 408.[2]Chappellaz, J., Barnola, J. M., Raynaud, D. et al., Ice core record of atmospheric methane over the past 160 000 years, Nature, 1990, 345: 127.[3]Raynaud, D., Jouzel, J., Barnola, J. M. et al., The ice record of greenhouse gases, Science, 1993, 259: 926.[4]Blake, D. R., Rowland, F. S., Continuing worldwide increase in tropospheric methane, 1978 to 1987, Science, 1988, 239: 1129.[5]Steele, L. P., Dlugokencky, E. J., Lang, P. M. et al., Slowing down of the global accumulation of atmospheric methane during the 1980s, Nature, 1992, 358: 313.[6]Dlugokencky, E. J., Steele, L. P., Lang, P. M. et al., The growth rate and distribution of atmospheric methane, J. Geophys. Res., 1994, 99: 17021.[7]Lowe, D. C., Brenninkmeijer, C. A. M., Brailsford, G. W. et al., Concentration and 13C records of atmospheric methane in New Zealand and Antarctica: evidence for changes in methane sources, J. Geophys. Res., 1994, 99: 16913.[8]Rasmusen, R. A., Khalil, M. A. K., Atmospheric methane in the recent and ancient atmosphere: concentrations, trends and interhemispheric gradient, J. Geophys. Res., 1984, 89(D7): 11599.[9]Blunier, T., Chappellaz, J., Schwander, J. et al., Atmospheric methane record from a Greenland ice core over the last 1000 years, Geoph. Res. Lett., 1993, 20(20): 2219.[10]Yao Tandong, One of the ten science and technology achievements 1997 in China: The recover of ice cores at the eleva-tion of 7000 m in Qinghai-Tibetan plateau and its significance, J. Glaciology & Geocryology (in Chinese), 1998, 20(1): 1.[11]Yao Tandong, Pu Jiancheng, Wang Ninglian et al., The discovery of a new densification in China, Chinese Science Bulle-tin (in Chinese), 1998, 43: 94.[12]Xu Baiqing, Yao Tandong, A study on the air bubble formation process at the elevation of 7100 m in Dasuopu glacier, J

  15. Physiographic and geological characteristics of shelves in north and west of Taiwan

    Ho-Shing; Yu


    [1]Barnola, J. M., Raynaud, D., Korotkevich, Y. S. et al., Vostok ice core provides 160,000-year record of atmospheric CO2, Nature, 1987, 329: 408.[2]Chappellaz, J., Barnola, J. M., Raynaud, D. et al., Ice core record of atmospheric methane over the past 160 000 years, Nature, 1990, 345: 127.[3]Raynaud, D., Jouzel, J., Barnola, J. M. et al., The ice record of greenhouse gases, Science, 1993, 259: 926.[4]Blake, D. R., Rowland, F. S., Continuing worldwide increase in tropospheric methane, 1978 to 1987, Science, 1988, 239: 1129.[5]Steele, L. P., Dlugokencky, E. J., Lang, P. M. et al., Slowing down of the global accumulation of atmospheric methane during the 1980s, Nature, 1992, 358: 313.[6]Dlugokencky, E. J., Steele, L. P., Lang, P. M. et al., The growth rate and distribution of atmospheric methane, J. Geophys. Res., 1994, 99: 17021.[7]Lowe, D. C., Brenninkmeijer, C. A. M., Brailsford, G. W. et al., Concentration and 13C records of atmospheric methane in New Zealand and Antarctica: evidence for changes in methane sources, J. Geophys. Res., 1994, 99: 16913.[8]Rasmusen, R. A., Khalil, M. A. K., Atmospheric methane in the recent and ancient atmosphere: concentrations, trends and interhemispheric gradient, J. Geophys. Res., 1984, 89(D7): 11599.[9]Blunier, T., Chappellaz, J., Schwander, J. et al., Atmospheric methane record from a Greenland ice core over the last 1000 years, Geoph. Res. Lett., 1993, 20(20): 2219.[10]Yao Tandong, One of the ten science and technology achievements 1997 in China: The recover of ice cores at the eleva-tion of 7000 m in Qinghai-Tibetan plateau and its significance, J. Glaciology & Geocryology (in Chinese), 1998, 20(1): 1.[11]Yao Tandong, Pu Jiancheng, Wang Ninglian et al., The discovery of a new densification in China, Chinese Science Bulle-tin (in Chinese), 1998, 43: 94.[12]Xu Baiqing, Yao Tandong, A study on the air bubble formation process at the elevation of 7100 m in Dasuopu glacier, J

  16. Glaciers of Europe

    Williams, Richard S.; Ferrigno, Jane G.


    ALPS: AUSTRIAN: An overview is provided on the occurrence of the glaciers in the Eastern Alps of Austria and on the climatic conditions in this area, Historical documents on the glaciers have been available since the Middle Ages. Special glaciological observations and topographic surveys of individual glaciers were initiated as early as 1846. Recent data in an inventory based on aerial photographs taken in 1969 show 925 glaciers in the Austrian Alps with a total area of 542 square kilometers. Present research topics include studies of mass and energy balance, relations of glaciers and climate, physical glaciology, a complete inventory of the glaciers, and testing of remote sensing methods. The location of the glacier areas is shown on Landsat multispectral scanner images; the improved capabilities of the Landsat thematic mapper are illustrated with an example from the Oztaler Alpen group. ALPS: SWISS: According to a glacier inventory published in 1976, which is based on aerial photography of 1973, there are 1,828 glacier units in the Swiss Alps that cover a total area of 1fl42 square kilometers. The Rhonegletscher, currently the ninth largest in the country, was one of the first to be studied in detail. Its surface has been surveyed repeatedly; velocity profiles were measured, and the fluctuations of its terminus were mapped and recorded from 1874 to 1914. Recent research on the glacier has included climatological, hydrological, and massbalance studies. Glaciological research has been conducted on various other glaciers in Switzerland concerning glacier hydrology, glacier hazards, fluctuations of glacier termini, ice mechanics, ice cores, and mass balance. Good maps are available showing the extent of glaciers from the latter decades of the 19th century. More recently, the entire country has been mapped at scales of 1:25,000, 1:50,000, 1:100,000, 1:200,000, and 1:500,000. The 1:25,000-scale series very accurately represents the glaciers as well as locates

  17. Rewriting Ice Sheet "Glacier-ology"

    Bindschadler, R.


    The revolution in glaciology driven by the suite of increasingly sophisticated satellite instruments has been no more extreme than in the area of ice dynamics. Years ago, glaciologists were (probably unwittingly) selective in what properties of mountain glaciers were also applied to ice sheets. This reinforced the view that they responded slowly to their environment. Notions of rapid response driven by the ideas of John Mercer, Bill Budd and Terry Hughes were politely rejected by the centrists of mainstream glaciological thought. How the tables have turned--and by the ice sheets themselves, captured in the act of rapidly changing by modern remote sensors! The saw-toothed record of sea-level change over past glacial-interglacial cycles required the existence of rapid ice loss processes. Satellite based observations, supported by hard-earned field observations have extended the time scale over which ice sheets can suddenly change to ever shorter intervals: from centuries, to decades, to years to even minutes. As changes continue to be observed, the scientific community is forced to consider new or previously ignored processes to explain these observations. The penultimate goal of ice-sheet dynamics is to credibly predict the future of both the Greenland and Antarctic ice sheets. In this important endeavor, there is no substitute for our ability to observe. Without the extensive data sets provided by remote sensing, numerical models can be neither tested nor improved. The impact of remote sensing on our existing ability to predict the future must be compared to our probable state of knowledge and ability were these data never collected. Among many satellite observed phenomena we would be largely or wholly ignorant of are the recent acceleration of ice throughout much of coastal Greenland; the sudden disintegration of multiple ice shelves along the Antarctic Peninsula; and the dramatic thinning and acceleration of the Amundsen Sea sector of West Antarctica. These

  18. High Resolution Airborne InSAR DEM of Bagley Ice Valley, South-central Alaska: Geodetic Validation with Airborne Laser Altimeter Data

    Muskett, R. R.; Lingle, C. S.; Echelmeyer, K. A.; Valentine, V. B.; Elsberg, D.


    surface of high accuracy for glaciological and geodetic research using ICEsat and small-aircraft laser altimeter profiling of this glaciologically important region of south-central Alaska.

  19. Snow crystal imaging using scanning electron microscopy: III. Glacier ice, snow and biota

    Rango, A.; Wergin, W.P.; Erbe, E.F.; Josberger, E.G.


    Low-temperature scanning electron microscopy (SEM) was used to observe metamorphosed snow, glacial firn, and glacial ice obtained from South Cascade Glacier in Washington State, USA. Biotic samples consisting of algae (Chlamydomonas nivalis) and ice worms (a species of oligochaetes) were also collected and imaged. In the field, the snow and biological samples were mounted on copper plates, cooled in liquid nitrogen, and stored in dry shipping containers which maintain a temperature of -196??C. The firn and glacier ice samples were obtained by extracting horizontal ice cores, 8 mm in diameter, at different levels from larger standard glaciological (vertical) ice cores 7.5 cm in diameter. These samples were cooled in liquid nitrogen and placed in cryotubes, were stored in the same dry shipping container, and sent to the SEM facility. In the laboratory, the samples were sputter coated with platinum and imaged by a low-temperature SEM. To image the firn and glacier ice samples, the cores were fractured in liquid nitrogen, attached to a specimen holder, and then imaged. While light microscope images of snow and ice are difficult to interpret because of internal reflection and refraction, the SEM images provide a clear and unique view of the surface of the samples because they are generated from electrons emitted or reflected only from the surface of the sample. In addition, the SEM has a great depth of field with a wide range of magnifying capabilities. The resulting images clearly show the individual grains of the seasonal snowpack and the bonding between the snow grains. Images of firn show individual ice crystals, the bonding between the crystals, and connected air spaces. Images of glacier ice show a crystal structure on a scale of 1-2 mm which is considerably smaller than the expected crystal size. Microscopic air bubbles, less than 15 ??m in diameter, clearly marked the boundaries between these crystal-like features. The life forms associated with the glacier were

  20. Integrated provenance-detrital thermochronology studies in ANDRILL AND-2A drill core: first evidence of an Oligocene exhumation episode (McMurdo Sound, Antarctica)

    Zattin, M.; Talarico, F. M.; Sandroni, S.


    with AFT ages as both the methodologies give a clear indication for sources located in the southern McMurdo Sound. The compositional shifts of TAM-derived clasts suggest a dynamic behavior (waxing and waning) of the Antarctic Ice Sheets. In particular, expansions of the ice-flow lines of Skelton and Mulock glaciers into the McMurdo Sound are similar to the glaciological reconstructions for the Last Glacial Maximum and, consistently with provenance and glaciological models based on the AND-1B record, they can be interpreted as the result of West Antarctic Ice Sheet influence on provenance and dispersal of sediments in the Ross Embayment.

  1. Properties of grain boundary networks in the NEEM ice core analyzed by combined transmission and reflection optical microscopy

    Binder, Tobias; Weikusat, Ilka; Garbe, Christoph; Svensson, Anders; Kipfstuhl, Sepp


    others visible in ice-penetrating radar measurements) on the generation of sub-grain boundaries. [1] S. Kipfstuhl et al., 2006, Journal of Glaciology, 52, 398-406 [2] T. Binder et al., 2013, Journal of Microscopy, 250, 130-141 [3] I. Weikusat et al., 2011, Journal of Glaciology, 57, 111-120

  2. Sensitivity Analysis and Variational Data Assimilation for ice flow - Application to the Mertz ice-tongue

    Martin, N.; Monnier, J.


    To be confident in the accuracy of the modelling of ice flows requires to con- front numerical experiments to actual observations. This type of flow is strongly sensitive to its input parameters such as rheological parameters and boundary conditions like the friction on the bedrock. Using optimal control theory, we build a global 4D-Var algorithm using direct and adjoint model of the variational problem thus providing local sensitivity analysis and data assimilation (see [1]). In order to compute approximation of these flows, one consider the non newtonian velocity- pressure Stokes system described using mixed finite element method. The treat- ment of the free surface is performed using an Arbitrary Lagrangian Eulerian de- scription with robus elastic deformation and the adjoint method is constructed by algorithmic differentiation of the direct code using Tapenade software (INRIA). We lean on prior developments of the software DassFlow (see [2]). One of the major question for inverse methods in glaciology is to infer the fric- tion coefficient at bottom through data assimilation because it cannot be measured. In other respect, our first results based on real data shows that the rheological expo- nent and/or the thermal coefficient of the constitutive law (distributed parameter) has the same type of influence (see Figure 1) and can be inferred as well. Another modeling issue lies in the dynamic of the grounding line when con- sidering the floating part of the ice domain. Then, sensitivity analysis of the model response with respect to this grounding line dynamic leads to a better understand- ing of this unstable process and its empirical modelling. We present a real data application on the Mertz ice-shelf (Antarctica). Topography and surface velocities data are being provided by B. Legrésy (see [3]). References [1] Martin, N. and Monnier, J. : A three fields finite elements solver for viscoplas- tic free surface flows and variational data assimilation. In

  3. Use of a new ultra-long-range terrestrial LiDAR system to monitor the mass balance of very small glaciers in the Swiss Alps

    Fischer, M.; Huss, M.; Hoelzle, M.


    Measuring glacier mass balance is important as it directly reflects the climatic forcing on the glacier surface. Today, repeated comparison of digital elevation models (DEMs) is a popular and widely used approach to derive surface elevation, volume and mass changes for a large number of glaciers. In high-mountain environments, airborne laser scanning (ALS) techniques currently provide the most accurate and highest resolution DEMs on the catchment scale, allowing the computation of glacier changes on an annual or even semi-annual basis. For monitoring individual glaciers though, terrestrial laser scanning (TLS) is easier and more cost-efficiently applied on the seasonal timescale compared to ALS. Since most recently, the application of the latest generation of ultra-long-range near infrared TLS systems allows the acquisition of surface elevation information over snow and ice of unprecedented quality and over larger zones than with previous near infrared TLS devices. Although very small glaciers represent the majority in number in most mountain ranges on Earth, their response to climatic changes is still not fully understood and field measurements are sparse. Therefore, a programme was set up in 2012 to monitor both the seasonal and annual surface mass balance of six very small glaciers across the Swiss Alps using the direct glaciological method. As often nearly the entire surface is visible from one single location, TLS is a highly promising technique to generate repeated high-resolution DEMs as well as to derive seasonal geodetic mass balances of very small ice masses. In this study, we present seasonal surface elevation, volume and geodetic mass changes for five very small glaciers in Switzerland (Glacier de Prapio, Glacier du Sex Rouge, St. Annafirn, Schwarzbachfirn and Pizolgletscher) derived from the comparison of seasonally repeated high-resolution DEMs acquired since autumn 2013 with the new ultra-long-range TLS device Riegl VZ-6000. We show the different

  4. The new Inventory of Italian Glaciers: Present knowledge, applied methods and preliminary results

    Smiraglia, Claudio; Diolaiuti, Guglielmina; D'Agata, Carlo; Maragno, Davide; Baroni, Carlo; Mortara, Gianni; Perotti, Luigi; Bondesan, Aldino; Salvatore, Cristina; Vagliasindi, Marco; Vuillermoz, Elisa


    A new Glacier Inventory is an indispensable requirement in Italy due to the importance of evaluating the present glacier coverage and the recent changes driven by climate. Furthermore Alpine glaciers represent a not negligible water and touristic resource then to manage and promote them is needed to know their distribution, size and features. The first Italian Glacier Inventory dates back to 1959-1962. It was compiled by the Italian Glaciological Committee (CGI) in cooperation with the National Research Council (CNR); this first inventory was mainly based on field data coupled with photographs (acquired on the field) and high resolution maps. The Italian glaciation resulted to be spread into 754 ice bodies which altogether were covering 525 km2. Moreover in the Eighties a new inventory was compiled to insert Italian data into the World Glacier Inventory (WGI); aerial photos taken at the end of the Seventies (and in some cases affected by a high and not negligible snow coverage) were used as the main source of data. No other national inventory were compiled after that period. Nevertheless during the last decade the largest part of the Italian Alpine regions have produced regional and local glacier inventories which in several cases are also available and queried through web sites and web GIS application. The actual need is now to obtain a complete, homogeneous and contemporary picture of the Italian Glaciation which encompasses the already available regional and local data and all the new updated information coming from new sources of data (e.g.: orthophotos, satellite imagines, etc..). The challenge was accepted by the University of Milan, the EvK2CNR Committee and the Italian Glaciological Committee who, with the sponsorship of Levissima Spa, are presently working to compile the new updated Italian Glacier Inventory. The first project step is to produce a unique homogeneous glacier database including glacier boundary and surface area and the main fundamental

  5. Reanalysis of a 10-year record (2004–2013 of seasonal mass balances at Langenferner/Vedretta Lunga, Ortler Alps, Italy

    S. P. Galos


    Full Text Available Records of glacier mass balance represent important data in climate science and their uncertainties affect calculations of sea level rise and other societally relevant environmental projections. In order to reduce and quantify uncertainties in mass balance series obtained by direct glaciological measurements, we present a detailed reanalysis workflow which was applied to the 10-year record (2004 to 2013 of seasonal mass balance of Langenferner, a small glacier in the European Eastern Alps. The approach involves a methodological homogenization of available point values and the creation of pseudo-observations of point mass balance for years and locations without measurements by the application of a process-based model constrained by snow line observations. We examine the uncertainties related to the extrapolation of point data using a variety of methods and consequently present a more rigorous uncertainty assessment than is usually reported in the literature. Results reveal that the reanalyzed balance record considerably differs from the original one mainly for the first half of the observation period. For annual balances these misfits reach the order of  > 300 kg m−2 and could primarily be attributed to a lack of measurements in the upper glacier part and to the use of outdated glacier outlines. For winter balances respective differences are smaller (up to 233 kg m−2 and they originate primarily from methodological inhomogeneities in the original series. Remaining random uncertainties in the reanalyzed series are mainly determined by the extrapolation of point data to the glacier scale and are on the order of ±79 kg m−2 for annual and ±52 kg m−2 for winter balances with values for single years/seasons reaching ±136 kg m−2. A comparison of the glaciological results to those obtained by the geodetic method for the period 2005 to 2013 based on airborne laser-scanning data reveals that no significant bias of the

  6. Seasonal changes in surface albedo of Himalayan glaciers from MODIS data and links with the annual mass balance

    F. Brun


    Full Text Available Few glaciological field data are available on glaciers in the Hindu Kush–Karakoram–Himalayan (HKH region, and remote sensing data are thus critical for glacier studies in this region. The main objectives of this study are to document, using satellite images, the seasonal changes of surface albedo for two Himalayan glaciers, Chhota Shigri Glacier (Himachal Pradesh, India and Mera Glacier (Everest region, Nepal, and to reconstruct the annual mass balance of these glaciers based on the albedo data. Albedo is retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS images, and evaluated using ground based measurements. At both sites, we find high coefficients of determination between annual minimum albedo averaged over the glacier (AMAAG and glacier-wide annual mass balance (Ba measured with the glaciological method (R2 = 0.75. At Chhota Shigri Glacier, the relation between AMAAG found at the end of the ablation season and Ba suggests that AMAAG can be used as a proxy for the maximum snow line altitude or equilibrium line altitude (ELA on winter-accumulation-type glaciers in the Himalayas. However, for the summer-accumulation-type Mera Glacier, our approach relied on the hypothesis that ELA information is preserved during the monsoon. At Mera Glacier, cloud obscuration and snow accumulation limits the detection of albedo during the monsoon, but snow redistribution and sublimation in the post-monsoon period allows for the calculation of AMAAG. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degree-day method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6 years than for Chhota Shigri Glacier (11 years. Thus the mass balance reconstruction

  7. Integrated geographical research in the Khovd River basin (Mongolia)

    Mukhanova, Mariia; Syromyatina, Margarita; Kurochkin, Yuriy; Chistyakov, Kirill


    Khovd River located in the endorheic basin of Grate Lakes Depression is a main river of western Mongolia. It has more than 500 km length and runs from the glaciers of the Tavan Bogd Mountains through different vegetation zones to the terminal Khar-Us lake. The main purpose of the study is to estimate the current state and dynamics of the geosystems in this river basin as it plays a critical part in the water supply of submontane desert steppe plains of western Mongolia. One of the objectives is to understand the formation and regime of water discharge in this inland river basin with glaciation. The results are mostly based on the 2013-2016 integrated field research including glaciological, meteorological, hydrological and dendrochronological measurements as well as hydrometeorological stations' data analysis and remote sensing data acquired from satellites. Last year the main attention was given to hydrological and hydrochemical research. In summer we measured TDS concentration in 71 points throughout the stream course of Khovd River and its tributaries. TDS is changing from 0-1 ppm at glaciers to 67 ppm at river mouth and 93 ppm at Khar-Us lake. The hydrochemical analysis shows that the water type is changing from hydrocarbonate-calcium at the beginning of the river to the sulfate-calcium at the mouth. Glaciers play a crucial role in feeding the river only in its upper part. Glaciological study revealed that the areas of the main glaciers were not much changed since 1989, while the glacier tongue regression was fixed. The total glacier area decreased approximately by 4.5 % in the Tsagaan-Gol basin and by 6.9 % in the Tsagaan-Us basin from 1989 to 2013. Large glaciers were retreating at an average rate of 28-34 m/year between 2001 and 2014. The hydrometeorological data analysis shows that most of the catchment area is characterized by aridization tendency for the last 10 years. This fact is well confirmed by the dendrochronological streamflow reconstruction of the

  8. Subglacial lake and meltwater flow predictions of the last North American and European Ice Sheets

    Livingstone, S. J.; Clark, C. D.; Tarasov, L.


    There is increasing recognition that subglacial lakes act as key components within the ice sheet system, capable of influencing ice-sheet topography, ice volume and ice flow. The subglacial water systems themselves are recognised as being both active and dynamic, with large discharges of meltwater capable of flowing down hydrological pathways both between lakes and to the ice-sheet margins. At present, much glaciological research is concerned with the role of modern subglacial lake systems in Antarctica. Another approach to the exploration of subglacial lakes involves identification of the geological record of subglacial lakes that once existed beneath ice sheets of the last glaciation. Investigation of such palaeo-subglacial lakes offers significant advantages because we have comprehensive information about the bed properties, they are much more accessible and we can examine and sample the sediments with ease. If we can find palaeo-subglacial lakes then we have the potential to advance understanding with regard to the topographic context and hydrological pathways that the phenomena form a part of; essentially we gain spatial and sedimentological information in relation to investigations of contemporary subglacial lakes and lose out on the short-time dynamics. In this work we present predictions of palaeo-subglacial lakes and meltwater drainage pathways under the former European and North American ice sheets during the last glaciation. We utilise data on the current topography and seafloor bathymetry, and elevation models of the ice and ground surface topography (interpolated to a 5 km grid) to calculate the hydraulic potential surface at the ice-sheet bed. Meltwater routing algorithms and the flooding of local hydraulic minima allow us to predict subglacial channels and lakes respectively. Given that specific ice-surface and bed topographies are only known from modelled outputs, and thus contain significant uncertainty, we utilise many such outputs to examine

  9. Design and Construction of the Qinghai-Tibet Railway-A Review on the 6th International Symposium on Permafrost Engineering%青藏铁路设计与建设--第六届国际冻土工程会议回顾

    金会军; 程国栋; 马巍; 何平


    The 6th International Symposium on Permafrost Engineering was successfully held in China in September 2004. About 150 scientists and engineers from 7 countries attended the symposium in Lanzhou on 5~7 September, and about 35 people from 6 countries participated in the field trip along the Qinghai-Tibet Highway/Railway on 8~13 September and the seminar in Lhasa on 14 September 2004. During the Symposium, the latest progress on permafrost engineering and the surveys, design and construction of the Qinghai-Tibet Railway were exchanged and inspected. Fifty-eight technical papers in English from the Symposium were published in the first volume of the Proceedings of the Symposium, as a supplement of the Journal of Glaciology and Geocryology , before the symposium. About 6 papers from the symposium are published in the second volume in the volume 27(1) of the Journal of the Glaciology and Geocryology , after the symposium.The Qinghai-Tibet Railway (QTR) under construction will traverse 632 km of permafrost, and the engineers are facing unprecedented engineering and environmental challenges. With the QTR under construction and to be completed in 2007, permafrost engineering has become the research focus of permafrost scientists and engineers in China. Many encouraging and promising achievements in permafrost engineering have been obtained during the past three years. However, there are still numerous engineering and environmental problems needing to be solved or resolved. In the discussions, some experts pointed out that methods, such as removal of snow cover on the embankments and toe areas, light-color embankments and side slope surfaces, awnings for shading the solar radiation, hairpin or tilted thermosyphons, could be applied to actively cool the roadbed of the QTR. Some new ideas on utilization of the natural cold reserves were proposed to protect the QTR permafrost roadbed from thawing. Many questions and answers on the survey, design, construction, operations

  10. Development of New Accurate, High Resolution DEMs and Merged Topographic-Bathymetric Grids for Inundation Mapping in Seward Alaska

    Marriott, D.; Suleimani, E.; Hansen, R.


    The Geophysical Institute of the University of Alaska Fairbanks and the Alaska Division of Geological and Geophysical Surveys continue to participate in the National Tsunami Hazard Mitigation Program by evaluating and mapping potential inundation of selected coastal communities in Alaska. Seward, the next Alaskan community to be mapped, has excellent bathymetric data but very poor topographic data available. Since one of the most significant sources of errors in tsunami inundation mapping is inaccuracy of topographic and bathymetric data, the Alaska Tsunami Modeling Team cooperated with the local USGS glaciology office to perform photogrammetry in the Seward area to produce a new DEM. Using ten air photos and the APEX photogrammetry and analysis software, along with several precisely located GPS points, we developed a new georeferenced and highly accurate DEM with a 5-meter grid spacing. A variety of techniques were used to remove the effects of buildings and trees to yield a bald earth model. Finally, we resampled the new DEM to match the finest resolution model grid, and combined it with all other data, using the most recent and accurate data in each region. The new dataset has contours that deviate by more than 100 meters in some places from the contours in the previous dataset, showing significant improvement in accuracy for the purpose of tsunami modeling.

  11. Design and realization of the drawing software for snow/ice stratigraphic profile

    温家洪; 杨文璐


    Snow/ice stratigraphic profile is one of the traditional and important research fields in glaciology.The profile drawn by hand, however, is a tough job.Using the Object Oriented Programming (OOP) Visual Basic (VB), we developed a Drawing Software for Snow/Ice Stratigraphic Profile (DSSISP).This paper introduces the functions, designing process and realizing methods of the drawing software.It presents the key techniques and aspects that should be payed attention to during the software development.Moreover, it also proposes the ideas for complete development of this drawing system.Legend database is a key aspect in the software designing.The major functions of the software include the stratigraphic profile drawing, edition and data management, which can help researchers draw the stratigraphic profile (including the scale, stratigraphic figure, text note and legend) quickly in a computer.In addition, the database technique is used to manage drawing data, which makes the figure drawing convenient and efficient.The drawing data is also convenient to be preserved, exchanged, processed and used.

  12. Building long-term and high spatio-temporal resolution precipitation and air temperature reanalyses by mixing local observations and global atmospheric reanalyses: the ANATEM method

    A. Kuentz


    Full Text Available Improving the understanding of past climatic or hydrologic variability has received a large attention in different fields of geosciences, such as glaciology, dendrochronology, sedimentology or hydrology. Based on different proxies, each research community produces different kind of climatic or hydrologic reanalyses, at different spatio-temporal scales and resolution. When considering climate or hydrology, numerous studies aim at characterising variability, trends or breaks using observed time-series of different regions or climate of world. However, in hydrology, these studies are usually limited to reduced temporal scale (mainly few decades, seldomly a century because they are limited to observed time-series, that suffers from a limited spatio-temporal density. This paper introduces a new model, ANATEM, based on a combination of local observations and large scale climatic informations (such as 20CR Reanalysis. This model allow to build long-term air temperature and precipitation time-series, with a high spatio-temporal resolution (daily time-step, few km2. ANATEM was tested on the air temperature and precipitation time-series of 22 watersheds situated on the Durance watershed, in the french Alps. Based on a multi-criteria and multi-scale diagnostic, the results show that ANATEM improves the performances of classical statistical models. ANATEM model have been validated on a regional level, improving spatial homogeneity of performances and on independent long-term time-series, being able to capture the regional low-frequency variabilities over more than a century (1883–2010.

  13. Recent Variations of The Italian Glaciers: Qualitative and Quantitative Data-base and Processings On A Fundamental Water Resource

    Diolaiuti, G.; D'Agata, C.; Stella, G.; Apadula, F.; Smiraglia, C.

    This paper introduces the preliminary results of a project applied primarily to the compilation of the first general and complete data-base of all Italian glaciers, avail- able to the scientific community, and secondly to the elaboration of the information contained in the data base to supply a strong contribution to the study of the spatial and temporal variabilities of the climatic signal inside the alpine glacier historical series. The project started in the year 2000 as a convention between Università degli Studi di Milano (Italy) and CESI (Italian Electrical Sperimental Center) and gives the first results and the free use by people in the 2002, the International Year of Mountains. Fundamental for the development of the project was the collaboration of the Italian Glaciological Committee (CGI) with its publications (from 1914 to 1977 SBollettino & cedil;del Comitato Glaciologico ItalianoT and from 1978 to 2000 SGeografia Fisica e Di- & cedil;namica Quaternaria). The data-base collects qualitative and quantitative information on glaciers monitored by the Italian Glaciological CommitteeSs operators during the century of their activity for a total of 902 glaciers (901 alpine glaciers and only Ap- pennine one, the Calderone Glacier). For every glacier were inserted in the data-base: 1) data about the glacial terminus elevations, date and method of the measure 2) name and position of the signals used by the operators in order to verify the variations of extension of glacial terminus 3) distance between the signal and the glacier terminus and relative angle of measure 4) operatorSs name 5) bibliographical source of the information 6) qualitative data (on cartographic material, photographies and papers). Currently only a part of the data collected in the data-base is directly available in the web site: ghiacciai Italiani/. Here the users are able to find, for every glacier, a table with all the references of qualitative (as cartography and

  14. Geology of Planina pri Jezeru and its environs (Slovenia

    Mihael Brenčič


    Full Text Available The article describes the results of detailed geological mapping of the wider environs of Planina pri Jezeru north of Bohinj. In the literature the Upper Triassic massive and bedded limestone, Jurassic limestone, Cretaceous clastic rocks and Pleistocene sediments have been reported in this area up to now. The article supplements existing lithostratigraphic information by defining exact locations of the Pleistocene sediments at Planina pri Jezeru and Planina v Lazu, and of Jurassic rocks. In Poljane a Neptunian dyke and bioclastic limestone, while north of Mizčna glava a flat-bedded microsparitic limestone were described for the first time.Correlation to the Triglav Lakes Valley Jurassic beds indicates equivalent facieses. Allochthon Cretaceous biocalcarenite and jasper situated east of Planina pri Jezeru are also described due to their importance for further glaciological studies. The results show that the recent lake Jezero na Planini pri Jezeru is formed due to the accumulation of Pleistocene glacial-lacustrine fine-grained sediment in till,deposited on the Dachstein limestone.

  15. Climatic Seesaws Across The North Pacific As Revealed By High-Mountain Ice Cores Drilled At Kamchatka And Wrangell-St. Elias Mountains

    Shiraiwa, T.; Goto-Azuma, K.; Kanamori, S.; Matoba, S.; Benson, C. S.; Muravyev, Y. D.; Salamatin, A. N.


    We drilled ca. 210-m deep ice cores at Mt. Ushkovsky (Kamchatka: 1998), King Col of Mt. Logan (2002) and Mt. Wrangell (2004). Thanks to the high accumulation rates up to 2 m per year in these mountains, the ice cores are expected to unveil the climate and atmospheric changes in the northern North Pacific during the last several centuries. The reconstructed annual accumulation rates time-series of Mt. Ushkovsky showed, for example, decadal to interdecadal oscillations which were closely correlated to the Pacific Decadal Oscillations (PDO). Comparison between the reconstructed accumulation rates between the Ushkovsky and our two ice cores from Wrangell-St. Elias mountains suggests that the PDO played an important role in determining the precipitation at both side of the northern North Pacific: positive PDO supplied high precipitation in the Pacific North America and the negative PDO did high in Kamchatka during the last two centuries. Beside the significance of the climate proxy signals, the physical properties of the ice cores and the related glaciological features at the three mountains provided unique feature of glaciers developing on high mountains with complicated topographies and high accumulation rates. It was shown that careful treatment of dynamic behavior in these high mountain glaciers are indispensable for the precise reconstruction of past accumulation time-series.

  16. A review of geological evidence for ancient El Niño activity in Peru

    Devries, Thomas J.


    Geological evidence (geomorphological, sedimentological, paleontological, and archeological) for the occurrence of El Niño events in Peru during the Quaternary has been reevaluated. New data concerning thermally anomalous molluscan assemblages in Holocene deposits of north central Peru are briefly described, as are new data regarding the distribution of warm- and cold- water mollusks in late Pliocene and early Pleistocene deposits of northwestern Peru. No conclusive evidence of prehistoric "El Niño" events was found in the new data or the reviewed literature. Most references to El Niño events are best characterized as descriptions of El Niño- like conditions. These conditions may accurately represent events or only mimic events. Past studies lack evidence of two necessary criteria for proof of an El Niño event: a demonstrably short-lived event, and the advection of warm coastal marine waters into the southeastern Pacific Ocean. The glaciological record of precipitation in the Andes, when combined with historical accounts of El Niño phenomena on the coast, is the sole example of a geological data set that meets both criteria.

  17. Mais comment s'écoule donc un glacier ? Aperçu historique

    Rémy, Frédérique; Testut, Laurent


    Ice and snow have often helped physicists understand the world. On the contrary it has taken them a very long time to understand the flow of the glaciers. Naturalists only began to take an interest in glaciers at the beginning of the 19th century during the last phase of glacier advances. When the glacier flow from the upslope direction became obvious, it was then necessary to understand how it flowed. It was only in 1840, the year of the Antarctica ice sheet discovery by Dumont d'Urville, that two books laid the basis for the future field of glaciology: one by Agassiz on the ice age and glaciers, the other one by canon Rendu on glacier theory. During the 19th century, ice flow theories, adopted by most of the leading scientists, were based on melting/refreezing processes. Even though the word 'fluid' was first used in 1773 to describe ice, more the 130 years would have to go by before the laws of fluid mechanics were applied to ice. Even now, the parameter of Glen's law, which is used by glaciologists to model ice deformation, can take a very wide range of values, so that no unique ice flow law has yet been defined. To cite this article: F. Rémy, L. Testut, C. R. Geoscience 338 (2006).

  18. Geomorphology and dynamics of supraglacial debris covers in the Western Alps

    Deline, P.; Gardent, M.; Kirkbride, M. P.; Le Roy, M.; Martin, B.


    In the alpine regions of France and NW Italy, many glaciers of a variety of sizes are at least partly debris-covered, but these have received less scientific research than clean glaciers. During the present period of glacier shrinkage - the area of glacier cover in France has reduced by 26% over the last 40 years -, growing debris cover needs to be understood as an influence on continuing retreat, with consequences for natural hazards, water resources and tourism. We present the results of a combined ongoing study of an inventory of debris-covered glaciers in France with site-specific studies of c. 12 glaciers of contrasting types, in order to understand spatial and temporal changes in supraglacial debris cover. Our specific aims are: 1. To understand the geomorphology of debris-covers and their formation, investigating the types of debris cover in relation to formative processes including extraglacial supply and development during transport. 2. To document the changing extents of supraglacial debris covers, using historical documents and aerial photographs. 3. To interpret areal changes in terms of glaciological and topographical controls on different glacier and debris cover types (catchment morphology, glacier structure, mass balance history, and rock wall collapse magnitude and frequency). 4. To understand the effect of debris cover on glacier dynamics and geomorphological evolution, related to insulation-related modifications to AAR, long profiles, and length changes on both short and long timescales. This includes investigation of the characteristics of debris-covered glacier depositional systems resulting from their modified dynamics.

  19. A GRASS GIS module to obtain an estimation of glacier behavior under climate change: A pilot study on Italian glacier

    Strigaro, Daniele; Moretti, Massimiliano; Mattavelli, Matteo; Frigerio, Ivan; Amicis, Mattia De; Maggi, Valter


    The aim of this work is to integrate the Minimal Glacier Model in a Geographic Information System Python module in order to obtain spatial simulations of glacier retreat and to assess the future scenarios with a spatial representation. The Minimal Glacier Models are a simple yet effective way of estimating glacier response to climate fluctuations. This module can be useful for the scientific and glaciological community in order to evaluate glacier behavior, driven by climate forcing. The module, called r.glacio.model, is developed in a GRASS GIS (GRASS Development Team, 2016) environment using Python programming language combined with different libraries as GDAL, OGR, CSV, math, etc. The module is applied and validated on the Rutor glacier, a glacier in the south-western region of the Italian Alps. This glacier is very large in size and features rather regular and lively dynamics. The simulation is calibrated by reconstructing the 3-dimensional dynamics flow line and analyzing the difference between the simulated flow line length variations and the observed glacier fronts coming from ortophotos and DEMs. These simulations are driven by the past mass balance record. Afterwards, the future assessment is estimated by using climatic drivers provided by a set of General Circulation Models participating in the Climate Model Inter-comparison Project 5 effort. The approach devised in r.glacio.model can be applied to most alpine glaciers to obtain a first-order spatial representation of glacier behavior under climate change.

  20. Accumulation and Melt Variability at the Western Slope of the Greenland Ice Sheet at Swiss Camp: 1990 - 2005

    Steffen, K.


    The Swiss Camp was established at the equilibrium line altitude (ELA) near Jakobshavn (~ 70° N), along the western slope of the Greenland ice sheet in spring 1990. Long-term glaciological measurements from the Danes predicted the ELA for this region. The elevation variability of the ELA will be discussed for the 1990 - 2005 time period. The surface slope of the ice sheet in this region is 1-2 degrees with large scale undulations (5 km wave length). The Swiss Camp was located in the accumulation regions during the first five years of the last decade, whereas in the later part of the 90's the camp was located at the ELA. The ELA moved to higher elevations during this decade due to increased melting. The fall-winter-spring accumulation variability and the summer melt will be discussed for the 15-year time record. The annual snow accumulation varied between 18 cm water equivalent (w.e.) to 75 cm w.e. during that period. Further, the sensitivity of albedo-feedback (snow fall events) on summer melt will be discussed based on in-situ data. Air temperature and accumulation records will be used to explain the variation of the ELA.

  1. Robust Adaptation Research in High Mountains: Integrating the Scientific, Social, and Ecological Dimensions of Glacio-Hydrological Change

    Graham McDowell


    Full Text Available Climate-related changes in glacierized watersheds are widely documented, stimulating adaptive responses among the 370 million people living in glacier-influenced watersheds as well as aquatic and riparian ecosystems. The situation denotes important interdependencies between science, society, and ecosystems, yet integrative approaches to the study of adaptation to such changes remain scarce in both the mountain- and non-mountain-focused adaptation scholarship. Using the example of glacio-hydrological change, it is argued here that this analytical limitation impedes the identification, development, and implementation of “successful” adaptations. In response, the paper introduces three guiding principles for robust adaptation research in glaciated mountain regions. Principle 1: Adaptation research should integrate detailed analyses of watershed-specific glaciological and hydro-meteorological conditions; glacio-hydrological changes are context-specific and therefore cannot be assumed to follow idealized trajectories of “peak water”. Principle 2: Adaptation research should consider the complex interplay between glacio-hydrological changes and socio-economic, cultural, and political conditions; responses to environmental changes are non-deterministic and therefore not deducible from hydrological changes alone. Principle 3: Adaptation research should be attentive to interdependencies, feedbacks, and tradeoffs between human and ecological responses to glacio-hydrological change; research that does not evaluate these socio-ecological dynamics may lead to maladaptive adaptation plans. These principles call attention to the linked scientific, social, and ecological dimensions of adaptation, and offer a point of departure for future climate change adaptation research in high mountains.

  2. High geothermal heat flux measured below the West Antarctic Ice Sheet.

    Fisher, Andrew T; Mankoff, Kenneth D; Tulaczyk, Slawek M; Tyler, Scott W; Foley, Neil


    The geothermal heat flux is a critical thermal boundary condition that influences the melting, flow, and mass balance of ice sheets, but measurements of this parameter are difficult to make in ice-covered regions. We report the first direct measurement of geothermal heat flux into the base of the West Antarctic Ice Sheet (WAIS), below Subglacial Lake Whillans, determined from the thermal gradient and the thermal conductivity of sediment under the lake. The heat flux at this site is 285 ± 80 mW/m(2), significantly higher than the continental and regional averages estimated for this site using regional geophysical and glaciological models. Independent temperature measurements in the ice indicate an upward heat flux through the WAIS of 105 ± 13 mW/m(2). The difference between these heat flux values could contribute to basal melting and/or be advected from Subglacial Lake Whillans by flowing water. The high geothermal heat flux may help to explain why ice streams and subglacial lakes are so abundant and dynamic in this region.

  3. Moulin distribution and formation on the southwest Greenland ice sheet

    Chu, V. W.; Smith, L. C.; Gleason, C. J.; Yang, K.; Poinar, K.; Joughin, I.; Pitcher, L. H.


    River moulins represent a significant connection between surface meltwater generated on the Greenland ice sheet and subglacial drainage networks, where increased meltwater can enhance ice sliding dynamics. In this study, a new high-resolution moulin map is created from WorldView-1/2 imagery acquired during the 2012 record melt year for a 12,500 km2 area near Russell Glacier in southwest Greenland. A total of 1,236 moulins are mapped and categorized as being located: in crevasse fields, along a single ice fracture, within drained lake basins, or having no visible formation mechanism. We find the presence of moulins up to 1787 m elevation, with 11% of moulins found above 1600 m elevation: higher than previously mapped moulins and where glaciological theory suggests few moulins should form. Our study observes moulins in both extensional and compressional ice flow regimes (28% of moulins are found in areas of high extensional strain rate >0.005 yr-1), suggesting that strain rates are not a strong indicator of the likelihood for moulin formation. Overall, moulin density tends to increase with higher bed elevation, thinner ice, lower surface slope, higher velocity, and higher strain rate. In sum, moulins are most common in crevassed, thinner ice near the ice sheet edge, but significant quantities also develop at high elevations. This indicates that future inland expansion of melting may create hydrologic connections between the surface and the bed at higher elevations than previously thought.

  4. Proceedings from glaciation and hydrogeology. Workshop on the impact of climate change and glaciations on rock stresses, groundwater flow and hydrochemistry - Past, present and future

    King-Clayton, L.; Chapman, N. [eds.] [QuantiSci Ltd (United Kingdom); Ericsson, L.O. [ed.] [SKB, Stockholm (Sweden); Kautsky, F. [ed.] [SKI, Stockholm (Sweden)


    Assessment of the long term safety of radioactive waste disposal requires assimilation of evidence for the impact of climate change and especially glaciation on the geosphere, particularly in terms of its implications for: the distribution and stability of stress regimes, groundwater flux and flow patterns, groundwater chemistry, and thermal conditions. This workshop was intended to promote informal scientific discussion and the exchange of information and ideas between a wide range of disciplines such as climatology, glaciology, hydrology, hydrochemistry, rock mechanics and structural geology. Participants from outside the radioactive waste community were welcome. Of particular need were palaeosignatures, direct observational information and models of the impact of continental ice sheets and periglacial conditions on crystalline bedrock. The workshop has highlighted the fact that there is a great deal of interest in the area of climate change and its impact on the performance of a deep geological repository, but that there are still many issues remaining that require further resolution. The first half of these proceedings gives overviews of the discussions and conclusions from the different sessions at the workshop, as well as the general conclusion and summary. In the second half, summaries of 49 contributions to the workshop are printed. These summaries have been indexed separately.

  5. Gulkana Glacier, Alaska-Mass balance, meteorology, and water measurements, 1997-2001

    March, Rod S.; O'Neel, Shad


    The measured winter snow, maximum winter snow, net, and annual balances for 1997-2001 in the Gulkana Glacier basin are determined at specific points and over the entire glacier area using the meteorological, hydrological, and glaciological data. We provide descriptions of glacier geometry to aid in estimation of conventional and reference surface mass balances and descriptions of ice motion to aid in the understanding of the glacier's response to its changing geometry. These data provide annual estimates for area altitude distribution, equilibrium line altitude, and accumulation area ratio during the study interval. New determinations of historical area altitude distributions are given for 1900 and annually from 1966 to 2001. As original weather instrumentation is nearing the end of its deployment lifespan, we provide new estimates of overlap comparisons and precipitation catch efficiency. During 1997-2001, Gulkana Glacier showed a continued and accelerated negative mass balance trend, especially below the equilibrium line altitude where thinning was pronounced. Ice motion also slowed, which combined with the negative mass balance, resulted in glacier retreat under a warming climate. Average annual runoff augmentation by glacier shrinkage for 1997-2001 was 25 percent compared to the previous average of 13 percent, in accordance with the measured glacier volume reductions.

  6. Volcanic synchronisation between the EPICA Dome C and Vostok ice cores (Antarctica 0–145 kyr BP

    R. Udisti


    Full Text Available This study aims at refining the synchronisation between the EPICA Dome C (EDC and Vostok ice cores in the time interval 0–145 kyr BP by using the volcanic signatures. 102 common volcanic events were identified by using continuous electrical conductivity (ECM, di-electrical profiling (DEP and sulfate measurements while trying to minimize the distortion of the glaciological chronologies. This is an update and a continuation of previous works performed over the 0–45 kyr interval that provided 56 tie points to the ice core chronologies (Udisti et al., 2004. This synchronisation will serve to establish Antarctic Ice Core Chronology 2012, the next synchronised Antarctic dating. A change of slope in the EDC-depth/Vostok-depth diagram is probably related to a change of accumulation regime as well as to a change of ice thickness upstream of the Lake Vostok, but we did not invoke any significant temporal change of surface accumulation at EDC relative to Vostok. No significant phase difference is detected between the EDC and Vostok isotopic records, but depth shifts between the Vostok 3G and 5G ice cores prevent from looking at this problem accurately. Three possible candidates for the Toba volcanic super-eruption ~73 kyr ago are suggested in the Vostok and EDC volcanic records. Neither the ECM, DEP nor the sulfate fingerprints for these 3 events are significantly larger than many others in the records.

  7. A 780-year record of explosive volcanism from DT263 ice core in east Antarctica

    ZHOU Liya; LI Yuansheng; Jihong Cole-da; TAN Dejun; SUN BO; REN Jiawen; WEI Lijia; WANG Henian


    Ice cores recovered from polar ice sheet Received and preserved sulfuric acid fallout from explosive volcanic eruptions. DT263 ice core was retrieved from an east Antarctic location. The ice core is dated using a combination of annual layer counting and volcanic time stratigraphic horizon as 780 years (1215-1996 A.D.). The ice core record demonstrates that during the period of approximately 1460-1800 A.D., the accumulation is sharply lower than the levels prior to and after this period. This period coincides with the most recent neoglacial climatic episode, the "Little Ice Age (LIA)", that has been found in numerous Northern Hemisphere proxy and historic records.The non-sea-salt SO2-4 concentrations indicate seventeen volcanic events in DT263 ice core. Compared with those from previous Antarctic ice cores, significant discrepancies are found between these records in relative volcanic flux of several well-known events. The discrepancies among these records may be explained by the differences in surface topography, accumulation rate, snow drift and distribution which highlight the potential impact of local glaciology on ice core volcanic records, analytical techniques used for sulfate measurement, etc. Volcanic eruptions in middle and high southern latitudes affect volcanic records in Antarctic snow more intensively than those in the Iow latitudes.

  8. Discovery and Significance of Quaternary Glacial Vestiges in the Hexigten Area of the Southern Da Hinggan Mountains, Inner Mongolia

    SUN Hongyan; TIAN Mingzhong; WU Fadong; ZHANG Jianping


    The question whether there have been Quaternary glaciations in the Da Hinggan area has puzzled glacial geologists for many years because no sufficient glacial evidence has been found in this area. The study of Quaternary glaciers in the Da Hinggan area is also a key issue of the glaciology in China because of the special location of this area. In the past two years,a large number of complete and typical glacial vestiges have been found in Hexigten in the southern Da Hinggan Mountains,such as fossil cirque groups,horns,knife-edge crests,terminal moraines,glacial stepped stones.These landforms are located at a watershed,which are thus impossible to be formed due to tectonic processes,water or weathering,but can only be formed by glaciation. The calculated flat indexes of the fossil cirques in the Hexigten are 1.7-4.5,4-5 and 1.3-5,which are within the range of 1.7-5 that is the flat index of real cirques. The typical and complete moraines have also been found in this area. All these glacial vestiges prove that the Quaternary glaciers did exist in the Da Hinggan Mountains of eastern China. Thus,it is of important scientific significance for the research on Chinese,even the global climatic and environmental evolution since the Quaternary.

  9. Characterization of glacier debris cover via in situ and optical remote sensing methods: a case study in the Khumbu Himalaya, Nepal

    K. A. Casey


    Full Text Available Field spectrometry and physical samples of debris, snow and ice were collected from the ablation zones of Ngozumpa and Khumbu glaciers of the Khumbu Himalaya, Nepal in November and December 2009. Field acquired spectral reflectances and mineral and chemical composition of samples were used as ground truth for comparison with satellite optical remote sensing data. Supraglacial debris was characterized by several optical remote sensing methods, including hyperspectral reflectance analysis, multispectral band composites and indices, spectral angle relationships, thermal band temperature and emissivity analysis, as well as repeat image derived glacier velocity and theoretical supraglacial particle transport. Supraglacial mineral components were identified and mineral abundances were estimated on Khumbu Himalayan glaciers. Mass flux was estimated by false color composites and glacier velocity displacement fields. Supraglacial temperatures were compared with mineral abundances, implying potential parameters to estimate differential melt. Overall, glaciologic implications of debris cover characterizations are applicable to (1 glacier energy balance, (2 glacial kinematics and (3 mapping glacial extent. The methods presented can be used in synergy to improve supraglacial debris quantification and reduce errors associated with debris covered ice extent mapping, surface radiative properties, as well as debris covered ice mass flux and loss estimations.

  10. Recent mass balance of the Purogangri Ice Cap, central Tibetan Plateau, by means of differential X-band SAR interferometry

    N. Neckel


    Full Text Available Due to their remoteness, altitude and harsh climatic conditions, little is known about the glaciological parameters of ice caps on the Tibetan Plateau. This study presents a geodetic mass balance estimate of the Purogangri Ice Cap, Tibet's largest ice field between 2000 and 2012. We utilized data from the actual TerraSAR-X mission and its add-on for digital elevation measurements and compared it with elevation data from the Shuttle Radar Topography Mission. The employed data sets are ideal for this approach as both data sets were acquired at X-band at nearly the same time of the year and are available at a fine grid spacing. In order to derive surface elevation changes we employed two different methods. The first method is based on differential synthetic radar interferometry while the second method uses common DEM differencing. Both approaches revealed a slightly negative mass budget of −44 ± 15 and −38 ± 23 mm w.eq. a−1 (millimeter water equivalent respectively. A slightly negative trend of −0.15 ± 0.01 km2 a−1 in glacier extent was found for the same time period employing a time series of Landsat data. Overall, our results show an almost balanced mass budget for the studied time period. Additionally, we detected one continuously advancing glacier tongue in the eastern part of the ice cap.

  11. Influence of high-order mechanics on simulation of glacier response to climate change: insights from Haig Glacier, Canadian Rocky Mountains

    S. Adhikari


    Full Text Available Evolution of glaciers in response to climate change has mostly been simulated using simplified dynamical models. Because these models do not account for the influence of high-order physics, corresponding results may exhibit some biases. For Haig Glacier in the Canadian Rocky Mountains, we test this hypothesis by comparing simulation results obtained from 3-D numerical models that deal with different assumptions concerning ice-flow physics, ranging from simple shear-deformation to comprehensive Stokes flow. In glacier retreat scenarios, we find a minimal role of high-order mechanics in glacier evolution, as geometric effects at our site (the presence of an overdeepened bed result in limited horizontal movement of ice (flow speed on the order of a few meters per year. Consequently, high-order and reduced models all predict that Haig Glacier ceases to exist by ca. 2080 under ongoing climate warming. The influence of high-order mechanics is evident, however, in glacier advance scenarios, where ice speeds are greater and ice dynamical effects become more important. To generalize these findings for other glacier applications, we advise that high-order mechanics are important and therefore should be considered while modelling the evolution of active glaciers. Reduced model predictions may, however, be adequate for other glaciologic and topographic settings, particularly where flow speeds are low.

  12. Antarctic icebergs melt over the Southern Ocean : Climatology and impact on sea ice

    Merino, Nacho; Le Sommer, Julien; Durand, Gael; Jourdain, Nicolas C.; Madec, Gurvan; Mathiot, Pierre; Tournadre, Jean


    Recent increase in Antarctic freshwater release to the Southern Ocean is suggested to contribute to change in water masses and sea ice. However, climate models differ in their representation of the freshwater sources. Recent improvements in altimetry-based detection of small icebergs and in estimates of the mass loss of Antarctica may help better constrain the values of Antarctic freshwater releases. We propose a model-based seasonal climatology of iceberg melt over the Southern Ocean using state-of-the-art observed glaciological estimates of the Antarctic mass loss. An improved version of a Lagrangian iceberg model is coupled with a global, eddy-permitting ocean/sea ice model and compared to small icebergs observations. Iceberg melt increases sea ice cover, about 10% in annual mean sea ice volume, and decreases sea surface temperature over most of the Southern Ocean, but with distinctive regional patterns. Our results underline the importance of improving the representation of Antarctic freshwater sources. This can be achieved by forcing ocean/sea ice models with a climatological iceberg fresh-water flux.

  13. A century of variation in the dependence of Greenland iceberg calving on ice sheet surface mass balance and regional climate change.

    Bigg, G R; Wei, H L; Wilton, D J; Zhao, Y; Billings, S A; Hanna, E; Kadirkamanathan, V


    Iceberg calving is a major component of the total mass balance of the Greenland ice sheet (GrIS). A century-long record of Greenland icebergs comes from the International Ice Patrol's record of icebergs (I48N) passing latitude 48° N, off Newfoundland. I48N exhibits strong interannual variability, with a significant increase in amplitude over recent decades. In this study, we show, through a combination of nonlinear system identification and coupled ocean-iceberg modelling, that I48N's variability is predominantly caused by fluctuation in GrIS calving discharge rather than open ocean iceberg melting. We also demonstrate that the episodic variation in iceberg discharge is strongly linked to a nonlinear combination of recent changes in the surface mass balance (SMB) of the GrIS and regional atmospheric and oceanic climate variability, on the scale of the previous 1-3 years, with the dominant causal mechanism shifting between glaciological (SMB) and climatic (ocean temperature) over time. We suggest that this is a change in whether glacial run-off or under-ice melting is dominant, respectively. We also suggest that GrIS calving discharge is episodic on at least a regional scale and has recently been increasing significantly, largely as a result of west Greenland sources.

  14. Orthothermographies and 3D modeling as potential tools in ice caves studies: the Peña Castil Ice Cave (Picos de Europa, Northern Spain

    Fernando Berenguer-Sempere


    Full Text Available Currently there are many studies focused on the investigation of climatic and glaciological condition of ice caves. Here we present another way to address these studies, applying some methods already used in fields other than geomorphology. The versatility and accuracy provided by the use of modern topography and thermography techniques, using Terrestrial Laser Scanner and current thermographic cameras- and the creation of 3D thermographic models and orthothermographies derived from them - is shown to be a useful tool as it is difficult to obtain data from fieldwork and traditional methods used in caves. This paper presents the potential uses of combined TLS and thermographic techniques for monitoring some important climatological parameters in the sensitive periglacial environment of the Iberian Atlantic high mountains: Peña Castil Ice Cave (Picos de Europa, Northern Spain. A systematic application of such combined technologies to these kind of caves, is expected to contribute to a quantitative and concise characterization of the evolution of the ice as shown by the results of this study.

  15. Frontiers in Geomorphometry and Earth Surface Dynamics: possibilities, limitations and perspectives

    Sofia, Giulia; Hillier, John K.; Conway, Susan J.


    Geomorphometry, the science of quantitative land-surface analysis, has become a flourishing interdisciplinary subject, with applications in numerous fields. The interdisciplinarity of geomorphometry is its greatest strength and also one of its major challenges. Gaps are still present between the process focussed fields (e.g. soil science, glaciology, volcanology) and the technical domain (such as computer science, statistics …) where approaches and theories are developed. Thus, interesting geomorphometric applications struggle to jump between process-specific disciplines, but also struggle to take advantage of advances in computer science and technology. This special issue is therefore focused on facilitating cross-fertilization between disciplines, and highlighting novel technical developments and innovative applications of geomorphometry to various Earth-surface processes. The issue collects a variety of contributions which fall into two main categories: Perspectives and Research, further divided into "Research and innovative techniques" and "Research and innovative applications". It showcases potentially exciting developments and tools which are the building blocks for the next step-change in the field.

  16. A statistical approach to iceberg calving: The role of disorder and the demise of deterministic predictability (Invited)

    Bassis, J. N.


    One of the discoveries in glaciology over the past decade with far reaching consequences is the realization that iceberg calving provides an efficient mechanism to transfer large amounts of ice to the ocean in a near instantaneous fashion. Most attempts at formulating models of the fracture process that precedes iceberg calving have focused on developing criteria that predict when an isolated crevasse can penetrate the entire ice thickness. In this presentation we argue that because the distribution of pre-existing flaws within the ice is something which is largely unknown, the statistical nature of fracture must be considered. We propose a statistical model of iceberg calving based on a combination of extreme value statistics - an approach increasingly common in modeling fracture of quasi-brittle materials - and statistical-thermodynamics - an approach which allows macroscopic, large-scale state variables to influence statistical dynamics of individual flaws. In the theory that we present, the probability of fracture and hence of iceberg calving is a function of the applied stress, ice thickness and fracture density. The size-distribution of fractures is determined using a statistical-thermodynamic approach specifically developed for fracture of disordered media. We compare predictions of our model against observed advance and retreat rates of Greenland outlet glaciers as well as Antarctic ice shelves. A key prediction of our model is the existence of fluctuations in the position of ice fronts, stable or otherwise. These fluctuations can occasionally bump an otherwise healthy tidewater glacier into a phase of irreversible, rapid retreat.

  17. Non-climatic signal in ice core records: lessons from Antarctic mega-dunes

    A. Ekaykin


    Full Text Available We present the results of glaciological investigations in the mega-dune area located 30 km to the east from Vostok Station (central East Antarctica implemented during the 58th, 59th and 60th Russian Antarctic Expedition (January 2013–January 2015. Snow accumulation rate and isotope content (δD, δ18O and δ17O were measured along the 2 km profile across the mega-dune ridge accompanied by precise GPS altitude measurements and GPR survey. It is shown that the spatial variability of snow accumulation and isotope content covaries with the surface slope. The accumulation rate regularly changes by one order of magnitude within the distance −1. The full cycle of the dune drift is thus about 410 years. Since the spatial anomalies of snow accumulation and isotopic composition are supposed to drift with the dune, an ice core drilled in the mega-dune area would exhibit the non-climatic 410 year cycle of these two parameters. We simulated a vertical profile of snow isotopic composition with such a non-climatic variability, using the data on the dune size and velocity. This artificial profile is then compared with the real vertical profile of snow isotopic composition obtained from a core drilled in the mega-dune area. We note that the two profiles are very similar. The obtained results are discussed in terms of interpretation of data obtained from ice cores drilled beyond the mega-dune areas.


    A. Richter


    Full Text Available Results of geodetic in-situ observations of ice-flow velocities in the southern part of subglacialLakeVostokare combined with data sets of the ice surface topography, ice thickness, surface accumulation, basal accretion and firn/ice density for interpretations regarding the glaciological setting of theLakeVostoksystem. Based on the ice-flow velocities and the ice thickness, mean surface accumulation rates are derived applying the flux gate method. These are representative for surface segments extending from the southern part ofLakeVostokto the Ridge B ice divide. They are consistent with the present-day accumulation rate at Vostok station and its variation upstream and thus suggest that the area has been close to steady state. In addition, ice-flow dynamics are investigated along a flow line segment extending from26 kmupstream to12 kmdownstream from Vostok station. The analysis suggests deficiencies in current modelling approaches within the transition zone from floating to grounded ice.

  19. Recent Russian remote sensing investigations in Antarctica within the framework of scientiifc traverses

    Sergey V.Popov


    This paper includes a short historical review of Russian and Soviet scientiifc traverses to study the Antarctic inland. The ifrst traverse left on April 2, 1956. It resulted in the opening of the ifrst Russian inland research station named Pionerskaya and provided the ifrst geophysical and glaciological data on regions inland of the Antarctic coast. By 1965, a number of regional inland scientiifc traverses had been completed and the ifrst Atlas of Antarctica was published in 1966. The atlas presented the main achievements of that time. After the discovery of Lake Vostok, Russian scientists commenced remote sensing investigations to study this unique natural phenomenon. The propagation of acoustic and electromagnetic waves in the glacier near Vostok Station were measured to provide important geophysical data. Radio-echo sounding data showed that Lake Vostok is isolated and separated from the rest of the Antarctic subglacial hydrosphere. The total area of the lake is 15 790 km2, excluding 365 km2 occupied by 11 islands. Relfection seismic soundings of Lake Vostok estimated a total volume of about 6 100 km3, an average depth of about 400 m, and a maximum depth of 1 200 m. Since 2008, there have been a number of scientiifc traverses between Mirny and Vostok stations and between Progress and Vostok stations. The data collected during the traverses have provided new insights into sub-ice topography and ice sheet structure, and have led to the discovery of subglacial lakes near Komsomolskaya Station and under Pionerskaya Station.

  20. Distributed energy balance modeling of South Cascade Glacier, Washington and assessment of model uncertainty

    Anslow, Faron S.; Hostetler, S.; Bidlake, W.R.; Clark, P.U.


    We have developed a physically based, distributed surface energy balance model to simulate glacier mass balance under meteorological and climatological forcing. Here we apply the model to estimate summer ablation on South Cascade Glacier, Washington, for the 2004 and 2005 mass balance seasons. To arrive at optimal mass balance simulations, we investigate and quantify model uncertainty associated with selecting from a range of physical parameter values that are not commonly measured in glaciological mass balance field studies. We optimize the performance of the model by varying values for atmospheric transmissivity, the albedo of surrounding topography, precipitation-elevation lapse rate, surface roughness for turbulent exchange of momentum, and snow albedo aging coefficient. Of these the snow aging parameter and precipitation lapse rates have the greatest influence on the modeled ablation. We examined model sensitivity to varying parameters by performing an additional 103 realizations with parameters randomly chosen over a ??5% range centered about the optimum values. The best fit suite of model parameters yielded a net balance of -1.69??0.38 m water equivalent (WE) for the 2004 water year and -2.10??0.30 m WE up to 11 September 2005. The 2004 result is within 3% of the measured value. These simulations account for 91% and 93% of the variance in measured ablation for the respective years. Copyright 2008 by the American Geophysical Union.

  1. Measuring melt and velocity of Alaskan mountain glaciers using phase-sensitive radar and differential GPS

    Neuhaus, S.; Tulaczyk, S. M.


    Alaskan glaciers show some of the highest rates of retreat worldwide, contributing to sea level rise. This retreat is due to both increased velocity and increased melt. We seek to understand the role of glacial meltwater on velocity. Matanuska glacier, a land terminating glacier in Alaska, has been well-studied using traditional glaciological techniques, but new technology has emerged that allows us to measure melt and velocity more accurately. We employed high-resolution differential GPS to create surface velocity profiles across flow in the ablation zone during the summer of 2015. We also measured surface ablation using stakes and measured basal melt using phase-sensitive radar designed by the British Antarctic Survey. The positions acquired by differential GPS are obtained to a resolution of less than 0.5m, while feature tracking using time-lapse photography for the same time period yields positions with greater and more variable uncertainty. The phase-sensitive radar provides ice thinning rates. Phase-sensitive radar together with ground penetrating radar provides us with an understanding of the internal structure of the glacier. This suite of data allows us to determine the relative importance of surface melt, basal melt, and internal deformation on ice velocity in warm mountain glaciers.

  2. 探测冰盖和多年冻土层的融冰探头研发%Development of Melting Probes for Exploring Ice Sheets and Permafrost Layers

    Norbert I. K(o)mle; Melanie Treffer; Gunter Kargl; Erika Kaufrnann; Manfred Steller


    The exploration of ice sheets by melting vertical holes into the ground has some tradition in terrestrial glaciology. Such probes have been used since the 1960's to investigate the vertical structure of the ice in Greenland and Antarctica and in alpine glaciers. In this paper we look into the possibility to develop similar devices for use on extraterrestrial icy bodies, like e.g. the polar areas on Mars or the icy satellites of the outer solar system. We report on some basic experiments performed in the cryo-vacuum laboratory of the Space Research Institute of the Austrian Academy of Sciences, Graz. In these experiments the penetration of a simple melting probe into compact and porous water ice (with a snow-like texture) was monitored, both under vacuum conditions and under air pressure. The observed penetration speeds for a given power supply are compared with a simple mathematical model. We conclude that a miniature melting probe with small overall dimensions and a reasonable power demand could well be part of the payload of a future planetary mission, for example to the poles of Mars. Such missions are currently under discussion in several space agencies. Moreover such probes could also e? ectively be used in terrestrial environments. A possible design is presented at the end of the paper.

  3. Reanalysing glacier mass balance measurement series

    M. Zemp


    Full Text Available Glacier-wide mass balance has been measured for more than sixty years and is widely used as an indicator of climate change and to assess the glacier contribution to runoff and sea level rise. Until recently, comprehensive uncertainty assessments have rarely been carried out and mass balance data have often been applied using rough error estimation or without consideration of errors. In this study, we propose a framework for reanalysing glacier mass balance series that includes conceptual and statistical toolsets for assessment of random and systematic errors, as well as for validation and calibration (if necessary of the glaciological with the geodetic balance results. We demonstrate the usefulness and limitations of the proposed scheme, drawing on an analysis that comprises over 50 recording periods for a dozen glaciers, and we make recommendations to investigators and users of glacier mass balance data. Reanalysing glacier mass balance series needs to become a standard procedure for every monitoring programme to improve data quality, including reliable uncertainty estimates.

  4. Use of high frequency radiometer and altimeter on board AMSU-B, AMSR-E and Altika/SARAL for observations of the Antarctic ice sheet surface.

    Adodo, Fifi; Picard, Ghislain; Remy, Frederique


    Snow surface properties quickly evolved according to local weather conditions, therefore are climate change indicator. These snow surface properties such as grain size, density, accumulation rate etc... are very important for evaluation and monitoring of the impact of global warming on the polar ice sheet. In order to retrieve these snowpack properties, we explore the high frequency microwave radiometer variable( Brightness Temperature (Tb)) on the Antarctic ice sheet on-board AMSU-B , AMSR-E in combination with the ALTIKA altimeter (37GHz) waveform parameters (Backscatter coefficient, Trailing edge Slope(TeS) and Leading edge Width(LeW)). We compare the radiometer brightness temperature to calculations with the DMRT- ML radiative transfer model which simulates brightness temperature in vertical and horizontal polarizations. With some assumptions, this combination allows a good retrieval of snowpack properties. We showed positive trend of the grains size on the Antarctic plateau especially at Dome C during the two last decades. This work will provide a higher accuracy of the estimation of snowpack surfaces properties and contribute to monitoring the ice sheet surface mass balance, well constraining of meteorological and glaciological models.

  5. Widespread expansion of glacier moraine-dammed lakes in the Chinese Himalaya

    Liu, Shiyin; Ng, Felix; Wang, Xin; Guo, Wanqin; Yao, Xiaojun; Yu, Pengchun; Xu, Junli; Ding, Yongjian


    More moraine-dammed lakes in the Himalaya may form and enlarge due to glacier retreat and increased meltwater availability under the climatic warming that has been recorded across this mountain range over the last few decades. Because of this, and because such lakes have caused major GLOF (glacial lake outburst flood) events before, international organisations have been developing lake inventories to evaluate flood risks in the Himalaya, mainly in the south. Here we present the first complete inventory of moraine-dammed lakes on the Chinese side, which shows expansion and formation dominate their behaviour from the 1970s to the 2000s. We found that while their number has remained at ≈1200, their combined area has drastically increased, and glacier retreat also helped focus this overall growth in a narrow elevation range where many large new lakes have appeared. Our discovery of a glacier-recession signal in the lakes' variation underlines the need to study the climatological and glaciological factors behind lake evolution.

  6. The U.S. Geological Survey in Alaska; 1981 programs

    Reed, Katherine M.; Gilmore, Robert F.; Harris, Linda-Lee; Tennison, Lisa D.


    This Circular describes the 1981 programs and projects of the U.S. Geological Survey in Alaska. A brief description of the Alaskan operations of each office and division of the Survey is followed by project descriptions arranged by geographic regions in which the work takes place. The largest program at present is related to oil and gas exploration, but programs also include mineral appraisal, water-resource studies, volcanic and seismic programs, topographic mapping, glaciological and geohazard studies, and many other activities. Alaska is the largest and the least populated, least explored, and least developed of the Nation 's States. The land area contains 375 million acres and comprises 16 percent of the onshore land and more than half of the Outer Continental Shelf of the Nation. After Native and State of Alaska land selections of 44 million acres have been made, approximately 60 percent, 225 million acres, of Alaska land will remain under Federal jurisdiction. Federal lands in Alaska then will comprise approximately 30 percent of all onshore land in the Nation 's public domain. (USGS)

  7. High Resolution Topography of Polar Regions from Commercial Satellite Imagery, Petascale Computing and Open Source Software

    Morin, Paul; Porter, Claire; Cloutier, Michael; Howat, Ian; Noh, Myoung-Jong; Willis, Michael; Kramer, WIlliam; Bauer, Greg; Bates, Brian; Williamson, Cathleen


    Surface topography is among the most fundamental data sets for geosciences, essential for disciplines ranging from glaciology to geodynamics. Two new projects are using sub-meter, commercial imagery licensed by the National Geospatial-Intelligence Agency and open source photogrammetry software to produce a time-tagged 2m posting elevation model of the Arctic and an 8m posting reference elevation model for the Antarctic. When complete, this publically available data will be at higher resolution than any elevation models that cover the entirety of the Western United States. These two polar projects are made possible due to three equally important factors: 1) open-source photogrammetry software, 2) petascale computing, and 3) sub-meter imagery licensed to the United States Government. Our talk will detail the technical challenges of using automated photogrammetry software; the rapid workflow evolution to allow DEM production; the task of deploying the workflow on one of the world's largest supercomputers; the trials of moving massive amounts of data, and the management strategies the team needed to solve in order to meet deadlines. Finally, we will discuss the implications of this type of collaboration for future multi-team use of leadership-class systems such as Blue Waters, and for further elevation mapping.

  8. Ice flow modelling at EPICA Dome C and Dome Fuji, East Antarctica

    F. Parrenin


    Full Text Available 1-D ice flow models are used to construct the age scales at the Dome C and Dome Fuji drilling sites (East Antarctica. The poorly constrained glaciological parameters at each site are recovered by fitting independent age markers identified on each core. We reconstruct past accumulation rates, that are larger than those modelled using the classical vapour saturation pressure relationship during glacial periods by up to a factor 1.5. During the Early Holocene, changes in reconstructed accumulation are not linearly related to changes in ice isotopic composition. A simple model of past elevation changes is developed and shows an amplitude variation of 110–120 m at both sites. We suggest that there is basal melting at Dome C (0.56±0.19 mm/yr. The reconstructed velocity profile is highly non linear at both sites, which suggests complex ice flow effects. This induces a non linear thinning function in both drilling sites, which is also characterized by bumps corresponding to variations in surface elevation with time.

  9. Glacial Isostatic Adjustment - a hot topic in cold regions

    Whitehouse, Pippa


    Glacial Isostatic Adjustment (GIA) modelling tackles the classic geodynamical problem of determining the solid Earth response to surface load changes by ice and ocean water whilst at the same time solving for the gravitationally-consistent redistribution of ice sheet meltwater across the global ocean. Understanding this process is important for quantifying both present-day ice mass balance and the response of ice sheets to past and future climatic change. The two fundamental unknowns in this problem are (i) the rheology of the solid Earth, and (ii) the history of global ice sheet change. In this talk I will discuss the myriad of approaches that are used to constrain these two components. In particular, I will focus on Antarctica, where the presence of a continuously-evolving ice sheet, situated on top of one of the most rheologically-diverse regions of the planet, provides us with a challenge that can only be resolved by drawing on knowledge from across the fields of geodynamics, glaciology, geology, geodesy and seismology.

  10. Changes in glaciers in the Swiss Alps and impact on basin hydrology: current state of the art and future research.

    Pellicciotti, F; Carenzo, M; Bordoy, R; Stoffel, M


    Switzerland is one of the countries with some of the longest and best glaciological data sets. Its glaciers and their changes in response to climate have been extensively investigated, and the number and quality of related studies are notable. However, a comprehensive review of glacier changes and their impact on the hydrology of glacierised catchments for Switzerland is missing and we use the opportunity provided by the EU-FP7 ACQWA project to review the current state of knowledge about past changes and future projections. We examine the type of models that have been applied to infer glacier evolution and identify knowledge gaps that should be addressed in future research in addition to those indicated in previous publications. Common characteristics in long-term series of projected future glacier runoff are an initial peak followed by a decline, associated with shifts in seasonality, earlier melt onset and reduced summer runoff. However, the quantitative predictions are difficult to compare, as studies differ in terms of model structure, calibration strategies, input data, temporal and spatial resolution as well as future scenarios used for impact studies. We identify two sources of uncertainties among those emerging from recent research, and use simulations over four glaciers to: i) quantify the importance of the correct extrapolation of air temperature, and ii) point at the key role played by debris cover in modulating glacier response. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. How do our prior assumptions about basal drag affect ice sheet forecasts?

    Arthern, Robert


    Forecasts of changes in the large ice sheets of Greenland and Antarctica often begin with an inversion to select initial values for state variables and parameters in the model, such as basal drag and ice viscosity. These inversions can be ill-posed in the sense that many different choices for the parameter values can match the observational data equally well. To recover a mathematically well-posed problem, assumptions must be made that restrict the possible values of the parameters, either by regularisation or by explicit definition of Bayesian priors. Common assumptions are that parameters vary smoothly in space or lie close to some preferred initial guess, but for glaciological inversions it is often unclear how smoothly the parameters should vary, or how reliable the initial guess should be considered. This is especially true of inversions for the basal drag coefficient that can vary enormously from place to place on length scales set by subglacial hydrology, which is itself extremely poorly constrained by direct observations. Here we use a combination of forward modelling, inversion and a theoretical analysis based on transformation group priors to investigate different ways of introducing prior information about parameters, and to consider the consequences for ice sheet forecasts.

  12. The Firn Model Inter-Comparison Experiment: Visualizing Firn Densification Models to Characterize Uncertainty in the Physics of Firn Densification

    Leahy, W. P.; Arthern, R. J.; Buizert, C.; Cummings, E.; Essery, R.; Ligtenberg, S.; Orsi, A. J.; Simonsen, S. B.; Brook, E.; Stevens, C.; Harris, P. D.; Lundin, J.; Waddington, E. D.


    Modeling firn densification accurately is necessary for a number of problems in glaciology. Knowledge of the age and depth of firn when it turns to ice is needed to accurately interpret climate records from ice cores. Determining ice-sheet mass balance from satellite altimetry requires knowing the depth-integrated porosity of firn. Multiple research groups have developed models of firn evolution, incorporating different physical processes. The Firn Model Inter-Comparison Experiment (FirnMICE) compares the steady-state and transient behavior of 10 firn-densification models. Each model was spun up to a steady-state, perturbed with a step change in accumulation or temperature, and run to a new steady state. Model output included: depth, density, age, depth and age of bubble close off, and depth-integrated porosity. FirnMICE results are available through an interactive online tool, allowing users to browse the suite of figures for each experiment. The FirnMICE website also includes animations and 3D visualizations of results.

  13. Effects of Climate Changes on Firn Properties and Gas Transport in Firn

    Stevens, C.; Lundin, J.; Vo, H.; Yoon, M.; Waddington, E. D.


    Knowledge of the physics of firn-density evolution and gas transport in firn has several important applications in glaciology, including (1) correcting for firn air content when estimating ice-sheet mass-balance changes from satellite altimetry and (2) determining the ice-age/gas-age difference for paleoclimate interpretations of ice-core records. The firn-physics group at the University of Washington is developing modular and open-source community models describing evolution of firn density, temperature, diffusivity, and other structural properties affecting gas transport. A novel aspect is that the gas model can be coupled to the density model, allowing bubble-close-off depth, lock-in depth, depth-integrated porosity, and effective diffusivity to evolve in the gas-transport model. This feature allows us to investigate changes in firn physical properties and the evolving impacts of those changes on gas diffusion, thermal and gravitational fractionation, and the mixing ratio of gasses in bubbles trapped in firn during climate change events. Here, we use ice-core derived and synthetic climate data to show the scope of these impacts for gradual and abrupt climate changes.

  14. Subglacial till formation: Microscale processes within the subglacial shear zone

    Hart, Jane K.


    This was a study of subglacial deformation till genesis from a modern temperate glacier, at Skálafellsjökull, Iceland. Detailed microscale properties of till samples (from Scanning Electron Microscope [SEM] and thin section analysis) were examined from a glacial site with in situ subglacial process monitoring and an exposed subglacial surface in the foreland. Two lithofacies were examined, a grey sandy till derived from the ash and basalt, and a silty reddish brown till derived from oxidized paleosols and/or tephra layers. These also represented a clay-content continuum from low (0.3%) to high (22.3%). The evolution from debris to subglacial till was investigated. This included a reduction in grain-size (21% for grey lithology, 13% reddish brown lithology), and reduction in rounding (RA) (32% for the grey lithology, 26% for the reddish brown lithology), and the quantification and analysis of the different grain erosion/comminution processes in the resultant till. It was shown that the microstructures within a till were dependent on shear strain and glaciological conditions (deformation history). The low clay content tills were dominated by linear structures (lineations and boudins, and anisotropic microfabric) whilst the higher clay content tills were dominated by rotational structures (turbates and plaster, and isotropic microfabric). These results are important in our understanding of the formation of both modern and Quaternary tills and informs our reconstruction of past glacial dynamics.

  15. Changes in ice-margin processes and sediment routing during ice-sheet advance across a marginal moraine

    Knight, P.G.; Jennings, C.E.; Waller, R.I.; Robinson, Z.P.


    Advance of part of the margin of the Greenland ice sheet across a proglacial moraine ridge between 1968 and 2002 caused progressive changes in moraine morphology, basal ice formation, debris release, ice-marginal sediment storage, and sediment transfer to the distal proglacial zone. When the ice margin is behind the moraine, most of the sediment released from the glacier is stored close to the ice margin. As the margin advances across the moraine the potential for ice-proximal sediment storage decreases and distal sediment flux is augmented by reactivation of moraine sediment. For six stages of advance associated with distinctive glacial and sedimentary processes we describe the ice margin, the debris-rich basal ice, debris release from the glacier, sediment routing into the proglacial zone, and geomorphic processes on the moraine. The overtopping of a moraine ridge is a significant glaciological, geomorphological and sedimentological threshold in glacier advance, likely to cause a distinctive pulse in distal sediment accumulation rates that should be taken into account when glacial sediments are interpreted to reconstruct glacier fluctuations. ?? 2007 Swedish Society for Anthropology and Geography.

  16. Volcanic synchronisation between the EPICA Dome C and Vostok ice cores (Antarctica 0–145 kyr BP

    F. Parrenin


    Full Text Available This study aims at refining the synchronisation between the EPICA Dome C (EDC and Vostok ice cores in the time interval 0–145 kyr BP by using the volcanic signatures. 111 common volcanic events were identified by using continuous electrical conductivity (ECM, di-electrical profiling (DEP and sulfate measurements while trying to minimize the distortion of the glaciological chronologies. This is an update and a continuation of previous works performed over the 0–45 kyr interval which provided 56 tie points to the ice core chronologies (Udisti et al., 2004. This synchronisation will serve for the establishment of the next synchronised Antarctic dating. A change of slope in the EDC-depth/Vostok-depth diagram is probably related to a change of accumulation regime as well as to a change of ice thickness upstream of the Vostok lake, but we did not invoke any significant temporal change of surface accumulation at EDC relative to Vostok. A significant phase difference is detected between the EDC and Vostok isotopic records during the 95–120 kyr interval, but not during Termination II. Three possible candidates for the Toba volcanic super-eruption ~73 kyr ago are suggested in the Vostok and EDC volcanic records. However the ECM, DEP and sulfate fingerprints for these three events are not significantly larger than many others in the records.

  17. Using Remote Sensing and Rpas for Archaeology and Monitoring in Western Greenland

    Pavelka, K.; Šedina, J.; Matoušková, E.; Faltýnová, M.; Hlaváčová, I.


    Since 2002, German low-cost scientific expeditions to Greenland have been performed. The objective was a geodetic survey and glaciology with GNSS technology - mainly the measurement of glacier profiles (height). The same glacier profiles along the route were measured during German expeditions in 2006, 2010, 2012 and 2015. The last international expedition was supplemented with RPAS (UAV) measurement, the testing of small corner reflectors for Terra SAR X satellite measurement and the use of image based modelling technology for historical monuments documentation, all in specific arctic conditions. The RPAS measurement was focused on the documentation of existing valuable archaeological sites near Ilulissat city and the testing of RPAS technology for the monitoring of the face of the moving glacier. Two typical church wooden constructions were documented by simple photogrammetric technology based on image correlation. Both experiments were evaluated as successfully case projects. The last part of the experiments deals with the monitoring of a moving inland glacier using SAR technology; four corner reflectors were installed on the glacier and on a massive nearby rock. Two ascending and two descending overflights of the Terra SAR X satellite in fine resolution mode were performed. The InSAR technology give inconclusive results, but some movements were detected; small and inexpensive corner reflectors of our own production have proven suitable. Experience and expertise from the measurement such as the first outputs from the expedition are the content of the present article.

  18. TanDEM-X双站SAR干涉测量及研究进展%TanDEM-X bistatic SAR interferometry and its research progress

    孙亚飞; 江利明; 柳林; 孙永玲; 汪汉胜


    This paper comprehensively describes the scientific research plan of the TanDEM -X/TerraSAR -X bistatic SAR mission, with emphasis placed on its scientific objectives, TanDEM-X satellite parameters, orbital configuration and data acquisition modes. Then, the advantages of the new InSAR techniques including bistatic SAR, Pol-InSAR and digital beam forming are briefly discussed and the progress of the techniques of TanDEM-X bistatic SAR interferometry is analyzed. These new SAR techniques will greatly promote the application potential of SAR interferometry in Earth sciences such as global topography mapping, glaciology, oceanography and geology.%较全面、系统地介绍了TanDEM-X/TerraSAR-X双站SAR科学计划,重点涉及其科学目标、TanDEM-X卫星参数、轨道结构以及干涉数据获取模式等相关内容,并讨论了双站SAR成像、极化InSAR和数字波束成形等干涉测量新技术及其研究进展。这些双站SAR新技术的实现将大大地推动SAR干涉测量在全球地形测绘、冰川学、海洋学及地质学等领域中的应用。

  19. Readiness of the Global Land Ice Measurements from Space (GLIMS) Database at NSIDC

    Troisi, V.; Scharfen, G.; Raup, B.; Khalsa, S. S.; Swick, R.; Wang, I.; Barry, R.; Dyurgerov, M.


    GLIMS (Global Land Ice Measurements from Space) is an international project to survey a majority of the world's 160,000 glaciers with data collected by the ASTER (Advanced Spaceborne Thermal Emission and reflection Radiometer) instrument aboard the EOS Terra spacecraft, and Landsat ETM+ (Enhanced Thematic Mapper Plus). Approximately 1,500 ASTER images suitable for GLIMS analyses have been acquired as of Fall 2002. A group of internationally distributed glaciologists at Regional Centers of expertise have begun to analyze the satellite data, derive glacier measurements (glacier geometry, surface velocity, and snowline elevation), and provide them in a consistent format for archival and use by the research community via the World Wide Web. The National Aeronautics Space Administration (NASA) and the United States Geological Survey (USGS) are supporting the GLIMS coordination and data management effort and providing the satellite data. With NASA funding, the National Snow and Ice Data Center (NSIDC) is developing the information management system for GLIMS. The database design, data transfer specification, ingest module were completed this year. User interfaces are being tested. The database is being populated with the initial results from Regional Centers. Contents include measurements (over time) of glacier length, area, boundaries, topography, surface velocity vectors, and snowline elevation. We are also adding historic glacier data from Central Asia. As contributions from the network of Regional Centers increase, the GLIMS information management system will provide an easy to use and widely accessible service for the glaciological community and other users needing information about the world's glaciers.

  20. Double Exposure: Photographing Climate Change

    Arnold, D. P.; Wake, C. P.; Romanow, G. B.


    Double Exposure, Photographing Climate Change, is a fine-art photography exhibition that examines climate change through the prism of melting glaciers. The photographs are twinned shots of glaciers, taken in the mid-20th century by world-renowned photographer Brad Washburn, and in the past two years by Boston journalist/photographer David Arnold. Arnold flew in Washburn's aerial "footprints", replicating stunning black and white photographs, and documenting one irreversible aspect of climate change. Double Exposure is art with a purpose. It is designed to educate, alarm and inspire its audiences. Its power lies in its beauty and the shocking changes it has captured through a camera lens. The interpretive text, guided by numerous experts in the fields of glaciology, global warming and geology, helps convey the message that climate change has already forced permanent changes on the face of our planet. The traveling exhibit premiered at Boston's Museum of Science in April and is now criss-crossing the nation. The exhibit covers changes in the 15 glaciers that have been photographed as well as related information about global warming's effect on the planet today.

  1. Signal processing techniques for phase-coded HF-VHF radars

    J. A. Baskaradas


    Full Text Available HF-VHF radar techniques are easy to employ and commonly used in geophysical applications. They include deep radio soundings, used for probing the ionosphere, stratosphere-mesosphere measurement, weather forecast and radio-glaciology. Fast algorithms and powerful processors facilitate the development of several kinds of low power radars, but the reduction of the transmitted power has to be compensated by on-line processing of an encoded signal to maintain a favorable signal-to-noise ratio suitable for detection. Moreover, radars have to reconstruct return echoes with different travel times due to various origins (multi-path, adjacent objects, etc.. Such needs can be accomplished by means of signal phase coding and one of the most attractive is the reversal phase code. The composite echo signal must be processed to extract the physical information useful for the measurement considered. In this paper some algorithms used for on-line processing of phase-coded signals will be described, both in time and frequency domain.

  2. Bayesian calibration of a post-LGM model of Laurentide ice-sheet evolution

    Tarasov, L.; Peltier, W. R.


    Though numerous inferences have been made with regard to the deglaciation history of the Wisconsin North American ice sheet complex, no attempt has been made to place objective confidence ranges on these inferences. Furthermore, past efforts to reconstruct the Wisconsin deglaciation history have relied on restricted discipline-specific constraints. Approaches based on dynamical glacial models have ignored geophysical constraints such as Relative Sea Level histories. Geophysical based reconstructions, on the other hand, have ignored glaciological self-consistency and Marine Limit data. To remedy this situation, we present a Bayesian calibration of a 3D thermo-mechanically coupled ice-sheet systems model using: 1) a large set of Relative Sea Level observations (from 415 sites), 2) Marine Limit observations, 3) a North-South transect of gravity measurements, 4) direct observations of the present day rate of basal uplift at Yellowknife, 5) and a new high-resolution ice margin chronology derived from geological and geomorphological observations. Given the large parameter space (O(20) parameters), Bayesian neural networks, trained from a thousand runs of the ice-sheet systems model, are employed to simulate the glacial model within the statistical analyses. The end result is a posterior distribution for model parameters (and thereby modelled glacial histories) given the observational data sets that thereby also takes into account data uncertainty. Strong support is provided for a multi-domed Laurentide ice-sheet. We also identify key dynamical processes (ie most relevant model parameters) along with critical geographic regions in need of further data.

  3. Global land ice measurements from space (GLIMS): remote sensing and GIS investigations of the Earth's cryosphere

    Bishop, Michael P.; Olsenholler, Jeffrey A.; Shroder, John F.; Barry, Roger G.; Rasup, Bruce H.; Bush, Andrew B. G.; Copland, Luke; Dwyer, John L.; Fountain, Andrew G.; Haeberli, Wilfried; Kaab, Andreas; Paul, Frank; Hall, Dorothy K.; Kargel, Jeffrey S.; Molnia, Bruce F.; Trabant, Dennis C.; Wessels, Rick L.


    Concerns over greenhouse‐gas forcing and global temperatures have initiated research into understanding climate forcing and associated Earth‐system responses. A significant component is the Earth's cryosphere, as glacier‐related, feedback mechanisms govern atmospheric, hydrospheric and lithospheric response. Predicting the human and natural dimensions of climate‐induced environmental change requires global, regional and local information about ice‐mass distribution, volumes, and fluctuations. The Global Land‐Ice Measurements from Space (GLIMS) project is specifically designed to produce and augment baseline information to facilitate glacier‐change studies. This requires addressing numerous issues, including the generation of topographic information, anisotropic‐reflectance correction of satellite imagery, data fusion and spatial analysis, and GIS‐based modeling. Field and satellite investigations indicate that many small glaciers and glaciers in temperate regions are downwasting and retreating, although detailed mapping and assessment are still required to ascertain regional and global patterns of ice‐mass variations. Such remote sensing/GIS studies, coupled with field investigations, are vital for producing baseline information on glacier changes, and improving our understanding of the complex linkages between atmospheric, lithospheric, and glaciological processes.

  4. Present state and dynamics of glacio-nival systems of Mongun-Taiga and Tavan-Bogdo-Ola mountain massifs

    K. V. Chistyakov


    Full Text Available Climate-induced variations of glacio-nival systems (snow patches, glaciers, stone-ice formations of the high-mountain massifs Mongun-Taiga and Tavan-Bogdo-Ola (north slope were investigated for 1966-2013 period using results of field observations and analysis of aerial photos. Regional 25-year climatic cycles of the variations have been determined. Characteristics of response of glacio-nival objects to the climate changes were obtained. Results of preliminary mass balance calculations made for the 2012/13 glaciological year and values of the mass balance index calculated for the period 1966-2013 for the Seliverstov Glacier together with recorded climate cooling, increase of snow accumulation, and slowing down of glacier snout retreats give evidence to beginning of new 25-year cycle that is expected to be more favorable phase for existence of the above glacio-nival systems. Five-phase scheme of retreats of the valley glaciers happened after the LIA maximum was constructed on the basis of results of field observations performed for many years. Each phase is characterized by different retreat mechanisms as well as by different response to the same climate change that can be used as a basis for forecasting of future glacial dynamics. Rates of the thermokarst processes determined from observations and general mechanisms of dynamics of stone-ice formations are also discussed in the paper.

  5. Parameter and state estimation with a time-dependent adjoint marine ice sheet model

    D. N. Goldberg


    Full Text Available To date, assimilation of observations into large-scale ice models has consisted predominantly of time-independent inversions of surface velocities for basal traction, bed elevation, or ice stiffness, and has relied primarily on analytically-derived adjoints of diagnostic ice velocity models. To overcome limitations of such "snapshot" inversions, i.e. their inability to assimilate time-dependent data, or to produce initial states with minimum artificial drift and suitable for time-dependent simulations, we have developed an adjoint of a time-dependent parallel glaciological flow model. The model implements a hybrid shallow shelf-shallow ice stress balance, involves a prognostic equation for ice thickness evolution, and can represent the floating, fast-sliding, and frozen bed regimes of a marine ice sheet. The adjoint is generated by a combination of analytic methods and the use of algorithmic differentiation (AD software. Several experiments are carried out with idealized geometries and synthetic observations, including inversion of time-dependent surface elevations for past thicknesses, and simultaneous retrieval of basal traction and topography from surface data. Flexible generation of the adjoint for a range of independent uncertain variables is exemplified through sensitivity calculations of grounded ice volume to changes in basal melting of floating and basal sliding of grounded ice. The results are encouraging and suggest the feasibility, using real observations, of improved ice sheet state estimation and comprehensive transient sensitivity assessments.

  6. A model to constrain 21st Century sea level rise from tidewater glaciers

    Ultee, E.; Bassis, J. N.


    Tidewater glaciers are large contributors to global mean sea level rise, both in their own right (e.g. Columbia Glacier, Alaska) and as outlets of the continental ice sheets. Tidewater glaciers are channeled through narrow fjords ( 100-101 km) that are difficult to resolve in continental-scale ice sheet models, hindering sea level rise projections. Moreover, tidewater glaciers respond to difficult-to-resolve local variables, such as precipitation rate and ocean forcing. Here we present a "flowline" model for networks of tidewater glaciers based on Nye's perfect plastic approximation, and we describe how it can be applied to generate constraints on the glaciological contribution to 21st Century sea level rise. The model can be forced with modeled or observed surface mass balance, or coupled with an ice sheet model upstream. Several test cases from Alaska and Greenland demonstrate our model's performance, and we illustrate how adjustments to the sole model parameter can constrain the decade- to century-scale ice flux to the ocean.

  7. Hydrology

    Brutsaert, Wilfried


    Water in its different forms has always been a source of wonder, curiosity and practical concern for humans everywhere. Hydrology - An Introduction presents a coherent introduction to the fundamental principles of hydrology, based on the course that Wilfried Brutsaert has taught at Cornell University for the last thirty years. Hydrologic phenomena are dealt with at spatial and temporal scales at which they occur in nature. The physics and mathematics necessary to describe these phenomena are introduced and developed, and readers will require a working knowledge of calculus and basic fluid mechanics. The book will be invaluable as a textbook for entry-level courses in hydrology directed at advanced seniors and graduate students in physical science and engineering. In addition, the book will be more broadly of interest to professional scientists and engineers in hydrology, environmental science, meteorology, agronomy, geology, climatology, oceanology, glaciology and other earth sciences. Emphasis on fundamentals Clarification of the underlying physical processes Applications of fluid mechanics in the natural environment

  8. Advances in ocean modeling for climate change research

    Holland, William R.; Capotondi, Antonietta; Holland, Marika M.


    An adequate understanding of climate variability and the eventual prediction of climate change are among the most urgent and far-reaching efforts of the scientific community. The climate system is in an ever-changing state with vast impact on mankind in all his activities. Both short and long-term aspects of climate variability are of concern, and the unravelling of "natural" variability from "man-induced" climate change is required to prepare for and ameliorate, if possible, the potentially devastating aspects of such change. In terms of scientific effort, the climate community can be thought of as the union of the disciplinary sciences of meteorology, oceanography, sea ice and glaciology, and land surface processes. Since models are based upon mathematical and numerical constructs, mathematics and computer sciences are also directly involved. In addition, some of the problems of man-induced climate change (release of greenhouse gases, the ozone-hole problem, etc.) are basically chemical in nature, and the expertise of the atmospheric and oceanic chemist is also required. In addition, some part of the response to climate perturbations will arise in the biological world, due to upsetting the balance in the great food web that binds communities together on both the land and the sea. Thus, the problems to be solved are extraordinarily complex and require the efforts of many kinds of scientist.

  9. A new DEM of the Austfonna ice cap by combining differential SAR interferometry with ICESat laser altimetry

    Geir Moholdt


    Full Text Available We present a new digital elevation model (DEM of the Austfonna ice cap in the Svalbard Archipelago, Norwegian Arctic. Previous DEMs derived from synthetic aperture radar (SAR and optical shape-from-shading have been tied to airborne radio echo-sounding surface profiles from 1983 which contain an elevation-dependent bias of up to several tens of metres compared with recent elevation data. The new and freely available DEM is constructed purely from spaceborne remote sensing data using differential SAR interferometry (DInSAR in combination with ICESat laser altimetry. Interferograms were generated from pairs of SAR scenes from the one-day repeat tandem phase of the European Remote Sensing Satellites 1/2 (ERS-1/2 in 1996. ICESat elevations from winter 2006–08 were used as ground control points to refine the interferometric baseline. The resulting DEM is validated against the same ground control points and independent surface elevation profiles from Global Navigation Satellite Systems (GNSS and airborne laser altimetry, yielding root mean square (RMS errors of about 10 m in all cases. This quality is sufficient for most glaciological applications, and the new DEM will be a baseline data set for ongoing and future research at Austfonna. The technique of combining satellite DInSAR with high-resolution satellite altimetry for DEM generation might also be a good solution in other glacier regions with similar characteristics, especially when data from TanDEM-X and CryoSat-2 become available.

  10. Flow Characteristics of Tidewater Glaciers in Greenland and Alaska using Ground-Based LiDAR

    Finnegan, D. C.; Stearns, L. A.; Hamilton, G. S.; O'Neel, S.


    LiDAR scanning systems have been employed to characterize and quantify multi-temporal glacier and ice sheet changes for nearly three decades. Until recently, LiDAR scanning systems were limited to airborne and space-based platforms which come at a significant cost to deploy and are limited in spatial and temporal sampling capabilities necessary to compare with in-situ field measurements. Portable ground-based LiDAR scanning systems are now being used as a glaciological tool. We discuss research efforts to employ ground-based near-infrared LiDAR systems at two differing tidewater glacier systems in the spring of 2009; Helheim Glacier in southeast Greenland and Columbia Glacier in southeast Alaska. Preliminary results allow us to characterize short term displacement rates and detailed observations of calving processes. These results highlight the operational limitations and capabilities of commercially available LiDAR systems, and allow us to identify optimal operating characteristics for monitoring small to large-scale tidewater glaciers in near real-time. Furthermore, by identifying the operational limitations of these sensors it allows for optimal design characteristics of new sensors necessary to meet ground-based calibration and validation requirements of ongoing scientific missions.

  11. A review of volume-area scaling of glaciers.

    Bahr, David B; Pfeffer, W Tad; Kaser, Georg


    Volume-area power law scaling, one of a set of analytical scaling techniques based on principals of dimensional analysis, has become an increasingly important and widely used method for estimating the future response of the world's glaciers and ice caps to environmental change. Over 60 papers since 1988 have been published in the glaciological and environmental change literature containing applications of volume-area scaling, mostly for the purpose of estimating total global glacier and ice cap volume and modeling future contributions to sea level rise from glaciers and ice caps. The application of the theory is not entirely straightforward, however, and many of the recently published results contain analyses that are in conflict with the theory as originally described by Bahr et al. (1997). In this review we describe the general theory of scaling for glaciers in full three-dimensional detail without simplifications, including an improved derivation of both the volume-area scaling exponent γ and a new derivation of the multiplicative scaling parameter c. We discuss some common misconceptions of the theory, presenting examples of both appropriate and inappropriate applications. We also discuss potential future developments in power law scaling beyond its present uses, the relationship between power law scaling and other modeling approaches, and some of the advantages and limitations of scaling techniques.

  12. Optical Remote Sensing of Glacier Characteristics: A Review with Focus on the Himalaya

    Roger G. Barry


    Full Text Available The increased availability of remote sensing platforms with appropriate spatial and temporal resolution, global coverage and low financial costs allows for fast, semi-automated, and cost-effective estimates of changes in glacier parameters over large areas. Remote sensing approaches allow for regular monitoring of the properties of alpine glaciers such as ice extent, terminus position, volume and surface elevation, from which glacier mass balance can be inferred. Such methods are particularly useful in remote areas with limited field-based glaciological measurements. This paper reviews advances in the use of visible and infrared remote sensing combined with field methods for estimating glacier parameters, with emphasis on volume/area changes and glacier mass balance. The focus is on the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER sensor and its applicability for monitoring Himalayan glaciers. The methods reviewed are: volumetric changes inferred from digital elevation models (DEMs, glacier delineation algorithms from multi-spectral analysis, changes in glacier area at decadal time scales, and AAR/ELA methods used to calculate yearly mass balances. The current limitations and on-going challenges in using remote sensing for mapping characteristics of mountain glaciers also discussed, specifically in the context of the Himalaya.

  13. Living and dying with glaciers: people's historical vulnerability to avalanches and outburst floods in Peru

    Carey, Mark


    Human populations worldwide are vulnerable to natural disasters. Certain conditions—such as geographical location or people's income level—can affect the degree to which natural disasters impact people's homes and livelihoods. This paper suggests that vulnerability to natural disasters increases when local people, scientists, and policymakers do not communicate and trust each other. Additionally, a breakdown in interaction and confidence among these groups can disrupt the implementation of sound science or well-intentioned policies. This case study analyzes how local people, scientists, and government officials responded to glacier hazards in Peru's Cordillera Blanca mountain range. Cordillera Blanca glacier retreat since the late-19th century has triggered some of the world's most deadly avalanches and glacial lake outburst floods. Although a Peruvian glaciology and lakes security office has "controlled" 35 Cordillera Blanca glacial lakes, 30 glacier disasters have killed nearly 30,000 people in this region since 1941. A lack of local faith in government officials and scientists as well as the State's failure to follow scientists' warnings about potential disasters have endangered or led to the death of thousands of local residents, many of which remain living in hazard zones today.

  14. Review and reassessment of hazards owing to volcano-glacier interactions in Colombia

    Huggel, Christian; Ceballos, Jorge Luis; Pulgarín, Bernardo; Ramírez, Jair; Thouret, Jean-Claude

    The Cordillera Central in Colombia hosts four important glacier-clad volcanoes, namely Nevado del Ruiz, Nevado de Santa Isabel, Nevado del Tolima and Nevado del Huila. Public and scientific attention has been focused on volcano-glacier hazards in Colombia and worldwide by the 1985 Nevado del Ruiz/Armero catastrophe, the world's largest volcano-glacier disaster. Important volcanological and glaciological studies were undertaken after 1985. However, recent decades have brought strong changes in ice mass extent, volume and structure as a result of atmospheric warming. Population has grown and with it the sizes of numerouscommunities located around the volcanoes. This study reviews and reassesses the current conditions of and changes in the glaciers, the interaction processes between ice and volcanic activity and the resulting hazards. Results show a considerable hazard potential from Nevados delRuiz, Tolima and Huila. Explosive activity within environments of snow and ice as well as non-eruption-related mass movements induced by unstable slopes, or steep and fractured glaciers, can produce avalanches that are likely to be transformed into highly mobile debris flows. Such events can have severe consequences for the downstream communities. Integrated monitoring strategies are therefore essential for early detection of emerging activity that may result in hazardous volcano-ice interaction. Corresponding efforts are currently being strengthened within the framework of international programmes.

  15. Estimating the risk of glacier cavity collapse during artificial drainage: The case of Tête Rousse Glacier

    Gagliardini, O.; Gillet-Chaulet, F.; Durand, G.; Vincent, C.; Duval, P.


    During the summer of 2010, the presence of a pressurized water-filled subglacial-cavity of at least 50,000 m3 was detected within the Tête Rousse Glacier (French Alps). Artificial drainage was started to avoid an uncontrolled rupture of the ice dam, but was interrupted soon after to evaluate the capacity of the cavity-roof to bear itself. The risk was that the release of pressure within the cavity during the artificial drainage would precipitate the collapse of the cavity roof and potentially flush out the remaining water flooding the valley below. An unprecedented modeling effort was deployed to answer the question of the cavity roof stability. We set up a model of the glacier with its water cavity, solved the three-dimensional full-Stokes problem, predicted the upper surface and cavity surface displacements for various drainage scenarios, and quantified the risk of the cavity failure during artificial drainage. We found that the maximum tensile stress in the cavity roof was below the rupture value, indicating a low risk of collapse. A post drainage survey of the glacier surface displacements has confirmed the accuracy of the model prediction. This practical application demonstrates that ice flow models have reached sufficient maturity to become operational and assist policy-makers when faced with glaciological hazards, thus opening new perspectives in risk management of glacier hazards in high mountain regions.

  16. Water, Ice, and Meteorological Measurements at Xiao Dongkemadi Glacier, Central Tibetan Plateau, Balance Years from 2008 to 2011

    Xiaobo, He; Baisheng, Ye; Yongjian, Ding; Jian, Zhang


    The glaciers on Tibetan Plateau play an important role in the catchment hydrology and climatology of this region. However, our knowledge with respect to water circulation in this remote area is scarce. Xiao Dongkemadi Glacier (XDG) is located near Tanggula Pass (the highest point on the Lanzhou-Lhasa road 5231ma.s.l.), central Tibetan Plateau (33°04'N, 92°04'E). Here, glacier mass balance and runoff directly reflects the glacier's response to local climate change, and glacier changes on the Tibetan Plateau strongly influence human welfare since water supplies in this arid/semi-arid region are predominantly from glacier melt. Due to its remote location, the mass balance of XDG has been monitored discontinuously since 1988 by the direct glaciological method. Recently, a more complete and fine-grained glacier monitoring system has been established on the cap of XDG, and is expected to make further contributions to research on the change of the cryospheric and climatic environment in the area. Winter snow accumulation and summer snow and ice ablation were measured at XDG, to estimate glacier mass-balance quantities for balance years from 2008 to 2011. Runoff from the basin containing the glacier and from an adjacent nonglacierized basin was gaged during all or parts of water years from 2008 and 2011. Air temperature, wind speed, precipitation, and incoming solar radiation were measured at selected locations on and near the glacier.

  17. Exploration of ocean waves created by iceberg calving and capsize using SPH (smoothed particle hydrodynamics)

    Macayeal, D. R.


    The interaction between icebergs, their parent ice shelves and the fluid in which they float (seawater) is one of the most demanding problems in glaciology because the interactions involve multiple widely divergent time scales, a variety of constitutive behaviors along with free surfaces and disconnected domains. As calving begins, compressibility and surface tension of seawater comes into play as free-falling ice encounters the ocean surface, producing jets of spray and filling the water with plumes of bubbles. As calving proceeds, incompressible hydrodynamics describes the interaction between the iceberg and the surface waves (tsunamis) the calving event creates in the ocean. In regions where the Froude number (which inversely measures the ability of the water to relieve pressure on the iceberg, ice shelf and seabed by radiating free-surface gravity waves) is greater than 1, hydraulic pressure coupling can produce extraordinary tensile and compressive stresses in the iceberg and ice shelf, triggering further calving. Eventually, a hydrostatic pressure regime develops in which icebergs may further evolve through capsize, which often produces such strong elastic stress within the iceberg sufficient to cause its disintegration. This presentation will focus on the use of SPH as a means of modeling ice/ocean interaction during iceberg calving. Goals of the investigation will be methodological and will evaluate the efficiency and accuracy of the computation of boundary forces which act on icebergs, ice shelves and seabed/fjord walls during iceberg calving and capsize.

  18. Seismic observations of glaciogenic ocean waves (micro-tsunamis) on icebergs and ice shelves

    Macayeal, Douglas R.; Okal, Emile A.; Aster, Richard C.; Bassis, Jeremy N.

    Seismometers deployed over a 3 year period on icebergs in the Ross Sea and on the Ross Ice Shelf, Antarctica, reveal that impulsive sources of ocean surface waves are frequent (e.g. ˜200 events per year in the Ross Sea) in the ice-shelf and iceberg-covered environment of coastal Antarctica. The 368 events recorded by our field deployment suggest that these impulsive events are generated by glaciological mechanisms, such as (1) small-scale calving and edge wasting of icebergs and ice-shelf fronts, (2) edge-on-edge closing and opening associated with iceberg collisions and (3) possibly the impulsive opening of void space associated with ice-shelf rifting and basal crevasse formation. The observations described here provide a background of glaciogenic ocean-wave phenomena relevant to the Ross Sea and suggest that these phenomena may be exploited in the future (using more purposefully designed observation schemes) to understand iceberg calving and ice-shelf disintegration processes.

  19. High-resolution boundary conditions of an old ice target near Dome C, Antarctica

    D. A. Young


    Full Text Available A high-resolution (1 km line spacing aerogeophysical survey was conducted over a region near the East Antarctic Ice Sheet's Dome C that may hold a 1.5 Myr climate record. We combined new ice thickness data derived from an airborne coherent radar sounder with unpublished data that was in part unavailable for earlier compilations, and we were able to remove older data with high positional uncertainties. We generated a revised high-resolution digital elevation model (DEM to investigate the potential for an old ice record in this region, and used laser altimetry to confirm a Cryosat-2 derived DEM for inferring the glaciological state of the candidate area. By measuring the specularity content of the bed, we were able to find an additional 50 subglacial lakes near the candidate site, and by Doppler focusing the radar data, we were able to map out the roughness of the bed at length scales of hundreds of meters. We find that the primary candidate region contains elevated rough topography interspersed with scattered subglacial lakes and some regions of smoother bed. Free subglacial water appears to be restricted from bed overlain by ice thicknesses of less than 3000 m. A site near the ice divide was selected for further investigation. The high resolution of this ice thickness data set also allows us to explore the nature of ice thickness uncertainties in the context of radar geometry and processing.

  20. A modern interpretation of the history of the Pleistocene glacial cycles

    V. M. Kotlyakov


    Full Text Available One of the, Glaciological descriptions of Greenland and Antarctica were among the most outstanding events in the geographical investigations of the Earth, made in the 20th century. They have shown that glaciations, traces of which were found in Europe and North America in the first half of the 19th century, waxed and waned during the Pleistocene repeatedly and were synchronous with the expansions and reductions of the Antarctic ice sheet. Further analyses of the sea-bed sediments confirmed the fact of such synchronicity, and revealed that the durations of the Pleistocene glacial cycles (on the order of one hundred thousand years were significantly longer then approximately forty thousand years alternations of the warm and cold climate conditions during the preceding Pliocene. In this paper, using wavelets, and methods of the theory of the nonlinear dynamical systems, patterns of the Pleistocene’s and Pliocene’s cyclic variations of climate are compared with each other, to understand the mechanisms which can be responsible for their excitation and evolution. 

  1. Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978–1987

    Korsgaard, Niels J.; Nuth, Christopher; Khan, Shfaqat A.; Kjeldsen, Kristian K.; Bjørk, Anders A.; Schomacker, Anders; Kjær, Kurt H.


    Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling in general. We present a historical medium-resolution DEM and orthophotographs that consistently cover the entire surroundings and margins of the Greenland Ice Sheet 1978–1987. About 3,500 aerial photographs of Greenland are combined with field surveyed geodetic ground control to produce a 25 m gridded DEM and a 2 m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision is better than 4 m. This dataset proved successful for topographical mapping and geodetic mass balance. Other uses include control and calibration of remotely sensed data such as imagery or InSAR velocity maps. PMID:27164457

  2. A coupled multivalued model for ice streams and its numerical simulation

    Calvo, Nati; Durany, Jose; Munoz, Ana I.; Schiavi, Emanuele; Vazquez, Carlos


    This paper deals with the numerical solution of a non-linear model describing a free-boundary problem arising in modern glaciology. Considering a shallow, viscous ice sheet flow along a soft, deformable bed, a coupled non-linear system of differential equations can be obtained. Particularly, an obstacle problem is then deduced and solved in the framework of its complementarity formulation. We present the numerical solution of the resulting multivalued system modelling the ice sheet non-Newtonian dynamics driven by the underlying drainage system. Our numerical results show the existence of fast ice streams when positive wave-like initial conditions are considered. The solutions are numerically computed with a decoupling iterative method and finite-element technique. A duality algorithm and a projected Gauss-Seidel method are the alternatives used to cope with the resulting variational inequality while the explicit treatment, Newton method or a duality method are proposed to deal with the non-linear source term. Finally, the numerical solutions are physically interpreted and some comparisons among the numerical methods are then discussed.

  3. Uncertainties and re-analysis of glacier mass balance measurements

    M. Zemp


    Full Text Available Glacier-wide mass balance has been measured for more than sixty years and is widely used as an indicator of climate change and to assess the glacier contribution to runoff and sea level rise. Until present, comprehensive uncertainty assessments have rarely been carried out and mass balance data have often been applied using rough error estimation or without error considerations. In this study, we propose a framework for re-analyzing glacier mass balance series including conceptual and statistical toolsets for assessment of random and systematic errors as well as for validation and calibration (if necessary of the glaciological with the geodetic balance results. We demonstrate the usefulness and limitations of the proposed scheme drawing on an analysis that comprises over 50 recording periods for a dozen glaciers and we make recommendations to investigators and users of glacier mass balance data. Reanalysis of glacier mass balance series needs to become a standard procedure for every monitoring programme to improve data quality and provide thorough uncertainty estimates.

  4. Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978-1987.

    Korsgaard, Niels J; Nuth, Christopher; Khan, Shfaqat A; Kjeldsen, Kristian K; Bjørk, Anders A; Schomacker, Anders; Kjær, Kurt H


    Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling in general. We present a historical medium-resolution DEM and orthophotographs that consistently cover the entire surroundings and margins of the Greenland Ice Sheet 1978-1987. About 3,500 aerial photographs of Greenland are combined with field surveyed geodetic ground control to produce a 25 m gridded DEM and a 2 m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision is better than 4 m. This dataset proved successful for topographical mapping and geodetic mass balance. Other uses include control and calibration of remotely sensed data such as imagery or InSAR velocity maps.

  5. Development and Applications of Dome A-DEM in Antarctic Ice Sheet

    LIU Jiying; WEN Jiahong; WANG Yafeng; WANG Weili; Beata M CATHSO; Kenneth C JEZEK


    Dome A, the highest dome of East Antarctic Ice Sheet, is being an area focused by international Antarctic community after Chinese Antarctic Expedition finally reached there in 2005, and with the ongoing International Polar Year (IPY) during August 2007. In this paper two data processing methods are used together to generate two 100-m cell size digital elevation models (DEMs) of the Dome A region (Dome A-DEM) by using Cokriging method to interpolate the ICESat GLAS data, with Ihde-DEM as a constraint. It provides fundamental data to glaciological and geophysical investigation in this area. The Dome A-DEM was applied to determining the ice-sheet surface elevations and coordinates of the south and north summits, defining boundaries of basins and ice flowlines, deducing subglacial topography, and mapping surface slope and aspect in Dome A region. The DEM shows there are two (north and south) summits in Dome A region. The coordinate and the surface elevation of the highest point (the north summit) are 80°21'29.86"S, 77°21'50.29"E and 4092.71±1.43m, respectively. The ice thickness and sub-ice bedrock elevation at north summit are 2420m and 1672m, respectively. Dome A region contains four drainage basins that meet together near the south summit. Ice flowlines, slope and aspect in detail are also derived using the DEM.

  6. Ideal climatic variables for the present-day geometry of the Gregoriev Glacier, Inner Tien Shan, Kyrgyzstan, derived from GPS data and energy-mass balance measurements

    K. Fujita


    Full Text Available We conducted 2 yr (2005–2007 of in situ meteorological and glaciological observations on the Gregoriev Glacier, a flat-top glacier within the Inner Tien Shan, Kyrgyzstan. Differential GPS surveys reveal a vertical surface deletion at the summit of the glacier. Based on snow density data and an energy-mass balance model, we estimate that the annual precipitation and summer mean temperature required to maintain the glacier in the modern state are 289 mm and −3.85 °C at the glacier summit (4600 m above sea level, a.s.l., respectively. The good agreement between the long-term estimated and observed precipitation at a nearby station in the Tien Shan (292 mm at 3614 m a.s.l. for the period 1930–2002 suggests that the glacier dynamics have been regulated by the long-term average accumulation. The glacier mass-balance, reconstructed based on meteorological data from the Tien Shan station for the past 80 yr, explains the observed fluctuations in glacier extent, particularly the negative mass balance in the 1990s.

  7. "EDML1": a chronology for the EPICA deep ice core from Dronning Maud Land, Antarctica, over the last 150 000 years

    U. Ruth


    Full Text Available A chronology called EDML1 has been developed for the EPICA ice core from Dronning Maud Land (EDML. EDML1 is closely interlinked with EDC3, the new chronology for the EPICA ice core from Dome-C (EDC through a stratigraphic match between EDML and EDC that consists of 322 volcanic match points over the last 128 ka. The EDC3 chronology comprises a glaciological model at EDC, which is constrained and later selectively tuned using primary dating information from EDC as well as from EDML, the latter being transferred using the tight stratigraphic link between the two cores. Finally, EDML1 was built by exporting EDC3 to EDML. For ages younger than 41 ka BP the new synchronized time scale EDML1/EDC3 is based on dated volcanic events and on a match to the Greenlandic ice core chronology GICC05 via 10Be and methane. The internal consistency between EDML1 and EDC3 is estimated to be typically ~6 years and always less than 450 years over the last 128 ka (always less than 130 years over the last 60 ka, which reflects an unprecedented synchrony of time scales. EDML1 ends at 150 ka BP (2417 m depth because the match between EDML and EDC becomes ambiguous further down. This hints at a complex ice flow history for the deepest 350 m of the EDML ice core.

  8. Ice-sheet dynamics through the Quaternary on the mid-Norwegian continental margin inferred from 3D seismic data.

    Montelli, A; Dowdeswell, J A; Ottesen, D; Johansen, S E


    Reconstructing the evolution of ice sheets is critical to our understanding of the global environmental system, but most detailed palaeo-glaciological reconstructions have hitherto focused on the very recent history of ice sheets. Here, we present a three-dimensional (3D) reconstruction of the changing nature of ice-sheet derived sedimentary architecture through the Quaternary Ice Age of almost 3 Ma. An extensive geophysical record documents a marine-terminating, calving Fennoscandian Ice Sheet (FIS) margin present periodically on the mid-Norwegian shelf since the beginning of the Quaternary. Spatial and temporal variability of the FIS is illustrated by the gradual development of fast-flowing ice streams and associated intensification of focused glacial erosion and sedimentation since that time. Buried subglacial landforms reveal a complex and dynamic ice sheet, with converging palaeo-ice streams and several flow-switching events that may reflect major changes in topography and basal thermal regime. Lack of major subglacial meltwater channels suggests a largely distributed drainage system beneath the marine-terminating part of the FIS. This palaeo-environmental examination of the FIS provides a useful framework for ice-sheet modelling and shows that fragmentary preservation of buried surfaces and variability of ice-sheet dynamics should be taken into account when reconstructing glacial history from spatially limited datasets.

  9. The impacts of moisture transport on drifting snow sublimation in the saltation layer

    Huang, Ning; Dai, Xiaoqing; Zhang, Jie


    Drifting snow sublimation (DSS) is an important physical process related to moisture and heat transfer that happens in the atmospheric boundary layer, which is of glaciological and hydrological importance. It is also essential in order to understand the mass balance of the Antarctic ice sheets and the global climate system. Previous studies mainly focused on the DSS of suspended snow and ignored that in the saltation layer. Here, a drifting snow model combined with balance equations for heat and moisture is established to simulate the physical DSS process in the saltation layer. The simulated results show that DSS can strongly increase humidity and cooling effects, which in turn can significantly reduce DSS in the saltation layer. However, effective moisture transport can dramatically weaken the feedback effects. Due to moisture advection, DSS rate in the saltation layer can be several orders of magnitude greater than that of the suspended particles. Thus, DSS in the saltation layer has an important influence on the distribution and mass-energy balance of snow cover.

  10. Creating Geoscience Leaders

    Buskop, J.; Buskop, W.


    The United Nations Educational, Scientific, and Cultural Organization recognizes 21 World Heritage in the United States, ten of which have astounding geological features: Wrangell St. Elias National Park, Olympic National Park, Mesa Verde National Park, Chaco Canyon, Glacier National Park, Carlsbad National Park, Mammoth Cave, Great Smokey Mountains National Park, Hawaii Volcanoes National Park, and Everglades National Park. Created by a student frustrated with fellow students addicted to smart phones with an extreme lack of interest in the geosciences, one student visited each World Heritage site in the United States and created one e-book chapter per park. Each chapter was created with original photographs, and a geological discovery hunt to encourage teen involvement in preserving remarkable geological sites. Each chapter describes at least one way young adults can get involved with the geosciences, such a cave geology, glaciology, hydrology, and volcanology. The e-book describes one park per chapter, each chapter providing a geological discovery hunt, information on how to get involved with conservation of the parks, geological maps of the parks, parallels between archaeological and geological sites, and how to talk to a ranger. The young author is approaching UNESCO to publish the work as a free e-book to encourage involvement in UNESCO sites and to prove that the geosciences are fun.

  11. Recent mass balance of Purogangri ice cap, central Tibetan Plateau, by means of differential X-band SAR interferometry

    N. Neckel


    Full Text Available Due to their remoteness, altitude and harsh climatic conditions, little is known about the glaciological parameters of ice caps on the Tibetan Plateau (TP. This study presents an interferometrical approach aiming at surface elevation changes of Purogangri ice cap, located on the central TP. Purogangri ice cap covers an area of 397 ± 9.7 km2 and is the largest ice cap on the TP. Its behavior is determined by dry and cold continental climate suggesting a polar-type glacier regime. We employed data from the actual TerraSAR-X mission and its add-on for Digital Elevation Measurements (TanDEM-X and compare it with elevation data from the Shuttle Radar Topography Mission (SRTM. These datasets are ideal for this approach as both datasets feature the same wavelength of 3.1 cm and are available at a fine grid spacing. Similar snow conditions can be assumed since the data were acquired in early February 2000 and late January 2012. The trend in glacier extend was extracted using a time series of Landsat data. Our results show a balanced mass budget for the studied time period which is in agreement with previous studies. Additionally, we detected an exceptional fast advance of one glacier tongue in the eastern part of the ice cap between 1999 and 2011.

  12. Glacier contribution to flow in two high-altitude streams of the semi-arid Huasco Basin, northern-central Chile

    Gascoin, Simon; Ponce, Rodrigo; Kinnard, Christophe; MacDonell, Shelley


    In the semi-arid north-central Chile, populated lowlands rely on runoff and groundwater recharge generated in the high altitude areas of the Andes mountain range. In spite of its importance in terms of water resources, the water balance in these areas is poorly known. In particular, the relative contribution of the cryosphere components (snowpack, glaciers, rock glaciers) to the regional water balance has not been thoroughly evaluated yet. We examine the hydrological importance of glaciers in the case of two well-monitored high-altitude watersheds of the Huasco Basin in northern-central Chile (29°S). We use data from a five years glaciological monitoring program to assess the quantity of water that comes from glaciers fusion per watershed. Then, we compare it with the measured discharge at five stream gauge stations located between 2620 m and 3980 m. The results reveal a substantial contribution of the glaciers to the hydrological balance of the study area. At the regional scale, the water balance is dominated by the snowpack dynamics.

  13. Gischig receives 2011 Natural Hazards Focus Group Award for Graduate Research


    Valentin Gischig has been awarded the AGU Natural Hazards Focus Group Award for Graduate Research, given annually to a recent Ph.D. recipient for outstanding contributions to natural hazards research. Gischig's thesis is entitled “Kinematics and failure mechanisms of the Randa rock slope instability (Switzerland).” He presented an invited talk and was formally presented with the award at the 2011 AGU Fall Meeting, held 5-9 December in San Francisco, Calif. Gischig received his M.Sc. in geophysics and glaciology at Eidgenössiche Technische Hochschule (ETH) Zürich, in Switzerland, in 2007. In 2011 he attained a Ph.D. in engineering geology/rock mechanics/landslide analysis under the supervision of Simon Loew, Jeffrey R. Moore, Florian Amann, and Keith F. Evans at ETH Zürich. Gischig is currently conducting postdoctoral research at ETH Zürich. His research interests include landslides, induced seismicity in enhanced geothermal systems, and coupled processes in rock mechanics.

  14. Antarctic subglacial groundwater: measurement concept and potential influence on ice flow

    Kulessa, Bernd; Siegert, Martin; Bougamont, Marion; Christoffersen, Poul; Key, Kerry; Andersen, Kristoffer; Booth, Adam; Smith, Andrew


    Is groundwater abundant in Antarctica and does it modulate ice flow? Answering this question matters because ice streams flow by gliding over a wet substrate of till. Water fed to ice-stream beds thus influences ice-sheet dynamics and, potentially, sea-level rise. It is recognised that both till and the sedimentary basins from which it originates are porous and could host a reservoir of mobile groundwater that interacts with the subglacial interfacial system. According to recent numerical modelling up to half of all water available for basal lubrication, and time lags between hydrological forcing and ice-sheet response as long as millennia, may have been overlooked in models of ice flow. Here, we review evidence in support of Antarctic groundwater and propose how it can be measured to ascertain the extent to which it modulates ice flow. We present new seismoelectric soundings of subglacial till, and new magnetotelluric and transient electromagnetic forward models of subglacial groundwater reservoirs. We demonstrate that multi-facetted and integrated geophysical datasets can detect, delineate and quantify the groundwater contents of subglacial sedimentary basins and, potentially, monitor groundwater exchange rates between subglacial till layers. We thus describe a new area of glaciological investigation and how it should progress in future.



    An improved topographic database for King George Island,one of the most frequently visited regions in Antarctica,is presented.A first step consisted in combining data from differential GPS surveys gained during the austral summers 1997~1998 and 1999~2000,with the current coastline from a SPOT satellite image mosaic,topographic information from existing maps and from the Antarctic Digital Database.From this data sets,a digital terrain model (DTM) was generated using Arc/Info GIS.In a second step,a satellite image map at the scale 1∶100 000 was assembled from contour lines derived from the DTM and the satellite mosaic.A lack of accurate topographic information in the eastern part of the island was identified.Additional topographic surveying or SAR interferometry should be used to improve the data quality in that area.The GIS integrated database will be indispensable for glaciological and climatological studies and administrative and scientific purposes.In future,the application of GIS techniques will be mandatory for environmental impact studies and environmental monitoring as well as for management plans on King George Island.

  16. Application of regional climate models to the Indian winter monsoon over the western Himalayas.

    Dimri, A P; Yasunari, T; Wiltshire, A; Kumar, P; Mathison, C; Ridley, J; Jacob, D


    The Himalayan region is characterized by pronounced topographic heterogeneity and land use variability from west to east, with a large variation in regional climate patterns. Over the western part of the region, almost one-third of the annual precipitation is received in winter during cyclonic storms embedded in westerlies, known locally as the western disturbance. In the present paper, the regional winter climate over the western Himalayas is analyzed from simulations produced by two regional climate models (RCMs) forced with large-scale fields from ERA-Interim. The analysis was conducted by the composition of contrasting (wet and dry) winter precipitation years. The findings showed that RCMs could simulate the regional climate of the western Himalayas and represent the atmospheric circulation during extreme precipitation years in accordance with observations. The results suggest the important role of topography in moisture fluxes, transport and vertical flows. Dynamical downscaling with RCMs represented regional climates at the mountain or even event scale. However, uncertainties of precipitation scale and liquid-solid precipitation ratios within RCMs are still large for the purposes of hydrological and glaciological studies. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. West Antarctic Ice Sheet retreat driven by Holocene warm water incursions

    Hillenbrand, Claus-Dieter; Smith, James A.; Hodell, David A.; Greaves, Mervyn; Poole, Christopher R.; Kender, Sev; Williams, Mark; Andersen, Thorbjørn Joest; Jernas, Patrycja E.; Elderfield, Henry; Klages, Johann P.; Roberts, Stephen J.; Gohl, Karsten; Larter, Robert D.; Kuhn, Gerhard


    Glaciological and oceanographic observations coupled with numerical models show that warm Circumpolar Deep Water (CDW) incursions onto the West Antarctic continental shelf cause melting of the undersides of floating ice shelves. Because these ice shelves buttress glaciers feeding into them, their ocean-induced thinning is driving Antarctic ice-sheet retreat today. Here we present a multi-proxy data based reconstruction of variability in CDW inflow to the Amundsen Sea sector, the most vulnerable part of the West Antarctic Ice Sheet, during the Holocene epoch (from 11.7 thousand years ago to the present). The chemical compositions of foraminifer shells and benthic foraminifer assemblages in marine sediments indicate that enhanced CDW upwelling, controlled by the latitudinal position of the Southern Hemisphere westerly winds, forced deglaciation of this sector from at least 10,400 years ago until 7,500 years ago—when an ice-shelf collapse may have caused rapid ice-sheet thinning further upstream—and since the 1940s. These results increase confidence in the predictive capability of current ice-sheet models.

  18. Field, experimental and numerical model developments in outburst flood understanding and opportunities for future work

    Carrivick, Jonathan


    Local-scale risks to society from a rapidly changing cryosphere include a range of mass flows and floods. Most of these slides, slumps, falls and flow events have been attributed to climatically-induced permafrost degradation, to glaciological mass loss and consequent meltwater production and sudden drainage of glacier lakes, or to volcano-ice interactions. This presentation will firstly overview outburst flood research and knowledge to date and it will do this from a field, experimental and numerical modeling perspective. Fieldwork examples from around the world and including Iceland, New Zealand, Greenland, and the European Alps will be argued to underpin all understanding but to be severely limited in spatiotemporal coverage. Laboratory experiments will be argued to be overly generalised and narrowly-focussed. Numerical models will be argued to be omitting or over-generalising major processes; particularly sediment transport and morphodynamics. This presentation will then look forwards, by placing an emphasis on several recent and major technological advances that should be enabling much improved monitoring and measurement in both the field and the laboratory. The opportunity for new numerical modelling approaches will be discussed from two viewpoints; that of the researcher interested in process mechanisms, and that of the natural hazard manager wishing for real-time information.

  19. Summary of FY-1978 consultant input for scenario methodology development

    Scott, B.L.; Benson, G.L.; Craig, R.A. (eds.); Harwell, M.A.


    Associated with commercial nuclear power production in the United States is the generation of potentially hazardous radioactive waste products. The Department of Energy (DOE), through the National Waste Terminal Storage (NWTS) Program, is seeking to develop nuclear waste isolation systems in geologic formations. These underground waste isolation systems will preclude contact with the biosphere of waste radionuclides in concentrations which are sufficient to cause deleterious impact on humans or their environments. Comprehensive analyses of specific isolation systems are needed to assess the postclosure expectations of the systems. Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) program has been established for developing the capability of making those analyses. The assessment of repository post-closure safety has two basic components: identification and analyses of breach scenarios and the pattern of events and processes causing each breach, and identification and analyses of the environmental consequences of radionuclide transport and interactions subsequent to a repository breach. Specific processes and events which might affect potential repository sites and, the rates and probabilities for those phenomena are presented. The description of the system interactions and synergisms and of the repository system as an evolving and continuing process are included. Much of the preliminary information derived from the FY-1978 research effort is summarized in this document. This summary report contains information pertaining to the following areas of study: climatology, geomorphology, glaciology, hydrology, meteorites, sea level fluctuations, structural geology and volcanology.

  20. 1-D-ice flow modelling at EPICA Dome C and Dome Fuji, East Antarctica

    F. Parrenin


    Full Text Available One-dimensional (1-D ice flow models are used to construct the age scales at the Dome C and Dome Fuji drilling sites (East Antarctica. The poorly constrained glaciological parameters at each site are recovered by fitting independent age markers identified within each core. We reconstruct past accumulation rates, that are larger than those modelled using the classical vapour saturation pressure relationship during glacial periods by up to a factor 1.5. During the Early Holocene, changes in reconstructed accumulation are not linearly related to changes in ice isotopic composition. A simple model of past elevation changes is developed and shows an amplitude variation of 110–120 m at both sites. We suggest that there is basal melting at Dome C (0.56±0.19 mm/yr. The reconstructed velocity profile is highly non-linear at both sites, which suggests complex ice flow effects. This induces a non-linear thinning function in both drilling sites, which is also characterized by bumps corresponding to variations in ice thickness with time.

  1. Influence of high-order mechanics on simulation of glacier response to climate change: insights from Haig Glacier, Canadian Rocky Mountains

    S. Adhikari


    Full Text Available Evolution of glaciers in response to climate change has mostly been simulated using simplified dynamical models. Because these models do not account for the influence of high-order physics, corresponding results may exhibit some biases. For Haig Glacier in the Canadian Rocky Mountains, we test this hypothesis by comparing simulation results obtained from 3-D numerical models that deal with different assumptions concerning physics, ranging from simple shear deformation to comprehensive Stokes flow. In glacier retreat scenarios, we find a minimal role of high-order mechanics in glacier evolution, as geometric effects at our site (the presence of an overdeepened bed result in limited horizontal movement of ice (flow speed on the order of a few meters per year. Consequently, high-order and reduced models all predict that Haig Glacier ceases to exist by ca. 2080 under ongoing climate warming. The influence of high-order mechanics is evident, however, in glacier advance scenarios, where ice speeds are greater and ice dynamical effects become more important. Although similar studies on other glaciers are essential to generalize such findings, we advise that high-order mechanics are important and therefore should be considered while modeling the evolution of active glaciers. Reduced model predictions may be adequate for other glaciologic and topographic settings, particularly where flow speeds are low and where mass balance changes dominate over ice dynamics in determining glacier geometry.

  2. Worldwide widespread decadal-scale decrease of glacier speed revealed using repeat optical satellite images

    T. Heid


    Full Text Available Matching of repeat optical satellite images to derive glacier velocities is an approach that is much used within glaciology. Lately, focus has been put into developing, improving, automating and comparing different image matching methods. This makes it now possible to investigate glacier dynamics within large regions of the world and also between regions to improve knowledge about glacier dynamics in space and time. In this study we investigate whether the negative glacier mass balance seen over large parts of the world has caused the glaciers to change their speeds. The studied regions are Pamir, Caucasus, Penny Ice Cap, Alaska Range and Patagonia. In addition we derive speed changes for Karakoram, a region assumed to have positive mass balance and that contains many surge-type glaciers. We find that the mapped glaciers in the five regions with negative mass balance have decreased their speeds over the last decades, Pamir by 43 % in average per decade, Caucasus by 8 % in average per decade, Penny Ice Cap by 25 % in average per decade, Alaska Range by 11 % in average per decade and Patagonia by 20 % in average per decade. Glaciers in Karakoram have generally increased their speeds, but surging glaciers and glaciers with flow instabilities are most prominent in this area.

  3. Equatorial mountain lakes show extended periods of thermal stratification with recent climate change

    Neal Michelutti


    Full Text Available Climate change in the Andes has already affected phenology, glaciology, and other ecosystem attributes, and now threatens to alter long-standing fundamental limnological properties. In the equatorial Andes, most lakes have traditionally been described as having waters that circulate continuously (polymictic, with only rare episodes of stratification. This characterization, albeit based on relatively few studies, is widely accepted, despite accelerated regional warming over the past 30 years.Here, we show that protracted periods of thermal stratification are presently the norm, not the exception, in equatorial mountain lakes. Annual circulation and stratification patterns recorded in four lakes from Ecuador’s southern Sierra show extended periods of stratification, which are stable and do not break down with nocturnal cooling. These data contrast with earlier research from this region, which reported full water column mixing and only infrequent stratification, but are not surprising in light of recent trends toward rising temperatures and declining wind velocities. Paleolimnological studies show that changes to the thermal regimes of these lakes likely began several decades ago and have resulted in ecosystem-scale changes including regime shifts in phytoplankton and declines in aquatic production.

  4. Evaluation of a high-resolution regional climate simulation over Greenland

    Lefebre, Filip [Universite catholique de Louvain, Institut d' Astronomie et de Geophysique G. Lemaitre, Louvain-la-Neuve (Belgium); Vito - Flemish Institute for Technological Research, Integral Environmental Studies, Mol (Belgium); Fettweis, Xavier; Ypersele, Jean-Pascal van; Marbaix, Philippe [Universite catholique de Louvain, Institut d' Astronomie et de Geophysique G. Lemaitre, Louvain-la-Neuve (Belgium); Gallee, Hubert [Laboratoire de Glaciologie et de Geophysique de l' Environnement, Grenoble (France); Greuell, Wouter [Utrecht University, Institute for Marine and Atmospheric Research, Utrecht (Netherlands); Calanca, Pierluigi [Swiss Federal Research Station for Agroecology and Agriculture, Zurich (Switzerland)


    A simulation of the 1991 summer has been performed over south Greenland with a coupled atmosphere-snow regional climate model (RCM) forced by the ECMWF re-analysis. The simulation is evaluated with in-situ coastal and ice-sheet atmospheric and glaciological observations. Modelled air temperature, specific humidity, wind speed and radiative fluxes are in good agreement with the available observations, although uncertainties in the radiative transfer scheme need further investigation to improve the model's performance. In the sub-surface snow-ice model, surface albedo is calculated from the simulated snow grain shape and size, snow depth, meltwater accumulation, cloudiness and ice albedo. The use of snow metamorphism processes allows a realistic modelling of the temporal variations in the surface albedo during both melting periods and accumulation events. Concerning the surface albedo, the main finding is that an accurate albedo simulation during the melting season strongly depends on a proper initialization of the surface conditions which mainly result from winter accumulation processes. Furthermore, in a sensitivity experiment with a constant 0.8 albedo over the whole ice sheet, the average amount of melt decreased by more than 60%, which highlights the importance of a correctly simulated surface albedo. The use of this coupled atmosphere-snow RCM offers new perspectives in the study of the Greenland surface mass balance due to the represented feedback between the surface climate and the surface albedo, which is the most sensitive parameter in energy-balance-based ablation calculations. (orig.)

  5. Internationally coordinated glacier monitoring - a timeline since 1894

    Nussbaumer, Samuel U.; Armstrong, Richard; Fetterer, Florence; Gärtner-Roer, Isabelle; Hoelzle, Martin; Machguth, Horst; Mölg, Nico; Paul, Frank; Raup, Bruce H.; Zemp, Michael


    Changes in glaciers and ice caps provide some of the clearest evidence of climate change, with impacts on sea-level variations, regional hydrological cycles, and natural hazard situations. Therefore, glaciers have been recognized as an Essential Climate Variable (ECV). Internationally coordinated collection and distribution of standardized information about the state and change of glaciers and ice caps was initiated in 1894 and is today organized within the Global Terrestrial Network for Glaciers (GTN-G). GTN-G ensures the continuous development and adaptation of the international strategies to the long-term needs of users in science and policy. A GTN-G Steering Committee coordinates, supports and advices the operational bodies responsible for the international glacier monitoring, which are the World Glacier Monitoring Service (WGMS), the US National Snow and Ice Data Center (NSIDC), and the Global Land Ice Measurements from Space (GLIMS) initiative. In this presentation, we trace the development of the internationally coordinated glacier monitoring since its beginning in the 19th century. Today, several online databases containing a wealth of diverse data types with different levels of detail and global coverage provide fast access to continuously updated information on glacier fluctuation and inventory data. All glacier datasets are made freely available through the respective operational bodies within GTN-G, and can be accessed through the GTN-G Global Glacier Browser ( Glacier inventory data (e.g., digital outlines) are available for about 180,000 glaciers (GLIMS database, RGI - Randolph Glacier Inventory, WGI - World Glacier Inventory). Glacier front variations with about 45,000 entries since the 17th century and about 6,200 glaciological and geodetic mass (volume) change observations dating back to the 19th century are available in the Fluctuations of Glaciers (FoG) database. These datasets reveal clear evidence that

  6. Managing glacier related risks in the Chucchún Catchment, Cordillera Blanca, Peru

    Muñoz, Randy; Gonzáles, César; Price, Karen; Frey, Holger; Huggel, Christian; Cochachin, Alejo; García, Javier; Mesa, Luis


    On April 11 2010, the city of Carhuaz and settlements in the Chucchún Catchment (Ancash region, Peru) suffered the impact of a glacier lake outburst flood. An avalanche of rock and ice from the Mount Hualcán hit the glacier lake 513, triggering a glacial lake outburst flood (GLOF) of 1 million m3 which destroyed farmland and several infrastructures. Although there was no loss of human life, the event caused panic in the population. In consequence, the Municipality of Carhuaz prioritized GLOF-related risk management. The Glacier Project, funded by Swiss Agency for Development and Cooperation, and executed by CARE Peru and the University of Zurich, fosters the coordination among public institutions (Glaciological Unit of the National Water Authority, the Ministry of Environment and Municipality) and the population for risk management. In this contribution we present all components of the risk management strategy as well as the lessons learned during the implementation. Risk management involves managing both glacier hazard as well as the vulnerability of the population. In this framework a glaciological and geomorphological characterization of Mount Hualcán and lake 513 was perfomed in order to model past and potential future outburst floods and to assess the slope stability conditions. Based on three potential GLOF scenarios of different magnitudes, a hazard map was produced for the entire catchment, which served as the basis for the vulnerability and risk assessment as well as for the design and the implementation of an Early Warning System (EWS), including evacuation planning. The EWS consists of 4 components: 1) knowledge of risk, through hazard and vulnerability characterization; 2) monitoring and alert, through the installation of monitoring stations on lake 513 for detecting avalanches with geophones and cameras; 3) broadcasting and communications, through the implementation of communication protocols between the Municipality of Carhuaz and emergency

  7. On the Evolution of Glaciated Continental Margins

    Sverre Laberg, Jan; Rydningen, Tom Arne; Safronova, Polina A.; Forwick, Matthias


    Glaciated continental margins, continental margins where a grounded ice sheet repeatedly has been at or near the shelf break, are found at both northern and southern high-latitudes. Their evolution are in several aspects different from their low-latitude counterparts where eustatic sea-level variations possess a fundamental control on their evolution and where fluvial systems provide the main sediment input. From studies of the Norwegian - Barents Sea - Svalbard and NE Greenland continental margins we propose the following factors as the main control on the evolution of glaciated continental margins: 1) Pre-glacial relief controlling the accommodation space, 2) Ice sheet glaciology including the location of fast-flowing ice streams where source area morphology exerts a fundamental control, 3) Composition of the glacigenic sediments where the clay content in previous studies have been found to be important, and 4) Sea-level controlled both by eustacy and isostacy. From three case studies, 1) the western Barents Sea, 2) part of the North Norwegian (Troms), and 3) the Mid-Norwegian margin, the influence on these factors for the sea-floor morphology, sedimentary processes of the continental slope - deep sea and continental margin architecture are discussed. The pre-glacial relief of the mid-Norwegian and Troms margins relates to the onset of rifting and plate break-up from the early Cenozoic while for the SW Barents Sea, plate shear was followed by rifting. A wide zone of extended continental crust occurs offshore mid-Norway while this zone is much narrower offshore Troms leading to a more pronounced pre-glacial relief. Regarding sediment delivery and ice sheet glaciology the western Barents Sea exemplifies very high sediment input corresponding to an estimated average erosion of the source area of ~0.4 mm/yr (SW Barents Sea), much of which is related to subglacial erosion of Mesozoic - Cenozoic sedimentary rocks from large paleo-ice streams. The mid-Norwegian margin

  8. Monitoring of land-based glaciers on James Ross Island, Antarctic Peninsula

    Laska, Kamil; Nyvlt, Daniel; Engel, Zbynek; Stachon, Zdenek


    glacier bed elevations of DD and WG were surveyed using ground-penetrating radar. The results of glaciological measurements over the period 2009-2014 reveal mostly positive annual mass balance on DD and WG except for the glaciological year 2011-2012 when net accumulation was recorded in the uppermost part of both glaciers. Spatial variability in annual mass balance is larger on DD where snow distribution and net accumulation is strongly determined by meteorological conditions. By contrast, interannual changes in spatial pattern of net balance are reduced on WG due to the topographic control of snow accumulation. Acknowledgments: This research was supported by the project of Masaryk University MUNI/A/0952/2013 and project LM2010009 CzechPolar (MSMT CR).

  9. Geographic Names of Iceland's Glaciers: Historic and Modern

    Sigurdsson, Oddur; Williams, Richard S.


    Climatic changes and resulting glacier fluctuations alter landscapes. In the past, such changes were noted by local residents who often documented them in historic annals; eventually, glacier variations were recorded on maps and scientific reports. In Iceland, 10 glacier place-names are to be found in Icelandic sagas, and one of Iceland's ice caps, Snaefellsjokull, appeared on maps of Iceland published in the 16th century. In the late 17th century, the first description of eight of Iceland's glaciers was written. Therefore, Iceland distinguishes itself in having a more than 300-year history of observations by Icelanders on its glaciers. A long-term collaboration between Oddur Sigurdsson and Richard S. Williams, Jr., led to the authorship of three books on the glaciers of Iceland. Much effort has been devoted to documenting historical glacier research and related nomenclature and to physical descriptions of Icelandic glaciers by Icelanders and other scientists from as far back as the Saga Age to recent (2008) times. The first book, Icelandic Ice Mountains, was published by the Icelandic Literary Society in 2004 in cooperation with the Icelandic Glaciological Society and the International Glaciological Society. Icelandic Ice Mountains was a glacier treatise written by Sveinn Palsson in 1795 and is the first English translation of this important scientific document. Icelandic Ice Mountains includes a Preface, including a summary of the history and facsimiles of page(s) from the original manuscript, a handwritten copy, and an 1815 manuscript (without maps and drawings) by Sveinn Palsson on the same subject which he wrote for Rev. Ebenezer Henderson; an Editor's Introduction; 82 figures, including facsimiles of Sveinn Palsson's original maps and perspective drawings, maps, and photographs to illustrate the text; a comprehensive Index of Geographic Place-Names and Other Names in the treatise; References, and 415 Endnotes. Professional Paper 1746 (this book) is the second

  10. Slope deformations in high-mountain regions as observed by InSAR: Examples from the Cordillera Blanca, Peru

    Frey, Holger; Strozzi, Tazio; Caduff, Rafael; Huggel, Christian; Klimeš, Jan; Vilímek, Vít; Wiesmann, Andreas; Kääb, Andreas; Cochachin, Alejo; Plummer, Stephen


    Steep topography, the world's highest concentration of tropical glaciers, numerous glacial lakes and strong seismic activity combined with a densely populated valley bottom in the Rio Santa basin characterize the Cordillera Blanca in Peru. Besides glacier-related processes, a variety of landslide types and processes is present outside the glaciated areas, favoured by the steep terrain, geological conditions, sparse vegetation, intense precipitation, and strong seismicity. This combination of high hazard potentials and vulnerabilities results in a long list of natural disasters. Information on surface displacements is very valuable for early detection of emerging hazard potentials and their assessment. Interferometric processing of SAR data (InSAR) provides the possibility to remotely detect different types of surface displacement processes, also in remote locations where no other monitoring data are available. This contribution, developed under the ESA-funded S:GLA:MO project (, shows the potential of InSAR products for hazard assessments and glaciological investigations in high-mountain regions. We present a selection of different surface displacements as observed in the Cordillera Blanca based on InSAR data: a landslide zone near the Rampac Grande village, where in 2009 a landslide caused casualties and property loss; a landslide at the entry of the Santa Cruz Valley, northern Cordillera Blanca, where the displacement history could be reconstructed over five years; surface displacements at the interior moraine slopes surrounding Laguna Palcacocha, a major glacier lake above the city of Huaraz, which are compared to and complemented by geophysical investigations in the field; surface displacements at the moraine damming Laguna Safuna Alta, a glacier lake in the northern part of the Cordillera Blanca; glacier velocities across the entire Cordillera Blanca, revealing ice flow velocities of more than 200 m yr-1 at certain locations at the end of

  11. Unveiling the Antarctic subglacial landscape.

    Warner, Roland; Roberts, Jason


    revealed by this approach, and we advocate its consideration in future ice thickness data syntheses. REFERENCES Budd, W.F., and R.C. Warner, 1996. A computer scheme for rapid calculations of balance-flux distributions. Annals of Glaciology 23, 21-27. Bamber, J.L., J.L. Gomez Dans and J.A. Griggs, 2009. A new 1 km digital elevation model of the Antarctic derived from combined satellite radar and laser data. Part I: Data and methods. The Cryosphere 3 (2), 101-111. Griggs, J.A., and J.L. Bamber, 2009. A new digital elevation model of Antarctica derived from combined radar and laser altimetry data. Part II: Validation and error estimates, The Cryosphere, 3(2), 113-123. Le Brocq, A.M., A.J. Payne and M.J. Siegert, 2006. West Antarctic balance calculations: Impact of flux-routing algorithm, smoothing algorithm and topography. Computers and Geosciences 23(10): 1780-1795. Lythe, M. B., D.G. Vaughan, and the BEDMAP Consortium 2001, BEDMAP: A new ice thickness and subglacial topographic model of Antarctica, J. of Geophys. Res., 106(B6),11,335-11,351. van de Berg, W.J., M.R. van den Broeke, C.H. Reijmer, and E. van Meijgaard, 2006. Reassessment of the Antarctic surface mass balance using calibrated output of a regional atmospheric climate model, J. Geophys. Res., 111, D11104,doi:10.1029/2005JD006495. Warner, R.C., and W.F. Budd, 2000. Derivation of ice thickness and bedrock topography in data-gap regions over Antarctica, Annals of Glaciology, 31, 191-197. Wright, A.P., M.J. Siegert, A.M. Le Brocq, and D.B. Gore, 2008. High sensitivity of subglacial hydrological pathways in Antarctica to small ice-sheet changes, Geophys. Res. Lett., 35, L17504, doi:10.1029/2008GL034937.

  12. Preliminary 3D In-situ measurements of the texture evolution of strained H2O ice during annealing using neutron Laue diffractometry

    Journaux, Baptiste; Montagnat, Maurine; Chauve, Thomas; Ouladdiaf, Bachir; Allibon, John


    Dynamic recrystallization (DRX) strongly affects the evolution of microstructure (grain size and shape) and texture (crystal preferred orientation) in materials during deformation at high temperature. Since texturing leads to anisotropic physical properties, predicting the effect of DRX is essential for industrial applications, for interpreting geophysical data and modeling geodynamic flows, and predicting ice sheet flow and climate evolution. A large amount of literature is available related to metallurgy, geology or glaciology, but there remains overall fundamental questions about the relationship between nucleation, grain boundary migration and texture development at the microscopic scale. Previous measurements of DRX in ice were either conducted using 2D ex-situ techniques such as AITA [1,2] or Electron Backscattering Diffraction (EBSD) [3], or using 3D statistical ex-situ [4] or in-situ [5] techniques. Nevertheless, all these techniques failed to observe at the scale of nucleation processes during DRX in full 3D. Here we present a new approach using neutron Laue diffraction, which enable to perform 3D measurements of in-situ texture evolution of strained polycrystalline H2O ice (>2% at 266 K) during annealing at the microscopic scale. Thanks the CYCLOPS instrument [6] (Institut Laue Langevin Grenoble, France) and the intrinsic low background of this setup, preliminary observations enabled us to follow, in H2O ice, the evolution of serrated grain boundaries, and kink-band during annealing. Our observations show a significant evolution of the texture and internal misorientation over the course of few hours at an annealing temperature of 268.5 K. In the contrary, ice kink-band structures seem to be very stable over time at near melting temperatures. The same samples have been analyzed ex-situ using EBSD for comparison. These results represent a first step toward in-situ microscopic measurements of dynamic recrystallization processes in ice during strain. This

  13. Numerical simualtions and implications of air inclusions on the microdynamics of ice and firn

    Steinbach, Florian; Weikusat, Ilka; Bons, Paul; Griera, Albert; Kerch, Johanna; Kuiper, Ernst-Jan; Llorens-Verde, Maria-Gema


    Dronning Maud Land (EDML) ice core. We propose that strain localisation has a strong control on the dominating recrystallisation mechanisms and can account for microstructural observations from alpine and polar ice cores. Our results confirm dynamic recrystallisation occurring in the uppermost levels of ice sheets as observed by Kipfstuhl et al. (2009) and Weikusat et al. (2009) in EDML core. References Azuma, N., et al. (2012) Journal of Structural Geology, 42, 184-193 Becker, J.K., et al. (2008) Computers & Geosciences, 34, 201-212 Bons, P.D., et al. (2008) Lecture Notes in Earth Sciences, 106 Faria, S.H., et al. (2010) Quaternary Science Reviews, 29, 338-351 Faria, S.H., et al. (2014) Journal of Structural Geology, 61, 21-49 Griera, A., et al. (2013) Tectonophysics, 587, 4-29 Kipfstuhl, S., et al. (2009) Journal of Geophysical Research, 114, B05204 Lebensohn, R.A. (2001) Acta Materialia, 49, 2723-2737 Llorens, M.G., et al. (2015) Journal of Glaciology, in press, doi:10.1017/jog.2016.28 Montagnat, M., et al. (2014) Journal of Structural Geology, 61, 78-108 Roessiger, J., et al. (2014) Journal of Structural Geology, 61, 123-132 Weikusat, I., et al. (2009) Journal of Glaciology, 55, 461-472

  14. Investigating the Microscopic Location of Trace Elements in High-Alpine Glacier Ice

    Avak, Sven Erik; Birrer, Mario; Laurent, Oscar; Guillong, Marcel; Wälle, Markus; Jenk, Theo Manuel; Bartels-Rausch, Thorsten; Schwikowski, Margit; Eichler, Anja


    proxies in glaciers partially affected by melting. References Della Lunga, D., Müller, W., Rasmussen, S. O. & Svensson, A. 2014: Location of cation impurities in NGRIP deep ice revealed by cryo-cell UV-laser-ablation ICPMS, Journal of Glaciology, 60, 970-988. Eichler, A., Schwikowski, M., Gäggeler, H. W. 2001: Meltwater-induced relocation of chemical species in Alpine firn, Tellus B, 53, 192-203. Reinhardt, H., Kriews, M., Miller, H., Schrems, O., Lüdke, C., Hoffmann, E. & Skole, J. 2001: Laser ablation inductively coupled plasma mass spectrometry: a new tool for trace element analysis in ice cores, Fresenius' Journal of Analytical Chemistry, 370, 629-636. Schwikowski, M., Barbante, C., Doering, T., Gäggeler, H. W., Boutron, C., Schotterer, U., Tobler, L., van de Velde, K., Ferrari, C., Cozzi, G., Rosman, K., Cescon, P. 2004: Post-17th-Century Changes of European Lead Emissions Recorded in High-Altitude Alpine Snow and Ice, Environmental Science & Technology, 38, 957-964. Sneed, S. B., Mayewski, P. A., Sayre, W. G., Handley, M. J., Kurbatov, A. V., Taylor, K. C., Bohleber, P., Wagenbach, D., Erhardt, T. & Spaulding, N. E. 2015: New LA-ICP-MS cryocell and calibration technique for sub-millimeter analysis of ice cores, Journal of Glaciology, 61, 233-242.

  15. Relationship between

    TIAN; Lide


    [1]Craig, H., Isotopic variations in meteoric waters, Science, 1961,133: 17020703.[2]Dansgaard, W., Stable isotope in precipitation, Tellus, 1964, 14(4): 436-468.[3]Merlivat, L., Jouzel, J., Global climate interpretation of the deuterium-oxygen 18 relationship for precipitation, J. Geophys.Res.. 1979, 84: 5029-5033.[4]Jouzel, J., Merlivat, L., Deuterium and oxygen-18 in precipitation: modeling of the isotope effects during snow formation.J. Geophys. Res., 1984, 89(D7): 11749-11757.[5]Sonntag, C., Klitzsch, E., Lohnert, E. P. et al., Palaeoclimatic information from deuterium and oxygen-18 in Carbon- 14-dated North Saharan groundwaters, in Isotope Hydrology, IAEA,Vienna, 1979, 569-581.[6]Armengaud, A., Koster, R. D., Jouzel, J. et al., Deuterium excess in Greenland snow: analysis with simple and complex models, J. Geophys. Res., 1998, 103(D8): 8947-8953.[7]Jouzel, J., Merlivat, L., Lorius, C., Deuterium excess in an East Antarctic ice core suggests higher relative humidity at the oceanic surface during the last glacial maximum, Nature, 1982, 299 (5885): 688-691.[8]Qin Dahe, Ren Jiawen, Wang Wenti, et al., Distribution of δD in 25 cm surface snow across the Antarctic, Science in China, Ser. B, 1992,22(7): 768-776.[9]Yao Tandong, Ding Liangfu, Pu Jianchen et al., Characteristic of δ 18O in snow and its relation with moisture sources in Tanggula Mountains, Tibetan Plateau, Chinese Science Bulletin (in Chinese), 1991, (20): 1570-1573.[10]Zhang Xinping, Shi Yafeng, Yao Tandong, Variational features of precipitation, δ 18O in Northeast Qinghai-Tibet Plateau.Science in China, Ser. D, 1995, 38(7): 854-864.[11]Zhang Xinping, Yao Tandong, Relations between weather systems affecting Tibetan Plateau and oxygen isotope in precipitation, Journal of Glaciology and Geocryology (in Chinese), 1995, 17(2): 125-131.[12]Tian Lide, Yao Tandong, Yang Zhihong, δ18O in precipitation and moisture sources upon the Tibetan Plateau, Cryosphere

  16. Programa 'nieves y glaciares tropicales' (NGT: resultados (1991-1996 obtenidos en Bolivia


    Full Text Available PROGRAMME “NEIGES ET GLACIERS TROPICAUX” (NGT: RÉSULTATS (1991-1996 OBTENUS EN BOLIVIE. Depuis 1991, avec ses partenaires la COBEE, l’IHH et le SENAMHI, l’ORSTOM a progressivement équipé 2 glaciers de la Cordillère Royale de Bolivie, les glaciers de Chacaltaya et Zongo. Cet équipement a permis de réaliser les bilans glaciologiques des 2 glaciers et les bilans hydrologique et énergétique du glacier Zongo. Les principaux résultats, glaciologique, hydrologique et énergétique, sont fournis dans cette communication. Un premier modèle physique du fonctionnement du glacier Zongo a été réalisé, avec des premiers résultats qui permettent d’entreprendre un modèle plus élaboré susceptible d’être généralisé à d’autres glaciers. Des carottages de neige et glace à haute altitude ont confirmé la possibilité d’exploiter ces véritables archives climatologiques. Desde 1991, con sus contrapartes COBEE, IHH y SENAMHI, el ORSTOM ha equipado progresivamente 2 glaciares de la Cordillera Real de Bolivia, los glaciares de Chacaltaya y Zongo. Este equipo ha permitido realizar los balances glaciológicos de los 2 glaciares y los balances hidrológico y energético del glaciar Zongo. Los principales resultados, glaciológicos, hidrológicos y energéticos, son proporcionados en esta comunicación. Se realizó un primer modelo físico del funcionamiento del glaciar Zongo, con primeros resultados que permiten comenzar un modelo más elaborado capaz de ser generalizado a otros glaciares. Extracciones de testigos de nieve y hielo a gran altura confirmaron la posibilidad de aprovechar estos verdaderos archivos climatológicos. PROGRAM “SNOWS AND GLACIERS IN THE TROPICS” (NGT: PRINCIPAL RESULTS IN BOLIVIA (1991-1996. Since 1991, two glaciers of the Royal Cordillera of Bolivia, the glaciers of Chacaltaya and Zongo, have been equipped by ORSTOM with his partners COBEE, IHH and SENAMHI. That equipment allowed to carry out the glaciological

  17. Eskers in the Keewatin region of the Laurentide Ice Sheet - inventory comparisons

    Jorge, Marco G.; Brennand, Tracy A.; Storrar, Robert D.; Dinney, Meaghan; Perkins, Andrew


    Eskers are the casts of subglacial, englacial or supraglacial meltwater channels, or ice-walled canyons and thus can provide a window into paleo ice-sheet hydrology. However, detailed, ice-sheet scale inventories (maps) are rare and, while recent studies provide new insights about the proxy value of esker morphology and internal structure, for a robust understanding of esker glaciological significance, more eskers need to be studied in detail. This poster compares two recent high-resolution inventories of eskers in the Keewatin region of the Laurentide Ice Sheet in order to better understand their reliability for paleo-glaciological inferences and morphogenetic investigations. The latest published inventory (A) of Keewatin eskers was produced by mapping ridge crestlines on 15 m cell-size Landsat ETM+ orthorectified imagery (Storrar et al., 2013). A new inventory (B) of Keewatin esker crestlines has been mapped from 10 m cell-size, orthorectified SPOT-4/5 satellite imagery (freely available at; Google Earth® imagery was used for verifying cases interpreted as potential eskers based on SPOT imagery. In this poster, we: i) present a morphometric comparison of the two inventories; and ii) assess whether the morphometric differences have a significant impact on derived interpretations by applying the same analysis framework (trends in esker morphometry over time based on ice sheet margin positions) used in recent studies based on inventory A to inventory B. In the compared datasets, gaps between esker ridges are not specified as non- or post-depositional. Inventory B generally displays higher esker ridge density and sinuosity, and lower ridge continuity (and thus length) than inventory A. These systematic differences are due to differences in spatial resolution (10 m vs. 15 m cell size) of the imagery, which determines the size of both the thinnest and shortest ridges and gaps that can be identified. On the other hand, differences in mapped

  18. Warming and glacier recession in the Rakaia valley, Southern Alps of New Zealand, during Heinrich Stadial 1

    Aaron E. Putnam; Joerg M. Schaefe; George H .Denton; DavidJ. A. Barrell; Bjørn G. Andersen; Tobias N.B. Koffman; Ann V. Rowan; Robert C. Finkel; Dylan H. Rood; Roseanne Schwartz; Marcus J. Vandergoes; Mitchell A. Plummer; Simon H. Brocklehurst; Samuel E. Kelley; Kathryn L. Ladig


    The termination of the last ice age featured a major reconfiguration of Earth's climate and cryosphere, yet the underlying causes of these massive changes continue to be debated. Documenting the spatial and temporal variations of atmospheric temperature during deglaciation can help discriminate among potential drivers. Here, we present a 10Be surface-exposure chronology and glaciological reconstruction of ice recession following the Last Glacial Maximum (LGM) in the Rakaia valley, Southern Alps of New Zealand. Innermost LGM moraines at Big Ben have an age of 17,840 +/- 240 yrs, whereas ice-marginal moraines or ice-molded bedrock surfaces at distances up-valley from Big Ben of 12.5 km (Lake Coleridge), approximately 25 km (Castle Hill), approximately 28 km (Double Hill), approximately 43 km (Prospect Hill), and approximately 58 km (Reischek knob) have ages of 17,020 +/- 70 yrs, 17,100 +/- 110 yrs, 16,960 +/- 370 yrs, 16,250 +/- 340 yrs, and 15,660 +/- 160 yrs, respectively. These results indicate extensive recession of the Rakaia glacier, which we attribute primarily to the effects of climatic warming. In conjunction with geomorphological maps and a glaciological reconstruction for the Rakaia valley, we use our chronology to infer timing and magnitude of past atmospheric temperature changes. Compared to an overall temperature rise of approximately 4.65?degrees C between the end of the LGM and the start of the Holocene, the glacier recession between approximately 17,840 and approximately 15,660 yrs ago is attributable to a net temperature increase of approximately 4.0?degrees C (from -6.25 to -2.25?degrees C), accounting for approximately 86% of the overall warming. Approximately 3.75?degrees C (approximately 70%) of the warming occurred between approximately 17,840 and approximately 16,250 yrs ago, with a further 0.75?degrees C (approximately 16%) increase between approximately 16,250 and approximately 15,660 yrs ago. A sustained southward shift of the

  19. Accuracy Assessment of Digital Surface Models from Unmanned Aerial Vehicles’ Imagery on Glaciers

    Saskia Gindraux


    Full Text Available The use of Unmanned Aerial Vehicles (UAV for photogrammetric surveying has recently gained enormous popularity. Images taken from UAVs are used for generating Digital Surface Models (DSMs and orthorectified images. In the glaciological context, these can serve for quantifying ice volume change or glacier motion. This study focuses on the accuracy of UAV-derived DSMs. In particular, we analyze the influence of the number and disposition of Ground Control Points (GCPs needed for georeferencing the derived products. A total of 1321 different DSMs were generated from eight surveys distributed on three glaciers in the Swiss Alps during winter, summer and autumn. The vertical and horizontal accuracy was assessed by cross-validation with thousands of validation points measured with a Global Positioning System. Our results show that the accuracy increases asymptotically with increasing number of GCPs until a certain density of GCPs is reached. We call this the optimal GCP density. The results indicate that DSMs built with this optimal GCP density have a vertical (horizontal accuracy ranging between 0.10 and 0.25 m (0.03 and 0.09 m across all datasets. In addition, the impact of the GCP distribution on the DSM accuracy was investigated. The local accuracy of a DSM decreases when increasing the distance to the closest GCP, typically at a rate of 0.09 m per 100-m distance. The impact of the glacier’s surface texture (ice or snow was also addressed. The results show that besides cases with a surface covered by fresh snow, the surface texture does not significantly influence the DSM accuracy.

  20. An assessment of the ICE6G_C(VM5a) glacial isostatic adjustment model

    Purcell, A.; Tregoning, P.; Dehecq, A.


    The recent release of the next-generation global ice history model, ICE6G_C(VM5a), is likely to be of interest to a wide range of disciplines including oceanography (sea level studies), space gravity (mass balance studies), glaciology, and, of course, geodynamics (Earth rheology studies). In this paper we make an assessment of some aspects of the ICE6G_C(VM5a) model and show that the published present-day radial uplift rates are too high along the eastern side of the Antarctic Peninsula (by ˜8.6 mm/yr) and beneath the Ross Ice Shelf (by ˜5 mm/yr). Furthermore, the published spherical harmonic coefficients—which are meant to represent the dimensionless present-day changes due to glacial isostatic adjustment (GIA)—contain excessive power for degree ≥90, do not agree with physical expectations and do not represent accurately the ICE6G_C(VM5a) model. We show that the excessive power in the high-degree terms produces erroneous uplift rates when the empirical relationship of Purcell et al. (2011) is applied, but when correct Stokes coefficients are used, the empirical relationship produces excellent agreement with the fully rigorous computation of the radial velocity field, subject to the caveats first noted by Purcell et al. (2011). Using the Australian National University (ANU) groups CALSEA software package, we recompute the present-day GIA signal for the ice thickness history and Earth rheology used by Peltier et al. (2015) and provide dimensionless Stokes coefficients that can be used to correct satellite altimetry observations for GIA over oceans and by the space gravity community to separate GIA and present-day mass balance change signals. We denote the new data sets as ICE6G_ANU.

  1. High-Resolution Monitoring of Glacier Dynamics During Calving Events at Helheim Glacier South-East Greenland

    Murray, T.; Rutt, I. C.; O'Farrell, T.; Edwards, S.; Selmes, N.; Martin, I.; James, T.; Aspey, R.; Bevan, S. L.; Loskot, P.; Baugé, T.


    By bringing together expertise in glaciology, GNSS (Global Navigation Satellite System) technology and processing, and wireless networks we have designed, installed and operated a wireless network of GNSS sensors very close to the margin of the heavily crevassed and fast-flowing Helheim Glacier in south-east Greenland. In 2012, we undertook field trials installing 3 GNSS sensors on the glacier's flowline, and observed the dynamic effects of a major calving event. In 2013, a full 20 node wireless network was installed together with 5 oblique cameras, instrumenting an area ~16 km^2 of the glacier margin. The network will run throughout the summer months. In combination with auxiliary data, such as airborne lidar measurement of surface topography, crevasse spacing and calving rates, oblique photogrammetry, and DEMs and velocity fields from TanDEM-X satellite imagery, the network provides velocity and elevation data of unprecedented resolution in time and space for the key marginal area of the glacier, where recent changes in glacier dynamics appear to have initiated. We present data showing the glacier's dynamic and topographic response to calving events. These data will provide rich opportunities for testing calving models and to improve understanding of the controls on the contribution of these tidewater glaciers to sea-level rise. The network has low energy consumption and a novel base-station topology providing diversity and redundancy: it is also robust to the loss of nodes as the glacier calves. Such a network would also be suitable for data collection in a number of harsh environmental settings such as earthquake, landslide or volcano monitoring.

  2. Emerging spatial patterns in Antarctic prokaryotes

    Chun Wie eChong


    Full Text Available Recent advances in knowledge of patterns of biogeography in terrestrial eukaryotic organisms have led to a fundamental paradigm shift in understanding of the controls and history of life on land in Antarctica, and its interactions over the long term with the glaciological and geological processes that have shaped the continent. However, while it has long been recognized that the terrestrial ecosystems of Antarctica are dominated by microbes and their processes, knowledge of microbial diversity and distributions has lagged far behind that of the macroscopic eukaryote organisms. Increasing human contact with and activity in the continent is leading to risks of biological contamination and change in a region whose isolation has protected it for millions of years at least; these risks may be particularly acute for microbial communities which have, as yet, received scant recognition and attention. Even a matter apparently as straightforward as Protected Area designation in Antarctica requires robust biodiversity data which, in most parts of the continent, remain almost completely unavailable. A range of important contributing factors mean that it is now timely to reconsider the state of knowledge of Antarctic terrestrial prokaryotes. Rapid advances in molecular biological approaches are increasingly demonstrating that bacterial diversity in Antarctica may be far greater than previously thought, and that there is overlap in the environmental controls affecting both Antarctic prokaryotic and eukaryotic communities. Bacterial dispersal mechanisms and colonization patterns remain largely unaddressed, although evidence for regional evolutionary differentiation is rapidly accruing and, with this, there is increasing appreciation of patterns in regional bacterial biogeography in this large part of the globe. In this review, we set out to describe the state of knowledge of Antarctic prokaryote diversity patterns, drawing analogy with those of eukaryote

  3. The APECS Virtual Poster Session: a virtual platform for science communication and discussion

    Renner, A.; Jochum, K.; Jullion, L.; Pavlov, A.; Liggett, D.; Fugmann, G.; Baeseman, J. L.; Apecs Virtual Poster Session Working Group, T.


    The Virtual Poster Session (VPS) of the Association of Polar Early Career Scientists (APECS) was developed by early career scientists as an online tool for communicating and discussing science and research beyond the four walls of a conference venue. Poster sessions often are the backbone of a conference where especially early career scientists get a chance to communicate their research, discuss ideas, data, and scientific problems with their peers and senior scientists. There, they can hone their 'elevator pitch', discussion skills and presentation skills. APECS has taken the poster session one step further and created the VPS - the same idea but independent from conferences, travel, and location. All that is needed is a computer with internet access. Instead of letting their posters collect dust on the computer's hard drive, scientists can now upload them to the APECS website. There, others have the continuous opportunity to comment, give feedback and discuss the work. Currently, about 200 posters are accessible contributed by authors and co-authors from 34 countries. Since January 2010, researchers can discuss their poster with a broad international audience including fellow researchers, community members, potential colleagues and collaborators, policy makers and educators during monthly conference calls via an internet platform. Recordings of the calls are available online afterwards. Calls so far have included topical sessions on e.g. marine biology, glaciology, or social sciences, and interdisciplinary calls on Arctic sciences or polar research activities in a specific country, e.g. India or Romania. They attracted audiences of scientists at all career stages and from all continents, with on average about 15 persons participating per call. Online tools like the VPS open up new ways for creating collaborations and new research ideas and sharing different methodologies for future projects, pushing aside the boundaries of countries and nations, conferences

  4. Preservation potential of subtle glacial landforms based on detailed mapping of recently exposed proglacial areas: application of unmanned aerial vehicle (UAV) and structure-from-motion (SfM)

    Ewertowski, Marek; Evans, David; Roberts, David; Tomczyk, Aleksandra; Ewertowski, Wojciech


    Ongoing glacier retreat results in the continuous exposure of proglacial areas. Such areas contain invaluable information about glacial process-form relationships manifest in specific landform assemblages. However, preservation potential of freshly exposed glacial landforms is very low, as proglacial terrains are one of the most dynamic parts of the landscape. Therefore, rapid mapping and geomorphological characterisation of such areas is important from a glaciological and geomorphological point of view for proper understanding and reconstruction of glacier-landform dynamics and chronology of glacial events. Annual patterns of recession and relatively small areas exposed every year, mean that the performing of regular aerial or satellite survey is expensive and therefore impractical. Recent advances in technology enables the development of low-cost alternatives for traditional aerial surveys. Small unmanned aerial vehicles (UAV) can be used to acquire high-resolution (several cm) low-altitude photographs. The UAV-based photographs can be subsequently processed through the structure-from-motion process to generate detailed orthophotomaps and digital elevation models. In this study we present case studies from the forelands of various glaciers on Iceland and Svalbard representing different types of proglacial landscapes: Fláajökull (annual push moraines); Hofellsjökul (bedrock bedforms and push moraines); Fjallsjökull (marginal drainage network); Rieperbreen (crevasse squeeze ridges and longitudinal debris stripes); Ayerbreen (transverse debris ridges); Foxfonna (longitudinal debris stripes);Hørbyebreen (geometric ridge network); Nordenskiöldbreen (fluted till surface); Ebbabreen (controlled moraine complex). UAV campaigns were conducted using a low-cost quadcopter platform. Resultant orthophotos and DEMs enabled mapping and assessment of recent glacial landscape development in different types of glacial landsystems. Results of our study indicate that

  5. Estimation of glacier mass balance: An approach based on satellite-derived transient snowlines and a temperature index driven by meteorological observations

    Tawde, S. A.; Kulkarni, A. V.; Bala, G.


    In the Himalaya, large area is comprised of glaciers and seasonal snow, mainly due to its high elevated mountain ranges. Long term and continuous assessment of glaciers in this region is important for climatological and hydrological applications. However, rugged terrains and severe weather conditions in the Himalaya lead to paucity in field observations. Therefore, in recent decades, glacier dynamics are extensively monitored using remote sensing in inaccessible terrain like Himalaya. Estimation of glacier mass balance using empirical relationship between mass balance and area accumulation ratio (AAR) requires an accurate estimate of equilibrium-line altitude (ELA). ELA is defined as the snowline at the end of the hydrological year. However, identification of ELA, using remote sensing is difficult because of temporal gaps, cloud cover and intermediate snowfall on glaciers. This leads to large uncertainty in glacier mass-balance estimates by the conventional AAR method that uses satellite-derived highest snowline in ablation season as an ELA. The present study suggests a new approach to improve estimates of ELA location. First, positions of modelled snowlines are optimized using satellite-derived snowlines in the early melt season. Secondly, ELA at the end of the glaciological year is estimated by the melt and accumulation models driven using in situ temperature and precipitation records. From the modelled ELA, mass balance is estimated using the empirical relationship between AAR and mass balance. The modelled mass balance is validated using field measurements on Chhota Shigri and Hamtah glaciers, Himachal Pradesh, India. The new approach shows a substantial improvement in glacier mass-balance estimation, reducing bias by 46% and 108% for Chhota Shigiri and Hamtah glaciers respectively. The cumulative mass loss reconstructed from our approach is 0.85 Gt for nine glaciers in the Chandra basin from 2001 to 2009. The result of the present study is in agreement with

  6. Supraglacial dust and debris: geochemical compositions from glaciers in Svalbard, southern Norway, Nepal and New Zealand

    K. A. Casey


    Full Text Available Alpine glacier samples were collected in four contrasting regions to measure supraglacial dust and debris geochemical composition and quantify regional variability. A total of 70 surface glacier ice, snow and debris samples were collected in Svalbard, southern Norway, Nepal and New Zealand. Trace elemental abundances in snow and ice samples were measured via inductively coupled plasma mass spectrometry (ICP-MS. Supraglacial debris mineral, bulk oxide and trace element composition were determined via X-ray diffraction (XRD and X-ray fluorescence spectroscopy (XRF. A total of 45 major, trace and rare earth elements and 10 oxide compound abundances are reported. Elemental abundances revealed sea salt aerosol and metal enrichment in Svalbard, low levels of crustal dust and marine influences to southern Norway, high crustal dust and anthropogenic enrichment in the Khumbu Himalayas, and sulfur and metals attributed to quiescent degassing and volcanic activity in northern New Zealand. Rare earth element and Al/Ti elemental ratios demonstrated distinct provenance of particulates in each study region. Ca/S elemental ratio data showed seasonal denudation in Svalbard and southern Norway. Ablation season atmospheric particulate transport trajectories were mapped in each of the study regions and suggest provenance pathways. The in situ data presented provides first-order glacier surface geochemical variability as measured in the four diverse alpine glacier regions. The surface glacier geochemical data set is available from the PANGAEA database at doi:10.1594/PANGAEA.773951. This geochemical surface glacier data is relevant to glaciologic ablation rate understanding as well as satellite atmospheric and land-surface mapping techniques currently in development.

  7. Response of Glaciers to Climate Change in Northwest China

    Li, Z.; Wang, P.


    In Northwest China, an extremely dry region, more than 20,000 mountain glaciers are developed. Glacial melt water is vital for local water resources, ecosystem in the lower reaches, peoples' living and city development there. During the past several decades, due to climate warming, the most glaciers in NW China are in a state of rapid retreating. To obtain the general idea on response of glaciers in that region, Tianshan Glaciological Station, Chinese Academy of Sciences selected more than ten glaciers in six sub-regions along Altai Mountain, Tianshan and Qilian Mountain, respectively, doing in-situ observations. Based on field observation and remote sensing technique, this study has revealed that the area reductions in different regions range between 8.8%~34.2 % during the past four decades. The potential impact of the glacier recession on water resource in future will be spatially different. For the Tarim River, the glacier runoff is estimated to maintain its current level or increase somewhat in next 30~50 years. In the north slope of Tianshan, the glaciers with a size smaller than 1 km2 are most likely to be melted away in next 20~40 years, and those larger than 5 km2 are melting intensively. In eastern Xinjiang, because the number of the glaciers is small and also because the climate is extremely dry, the glacier retreating are causing the water shortage problem. For Ili River and Irtysh River, because they are dominant by snow melt runoff, the impact of the glacier shrinkage and temperature rise would be limited on the quantity of the river runoff, but significant on the annual distribution of the river runoff. For Qilian Mountains, glaciers are quite small. The vanishing of small glacier will have significant impact on local water resources in near future.

  8. Reconstructing glacier mass balances in the Central Andes of Chile and Argentina using local and regional hydro-climatic data

    M. H. Masiokas


    Full Text Available Despite the great number and variety of glaciers in southern South America, in situ glacier mass balance records are extremely scarce and glacier–climate relationships are still poorly understood in this region. Here we use the longest (> 35 years and most complete in situ mass balance record, available for glaciar Echaurren Norte in the Andes at ~34° S, to develop a minimal glacier surface mass balance model that relies on nearby monthly precipitation and air temperature data as forcing. This basic model is able to explain 78 % of the variance in the annual glacier mass balance record over the 1978–2013 calibration period. An attribution assessment indicates that precipitation variability constitutes the most important forcing modulating annual glacier mass balances at this site. A regionally-averaged series of mean annual streamflow records from both sides of the Andes is then used to estimate, through simple linear regression, this glacier's annual mass balance variations since 1909. The reconstruction model captures 68 % of the observed glacier mass balance variability and shows three periods of sustained positive mass balances embedded in an overall negative trend totaling almost −42 m w.eq. over the past 105 years. The three periods of sustained positive mass balances (centered in the 1920s–1930s, in the 1980s and in the first decade of the 21st century coincide with several documented glacier advances in this region. Similar trends observed in other shorter glacier mass balance series suggest the glaciar Echaurren Norte reconstruction is representative of larger-scale conditions and could be useful for more detailed glaciological, hydrological and climatological assessments in this portion of the Andes.

  9. Multiple drivers of Holocene lake level changes at a lowland lake in northeastern Germany

    Dietze, Elisabeth; Słowiński, Michał; Zawiska, Izabela; Veh, Georg; Brauer, Achim


    Many northeastern German lakes experienced significant water level drops in the recent past, which were attributed to global climate change, but due to the short observation period not fully understood. At lake Fürstenseer See, a groundwater-fed lake with complex basin morphology within the Müritz national park, an acoustic sub-bottom profile was analyzed together with a transect of four sediment cores to assess full Holocene water level amplitudes and the evolution of lake level changes during the Holocene. At core sites in 10 and 15 m water depth, past shifts in the sediment limit, i.e. the limit between preferential sand and mud deposition depending on absolute lake level, allowed to quantify an 8 m maximum Holocene amplitude of lake level changes (+4 m higher to -4 m lower stands), which clearly exceeded the observed fluctuations of 1.3 m between 1973 and 2013. At sites in 20 and 23 m water depth, changes in sediment facies reflected lake level changes qualitatively. During high lake stands massive organic muds were deposited in the deepest part of the lake basin, whereas during lower lake levels sub-basins became isolated causing an exceedance of the thresholds for carbonate accumulation. The highly-resolved continuous m-XRF-Calcium record of the longest core resembles these sediment facies shifts and allows to determine a relative Holocene lake level history. However, temporal interpretation of the causes and conditions that link carbonate preservation with local water level changes was rather complex and non-stationary. Apart from glaciological and climatic reasons also eco-hydrological feedbacks (i.e. vegetation composition affecting groundwater recharge) and anthropogenic triggers will be discussed in detail. This is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution Analysis (ICLEA) and the Terrestrial Environmental Observatories network (TERENO) financed by the Helmholtz Association.

  10. Capabilities and performance of Elmer/Ice, a new-generation ice sheet model

    O. Gagliardini


    Full Text Available The Fourth IPCC Assessment Report concluded that ice sheet flow models, in their current state, were unable to provide accurate forecast for the increase of polar ice sheet discharge and the associated contribution to sea level rise. Since then, the glaciological community has undertaken a huge effort to develop and improve a new generation of ice flow models, and as a result a significant number of new ice sheet models have emerged. Among them is the parallel finite-element model Elmer/Ice, based on the open-source multi-physics code Elmer. It was one of the first full-Stokes models used to make projections for the evolution of the whole Greenland ice sheet for the coming two centuries. Originally developed to solve local ice flow problems of high mechanical and physical complexity, Elmer/Ice has today reached the maturity to solve larger-scale problems, earning the status of an ice sheet model. Here, we summarise almost 10 yr of development performed by different groups. Elmer/Ice solves the full-Stokes equations, for isotropic but also anisotropic ice rheology, resolves the grounding line dynamics as a contact problem, and contains various basal friction laws. Derived fields, like the age of the ice, the strain rate or stress, can also be computed. Elmer/Ice includes two recently proposed inverse methods to infer badly known parameters. Elmer is a highly parallelised code thanks to recent developments and the implementation of a block preconditioned solver for the Stokes system. In this paper, all these components are presented in detail, as well as the numerical performance of the Stokes solver and developments planned for the future.

  11. Predictive Uncertainty Estimation on a Precipitation and Temperature Reanalysis Ensemble for Shigar Basin, Central Karakoram

    Paolo Reggiani


    Full Text Available The Upper Indus Basin (UIB and the Karakoram Range are the subject of ongoing hydro-glaciological studies to investigate possible glacier mass balance shifts due to climatic change. Because of the high altitude and remote location, the Karakoram Range is difficult to access and, therefore, remains scarcely monitored. In situ precipitation and temperature measurements are only available at valley locations. High-altitude observations exist only for very limited periods. Gridded precipitation and temperature data generated from the spatial interpolation of in situ observations are unreliable for this region because of the extreme topography. Besides satellite measurements, which offer spatial coverage, but underestimate precipitation in this area, atmospheric reanalyses remain one of the few alternatives. Here, we apply a proven approach to quantify the uncertainty associated with an ensemble of monthly precipitation and temperature reanalysis data for 1979–2009 in Shigar Basin, Central Karakoram. A Model-Conditional Processor (MCP of uncertainty is calibrated on precipitation and temperature in situ data measured in the proximity of the study region. An ensemble of independent reanalyses is processed to determine the predictive uncertainty of monthly observations. As to be expected, the informative gain achieved by post-processing temperature reanalyses is considerable, whereas significantly less gain is achieved for precipitation post-processing. The proposed approach indicates a systematic assessment procedure for predictive uncertainty through probabilistic weighting of multiple re-forecasts, which are bias-corrected on ground observations. The approach also supports an educated reconstruction of gap-filling for missing in situ observations.

  12. Features of Tibet Yangbajing National Geopark and Construction Scheme Design%西藏羊八井国家地质公园地质遗迹资源特征及建设方案策划

    章秉辰; 雷正化


    To declare and construction of Yangbajing National Geopark,Through Yangbajain and the surrounding areas of geological heritage re- sources research, Think Tibet Yangbajing is located on the junction of eastern Mediterranean-Himalayan global tectonic belt, EW-trending huge structural zone and SN-trending active tectonics in Qinghai-Tibet Plateau, where the geological resources cannot find in other places. Geothermal geological resources are quite unique with rare and varied geothermal landscape. All these typical geoconservation resources offer conditions for constructing a geopark with distinct featureswhich is mainly based on geothermal geology,supplemented with plateau geology and glaciology.%为了西藏羊八井国家地质公园的申报与建设,通过对羊八井及周边地区地质遗迹资源研究,认为西藏羊八井处于地中海一喜马拉雅环球构造带的东部,青藏高原上东西向巨型构造带与南北向活动构造带的交汇处,这里的高原地质资源是其它地方所没有的,地热地质资源也十分独特,丰富多彩的地热景观更是少有,这些典型的地质遗迹资源为规划建设一个以地热地质为主、高原地质、冰川地质为辅,特色鲜明的地质公园提供了条件。

  13. Sustainability of water resources management in the Indus Basin under changing climatic and socio economic conditions

    D. R. Archer


    Full Text Available Pakistan is highly dependent on water resources originating in the mountain sources of the upper Indus for irrigated agriculture which is the mainstay of its economy. Hence any change in available resources through climate change or socio-economic factors could have a serious impact on food security and the environment. In terms of both ratio of withdrawals to runoff and per-capita water availability, Pakistan's water resources are already highly stressed and will become increasingly so with projected population changes. Potential changes to supply through declining reservoir storage, the impact of waterlogging and salinity or over-abstraction of groundwater, or reallocations for environmental remediation of the Indus Delta or to meet domestic demands, will reduce water availability for irrigation.

    The impact of climate change on resources in the Upper Indus is considered in terms of three hydrological regimes – a nival regime dependent on melting of winter snow, a glacial regime, and a rainfall regime dependent on concurrent rainfall. On the basis of historic trends in climate, most notably the decline in summer temperatures, there is no strong evidence in favour of marked reductions in water resources from any of the three regimes. Evidence for changes in trans-Himalayan glacier mass balance is mixed. Sustainability of water resources appears more threatened by socio-economic changes than by climatic trends. Nevertheless, analysis and the understanding of the linkage of climate, glaciology and runoff is still far from complete; recent past climate experience may not provide a reliable guide to the future.




    Some geologists reported that U-shaped valleys,moulins,rock blockfield and other Quaternary remnants of glaciation had been discovered in Jiexi and Fengshun in Eastern Guangdong. But that has lack of evidence,and the so-called moulins occurring in groups in that area have been proved to be potholes in reality formed by fluvial erosion of the bedrock at river floor.This paper has dealt in some detail with the structures,lithology,geomorphology,fluvial process and other condifions that control the formation of those potholes.However,the problem about Quaternary glaciology in Guangdong is still worthy of further study since a series of Quaternary remnants of glaciation have been reported to exist in Fengkai-Huaiji area of Western Guangdong.%一些地质学家在粤东揭西和丰顺所发现的U形谷、冰碛物和石海等第四纪冰川遗迹的证据不足,该区成群出现的“冰臼”,实际上是河床基岩为河流侵蚀所形成的壶穴。控制壶穴形成的构造、岩性、地貌和河流作用等条件,文中作了较为充分的论述。粤西北封开—怀集地区已发现一系列第四纪冰川遗迹,因此广东的第四纪冰川问题,今后仍值得进一步研究。

  15. Application of Laser Induced Breakdown Spectroscopy under Polar Conditions

    Clausen, J. L.; Hark, R.; Bol'shakov, A.; Plumer, J.


    Over the past decade our research team has evaluated the use of commercial-off-the-shelf laser-induced breakdown spectroscopy (LIBS) for chemical analysis of snow and ice samples under polar conditions. One avenue of research explored LIBS suitability as a detector of paleo-climate proxy indicators (Ca, K, Mg, and Na) in ice as it relates to atmospheric circulation. LIBS results revealed detection of peaks for C and N, consistent with the presence of organic material, as well as major ions (Ca, K, Mg, and Na) and trace metals (Al, Cu, Fe, Mn, Ti). The detection of Ca, K, Mg, and Na confirmed that LIBS has sufficient sensitivity to be used as a tool for characterization of paleo-climate proxy indicators in ice-core samples. Techniques were developed for direct analysis of ice as well as indirect measurements of ice via melting and filtering. Pitfalls and issues of direct ice analysis using several cooling techniques to maintain ice integrity will be discussed. In addition, a new technique, laser ablation molecular isotopic spectroscopy (LAMIS) was applied to detection of hydrogen and oxygen isotopes in ice as isotopic analysis of ice is the main tool in paleoclimatology and glaciology studies. Our results demonstrated that spectra of hydroxyl isotopologues 16OH, 18OH, and 16OD can be recorded with a compact spectrograph to determine hydrogen and oxygen isotopes simultaneously. Quantitative isotopic calibration for ice analysis can be accomplished using multivariate chemometric regression as previously realized for water vapor. Analysis with LIBS and LAMIS required no special sample preparation and was about ten times faster than analysis using ICP-MS. Combination of the two techniques in one portable instrument for in-field analysis appears possible and would eliminate the logistical and cost issues associated with ice core management.

  16. Warm pool/cold tongue El Niño and Indian winter Monsoon

    Dimri, A. P.


    In view of the recent global changes in the hydrological, glaciological, agricultural, socio-economic studies, etc., particularly, over the northern Indian region, Indian winter (December, January, February—DJF) monsoon (IWM) has important role. Geographical positioning of the Indian subcontinent having mighty Himalayas in the north and surrounding ocean in the south makes assessment of IWM important and interesting to study. During IWM, the western Himalayas (WH) receives almost one-third of annual precipitation due to eastward moving extratropical cyclonic storms, western disturbances (WDs), embedded within the large scale subtropical westerly jet (SWJ). In addition, IWM is found to be in phase with the El Niño—Southern Oscillation (ENSO). With reference to the recent decade's finding of having different phases of El Niño- warm pool (WP) and cold tongue (CT)—it is imperative to see how these phases affect IWM. In the present study a simple mechanism between IWM with different phases of these El Niño and their relationship is studied and deliberated upon. WP and CT El Niño phase composites are prepared and their corresponding role in tandem with IWM is provided. It is found that during WP (CP) El Niño phase WH (foothill of the Indian Himalayan) region receives higher amount of winter precipitation. It is attributed to the fact that equatorial central Pacific warming makes more conducive proposition for intensification of the WDs and thus associated higher precipitation over western part of the Indian Himalayas. Northward shift of confluence over northern Atlantic region during WP El Niño phase dampens the SWJ leading to longer residence time for weather events—WDs—over the WH region. In addition, strengthening of Hadley cell leads to higher northward transport of moisture from the Indian Ocean region.

  17. Human dimension in scientific models in high-mountain climate change and risk projects: Peruvian-Swiss experiences

    Vicuña, Luis; Jurt, Christine; Minan, Fiorella; Huggel, Christian


    Models in a range of scientific disciplines are increasingly seen as indispensable for successful adaptation. Governments as well as international organizations and cooperations put their efforts in basing their adaptation projects on scientific results. Thereby, it is critical that scientific models are first put into the particular context in which they will be applied. This paper addresses the experience of the project 'Glaciers 513- Climate change adaptation and disaster risk management for glacier retreat in the Andes' conducted in the districts of Carhuaz (Ancash region) and Santa Teresa (Cusco region) in Peru. The Peruvian and the Swiss governments put their joint efforts in an adaptation project in the context of climate change and the retreat of the glaciers. The project is led by a consortium of Care Peru and the University of Zurich with additional Swiss partners and its principal aim is to improve the capacity for integral adaptation and reduce the risk of disasters from glaciers and high-mountain areas, and effects of climate change, particularly in the regions of Cusco and Ancash. The paper shows how the so called "human dimension" on the one hand, and models from a range of disciplines, including climatology, glaciology, and hydrology on the other hand, were conceptualized and perceived by the different actors involved in the project. Important aspects have been, among others, the role of local knowledge including ancestral knowledge, demographic information, socio-economic indicators as well as the social, political and cultural framework and the historical background. Here we analyze the role and context of local knowledge and the historical background. The analysis of the implications of the differences and similarities of the perceptions of a range of actors contributes to the discussion about how, and to what extent scientific models can be contextualized, what kind of information can be helpful for the contextualization and how it can be

  18. Ice sheets viewed from the ocean: the contribution of marine science to understanding modern and past ice sheets.

    Ó Cofaigh, Colm


    Over the last two decades, marine science, aided by technological advances in sediment coring, geophysical imaging and remotely operated submersibles, has played a major role in the investigation of contemporary and former ice sheets. Notable advances have been achieved with respect to reconstructing the extent and flow dynamics of the large polar ice sheets and their mid-latitude counterparts during the Quaternary from marine geophysical and geological records of landforms and sediments on glacier-influenced continental margins. Investigations of the deep-sea ice-rafted debris record have demonstrated that catastrophic collapse of large (10(5)-10(6) km(2)) ice-sheet drainage basins occurred on millennial and shorter time scales and had a major influence on oceanography. In the last few years, increasing emphasis has been placed on understanding physical processes at the ice-ocean interface, particularly at the grounding line, and on determining how these processes affect ice-sheet stability. This remains a major challenge, however, owing to the logistical constraints imposed by working in ice-infested polar waters and ice-shelf cavities. Furthermore, despite advances in reconstructing the Quaternary history of mid- and high-latitude ice sheets, major unanswered questions remain regarding West Antarctic ice-sheet stability, and the long-term offshore history of the East Antarctic and Greenland ice sheets remains poorly constrained. While these are major research frontiers in glaciology, and ones in which marine science has a pivotal role to play, realizing such future advances will require an integrated collaborative approach between oceanographers, glaciologists, marine geologists and numerical modellers.

  19. Using data assimilation to investigate the causes of Southern Hemisphere high latitude cooling from 10 to 8 ka BP

    P. Mathiot


    Full Text Available Paleoclimate records show an atmospheric and oceanic cooling in the high latitudes of the Southern Hemisphere from 10 to 8 ka BP. In order to study the causes of this cooling, simulations covering the early Holocene period have been performed with the climate model of intermediate complexity LOVECLIM constrained to follow the signal recorded in climate proxies using a data assimilation method based on a particle filtering. The selected proxies represent oceanic and atmospheric surface temperature in the Southern Hemisphere derived from terrestrial, marine and glaciological records. Using our modeling framework, two mechanisms potentially explaining the 10–8 ka BP cooling pattern are investigated. The first hypothesis is a change in atmospheric circulation. The state obtained by data assimilation displays a modification of the meridional atmospheric circulation around Antarctica, producing a 0.6 °C drop in atmospheric temperatures over Antarctica from 10 to 8 ka BP without congruent cooling of the atmospheric and sea-surface temperature in the Southern Ocean. The second hypothesis is a cooling of the sea surface temperature in the Southern Ocean, simulated here as the response to a higher West Antarctic Ice Sheet melting rate. Using data assimilation, we constrain the fresh water flux to increase by 100 mSv from 10 to 8 ka BP. This perturbation leads to an oceanic cooling of 0.5 °C and a strengthening of Southern Hemisphere westerlies (+6%. However, the observed cooling in Antarctic and the Southern Ocean proxy records can only be reconciled with the combination of a modified atmospheric circulation and an enhanced freshwater flux.

  20. Using data assimilation to investigate the causes of Southern Hemisphere high latitude cooling from 10 to 8 ka BP

    P. Mathiot


    Full Text Available From 10 to 8 ka BP (thousand years before present, paleoclimate records show an atmospheric and oceanic cooling in the high latitudes of the Southern Hemisphere. During this interval, temperatures estimated from proxy data decrease by 0.8 °C over Antarctica and 1.2 °C over the Southern Ocean. In order to study the causes of this cooling, simulations covering the early Holocene have been performed with the climate model of intermediate complexity LOVECLIM constrained to follow the signal recorded in climate proxies using a data assimilation method based on a particle filtering approach. The selected proxies represent oceanic and atmospheric surface temperature in the Southern Hemisphere derived from terrestrial, marine and glaciological records. Two mechanisms previously suggested to explain the 10–8 ka BP cooling pattern are investigated using the data assimilation approach in our model. The first hypothesis is a change in atmospheric circulation, and the second one is a cooling of the sea surface temperature in the Southern Ocean, driven in our experimental setup by the impact of an increased West Antarctic melting rate on ocean circulation. For the atmosphere hypothesis, the climate state obtained by data assimilation produces a modification of the meridional atmospheric circulation leading to a 0.5 °C Antarctic cooling from 10 to 8 ka BP compared to the simulation without data assimilation, without congruent cooling of the atmospheric and sea surface temperature in the Southern Ocean. For the ocean hypothesis, the increased West Antarctic freshwater flux constrainted by data assimilation (+100 mSv from 10 to 8 ka BP leads to an oceanic cooling of 0.7 °C and a strengthening of Southern Hemisphere westerlies (+6%. Thus, according to our experiments, the observed cooling in Antarctic and the Southern Ocean proxy records can only be reconciled with the reconstructions by the combination of a modified atmospheric circulation and an enhanced

  1. Mass balance re-analysis of Findelengletscher, Switzerland; benefits of extensive snow accumulation measurements

    Leo eSold


    Full Text Available A re-analysis is presented here of a 10-year mass balance series at Findelengletscher, a temperate mountain glacier in Switzerland. Calculating glacier-wide mass balance from the set of glaciological point balance observations using conventional approaches, such as the profile or contour method, resulted in significant deviations from the reference value given by the geodetic mass change over a five-year period. This is attributed to the sparsity of observations at high elevations and to the inability of the evaluation schemes to adequately estimate accumulation in unmeasured areas. However, measurements of winter mass balance were available for large parts of the study period from snow probings and density pits. Complementary surveys by helicopter-borne ground-penetrating radar (GPR were conducted in three consecutive years. The complete set of seasonal observations was assimilated using a distributed mass balance model. This model-based extrapolation revealed a substantial mass loss at Findelengletscher of -0.43m w.e. a^-1 between 2004 and 2014, while the loss was less pronounced for its former tributary, Adlergletscher (-0.30m w.e. a^-1. For both glaciers, the resulting time series were within the uncertainty bounds of the geodetic mass change. We show that the model benefited strongly from the ability to integrate seasonal observations. If no winter mass balance measurements were available and snow cover was represented by a linear precipitation gradient, the geodetic mass balance was not matched. If winter balance measurements by snow probings and snow density pits were taken into account, the model performance was substantially improved but still showed a significant bias relative to the geodetic mass change. Thus the excellent agreement of the model-based extrapolation with the geodetic mass change was owed to an adequate representation of winter accumulation distribution by means of extensive GPR measurements.

  2. The Glaciers of HARMONIE

    Mottram, Ruth; Gleeson, Emily; Pagh Nielsen, Kristian


    Developed by the large ALADIN-HIRLAM consortium, the numerical weather prediction (NWP) model system HARMONIE is run by a large number of national weather services and research institutions in Europe, the Middle East and North Africa for weather forecasting. It is now being adopted for climate research purposes as a limited area model in a form known as HCLIM. It is currently run for a number of domains, mostly in Europe but also including Greenland, at a very high resolution (~2.5 km). HARMONIE is a convection permitting non-hydrostatic model that includes the multi-purpose SURFEX surface model. By improving the characterization of glacier surfaces within SURFEX we show that weather forecast errors over both the Greenland ice sheet and over Icelandic glaciers can be significantly reduced. The improvements also facilitate increasingly accurate ice melt and runoff computations, which are important both for ice surface mass balance estimations and hydropower forecasting. These improvements will also benefit the operational HARMONIE domains that cover the Svalbard archipelago, the Alps and the Scandinavian mountain glaciers. Future uses of HCLIM for these regions, where accurately characterizing glacial terrain will be crucial for climate and glaciological applications, are also expected to benefit from this improvement. Here, we report the first results with a new glacier surface scheme in the HARMONIE model, validated with observations from the PROMICE network of automatic weather stations in Greenland. The scheme upgrades the existing surface energy balance over glaciers by including a new albedo parameterization for bare glacier ice and appropriate coefficients for calculating the turbulent fluxes. In addition the snow scheme from the SURFEX land surface module has been upgraded to allow the retention and refreezing of meltwater in the snowpack. These changes allow us to estimate surface mass balance over glaciers at a range of model resolutions that can take full

  3. Understanding how Alpine Valley-Glacier Overdeepenings affect Seasonal Glacial Dynamics

    Higson, Will


    Recent advances within the fields of photogrammetry and UAV technology has opened up the potential for use in glaciological fields due to high resolution imagery (1-20 cm), low costs, increased portability and improved ortho-mosaic software. Glaciers tend to move slowly and from lower resolution satellite data, smaller scale changes can be harder to infer, particularly over shorter, seasonal time periods. High resolution imagery from 5 sets of flights using a 'DJI Phantom 4' unmanned aerial vehicle (UAV) were recorded over the lower 2 km of Findelen Glacier, Switzerland between 22 August and 6 September. 3-dimensional ortho-mosaics were created using Agisoft PhotoScan software of each flight. Photogrammetry was rectified by nine ground control points (GCP) positioned at the margins of the glacier in static locations and georeferenced to l-20 cm error using Magellan ProMark 3 DGPS equipment. Pixel sizing was suitable for feature tracking software (5 +/- 2 cm) but varied based on relative altitude and velocity at time of capture which was set to 2.5 m/s. vertical and horizontal overlap were high (89% & 70% respectively). Feature tracking of the glacier over 17 days combined with DEM change comparison shows a flattening slope angle and slowing of velocity before an assumed reigel and an increased velocity post-reigel. Glacier surface flow velocities over this period were found to be in the region of 1.5 m. However, this does not account for error levels of 40 cm throw doubt on findings, considered due to a lack of GCPs on the glacier itself. A repeat survey is scheduled to reduce error and seek to compare annual changes in glacial dynamics. Importantly, this method (which enables feature tracking at these high resolutions) is suitable for measuring smaller seasonal changes within glacier dynamics. Keywords: UAV, Feature Tracking, Glacier Dynamics, Overdeepening, Photogrammetry.

  4. UAV photogrammetry and structure from motion to assess calving dynamics at Store Glacier, a large outlet draining the Greenland ice sheet

    Ryan, J. C.; Hubbard, A. L.; Box, J. E.; Todd, J.; Christoffersen, P.; Carr, J. R.; Holt, T. O.; Snooke, N.


    This study presents the application of a cost-effective, unmanned aerial vehicle (UAV) to investigate calving dynamics at a major marine-terminating outlet glacier draining the western sector of the Greenland ice sheet. The UAV was flown over Store Glacier on three sorties during summer 2013 and acquired over 2000 overlapping, geotagged images of the calving front at an ~40 cm ground sampling distance. Stereo-photogrammetry applied to these images enabled the extraction of high-resolution digital elevation models (DEMs) with vertical accuracies of ± 1.9 m which were used to quantify glaciological processes from early July to late August 2013. The central zone of the calving front advanced by ~500 m, whilst the lateral margins remained stable. The orientation of crevasses and the surface velocity field derived from feature tracking indicates that lateral drag is the primary resistive force and that ice flow varies across the calving front from 2.5 m d-1 at the margins to in excess of 16 m d-1 at the centreline. Ice flux through the calving front is 3.8 × 107 m3 d-1, equivalent to 13.9 Gt a-1 and comparable to flux-gate estimates of Store Glacier's annual discharge. Water-filled crevasses were present throughout the observation period but covered a limited area of between 0.025 and 0.24% of the terminus and did not appear to exert any significant control over fracture or calving. We conclude that the use of repeat UAV surveys coupled with the processing techniques outlined in this paper have great potential for elucidating the complex frontal dynamics that characterise large calving outlet glaciers.

  5. High-Resolution Monitoring of Himalayan Glacier Dynamics Using Unmanned Aerial Vehicles

    Immerzeel, W.; Kraaijenbrink, P. D. A.; Shea, J.; Shrestha, A. B.; Pellicciotti, F.; Bierkens, M. F.; de Jong, S. M.


    Himalayan glacier tongues are commonly debris covered and play an important role in modulating the glacier response to climate . However, they remain relatively unstudied because of the inaccessibility of the terrain and the difficulties in field work caused by the thick debris mantles. Observations of debris-covered glaciers are therefore limited to point locations and airborne remote sensing may bridge the gap between scarce, point field observations and coarse resolution space-borne remote sensing. In this study we deploy an Unmanned Airborne Vehicle (UAV) on two debris covered glaciers in the Nepalese Himalayas: the Lirung and Langtang glacier during four field campaigns in 2013 and 2014. Based on stereo-imaging and the structure for motion algorithm we derive highly detailed ortho-mosaics and digital elevation models (DEMs), which we geometrically correct using differential GPS observations collected in the field. Based on DEM differencing and manual feature tracking we derive the mass loss and the surface velocity of the glacier at a high spatial resolution and accuracy. We also assess spatiotemporal changes in supra-glacial lakes and ice cliffs based on the imagery. On average, mass loss is limited and the surface velocity is very small. However, the spatial variability of melt rates is very high, and ice cliffs and supra-glacial ponds show mass losses that can be an order of magnitude higher than the average. We suggest that future research should focus on the interaction between supra-glacial ponds, ice cliffs and englacial hydrology to further understand the dynamics of debris-covered glaciers. Finally, we conclude that UAV deployment has large potential in glaciology and it represents a substantial advancement over methods currently applied in studying glacier surface features.

  6. Forcing Mechanisms for the Variations of Near-surface Temperature Lapse Rates along the Himalayas, Tibetan Plateau (HTP) and Their Surroundings

    Kattel, D. B.; Yao, T.; Ullah, K.; Islam, G. M. T.


    This study investigates the monthly characteristics of near-surface temperature lapse rates (TLRs) (i.e., governed by surface energy balance) based on the 176 stations 30-year (1980 to 2010) dataset covering a wide range of topography, climatic regime and relief (4801 m) in the HTP and its surroundings. Empirical analysis based on techniques in thermodynamics and hydrostatic system were used to obtain the results. Steepest TLRs in summer is due to strong dry convection and shallowest in winter is due to inversion effect is the general pattern of TLR that reported in previous studies in other mountainous region. Result of this study reports a contrast variation of TLRs from general patterns, and suggest distinct forcing mechanisms in an annual cycle. Shallower lapse rate occurs in summer throughout the regions is due to strong heat exchange process within the boundary layer, corresponding to the warm and moist atmospheric conditions. There is a systematic differences of TLRs in winter between the northern and southern slopes the Himalayas. Steeper TLRs in winter on the northern slopes is due to intense cooling at higher elevations, corresponding to the continental dry and cold air surges, and considerable snow-temperature feedback. The differences in elevation and topography, as well as the distinct variation of turbulent heating and cooling, explain the contrast TLRs (shallower) values in winter on the southern slopes. Distinct diurnal variations of TLRs and its magnitudes between alpine, dry, humid and coastal regions is due to the variations of adiabatic mixing during the daytime in the boundary layer i.e., associated with the variations in net radiations, elevation, surface roughness and sea surface temperature. The findings of this study is useful to determine the temperature range for accurately modelling in various field such as hydrology, glaciology, ecology, forestry, agriculture, as well as inevitable for climate downscaling in complex mountainous terrain.


    Köhler, Piotr


    Polish expedition to Spitsbergen in 1934 was already the second Polish polar expedition to the Arctic. It was scientific-mountaineering in character. 7 persons took part in it: Witold Biernawski (1898-1957)--film-maker and radiotelegraph operator, Stefan Bernadzikiewicz (1907-1939)--expedition leader, Henryk Mogilnicki (1906-1999)--photographer and radiotelegraph operator, Stefan Zbigniew Różycki (1906-1988)--geologist, Stanisław Siedlecki (1912-2002)--meteorological observer, Sylweriusz Bohdan Zagrajski (1892-1940)--triangulator, Antoni Rogal-Zawadzki (1896-1974)--topographer and photogrammetrist. The purpose of this expedition was to collect data in geology and cartography, and to a lesser degree--in glaciology, botany, zoology and meteorology. It lasted from May 20 to September 16, 1934. The time between June 20 - August 28 the group spent on Spitsbergen's Torell Land. The outcome: an area of app. 300 square kilometres of previously undiscovered land was marked by triangular system, covered by photogrammetric photos and surveyed. Geological research covered the land of app. 500 square kilometres and the group collected geological specimens of app. 800 kg in weight. On the basis of their research, two maps (at a scale of 1:50 000 and 1:200 000) were published. The participants collected also botanical and zoological material. Meteorological observations were carried out at the base over Van Keulen fjord throughout the whole expedition. Different objects on Torell Land were named by the expedition, their names referring largely to Poland (Annex I). Approximately 200 photographs and a film were shot by the expedition. Apart from scientific research, the participants published also diaries of the expedition.

  8. Eskers and other evidence of wet-based glaciation in Phlegra Montes, Mars.

    Gallagher, Colman; Balme, Matt


    Although glacial landsystems produced under warm/wet based conditions are very common on Earth, glaciological and landform evidence indicates that glaciation on Mars during the Amazonian period (3 Ga to present) has been characterised by cold/dry based glaciers, consistent with the prevailing cold, hyperarid conditions. However, this presentation describes a system of sinuous ridges, interpreted as eskers (1), emerging from the degraded piedmont terminus of a Late Amazonian (˜150 Ma) glacier in the southern Phlegra Montes region of Mars. This is probably the first identification of martian eskers that can be directly linked to their parent glacier. Together with their contextual landform assemblage, the eskers are indicative of glacial melting and subglacial meltwater routing but the confinement of the system to a well-defined, regionally significant graben, and the absence of eskers elsewhere in the region, suggests that melting was a response to locally enhanced geothermal heat flux, rather than regional, climate-induced warming. Now, however, new observations reveal the presence of many assemblages of glacial abrasion forms and associated channels that could be evidence of more widespread wet-based glaciation in Phlegra Montes, including the collapse of several distinct ice domes. This landform assemblage has not been described in other glaciated, mid-latitude regions of the martian northern hemisphere. Moreover, Phlegra Montes are flanked by lowlands displaying evidence of extensive volcanism, including contact between plains lava and piedmont glacial ice. These observations suggest that the glaciation of Phlegra Montes might have been strongly conditioned by both volcanism and more restricted forms of ground-heating. These are important new insights both to the forcing of glacial dynamic and melting behaviour on Mars by factors other than climate and to the production of liquid water on Mars during the Late Amazonian. (1) Gallagher, C. and Balme, M. (2015

  9. Field Investigation of Surface-Lake Processes on Ice Shelves: Results of the 2015/16 Field Campaign on McMurdo Ice Shelf, Antarctica

    MacAyeal, Doug; Banwell, Alison; Willis, Ian; Macdonald, Grant


    Ice-shelf instability and breakup of the style exhibited by Larsen B Ice Shelf in 2002 remains the most difficult glaciological process of consequence to observe in detail. It is, however, vital to do so because ice-shelf breakup has the potential to influence the buttressing controls on inland ice discharge, and thus to affect sea level. Several mechanisms enabling Larsen B style breakup have been proposed, including the ability of surface lakes to introduce ice-shelf fractures when they fill and drain, thereby changing the surface loads the ice-shelf must adjust to. Our model suggest that these fractures resulted in a chain-reaction style drainage of >2750 surface lakes on the Larsen B in the days prior to its demise. To validate this and other models, we began a field project on the McMurdo Ice Shelf (MIS) during the 2015/16 austral summer. Advantages of the MIS study site are: there is considerable surface melting during 3-6 weeks of the summer season, the ice is sufficiently thin (logistical support (McMurdo Station). Here we show initial results from the field campaign, including GPS and water-depth observations of a lake that has filled and drained over multiple week timescales in previous austral summers. We also report on the analysis of high-resolution WorldView satellite imagery from several summers that reveals the complexity of surface meltwater movement in channels and subsurface void spaces. Initial reconnaissance of the largest surface-lake features reveal that they have a central circular depression surrounded by an uplifted ring, which supports one of the central tenets of our ice-shelf flexure theory. A second field season is anticipated for the 2016/17 austral summer.

  10. Identifying the AD 1257 Salamas volcanic event from micron-size tephra composition in two East Antarctic ice cores

    Petit, Jean Robert; Narcisi, Biancamaria; Batanova, Valentina G.; Joël, Savarino; Komorowski, Jean Christophe; Michel, Agnes; Metrich, Nicole; Besson, Pascale; Vidal, Celine; Sobolev, Alexander V.


    A wealth of valuable data about the history of explosive volcanic history can be extracted from polar ice successions. Both the volatile by-products and the solid silicate (tephra) components of volcanic plumes can be incorporated into snow layers, providing tools for chronostratigraphic correlations and for interpretation of climate-volcanism interactions. Volcanic events from low-latitude regions are of particular interest as the related sulphate aerosol travelling through the stratosphere can reach the polar sheets forming inter-hemispheric (Greenland and Antarctica) signals preserved in the ice. Within the glaciological record of globally significant volcanic markers, the AD1259 signal represents one of most prominent events over the last thousands years. Its source has been long debated. On the basis of recent field investigations (Lavigne et al., 2013; Vidal et al., 2015), it has been proposed that Mount Samalas on Lombok Island (Indonesia) represents the source responsible for the polar event. With the goal of bringing distal tephrochronological evidence to source identification, we have attempted to identify volcanic ash associated to the AD 1259 sulphate pulse. To this purpose we used firn and ice-core samples from two East Antarctic Plateau sites: Concordia-Dome C (75°06' S, 123°20' E, 3233 m) and Talos Dome (72°49'S, 159°11'E, 2315 m). Our high-resolution studies included sample processing in a Class 100 clean room using established ultra-clean procedures for insoluble microparticle analyses, Coulter counter grain size measurements, scanning electron microscope observations and the geochemical (major elements) composition from the recently set ISTERRE Jeol JXA 8230 Superprobe and calibrated for small particles analysis. Despite the difficulty of studying such minute fragments, within both cores we located and characterised multiple tiny (micron-size) glass shards concomitant with the volcanic peak. We present preliminary results alongside comparison

  11. Morphological dynamics of an englacial channel

    G. Vatne


    Full Text Available Despite an interest in the hydraulic functioning of supraglacial and englacial channels over the last four decades, the processes and forms of such ice-bounded streams have remained poorly documented. Recent glaciological research has demonstrated the potential significance of so-called "cut and closure" streams, where englacial or subglacial flowpaths are created from the long-term incision of supraglacial channels. These flowpaths are reported to exhibit step-pool morphology, comprising knickpoints and/or knickzones, albeit exaggerated in dimensions in comparison to their supraglacial channel counterparts. However, little is known of the development of such channels' morphology. Here, we examine the spatial organization of step-pools and the upstream migration of steps, many of which form knickzones, with repeated surveys over a 10 year period in an englacial conduit in cold-based Austre Brøggerbreen, Svalbard. The observations show upstream knickpoint recession to be the dominant process for channel evolution. This is paralleled by an increase in average step height and conduit gradient over time. Characteristic channel reach types and step-riser forms are consistently observed in each of the morphological surveys reported. We suggest that the formation of steps has a hydrodynamic origin, where step-pool geometry is more efficient for energy dissipation than meanders, and that the englacial channel system is one in rapid transition rather than in dynamic equilibrium. The evolution and recession of knickzones reported here result in the formation of a 37 m moulin, suggesting over time the englacial channel may evolve towards a stable end-point characterised by a singular vertical descent to the local hydraulic base level. In light of this, our observations highlight the need to further examine the adjustment processes in cut-and-closure channels to better understand their coupling to supraglacial meltwater sources and role and potential

  12. Glacial history of a mid-altitude mountain massif: cartography and dating in the Chablais area (France, Switzerland)

    Perret, A.; Reynard, E.; Delannoy, J.-J.


    The Chablais area, considered as one of the cradles of glaciology (de Charpentier, 1841; Morlot, 1859), has been studied for a long time but several questions still remain unresolved. This study aims to reconstruct the glacial history of the massif, in order to explain the glacial landforms, which constitute an important part of the local geomorphology. The study focuses on the last glacial cycle (OIS 5 - OIS 2). The area is primarily associated with the the Valais glacier, by several local glacial flows and, to a lesser extent, by the Giffre glacier. Its position at the interface of the important Valais glacial flow and less powerful local flows is a specificity of the study area, which implies several bifurcations, penetration of the main glacier into laterals valleys, damming situations, and different responses of the various ice bodies to climatic changes. The study is divided in four steps. (1) The first step was to carry out a wide bibliographic survey to identify the state of knowledge, especially in relation to areas previously poorly studied and areas that needed to be reconsidered given developments in dating methods. (2) Field surveys allowed us to complete observations and prepare local geomorphological maps (of glacial landforms and associated phenomena). (3) The third step was to assemble heterogeneous data (old and new maps, Digital Terrain Models, aerial photographies) in a GIS to establish maps of glacial stages. (4) Finally, the absolute and relative chronology of deglaciation (Guitter, 2003) was completed by cosmogenic nuclide dating. Results have allowed us to address the conditions of glacial landform deposition and evolution in a mid-altitude mountain range, and show the need to be prudent in comparing results of different dating methods. Our results suggest that the ages obtained are overall too young in regard to 10Be ages on the northern alpine foreland (Ivy-Ochs et al., 2004) and are in conflict with 14C dates obtained in the area

  13. Developing an observational benchmark for climate-glacier interactions in the Southern Alps of New Zealand

    Cullen, N. J.; Conway, J.; Anderson, B.; Mackintosh, A.; Sirguey, P. J.; Fitzsimons, S.; Lorrey, A. M.


    Understanding the response of mountain glaciers to climate variability is crucial for any prediction of sea level rise, the management of water resources, and assessing the risk of natural hazards triggered by glacier retreat. The Southern Alps are important to our understanding of climate change because their location in the southwest Pacific means that they are ideally placed to detect changes in Southern Hemisphere atmospheric circulation. Changes in the regional ocean-atmosphere system, notably the arrangement of the westerly jet stream, sea surface temperature and surface level pressure in the New Zealand region are important controls on glacier behavior. To continue to build our understanding of the linkages between climate-glacier interactions in the Southern Alps a glaciological and meteorological program on Brewster Glacier has been maintained through the collaborative effort of the University of Otago, Victoria University and NIWA. The program will move into its 10th year next year, making it the longest mass balance program ever conducted in the Southern Alps. It has provided a platform for a number of studies over this time, with the most recent effort being an intensive meteorological measurement campaign in the ablation area of the glacier. This effort has not been without its challenges but we now have the longest and arguably the highest quality meteorological data set ever obtained from a glacier surface in the Southern Alps (2+ years). In particular, the radiation and eddy correlation data obtained through this effort have enabled us to significantly reduce uncertainties associated with energy and mass balance modelling. By presenting these new observational and modelling results we hope to provide the broader cryospheric community with insights into what our current state of knowledge is and how this platform is spawning new projects linked to remote sensing and atmospheric chemistry.

  14. Space activity impact on science and technology. Proceedings of the twenty-fourth international astronautical congress, Baku, USSR, October 7--13, 1973

    Napolitano, L.G.; Contensou, P.; Hilton, W.F. (eds.)


    Topics covered include: Soviet automatic vehicles for lunar exploration and their influence on the progress of automatics and control theory; the problems of space technology and their influence on science and technics; industrial use of aerospace technology; development of liquid-propellant rocket engine engineering and its influence on science and technology in the USSR; space medicine and public health; impact of space activity on technology in a country the size of France; astronautics as a stimulus for celestial mechanics; space activity impact on the science and technology of rotating bodies; skylab systems flight performance, an interim report; the design and utilization of a spacelab for sortie missions; the spacelab program; man and the environment, remote sensing from space; EOLE application program for meteorological experiments, complementary experiences; machine processing methods for earth observational data; recent advances in geologic applications of remote sensing from space; infrared scanning for meteorological purposes; spatial antartic glaciology; reflection spectra usage in recognition of plant covers; experimental investigation of aeronautical and maritime communications and surveillance using satellites; the ESRO MAROTS program; the problem of habitability in spaceships; atmosphere revitalization for manned spacecraft; prospects of international cooperation in medical sciences; developing a technology base in planetary entry aerothermodynamics; scientific results of the automatic ionospheric laboratory Yantar 4 flight; nonlinear unsteady motions in solid propellant rockets with application to large motors; investigation of the physical and mechanical properties of the lunar sample brought by Luna 20 and along the route of motion of Lunokhod 2; orbiting astronomical observatory Copernicus; the delta launch vehicle model 2914 series; space tug mission and program planning; space and education; and safety in youth rocket experiments. (GHT)

  15. Picture This: The Art of Using Museum and Science Collaborations to Teach about Climate Change

    Fiondella, F.; Fowler, R.; Davi, N. K.; Gawthrop, E.


    Connecting scientists and their research to photography galleries and museums is an effective way to promote climate literacy among a new, diverse audience. This approach requires creativity and a willingness to reach out to and work with staff unfamiliar with scientific institutions, but can result in broad exposure and understanding of the impacts of climate change. In this presentation we highlight the successful science-art collaboration among the International Center of Photography, Lamont-Doherty Earth Observatory and the International Research Institute for Climate and Society. The collaboration revolved around ICP's 2014-2015 exhibition of renowned photographer Sebastiao Salgado's Genesis, an eight-year worldwide survey of wildlife, landscapes, seascapes and indigenous peoples. Salgado's photographs acted as a springboard for a unique public education program based at ICP and aimed at raising awareness of the urgent issue of climate change. Over the course of six months, Lamont and IRI scientists with expertise in climatology, dendrochronology, seismology and glaciology led gallery tours for the public, making links between their research and the places and people of Salgado's photography. Lamont and IRI staff also gave talks throughout the exhibition period on topics ranging from climate change adaptation to the use of photography to help the public visualize the impacts of Earth's changing climate. The research institutions also took over ICP's Instagram feed for a week, showcasing the climate-related field work of more than a dozen scientists. All three institutions, the participating scientists and program attendees deemed the collaboration a success. We'll explain what made this collaboration successful and provide tips on how scientists and their institutes can form similar collaborations with museums and other arts-based organizations.

  16. Sustainability of water resources management in the Indus Basin under changing climatic and socio economic conditions

    D. R. Archer


    Full Text Available Pakistan is highly dependent on water resources originating in the mountain sources of the upper Indus for irrigated agriculture which is the mainstay of its economy. Hence any change in available resources through climate change or socio-economic factors could have a serious impact on food security and the environment. In terms of both ratio of withdrawals to runoff and per-capita water availability, Pakistan's water resources are already highly stressed and will become increasingly so with projected population changes. Potential changes to supply through declining reservoir storage, the impact of waterlogging and salinity or over-abstraction of groundwater, or reallocations for environmental remediation of the Indus Delta or to meet domestic demands, will reduce water availability for irrigation.

    The impact of climate change on resources in the Upper Indus is considered in terms of three hydrological regimes – a nival regime dependent on melting of winter snow, a glacial regime, and a rainfall regime dependent on concurrent rainfall. On the basis of historic trends in climate, most notably the decline in summer temperatures, there is no strong evidence in favour of marked reductions in water resources from any of the three regimes. Evidence for changes in trans-Himalayan glacier mass balance is mixed. Sustainability of water resources appears more threatened by socio-economic changes than by climatic trends. Nevertheless, analysis and the understanding of the linkage of climate, glaciology and runoff is still far from complete; recent past climate experience may not provide a reliable guide to the future.

  17. The Pleasures and Perils of Popularization

    Grinspoon, David H.


    Carl Sagan often reminded us that we are privileged to be space explorers, and we should never take public support for granted. As jobs go, planetary exploration sure beats flipping burgers. It can also seem like a bourgeois extravagance in a world with some serious mayhem and deprivation. We've all encountered the attitude epitomized by the recent Onion headline: "NASA Announces Plan to Launch $700 Million into Space". But planetary science is highly relevant to some burning societal issues. Indeed it is slightly strange to see concepts we labored over in grad school, like "albedo", "insolation” and "infrared opacity” now tossed about in Newsweek. Today, the man and woman in the street are quite aware that climate modeling and glaciology are relevant. It is up to us to explain that comparative planetology is also indispensable. In my career so far, I've tried to balance deep involvement in both research and public outreach. Sometimes this feels like too many jobs, but at least sometimes they are synergistic. Being an active researcher, you can speak to the public with an inside, authentic, behind-the-scenes voice. Interacting with the media on a regular basis helps you (indeed forces you) to stay current in a broad range of subject matter, and that can nurture your research. That all sounds pretty high minded, but public speaking, writing, and media interviews are great fun, and they get easier. Actually, writing is often as much fun as dental work. But usually worth it. These activities feed the soul (and the ego and even occasionally the bank account...). If they help spread the word about the wonders of the solar system, the mysteries of life in the universe and the experiences of working scientists, well that's pretty cool, too.

  18. Evolving patterns of coupled glacio-hydrology across the Pacific Northwest Region, USA

    Frans, C. D.; Istanbulluoglu, E.; Lettenmaier, D. P.; Fountain, A. G.; Bachmann, M.; Clarke, G. K. C.


    Recession of mountain glaciers in partially glacierized headwater catchments has the potential to impact watershed dynamics in a range of ways, including reduced low flows, erosion of exposed steep soils, increased sediment transport, and ecosystem succession. The response of glaciers and glacierized watershed processes to progressive climatic warming will vary greatly with local environmental attributes (aspect, hypsometry, slope, debris cover) and climatic forcing (topography driven climatic gradients, prevailing wind direction, precipitation variability and perturbation). To identify the relative influence of these controlling factors and to identify locations where these changes will have significant influence on stream discharge in the U.S. Pacific Northwest (PNW), we gather a rich data set of glacio-hydrological variables and use a recently developed glacio-hydrology model in conjunction with data to evaluate the hydrologic response of partially glacierized river basins at a range of spatial and temporal scales. The distributed hydrologic modeling framework, which incorporates a physical representation of changes in glacier area through glacier dynamics, allows the analysis of hydrologic and glaciological change at extended temporal and fine spatial scales. Among the river basins we examine are the Hoh River on the Olympic Peninsula of Western Washington, the Hood River in Northern Oregon, the Nisqually River in the Puget Sound drainage basin, and multiple watersheds in the North Cascades Region. For each of these basins, tipping points of hydrologic response to glacier recession are identified and projected. We 1) describe varied patterns of coupled glacio-hydrologic response 2) identify influential environmental controls and 3) identify vulnerable areas in space and time. We close with a discussion of the implications of ongoing and projected glacio-hydrologic changes for the management of water and natural resources in the PNW.

  19. Investigating a newly discovered firn aquifer on Disko Ice Cap, west Greenland: Insights from ground observations, remote sensing, and modeling

    Trusel, L. D.; Das, S. B.; Smith, B.; Kuipers Munneke, P.; Evans, M. J.; Frey, K. E.; Osman, M.; York, A.


    Expanding and intensifying surface melt have accelerated contributions from Greenland to global sea level rise in recent decades. Yet, important questions remain regarding the evolution and eventual fate of this meltwater over time and space, a fact underscored by recent observations of expansive aquifers within the Greenland Ice Sheet firn. In April 2015 we observed liquid water retained at depth in an ice cap on Disko Island, central west Greenland. Two adjacent ~20 m firn/ice cores were collected before intercepting a layer saturated with liquid water as evident by water drainage from our cores. Borehole temperature profiling confirms increasing temperature with depth, revealing 0°C isothermal firn below ~10 m depth. Detailed physical stratigraphic analyses conducted on these cores allow us to assess firn properties and their small scale (1 m) and likely impermeable refrozen melt horizons exist above the inferred aquifer surface, raising questions about processes of aquifer formation. To discern the spatial character of the observed firn liquid water and melt stratigraphy, we utilize ground penetrating radar collected in 2014, as well as airborne radar data collected through NASA Operation IceBridge in 2012 and 12 days prior to our field observations in 2015. Glaciochemical analyses on our ice cores reveal preservation of an annual signal allowing derivation of net snow accumulation rates. Combined with surface mass balance modeled by RACMO2.3 and melt assessed via microwave remote sensing, we investigate the recently prevailing climatic and glaciological conditions on Disko. This work will provide new insights into mechanisms of firn aquifer formation and sustenance more broadly, as well as the representation of aquifers in existing radar observations and firn models.

  20. On the gas-ice depth difference (Δdepth along the EPICA Dome C ice core

    J. Schwander


    Full Text Available We compare a variety of methods for estimating the gas/ice depth offset (Δdepth at EPICA Dome C (EDC, East Antarctica. (1 Purely based on modelling efforts, Δdepth can be estimated combining a firn densification with an ice flow model. Observations allow direct and indirect estimate of Δdepth. (2 The diffusive column height can be estimated from δ15N and converted to Δdepth using an ice flow model and assumptions about past average firn density and thickness of the convective zone. (3 Ice and gas synchronisation of the EDC ice core to the GRIP, EDML and TALDICE ice cores shifts the ice/gas offset problem into higher accumulation ice cores where it can be more accurately evaluated. (4 Finally, the bipolar seesaw hypothesis allows us to synchronise the ice isotopic record with the gas CH4 record, the later being taken as a proxy of Greenland temperature. The bipolar seesaw antiphase relationship is generally supported by the ice-gas cross synchronisation between EDC and the GRIP, EDML and TALDICE ice cores, which provide support for method 4. Applying the bipolar seesaw hypothesis to the deeper section of the EDC core confirms that the ice flow is complex and can help improving our reconstruction of the thinning function and thus of the EDC age scale. We confirm that method 1 overestimates the glacial Δdepth at EDC and we suggested that it is due to an overestimation of the glacial Close Off Depth by the firn densification model. In contrast we find that the glaciological models probably underestimate the Δdepth during termination II. Finally, we show that method 2 based on 15N data produces for the last deglaciation a Δdepth estimate which is in good agreement with methods 3 and 4.

  1. Shift from Snowfall to Rainfall in the Canadian Rockies: Consequences for Snowpacks, Glacier Mass Balance and Streamflow in an Emerging Drought

    Pomeroy, J. W.; Fang, X.; Pradhananga, D.; Schirmer, M.; Conway, J. P.; Helgason, W.; Whitfield, P. H.


    The winter and spring of 2014-15 brought abnormal warmth to much of Western Canada and a transition from snowfall to rainfall for many winter and spring precipitation events in the Canadian Rocky Mountains where snowfall normally dominates precipitation volumes in these seasons. Spring and summer remained abnormally warm and exceptionally dry. The impact of a warm winter and dry spring and summer resulted in substantial reduction in snowfall and a shift to earlier rainfall in the Canadian Rockies. As a result peak snow accumulation was from 1/3 to 1/2 of long term averages at upper middle elevations and low elevation valley snowpacks ablated shortly after forming in early December. Snowmelt occurred 2 to 6 weeks earlier than average, resulting in earlier than normal spring freshets and exposure of glacier firn and ice. June 1st snow accumulation was completely ablated or at record low values for most observation stations. The shift from winter and spring snowfall to rainfall and subsequent low summer rainfall resulted in the emergence of exceptionally wide-spread forest fires, rapid glacier melt, low streamflow and severe agricultural drought in Western Canada. By mid-July the seasonal snowpack had largely ablated, discharge rates in the Bow River at Calgary were 40% of average, many mountain streams had dried up and the Athabasca Glacier had experienced 3 m of ice melt. The Cold Regions Hydrological Model was used to simulate the impacts of the snowfall to rainfall transition on the snow redistribution, sublimation and melt processes, runoff and evapotranspiration that control the water balance of selected mountain environments in this period, employing Harder and Pomeroy's Psychrometric Energy Balance Method to estimate precipitation phase. The results help to diagnose how a "warm drought" impacts the hydrology and glaciology of cold regions environments and suggest the possible impacts of future warmer climates and increased rainfall fraction on this region.

  2. Ice Core Records of Recent Northwest Greenland Climate

    Osterberg, E. C.; Wong, G. J.; Ferris, D.; Lutz, E.; Howley, J. A.; Kelly, M. A.; Axford, Y.; Hawley, R. L.


    Meteorological station data from NW Greenland indicate a 3oC temperature rise since 1990, with most of the warming occurring in fall and winter. According to remote sensing data, the NW Greenland ice sheet (GIS) and coastal ice caps are responding with ice mass loss and margin retreat, but the cryosphere's response to previous climate variability is poorly constrained in this region. We are developing multi-proxy records (lake sediment cores, ice cores, glacial geologic data, glaciological models) of Holocene climate change and cryospheric response in NW Greenland to improve projections of future ice loss and sea level rise in a warming climate. As part of our efforts to develop a millennial-length ice core paleoclimate record from the Thule region, we collected and analyzed snow pit samples and short firn cores (up to 21 m) from the coastal region of the GIS (2Barrel site; 76.9317o N, 63.1467o W, 1685 m el.) and the summit of North Ice Cap (76.938o N, 67.671o W, 1273 m el.) in 2011, 2012 and 2014. The 2Barrel ice core record has statistically significant relationships with regional spring and fall Baffin Bay sea ice extent, summertime temperature, and annual precipitation. Here we evaluate relationships between the 2014 North Ice Cap firn core glaciochemical record and climate variability from regional instrumental stations and reanalysis datasets. We compare the coastal North Ice Cap record to more inland records from 2Barrel, Camp Century and NEEM to evaluate spatial and elevational gradients in recent NW Greenland climate change.

  3. Contrasted glacier mass balance of debris-free glaciers between the southern and the inner part of the Everest region revealed by in-situ measurements since 2007

    Wagnon, Patrick; Futi Sherpa, Sonam; Brun, Fanny; Berthier, Etienne; Vincent, Christian; Lejeune, Yves; Arnaud, Yves; Bhakta Kayastha, Rijan; Sinisalo, Anna


    Three debris-free glaciers are currently monitored in the Everest region (Central Himalaya, Nepal) and their annual glaciological glacier-wide mass balances (Ba) strongly differ. Mera Glacier (5.1 km2 in 2012) is located in the southern part and has been in steady state over the last 8 years, whereas Pokalde (0.1 km2 in 2011) and Changri Nup glaciers (0.9 km2 in 2013), 30 km farther north in the drier inner part of the range, have been losing mass rapidly with a Ba of -0.69 ± 0.28 m w.e. a-1 (2009-2015) and -1.24 ± 0.27 m w.e. a-1 (2010-2015), respectively. A qualitative comparison between Ba and annual or seasonal meteorological variables acquired at the elevation of glaciers suggests that these glaciers are sensitive to precipitation, to the incoming radiative energy fluxes and, occasionally, to very severe cyclonic storms originating in the Bay of Bengal. This contrasted mass balance pattern over rather short distances is related (i) to the low elevation of Pokalde and Changri Nup glaciers sometimes restricting them to a single ablation zone and (ii) to a steeper vertical gradient of mass balance for glaciers located in the inner arid part. This difference in gradient is potentially related to the across-range contrast in annual precipitation (south-to-north horizontal gradient of precipitation ≥ -21 mm km-1 i.e. -2% km-1) and a decreasing trend of precipitation at high elevation inside the range

  4. Changes in Black Carbon Deposition to Antarctica from Two Ice Core Records, A.D. 1850-2000

    Bisiaux, Marion M.; Edward, Ross; McConnell, Joseph R.; Curran, Mark A. J.; VanOmmen, Tas D.; Smith, Andrew M.; Neumann, Thomas A.; Pasteris, Daniel R.; Penner, Joyce E.; Taylor, Kendrick


    Continuous flow analysis was based on a steady sample flow and in-line detection of BC and other chemical substances as described in McConnell et al. (2007). In the cold room, previously cut one meter ice core sticks of 3x3cm, are melted continuously on a heated melter head specifically designed to eliminate contamination from the atmosphere or by the external parts of the ice. The melted ice from the most inner part of the ice stick is continuously pumped by a peristaltic pump and carried to a clean lab by Teflon lines. The recorded signal is continuous, integrating a sample volume of about 0.05 mL, for which the temporal resolution depends on the speed of melting, ice density and snow accumulation rate at the ice core drilling site. For annual accumulation derived from the WAIS and Law Dome ice cores, we assumed 3.1 cm water equivalent uncertainty in each year's accumulation from short scale spatial variability (glaciological noise) which was determined from several measurements of annual accumulation in multiple parallel ice cores notably from the WAIS Divide ice core site (Banta et al., 2008) and from South Pole site (McConnell et al., 1997; McConnell et al., 2000). Refractory black carbon (rBC) concentrations were determined using the same method as in (Bisiaux et al., 2011) and adapted to continuous flow measurements as described by (McConnell et al., 2007). The technique uses a single particle intracavity laser induced incandescence photometer (SP2, Droplet Measurement Technologies, Boulder, Colorado) coupled to an ultrasonic nebulizer/desolvation (CETAC UT5000) Flow Injection Analysis (FIA). All analyses, sample preparation etc, were performed in a class 100 cleanroom using anti contamination "clean techniques". The samples were not acidified.

  5. Critical investigation of calculation methods for the elastic velocities in anisotropic ice polycrystals

    Maurel, Agnès; Mercier, Jean-François; Montagnat, Maurine


    Crystallographic texture (or fabric) evolution with depth along ice cores can be evaluated using borehole sonic logging measurements. These measurements provide the velocities of elastic waves that depend on the ice polycrystal anisotropy, and they can further be related to the ice texture. To do so, elastic velocities need to be inverted from a modeling approach that relate elastic velocities to ice texture. So far, two different approaches can be found. A classical model is based on the effective medium theory; the velocities are derived from elastic wave propagation in a homogeneous medium characterized by an average elasticity tensor. Alternatively, a velocity averaging approach was used in the glaciology community that averages the velocities from a given population of single crystals with different orientations. In this paper, we show that the velocity averaging method is erroneous in the present context. This is demonstrated for the case of waves propagating along the clustering direction of a highly textured polycrystal, characterized by crystallographic c axes oriented along a single maximum (cluster). In this case, two different shear wave velocities are obtained while a unique velocity is theoretically expected. While making use of this velocity averaging method, reference work by Bennett (1968) does not end with such an unphysical result. We show that this is due to the use of erroneous expressions for the shear wave velocities in a single crystal, as the starting point of the averaging process. Because of the weak elastic anisotropy of ice single crystal, the inversion of the measured velocities requires accurate modeling approaches. We demonstrate here that the inversion method based on the effective medium theory provides physically based results and should therefore be favored.

  6. Fluctuations of Glaciar Esperanza Norte in the north Patagonian Andes of Argentina during the past 400 yr

    L. Ruiz


    Full Text Available The number of studies of Little Ice Age (LIA glacier fluctuations in southern South America has increased in recent years but is largely biased towards sites in the south Patagonian Andes. In this paper we present a detailed record of length and areal fluctuations of Glaciar Esperanza Norte (GEN in the north Patagonian Andes of Argentina during the past four centuries. The GEN record was reconstructed through the dendro-geomorphological dating of moraines and the analysis of satellite imagery, aerial photographs and documentary material complemented with extensive field surveys. The maximum LIA extent at GEN was associated with an outer moraine dated to the mid 17th century. At least 19 subsequent readvances or standstills evidenced by morainic ridges were identified inside the most extensive LIA moraine. The dating and spacing of these moraines and the additional information available indicate that the ice front retreated much more rapidly during the 20th century than during earlier centuries. Comparison with the record of LIA fluctuations of Glaciar Frías, an ice mass of similar characteristics located 110 km to the north of GEN, shows a similar pattern of recession over the past 400 yr. Both glacier records have the peak LIA event occurring roughly during the same interval (early-mid 17th century and show a minor readvance during the 1970s, but there are still a few discrepancies in the dating of some inner moraines. These differences may be due to local, specific factors or associated with the inherent uncertainties in the dating of the moraines. The chronologies of GEN and Frías are among the most detailed currently available in Patagonia, but a larger number of study sites is needed to develop robust, regionally representative glacier chronologies. Detailed glaciological, geomorphological and meteorological data are also needed to understand the glacier-climate relationships in this region and develop reliable paleoclimatic

  7. Surface elevation change artifact at the NEEM ice core drilling site, North Greenland.

    Berg Larsen, Lars; Schøtt Hvidberg, Christine; Dahl-Jensen, Dorthe; Lilja Buchardt, Susanne


    The NEEM deep drilling site (77.45°N 51.06°W) is located at the main ice divide in North Greenland. For the ice core drilling project, a number of buildings was erected and left on the snow surface during the five-year project period. The structures created snowdrifts that formed accordingly to the predominant wind direction on the lee side on the buildings and the overwintering cargo. To get access to the buildings, the snowdrifts and the accumulated snow were removed and the surface in the camp was leveled with heavy machinery each summer. In the camp a GPS reference pole was placed as a part of the NEEM strain net, 12 poles placed in three diamonds at distances of 2,5 km, 7,5 km and 25 km they were all measured with high precision GPS every year. Around the reference pole, a 1 km x 1 km grid with a spacing of 100 m was measured with differential GPS each year. In this work, we present results from the GPS surface topography measurements in and around the campsite. The mapping of the topography in and around the campsite shows how the snowdrifts evolve and are the reason for the lift of the camp site area. The accumulated snowdrifts are compared to the dominant wind directions from year to year. The annual snow accumulation at the NEEM site is 0.60 m. The reference pole in the camp indicates an additional snow accumulation of 0.50 m per year caused by collected drifting snow. The surface topography mapping shows that this artificially elevated surface extends up to several kilometers out in the terrain. This could have possible implications on other glaciological and geophysical measurements in the area i.e. pit and snow accumulation studies.

  8. Assimilation of Antarctic velocity observations provides evidence for uncharted pinning points

    J. J. Fürst


    Full Text Available In ice flow modelling, the use of control methods to assimilate the dynamic and geometric state of an ice body has become common practice. These methods have primarily focussed on inverting for one of the two least known properties in glaciology, namely the basal friction coefficient or the ice viscosity parameter. Here, we present an approach to infer both properties simultaneously for the whole of the Antarctic ice sheet. During the assimilation, the root-mean-square deviation between modelled and observed surface velocities is reduced to 12.3 m a−1, with a value of 16.4 m a−1 for the ice shelves. An exception in terms of the velocity mismatch is the Thwaites Glacier ice shelf, where the RMS value attains almost 80 m a−1. The reason is that the underlying BEDMAP2 geometry ignores the presence of an ice rise, that exerts major control on the dynamics of the eastern part of the ice shelf. On these grounds, we suggest an approach to account for pinning points not included in BEDMAP2 by locally allowing an optimisation of basal friction during the inversion. In this way, the velocity mismatch on the Thwaites ice shelf is more than halved. A characteristic velocity mismatch pattern emerges for unaccounted pinning points close to the marine shelf front. This pattern is exploited to manually identify 7 uncharted features around Antarctica that exert significant resistance to the shelf flow. Potential pinning points are detected on Fimbul, West, Shakelton, Nickerson and Venable ice shelves. As pinning points can provide substantial resistance to shelf flow, with considerable consequences if they became ungrounded in the future, the model community is in need of detailed bathymetry there. Our data assimilation points to some of these dynamically important features, not present in BEDMAP2, and implicitly quantifies their relevance.

  9. Rapid wastage of the Hazen Plateau ice caps, northeastern Ellesmere Island, Nunavut, Canada

    Serreze, Mark C.; Raup, Bruce; Braun, Carsten; Hardy, Douglas R.; Bradley, Raymond S.


    Two pairs of small stagnant ice bodies on the Hazen Plateau of northeastern Ellesmere Island, the St. Patrick Bay ice caps and the Murray and Simmons ice caps, are rapidly shrinking, and the remnants of the St. Patrick Bay ice caps are likely to disappear entirely within the next 5 years. Vertical aerial photographs of these Little Ice Age relics taken during August of 1959 show that the larger of the St. Patrick Bay ice caps had an area of 7.48 km2 and the smaller one 2.93 km2; the Murray and Simmons ice caps covered 4.37 and 7.45 km2 respectively. Outlines determined from ASTER satellite data for July 2016 show that, compared to 1959, the larger and the smaller of the St. Patrick Bay ice caps had both been reduced to only 5 % of their former area, with the Murray and Simmons ice caps faring better at 39 and 25 %, likely reflecting their higher elevation. Consistent with findings from other glaciological studies in the Queen Elizabeth Islands, ASTER imagery in conjunction with past GPS surveys documents a strikingly rapid wastage of the St. Patrick Bay ice caps over the last 15 years. These two ice caps shrank noticeably even between 2014 and 2015, apparently in direct response to the especially warm summer of 2015 over northeastern Ellesmere Island. The well-documented recession patterns of the Hazen Plateau ice caps over the last 55+ years offer an opportunity to examine the processes of plant recolonization of polar landscapes.

  10. Representation of horizontal strain due to tidal bending by observation and modeling

    Rack, Wolfgang; King, Matt; Marsh, Oliver; Wild, Christian; Floricioiu, Dana


    An important control of ice sheet mass balance is the ice dynamics in the grounding zones around Antarctica. On many outflow glaciers a large temporal variability in ice flow has been observed, which is at least partly related to tides. Here we investigate the tide induced short term ice deformation in an ice shelf grounding zone and the related bending stresses and strain. We make use of the arguably most precise measurement method, differential SAR interferometry, in combination with ground based measurements and model assumptions for tidal bending. Ground validation and satellite data have been acquired within a dedicated field campaign. The Southern McMurdo Ice Shelf in the Western Ross Ice Shelf region was chosen as the experiment site. This area is optimal for the data interpretation because of a simple grounding line configuration, small ice flux, and favourable satellite imaging geometry. It is also a safe area which allowed the installation of tiltmeters and GPS stations, and glaciological measurements such as ice thickness and snow accumulation. From November 2014 to January 2015 the tidal movement was recorded over a period of 2.5 months. TerrSAR-X radar images have been acquired over the same period as a basis to derive ice shelf flexure maps. Despite the viscoelastic effects in ice shelf bending a simple elastic bending model for a beam of finite ice thickness can largely explain the GPS-observed surface strain. Using the same model and taking into account the viewing geometry of the satellite radar, it is now possible to separate horizontal and vertical displacement components in the satellite data. As a result we can obtain more realistic ice shelf flexure profiles from the interferometric SAR measurement. The newly derived flexure profiles are therefore more suitable to recover viscoelastic effects of tidal bending in grounding zones of ice shelves and outlet glaciers. These effects would have otherwise remained unnoticed.

  11. Global dynamic topography: geoscience communities requirements

    Dewez, T.; Costeraste, J.


    The advent of free-of-charge global topographic data sets SRTM and Aster GDEM have enabled testing a host of geoscience hypotheses. This is because they first revealed the relief of previously unavailable earth landscapes, enabled quantitative geomorphometric analyses across entire landscapes and improved the resolution of measurements. Availability of such data is now considered standard, and though resolved at 30-m to 90-m pixel, which is amazing seeing where we come from, they are now regarded as mostly obsolete given the sub-meter imagery coming through web services like Google Earth. Geoscientists now appear to desire two additional features: field-scale-compatible elevation datasets (i.e. meter-scale digital models and sub-meter elevation precision) and dispose of regularly updated topography to retrieve earth surface changes, while retaining the key for success: data availability at no charge. A new satellite instrument is currently under phase 0 study at CNES, the French space agency, to fulfil these aims. The scientific community backing this demand is that of natural hazards, glaciology and to a lesser extent the biomass community. The system under study combines a native stereo imager and a lidar profiler. This combination provides spatially resolved elevation swaths together with absolute along-track elevation control point profiles. Data generated through this system, designed for revisit time better than a year, is intended to produce not only single acquisition digital surface models, colour orthoimages and small footprint full-wave-form lidar profiles to update existing topographic coverages, but also time series of them. This enables 3D change detection with centimetre-scale planimetric precision and metric vertical precision, in complement of classical spectral change appoaches. The purpose of this contribution, on behalf of the science team, is to present the mission concepts and philosophy and the scientific needs for such instrument including

  12. Scattering and absorption properties of near-surface aerosol over Gangetic–Himalayan region: the role of boundary layer dynamics and long-range transport

    U. C. Dumka


    Full Text Available Knowledge of light scattering and absorption properties of atmospheric aerosols is of vital importance in evaluating their types, sources and radiative forcing. This is of particular interest over the Gangetic–Himalayan (GH region due to large aerosol loading over the plains and the uplift over the Himalayan range causing serious effects on atmospheric heating, glaciology and monsoon circulation. In this respect, Ganges Valley Aerosol Experiment (GVAX was initiated over the region aiming to examine the aerosol properties, source regions, uplift mechanisms and aerosol-cloud interactions. The present study examines the temporal (monthly, seasonal evolution of scattering (σsp and absorption (σap coefficients, their wavelength dependence, and the role of the Indo-Gangetic plains (IGP, boundary-layer dynamics (BLD and long-range transport (LRT in the aerosol uplift over the Himalayas. The measurements are performed at the elevated site Nainital via the Atmospheric Radiation Measurement Mobile Facility including several instruments (Nephelometer, Particle Soot Absorption Photometer, etc. during June 2011 to March 2012. The σsp and σap exhibit a pronounced seasonal variation with monsoon low and post-monsoon (November high, while the scattering wavelength exponent exhibits higher values during monsoon, in contrast to the absorption Ångström exponent which maximizes in December–March. The analysis is performed separately for particles bellow 10 and 1μm in diameter in order to examine the influence of the particle size on optical properties. The elevated-background measuring site provides the advantage of examining the LRT of natural and anthropogenic aerosols from the IGP and southwest Asia and the role of BLD in the aerosol lifting processes, while the aerosols are found to be well-mixed and aged-type dominant.

  13. Contrasting medial moraine development at adjacent temperate, maritime glaciers: Fox and Franz Josef Glaciers, South Westland, New Zealand

    Brook, Martin; Hagg, Wilfried; Winkler, Stefan


    Medial moraines form important pathways for sediment transportation in valley glaciers. Despite the existence of well-defined medial moraines on several glaciers in the New Zealand Southern Alps, medial moraines there have hitherto escaped attention. The evolving morphology and debris content of medial moraines on Franz Josef Glacier and Fox Glacier on the western flank of the Southern Alps is the focus of this study. These temperate maritime glaciers exhibit accumulation zones of multiple basins that feed narrow tongues flowing down steep valleys and terminate 400 m above sea level. The medial moraines at both glaciers become very prominent in the lower ablation zones, where the medial moraines widen, and develop steeper flanks coeval with an increase in relative relief. Medial moraine growth appears somewhat self-limiting in that relief and slope angle increase eventually lead to transport of debris away from the medial moraine by mass-movement-related processes. Despite similarities in overall morphologies, a key contrast in medial moraine formation exists between the two glaciers. At Fox Glacier, the medial moraine consists of angular rockfall-derived debris, folded to varying degrees along flow-parallel axes throughout the tongue. The debris originates above the ELA, coalesces at flow-unit boundaries, and takes a medium/high level transport pathway before subsequently emerging at point-sources aligned with gently dipping fold hinges near the snout. In contrast at Franz Josef Glacier, the medial moraine emerges farther down-glacier immediately below a prominent rock knob. Clasts show a mix of angular to rounded shapes representing high level transport and subglacially transported materials, the latter facies possibly also elevated by supraglacial routing of subglacial meltwater. Our observations confirm that a variety of different debris sources, transport pathways, and structural glaciological processes can interact to form medial moraines within New Zealand

  14. Fluctuations of Glaciar Esperanza Norte in the North Patagonian Andes of Argentina during the past 400 yr

    L. Ruiz


    Full Text Available The number of studies of Little Ice Age (LIA glacier fluctuations in Southern South America has increased in recent years but is largely biased towards sites in the South Patagonian Andes. In this paper we present a detailed record of length and areal fluctuations of Glaciar Esperanza Norte (GEN, in the North Patagonian Andes of Argentina, during the past four centuries. The GEN record was reconstructed through the dendro-geomorphological dating of moraines and the analysis of satellite imagery, aerial photographs and documentary material complemented with extensive field surveys. The maximum LIA extent at GEN was associated with an outer moraine dated to the mid 17th century. At least 19 subsequent readvances or standstills evidenced by morainic ridges were identified inside the most extensive LIA moraine. The dating and spacing of these moraines and the additional information available indicate that the ice front retreated much more rapidly during the 20th century than during earlier centuries. Comparison with the record of LIA fluctuations of Glaciar Frías, an ice mass of similar characteristics located 110 km to the north of GEN, shows a similar pattern of recession over the past 400 yr. Both glacier records have the peak LIA event occurring roughly during the same interval and show a minor readvance during the 1970s, but there are still a few discrepancies in the dating of some inner moraines. These differences may be due to local, specific factors or associated with the inherent uncertainties in the dating of the moraines. The chronologies of GEN and Frías are among the most detailed currently available in Patagonia, but a larger number of study sites is needed to develop robust, regionally representative glacier chronologies. Detailed glaciological, geomorphological and meteorological data are also needed to understand the glacier-climate relationships in this region and develop reliable paleoclimatic reconstructions.

  15. Investigation of snow-firn thickness and ground in the East Antarctica by means of geophysical radar

    S. V. Popov


    Full Text Available Results of field investigations of snow-and-firn thickness and ground structures performed with the use of geophysical radar GPR (Ground-Penetrating Radar are discussed in the paper. Industrial radar GSSI SIR10B (Geophysical Survey Systems, Inc., USA with «5106» antenna (pulses frequency of 200 MHz was used. Its mean wavelength is 1.57±0.18 km. The main purpose of this work was to test this new technique for solution of glaciological and geological problems. The works were done during the austral summer season of 2012–2013 (58th Russian Antarctic Expedition in the Eastern Antarctica and mainly concentrated in the vicinity of the Lake Vostok, between the Russian stations Vostok and Progress (the Larsemann Hills. The GPR sounding was carried out together with precise geodetic measurements. The electromagnetic wave propagation in the snow-firn layer was analyzed using the data on density obtained from the 5G borehole at the Vostok Station. Investigations near the Vostok Station focused on a huge snow ridge or so-called “megadune” located eastward from the station at a distance of 30 km. About 80 km of the GPR cross-sections were collected there. Eight internal layers were traced. They demonstrated wavy forms with amplitudes of about 10 m high which corresponded to the megadunes. Main result of GPR investigations in the Larsemann Hills was our understanding of the snow-firn and ground structures in this region. The GPR data collected on structures of crevasses near Progress-1, shallow glacier near the Progress-3, and ground not far from Progress-2 are also discussed. Methodological recommendations on using the GPR under conditions of the Eastern Antarctica were developed.

  16. Automated mapping of glacial overdeepenings beneath contemporary ice sheets: Approaches and potential applications

    Patton, Henry; Swift, Darrel A.; Clark, Chris D.; Livingstone, Stephen J.; Cook, Simon J.; Hubbard, Alun


    Awareness is growing on the significance of overdeepenings in ice sheet systems. However, a complete understanding of overdeepening formation is lacking, meaning observations of overdeepening location and morphometry are urgently required to motivate process understanding. Subject to the development of appropriate mapping approaches, high resolution subglacial topography data sets covering the whole of Antarctica and Greenland offer significant potential to acquire such observations and to relate overdeepening characteristics to ice sheet parameters. We explore a possible method for mapping overdeepenings beneath the Antarctic and Greenland ice sheets and illustrate a potential application of this approach by testing a possible relationship between overdeepening elongation ratio and ice sheet flow velocity. We find that hydrological and terrain filtering approaches are unsuited to mapping overdeepenings and develop a novel rule-based GIS methodology that delineates overdeepening perimeters by analysis of closed-contour properties. We then develop GIS procedures that provide information on overdeepening morphology and topographic context. Limitations in the accuracy and resolution of bed-topography data sets mean that application to glaciological problems requires consideration of quality-control criteria to (a) remove potentially spurious depressions and (b) reduce uncertainties that arise from the inclusion of depressions of nonglacial origin, or those in regions where empirical data are sparse. To address the problem of overdeepening elongation, potential quality control criteria are introduced; and discussion of this example serves to highlight the limitations that mapping approaches - and applications of such approaches - must confront. We predict that improvements in bed-data quality will reduce the need for quality control procedures and facilitate increasingly robust insights from empirical data.

  17. Mass balance evolution of Martial Este Glacier, Tierra del Fuego (Argentina for the period 1960–2099

    M. Buttstädt


    Full Text Available The Martial Este Glacier in southern Tierra del Fuego was studied in order to estimate the surface mass balance from 1960 until 2099. For this reason a degree-day model was calibrated. Air temperature and precipitation data obtained from 3 weather stations as well as glaciological measurements were applied. The model was driven using a vertical air temperature gradient of 0.69 K/100 m, a degree-day factor for snow of 4.7 mm w.e. K−1 day−1, a degree-day factor for ice of 9.4 mm w.e. K−1 day−1 and a precipitation gradient of 22%/100 m. For the purpose of surface mass balance reconstruction for the time period 1960 until 2006 a winter vertical air temperature gradient of 0.57 K/100 m and a summer vertical air temperature gradient of 0.71 K/100 m were added as well as a digital terrain model. The key finding is an almost continuous negative mass balance of −772 mm w.e. a−1 throughout this period. While the calculation of the mass balance for the period 1960–2006 is based on instrumental records, the mass balance for the years 2007 until 2099 was estimated based on the IPCC SRES A2-scenario. To accomplish this estimation, the dataset of the global climate model HadCM3 was statistically downscaled to fit local conditions at Martial Este Glacier. Subsequently, the downscaled air temperature and precipitation were applied to a volume-area scaling glacier change model. Findings reveal an enduring deglaciation resulting in a surface area reduction of nearly 93% until 2099. This implicates that the Martial Este Glacier might be melted off at the beginning of the 22nd century.

  18. Analysis of Snow Line and Albedo Conditions By Means of Time-Lapse Photography on Tapado Glacier, Chile

    Vivero, S.; MacDonell, S.; McPhee, J. P.


    In the semiarid Coquimbo Region of Chile, high-altitude glaciers and seasonal snow are important sources of freshwater for irrigated agriculture and urban consumption. Due to the aridity of the environment, losses due to sublimation are large which means that accurate melt modelling is essential in order to reliably estimate streamflow. Since 2008, the CEAZA glaciology group has been studying the energy and mass balance of the largest glacier in the catchment, the Tapado Glacier using field and remote sensing measurements, and numerical modelling. The Tapado glacier system (30°08' S, 69°55' W) is a complex assemblage of uncovered and debris-covered ice located at the head of the Elqui basin between 4500 and 5536 m a.s.l. Energy balance modelling studies at the site have been limited in scope due to the development of ice pinnacles or penitentes on snow and ice surfaces. These features complicate energy distribution across the surface, due to modifications of parameters such as albedo. In this paper, we use time-lapse photography and automatic weather station (AWS) measurements to investigate how the development of penitentes impacts the spatial and temporal variability of albedo across the glacier surface and whether terrestrial photography is appropriate for use at such locations. Oblique photographs obtained from a high vantage point were georeferenced using a high resolution digital elevation model available for the entire glacier and its environs. By comparing the photographic data with point albedo measurements made at an AWS, distributed albedo maps were produced. Preliminary results suggest that distributed albedo values may be underestimated by the formation and development of penitentes during the ablation season. Moreover, it was observed that the evolution of the snow line during summer was not only topographically controlled but also modified by occasional convective snowfalls. Time-lapse photography provided to be a cost-effective tool for monitoring

  19. Revealing glacier flow and surge dynamics from animated satellite image sequences: examples from the Karakoram

    Paul, F.


    Although animated images are very popular on the internet, they have so far found only limited use for glaciological applications. With long time series of satellite images becoming increasingly available and glaciers being well recognized for their rapid changes and variable flow dynamics, animated sequences of multiple satellite images reveal glacier dynamics in a time-lapse mode, making the otherwise slow changes of glacier movement visible and understandable to the wider public. For this study, animated image sequences were created for four regions in the central Karakoram mountain range over a 25-year time period (1990-2015) from freely available image quick-looks of orthorectified Landsat scenes. The animations play automatically in a web browser and reveal highly complex patterns of glacier flow and surge dynamics that are difficult to obtain by other methods. In contrast to other regions, surging glaciers in the Karakoram are often small (10 km2 or less), steep, debris-free, and advance for several years to decades at relatively low annual rates (about 100 m a-1). These characteristics overlap with those of non-surge-type glaciers, making a clear identification difficult. However, as in other regions, the surging glaciers in the central Karakoram also show sudden increases of flow velocity and mass waves travelling down glacier. The surges of individual glaciers are generally out of phase, indicating a limited climatic control on their dynamics. On the other hand, nearly all other glaciers in the region are either stable or slightly advancing, indicating balanced or even positive mass budgets over the past few decades.

  20. Detection of surface elevation changes using an unmanned aerial vehicle on the debris-free Storbreen glacier in Norway

    Kraaijenbrink, Philip; Andreassen, Liss; Immerzeel, Walter


    Recent studies have shown that the application of unmanned aerial vehicles (UAVs) has great potential to investigate the dynamic behavior of glaciers. The studies have successfully deployed UAVs over generally contrast-rich surfaces of debris-covered glaciers and highly crevassed bare ice glaciers. In this study, the potential of UAVs in glaciology is further exploited, as we use a fixed-wing UAV over the largely snow-covered Storbreen glacier in Norway in September 2015. The acquired UAV-imagery was processed into accurate digital elevation models and image mosaics using a Structure from Motion workflow. Georeferencing of the data was obtained by ingesting ground control points into the workflow that were accurately measured with a differential global navigation satellite system (DGNSS). Geodetic accuracy was determined by comparison with DGNSS surface profiles and stake positions that were measured on the same day. The processed data were compared with a LIDAR survey and airborne imagery acquisition from September and October 2009 to examine mass loss patterns and glacier retreat. Results show that the UAV is capable of producing high-quality elevation models and image mosaics for the low-contrast snow-covered Storbreen at unprecedented detail. The accuracy of the output product is lower when compared to contrast-rich debris-covered glaciers, but still considerably more accurate than spaceborne data products. Comparison with LIDAR data shows a spatially heterogeneous downwasting pattern of about 0.75 m a-1 over 2009-2015 for the upper part of Storbreen. The lower part exhibits considerably more downwasting in the range of 0.9-2.1 m a-1. We conclude that UAVs can be valuable for surveys of snow-covered glaciers to provide sufficient accurate elevation models and image mosaics, and we recommend the use of UAVs for the routine monitoring of benchmark glaciers such as Storbreen.

  1. Tectonics, Microbes and Ice: Subglacial volcanism as a generator for microbial habitat beneath the West Antarctic Ice Sheet

    Skidmore, M. L.; Blankenship, D. D.; Carter, S. P.


    Glaciological processes under ice masses, including ice sheets provide sustainable habitat for microbes, forming an aquatic environment through basal melting and providing nutrients and energy from bedrock comminution. In all subglacial settings investigated to date, viable microbes have been documented. Tectonic activity beneath ice masses, including volcanism is associated with an elevated heat flux, leading to enhanced basal ice melt and may also be accompanied by hydrothermal fluids, often rich in reduced metals including Fe and gases such as CO2, H2 and H2S that are potential chemical energy sources for microbes. However, the importance of subglacial volcanism beneath the West Antarctic Ice Sheet (WAIS) in terms of increasing both water and chemical energy fluxes remains unknown despite evidence for subglacial volcanic features and enhanced heat flux. The role of subglacial volcanism in supporting subglacial microbial communities has been documented in Icelandic caldera lake systems, indicating crustal carbon and energy sources, could support a microbial ecosystem independent of photosynthetic carbon. Further, phylogenetic analysis of 16S rRNA gene sequences from WAIS subglacial sediments suggests that organisms with Fe and S oxidizing metabolisms may be important members of the microbial community in these environments. Given the abundance and interconnectivity of water beneath the WAIS, the distribution of volcanism relative to the subglacial hydrologic catchments could have a significant role in contributing to the water and chemical energy fluxes for downstream environments. Therefore, tectonics may modulate the critical hydrologic and geochemical balance that determines subglacial microbial habitat distribution. We will present potential biological implications of an updated geophysical and hydrological context for West Antarctica’s Whillans and Kamb ice streams with an emphasis on selecting targets for further characterization.

  2. Water-Related Seismic Sources in Glaciers and Ice Sheets (Invited)

    Walter, F. T.; Heeszel, D.; Kilb, D. L.; Roux, P.; Husen, S.; Kissling, E. H.; Luethi, M. P.; Funk, M.; Clinton, J. F.; Fricker, H.


    Liquid water can have a profound impact on the flow of glaciers and ice sheets. Acceleration of ice flow via enhanced basal motion, hydro-fracturing and cryo-hydrologic warming are just three possible mechanisms that can drastically alter ice dynamics. At the same time, subsurface water flow is difficult to measure as the englacial and subglacial drainage systems are highly inaccessible. Although tracer experiments, speleological methods, radar measurements and deep drilling provide some information about water flow and changes thereof, more data on hydraulic processes are needed for the development and testing of numerical ice flow models. Recent studies have suggested that passive seismic techniques can be used to monitor englacial and subglacial water flow. This inter-disciplinary approach is motivated by the analogy between fluid-induced seismic sources in glaciers and volcanoes, which was first proposed in the late 70's. As seismological analysis is a valuable tool to monitor hydro-thermal activity in volcanic regions, it may consequently also reveal transient or sudden changes in a glacier's water drainage system. Here, we present results from continuous and event-based seismic monitoring exercises on Swiss mountain glaciers and the ablation zone of the Greenland ice sheet. We examine 'icequakes', sustained tremors and seismic background noise, whose sources are closely connected to the presence or movement of water. Analyzing icequake moment tensors and signal characteristics, spectrograms, noise source locations and simple models of resonating cracks, we can monitor the development and evolution of water passages below the glacier surface. Accordingly, our seismic measurements elucidate an area of the glacier, which has been difficult to investigate with traditional glaciological techniques.

  3. A novel method to determine the half-life of 32Si

    Schnabel, C.; Beer, J.; Clausen, H. B.


    A novel method using high-resolution 10Be concentrations to correct 32Si data from independently dated depth profiles is presented. It is demonstrated that by correcting 32Si deposition rates for temporal changes based on production rate fluctuations the derived half-life of 32Si agrees with half-life determinations based on physical measurements of artificial samples. Currently, the half-life of 32Si is not accurately known. Moreover, results from physical measurements of artificial samples yielded much shorter half-lives (100-172 yr) than results based on depth profiles. For depth profiles most results were between 250 and 300 yr (Clausen, 1973), with the exception of a relatively recent work on a varved lake sediment which resulted in 178 yr (Nijampurkar et al., 1998). Using high-resolution 10Be concentrations from the Dye3 ice-core each data point of the Northern hemisphere ice-core 32Si concentrations is corrected for temporal variations in deposition rate. This means that we assume that temporal variations in 32Si and 10Be deposition are identical instead of using the assumption of constant deposition rates that resulted in the long half-lives. In the case of the varved lake sediment, 32Si/Si ratios are corrected in the same way as 32Si concentrations for the ice cores. We present our results that half-lives of longer than 180 yr can be ruled out for 32Si and propose using 10Be and 32Si concentrations from the same samples of independently dated profiles as a new method to apply 32Si for dating purposes. Preliminary results have been presented at the QRA meeting in Glasgow 2006 {schnabel et al., 2006]. HB Clausen, Journal of Glaciology 12 (1973) 411. VN Nijampurkar et al., Earth and Planetary Science Letters 163 (1998) 191. C. Schnabel, J. Beer, HB Clausen, QRA annual discussion meeting Glasgow, 2006.

  4. Non-climatic signal in ice core records: lessons from Antarctic megadunes

    Ekaykin, Alexey; Eberlein, Lutz; Lipenkov, Vladimir; Popov, Sergey; Scheinert, Mirko; Schröder, Ludwig; Turkeev, Alexey


    We present the results of glaciological investigations in the megadune area located 30 km to the east of Vostok Station (central East Antarctica) implemented during the 58th, 59th and 60th Russian Antarctic Expedition (January 2013-2015). Snow accumulation rate and isotope content (δD, δ18O and δ17O) were measured along the 2 km profile across the megadune ridge accompanied by precise GPS altitude measurements and ground penetrating radar (GPR) survey. It is shown that the spatial variability of snow accumulation and isotope content covaries with the surface slope. The accumulation rate regularly changes by 1 order of magnitude within the distance negative correlation with the snow accumulation. Analysing dxs / δD and 17O-excess / δD slopes (where dxs = δD - 8 ṡ δ18O and 17O-excess = ln(δ17O / 1000 + 1) -0.528 ṡ ln (δ18O / 1000 + 1)), we conclude that the spatial variability of the snow isotopic composition in the megadune area could be explained by post-depositional snow modifications. Using the GPR data, we estimated the apparent dune drift velocity (4.6 ± 1.1 m yr-1). The full cycle of the dune drift is thus about 410 years. Since the spatial anomalies of snow accumulation and isotopic composition are supposed to drift with the dune, a core drilled in the megadune area would exhibit the non-climatic 410-year cycle of these two parameters. We simulated a vertical profile of snow isotopic composition with such a non-climatic variability, using the data on the dune size and velocity. This artificial profile is then compared with the real vertical profile of snow isotopic composition obtained from a core drilled in the megadune area. We note that the two profiles are very similar. The obtained results are discussed in terms of interpretation of data obtained from ice cores drilled beyond the megadune areas.

  5. The seasonal in-situ mass balance, temperature and precipitation of Yala Glacier, Langtang Valley, Nepal, from 2011 to 2015

    Stumm, Dorothea; Fujita, Koji; Gurung, Tika; Joshi, Sharad; Litt, Maxime; Shea, Joseph; Sherpa, Mingma; Sinisalo, Anna; Wagnon, Patrick


    In-situ glacier mass balance measurements are still scarce in the Hindu Kush Himalayan (HKH) region and little is known about the seasonal balances. The glaciers in the Nepalese Himalaya have been considered summer accumulation glacier types because of the assumption that the majority of the accumulation occurs in the summer months during the monsoon. The glacier mass balance of Yala Glacier in the Langtang Valley of Nepal has been measured using the glaciological method since autumn 2011. Stakes were measured biannually in pre- and post-monsoon, usually in early May and in November, respectively. The measured mass balance gradient for the summer balance was larger than the winter balance, which is typical for glaciers with distinct ablation and accumulation seasons. On Yala Glacier, the summer balance was negative, and the winter balance was positive in all years with measurements. However, the annual net balance was negative for all four mass balance years from 2011 to 2015. The mass balances were further compared to temperature and precipitation data measured at nearby climate stations during the same time periods. In October 2013 and 2014, the Central Himalayas received large amounts of precipitation brought by the cyclones Phailin and Hudhud. These precipitation events contributed to the summer balance since the measurements were taken after the cyclones passed. In conclusion, on Yala Glacier accumulation processes dominated ablation processes during the winter, and ablation processes dominated during the summer, which could be explained by the low elevation range of Yala Glacier and precipitation from westerlies in the winter. Hence, this should be kept in mind when using the term 'summer accumulation glacier' for Yala Glacier. For future research in the HKH region, seasonal mass balances should be measured, and the processes impacting the mass balance and the role of winter precipitation should be investigated for other glaciers in the HKH region.

  6. Glacier topography and elevation changes from Pléiades very high resolution stereo images

    E. Berthier


    Full Text Available In response to climate change, most glaciers are losing mass and hence contribute to sea-level rise. Repeated and accurate mapping of their surface topography is required to estimate their mass balance and to extrapolate/calibrate sparse field glaciological measurements. In this study we evaluate the potential of Pléiades sub-meter stereo imagery to derive digital elevation models (DEMs of glaciers and their elevation changes. Our five validation sites are located in Iceland, the European Alps, the Central Andes, Nepal and Antarctica. For all sites, nearly simultaneous field measurements were collected to evaluate the Pléiades DEMs. For Iceland, the Pléiades DEM is also compared to a Lidar DEM. The vertical biases of the Pléiades DEMs are less than 1 m if ground control points (GCPs are used, but reach up to 6 m without GCPs. Even without GCPs, vertical biases can be reduced to a few decimetres by horizontal and vertical co-registration of the DEMs to reference altimetric data on ice-free terrain. Around these biases, the vertical precision of the Pléiades DEMs is ±1 m and even ±0.5 m on the flat glacier tongues (1-sigma confidence level. We also demonstrate the high potential of Pléiades DEMs for measuring seasonal, annual and multi-annual elevation changes with an accuracy of 1 m or better. The negative glacier-wide mass balances of the Argentière Glacier and Mer de Glace (−1.21 ± 0.16 and −1.19 ± 0.16 m.w.e. yr−1, respectively are revealed by differencing SPOT5 and Pléiades DEMs acquired in August 2003 and 2012 demonstrating the continuing rapid glacial wastage in the Mont-Blanc area.

  7. "EDML1": a chronology for the EPICA deep ice core from Dronning Maud Land, Antarctica, over the last 150 000 years

    U. Ruth


    Full Text Available A chronology called EDML1 has been developed for the EPICA ice core from Dronning Maud Land (EDML. EDML1 is closely interlinked with EDC3, the new chronology for the EPICA ice core from Dome-C (EDC through a stratigraphic match between EDML and EDC that consists of 322 volcanic match points over the last 128 ka. The EDC3 chronology comprises a glaciological model at EDC, which is constrained and later selectively tuned using primary dating information from EDC as well as from EDML, the latter being transferred using the tight stratigraphic link between the two cores. Finally, EDML1 was built by exporting EDC3 to EDML. For ages younger than 41 ka BP EDML1/EDC3 is based on dated volcanic events and on a match to the Greenlandic GICC05 time scale via 10Be and methane. The internal consistency between EDML1 and EDC3 is estimated to be typically ~6 years and always less than 450 years over the last 128 ka (always less than 130 years over the last 60 ka, which reflects an unprecedented synchrony of time scales. EDML1 ends at 150 ka BP (2417 m depth because the match between EDML and EDC becomes ambiguous further down. This hints to a complex ice flow history for the deepest 350 m of the EDML ice core, which amongst other reasons may be caused by spatial variations of the geothermal heat flux.

  8. Terrestrial and submarine evidence for the extent and timing of the Last Glacial Maximum and the onset of deglaciation on the maritime-Antarctic and sub-Antarctic islands

    Hodgson, Dominic A.; Graham, Alastair G. C.; Roberts, Stephen J.; Bentley, Michael J.; Cofaigh, Colm Ó.; Verleyen, Elie; Vyverman, Wim; Jomelli, Vincent; Favier, Vincent; Brunstein, Daniel; Verfaillie, Deborah; Colhoun, Eric A.; Saunders, Krystyna M.; Selkirk, Patricia M.; Mackintosh, Andrew; Hedding, David W.; Nel, Werner; Hall, Kevin; McGlone, Matt S.; Van der Putten, Nathalie; Dickens, William A.; Smith, James A.


    This paper is the maritime and sub-Antarctic contribution to the Scientific Committee for Antarctic Research (SCAR) Past Antarctic Ice Sheet Dynamics (PAIS) community Antarctic Ice Sheet reconstruction. The overarching aim for all sectors of Antarctica was to reconstruct the Last Glacial Maximum (LGM) ice sheet extent and thickness, and map the subsequent deglaciation in a series of 5000 year time slices. However, our review of the literature found surprisingly few high quality chronological constraints on changing glacier extents on these timescales in the maritime and sub-Antarctic sector. Therefore, in this paper we focus on an assessment of the terrestrial and offshore evidence for the LGM ice extent, establishing minimum ages for the onset of deglaciation, and separating evidence of deglaciation from LGM limits from those associated with later Holocene glacier fluctuations. Evidence included geomorphological descriptions of glacial landscapes, radiocarbon dated basal peat and lake sediment deposits, cosmogenic isotope ages of glacial features and molecular biological data. We propose a classification of the glacial history of the maritime and sub-Antarctic islands based on this assembled evidence. These include: (Type I) islands which accumulated little or no LGM ice; (Type II) islands with a limited LGM ice extent but evidence of extensive earlier continental shelf glaciations; (Type III) seamounts and volcanoes unlikely to have accumulated significant LGM ice cover; (Type IV) islands on shallow shelves with both terrestrial and submarine evidence of LGM (and/or earlier) ice expansion; (Type V) Islands north of the Antarctic Polar Front with terrestrial evidence of LGM ice expansion; and (Type VI) islands with no data. Finally, we review the climatological and geomorphological settings that separate the glaciological history of the islands within this classification scheme.

  9. An optimized multi-proxy, multi-site Antarctic ice and gas orbital chronology (AICC2012: 120–800 ka

    H. Fischer


    Full Text Available An accurate and coherent chronological framework is essential for the interpretation of climatic and environmental records obtained from deep polar ice cores. Until now, one common ice core age scale has been developed based on an inverse dating method (Datice combining glaciological modelling with absolute and stratigraphic markers between 4 ice cores covering the last 50 ka (thousand of years before present (Lemieux-Dudon et al., 2010. In this paper, together with the companion paper of Veres et al. (2012, we present an extension of this work back to 800 ka for the NGRIP, TALDICE, EDML, Vostok and EDC ice cores using an improved version of the Datice tool. The AICC2012 (Antarctic Ice Core Chronology 2012 chronology includes numerous new gas and ice stratigraphic links as well as improved evaluation of background and associated variance scenarios. This paper concentrates on the long timescales between 120–800 ka. In this frame, new measurements of δ18Oatm over Marine Isotope Stage (MIS 11–12 on EDC and a complete δ18Oatm record of the TALDICE ice cores permit us to derive new orbital gas age constraints. The coherency of the different orbitally deduced ages (from δ18Oatm, δO2/N2 and air content has been verified before implementation in AICC2012. The new chronology shows only small differences, well within the original uncertainty range, when compared with the previous ice core reference age scale EDC3. For instance, the duration of the last four interglacial periods is not affected by more than 5%. The largest deviation between AICC2012 and EDC3 (4.4 ka is obtained around MIS 12. Despite significant modifications of the chronological constraints around MIS 5, now independent of speleothem records in AICC2012, the date of Termination II is very close to the EDC3 one.

  10. Linear permeability evolution of expanding conduits due to feedback between flow and fast phase change

    Wang, Lichun; Cardenas, M. Bayani


    Conduits are ubiquitous and critical pathways for many fluids relevant for geophysical processes such as magma, water, and gases. Predicting flow through conduits is challenging when the conduit geometry coevolves with the flow. We theoretically show that the permeability (k) of a conduit whose walls are eroding due to fast phase change increases linearly with time because of a self-reinforcing mechanism. This simple result is surprising given complex feedbacks between flow, transport, and phase change. The theory is congruent with previous experimental observations of fracture dissolution in calcite. Supporting computational fracture dissolution experiments showed that k only slightly increases until the dissolution front reaches the narrowest conduit constriction, after which the linear evolution of k manifests. The theory holds across multiple scales and a broad range of Peclet and Damkohler numbers and thus advances the prediction of dynamic mass fluxes through expanding conduits in various geologic and environmental settings.Plain Language SummaryGeological conduits are ubiquitous present in the subsurface. In many situations, these conduits may enlarge through time due to erosion of its walls by dissolution and melting. This leads to strongly coupled flow and reactive transport processes where the flow dictates the wall's erosion and vice versa. As the conduit expands, so does its permeability and thus flow. Thus, predicting fluid flow and relevant transport processes through expanding conduits is challenging. In this study, we presented a theory for the linear time dependence of permeability for expanding conduits. The theory is congruent with previous observations from fracture dissolution in calcite. An additional series of our own computational experiments also aligns with the theory. The theory will be of interest to geoscientists and engineers in many fields such as hydrology, glaciology, and petroleum engineering, to name a few.

  11. Parallels Between Antarctic Travel in 1950 and Planetary Travel in 2050 (to Accompany Notes on "The Norwegian British-Swedish Antarctic Expedition 1949-52")

    Swithinbank, Charles


    Objectives (Slides 2, 12, 21-22) To explore as much as possible of 1 million km2 of unexplored territory. We were the first expedition to winter in Antarctica between 95 E and 57 W - nearly half the coastline of Antarctica. It was understood that we must be self-sufficient in every respect for 2 years. There could be no firm or detailed plans for inland exploration until we found where it was possible to make a landing. Geology (Slide 20) Our two geologists traveled far from the Advance Base during both field seasons. Carrying fuel supplies (dog food) for a month, man food (dehydrated) and rock specimens acquired along the way, they covered a vast area. The surveyor drove his own dogs with the geophysicist as assistant. While the geologists were hacking away at rocks, the survey team lugged a theodolite up peaks to extend a triangulation network. Glaciology (Slides 21-22) The glaciologists each had an assistant from the support staff, so they could either travel together or divided into two parties to cover more ground. At each camp they dug a pit to determine the rate of snow accumulation, drilled (by hand) to a depth of 10 m to measure ice temperatures, and in places set up and surveyed ice-movement markers to be resurveyed the following season. Geophysics (Slides 33, 34-36, 38) The principal object was to determine the thickness of ice by seismic sounding the only means known at the time. After experiments as far as the Advance Base in the 1950-51 summer, both Weasels were devoted to a seismic sounding traverse in 1951-52 as far inland as supplies would allow. The party reached 620 km inland and found ice thicknesses of 2,500 m.

  12. The current state of glaciers within the Koryak Highland and assessment of their development by the middle of this century

    M. D. Ananicheva


    Full Text Available The Koryak Upland, located in Russian Far East, has so far been poorly studied in terms of glaciology. The information contained in the USSR Glacier Inventory (1982 was obtained by analysis of topographic maps and aerial photography. On the publication date, the Inventory of Koryak Upland included 715 glaciers. To study of the current state of Koryak glaciers, we used satellite imageries – Landsat, Terra /Aqua (EOS AM-1 and ASTER. Deciphering the scenes showed that a significant portion of the glaciers melted away since the mid-1970's until now. We have found only 237 glaciers. Some glaciers are appeared to be rock glaciers, filled with detrital material, cemented by ice in a single body. They might be taken for real glaciers while categorization. The analysis of the retreat (reduction in area of Koryak glaciers by groups with the same morphological type and the same aspect was conducted. The total retreat of the glaciers of this region varied from 40 (for those measured in situ to 70% (mean total as compared to aerial photography surveys (1950. This is the most intense reduction among the studied glacier systems of the Russian Subarctic. It can be explained by the changes in atmospheric circulation due to climate change, the Koryak Upland dries out while the increasing of annual air temperatures. Significant reduction of the glacier area was an incentive for us to undertake a work to assess the evolution of the glaciers in the near future. We used a GCM – ECHAM5 (B1 as the climatic scenario. The projection method has got further development: we have estimated the evolution of glacier systems in which the prevailing type is corries (relatively small circus glacier. The results show a diverse picture of glacier reduction by area, but in general the glacierization will not disappear for the period 2049–2060, reducing the extent by only 17% of the contemporary state.

  13. The Glacier Inventory of the Central Andes of Argentina (31°-35°S)

    Ferri Hidalgo, L.; Zalazar, L.; Castro, M.; Pitte, P.; Masiokas, M. H.; Ruiz, L.; Villalba, R.; Delgado, S.; Gimenez, M.; Gargantini, H.


    The National Law for protection of glaciers in Argentina envisages the development of a National Inventory of Glaciers. All glaciers and periglacial landforms which are important as strategic water resource must be properly identified and mapped. Here we present a detailed and complete glacier and rock glacier inventory of the Central Andes of Argentina between 31° and 35°S. This semi-arid region contains some of the highest mountains of South America and concentrates the second most glacierized area in Argentina after the Patagonian Andes. To develop the inventory, we used remotely sensed data and related techniques complemented with field surveys. Clean ice and perennial snowfields were identified applying an automatic extraction method on medium spatial-resolution images. Debris-covered and rock glaciers were manually digitized on higher spatial-resolution images. With minor modifications, the present digital inventory is consistent with GLIMS standards. For each glacier, we derived 38 database fields, adding five specific attributes for rock glaciers, which are not included in the original GLIMS database. In total we identified 8069 glaciers covering an area of 1768 km2. Debris-covered ice and rock glaciers represent 57% of the total inventoried area. In this region, rock glaciers are a common feature in the arid landscape and constitute an important water reserve at regional scale. Many glaciers were characterized by gradual transition from debris-covered glaciers, in the upper part, to rock glaciers, in the lower sector. The remaining 43% includes clean ice glaciers and permanent snowfields. These are mostly mountain and valley-type glaciers with medium-to-small sizes. This detailed inventory constitutes a valuable contribution to the ongoing global efforts (e.g. WGI, RGI and GLIMS) to map the world's glaciers. It is also the base for ongoing glaciological, climatological and hydrological studies in this portion of southern Andes.



    ABSTRACT A GIS is proposed as a tool for the managing plan for the Antarctic specially managed area (ASMA) in Admiralty Bay.The ASMA comprises the area considered to be within the glacial drainage basin of the bay.Furthermore,it includes part of SSSI No.8 adjacent to the area but outside of the glacial drainage basin.Three stations and six refuges are located in the area.Using a SPOT satellite image map,the limits of the ASMA are marked and its area is re_calculated.It consists of 362 km2,including 186 km2 island ice field and small cirque glaciers and 32 km2 ice_free field.The rest comprises water of the bay and a small adjacent area (8 km2) of the Bransfield Strait. The ASMA_GIS will consists of 12 data layers ranging from the physiographic settings to the biological and administrative features.All data will be implemented into Arc/Info GIS according to the cartographic guidelines of the SCAR WG_GGI.First,five plans of information will be realised using a topographic database compiled from various sources and data from the revised bathymetric chart published by the Brazilian Navy Hydrographic Survey and also including: 1) Limits of the ASMA and protected areas;2) Glaciological features (e.g.drainage basin limits) and 3) Human presence (e.g.stations and historical sites).These basic GIS layers will be operational in early 2001.Then,additional data on the remaining layers (e.g.hydrology,geology and geomorphology) will be included from published sources. The ASMA_GIS will form an important database for environmental monitoring and studies surveying temporal changes of features such as glacier front positions or bird breading sites.

  15. Cross-Comparison of Albedo Products for Glacier Surfaces Derived from Airborne and Satellite (Sentinel-2 and Landsat 8 Optical Data

    Kathrin Naegeli


    Full Text Available Surface albedo partitions the amount of energy received by glacier surfaces from shortwave fluxes and modulates the energy available for melt processes. The ice-albedo feedback, influenced by the contamination of bare-ice surfaces with light-absorbing impurities, plays a major role in the melting of mountain glaciers in a warming climate. However, little is known about the spatial and temporal distribution and variability of bare-ice glacier surface albedo under changing conditions. In this study, we focus on two mountain glaciers located in the western Swiss Alps and perform a cross-comparison of different albedo products. We take advantage of high spectral and spatial resolution (284 bands, 2 m imaging spectrometer data from the Airborne Prism Experiment (APEX and investigate the applicability and potential of Sentinel-2 and Landsat 8 data to derive broadband albedo products. The performance of shortwave broadband albedo retrievals is tested and we assess the reliability of published narrow-to-broadband conversion algorithms. The resulting albedo products from the three sensors and different algorithms are further cross-compared. Moreover, the impact of the anisotropy correction is analysed depending on different surface types. While degradation of the spectral resolution impacted glacier-wide mean albedo by about 5%, reducing the spatial resolution resulted in changes of less than 1%. However, in any case, coarser spatial resolution was no longer able to represent small-scale variability of albedo on glacier surfaces. We discuss the implications when using Sentinel-2 and Landsat 8 to map dynamic glaciological processes and to monitor glacier surface albedo on larger spatial and more frequent temporal scales.

  16. Structure-from-Motion Using Historical Aerial Images to Analyse Changes in Glacier Surface Elevation

    Nico Mölg


    Full Text Available The application of structure-from-motion (SfM to generate digital terrain models (DTMs derived from different image sources has strongly increased, the major reason for this being that processing is substantially easier with SfM than with conventional photogrammetry. To test the functionality in a demanding environment, we applied SfM and conventional photogrammetry to archival aerial images from Zmuttgletscher, a mountain glacier in Switzerland, for nine dates between 1946 and 2005 using the most popular software packages, and compared the results regarding bundle adjustment and final DTM quality. The results suggest that by using SfM it is possible to produce DTMs of similar quality as with conventional photogrammetry. Higher point cloud density and less noise allow a higher ground resolution of the final DTM, and the time effort from the user is 3–6 times smaller, while the controls of the commercial software packages Agisoft PhotoScan (Version 1.2; Agisoft, St. Petersburg, Russia and Pix4Dmapper (Version 3.0; Pix4D, Lausanne, Switzerland are limited in comparison to ERDAS photogrammetry. SfM performs less reliably when few images with little overlap are processed. Even though SfM facilitates the largely automated production of high quality DTMs, the user is not exempt from a thorough quality check, at best with reference data where available. The resulting DTM time series revealed an average change in surface elevation at the glacier tongue of −67.0 ± 5.3 m. The spatial pattern of changes over time reflects the influence of flow dynamics and the melt of clean ice and that under debris cover. With continued technological advances, we expect to see an increasing use of SfM in glaciology for a variety of purposes, also in processing archival aerial imagery.

  17. Sensitivity of glacier runoff projections to baseline climate data in the Indus River Basin

    Michele eKoppes


    Full Text Available Quantifying the contribution of glacier runoff to water resources is particularly important in regions such High Mountain Asia, where glaciers provide a large percentage of seasonal river discharge and support large populations downstream. In remote areas, direct field measurements of glacier melt rates are difficult to acquire and rarely observed, so hydro-glaciological modeling and remote sensing approaches are needed. Here we present estimates of glacier melt contribution to the Upper Indus watershed over the last 40 years using a suite of seven reanalysis climate datasets that have previously been used in hydrological models for this region, a temperature-index melt model and > 29,000 km2 of ice cover. In particular, we address the uncertainty in estimates of meltwater flux that is introduced by the baseline climate dataset chosen, by comparing the results derived from each. Mean annual glacier melt contribution varies from 8 km3 yr-1 and 169 km3 yr-1, or between 4-78% of the total annual runoff in the Indus, depending on temperature dataset applied. Under projected scenarios of an additional 2-4°C of regional warming by 2100 AD, we find annual meltwater fluxes vary by >200% depending on the baseline climate dataset used and, importantly, span a range of positive and negative trends. Despite significant differences between climate datasets and the resulting spread in meltwater fluxes, the spatial pattern of melt is highly correlated and statistically robust across all datasets. This allows us to conclude with confidence that fewer than 10% of the >20,000 glaciers in the watershed contribute more than 80% of the total glacier runoff to the Indus. These are primarily large, low elevation glaciers in the Karakoram and Hindu Kush. Additional field observations to ground-truth modeled climate data will go far to reduce the uncertainty highlighted here and we suggest that efforts be focused on those glaciers identified to be most significant to

  18. 2008 Rock Deformation GRC - Conference August 3-8, 2008

    James G. Hirth


    The GRC on Rock Deformation highlights the latest research in brittle and ductile rock mechanics from experimental, field and theoretical perspectives. The conference promotes a multi-disciplinary forum for assessing our understanding of rock strength and related physical properties in the Earth. The theme for the 2008 conference is 'Real-time Rheology'. Using ever-improving geophysical techniques, our ability to constrain the rheological behavior during earthquakes and post-seismic creep has improved significantly. Such data are used to investigate the frictional behavior of faults, processes responsible for strain localization, the viscosity of the lower crust, and viscous coupling between the crust and mantle. Seismological data also provide information on the rheology of the lower crust and mantle through analysis of seismic attenuation and anisotropy. Geologists are improving our understanding of rheology by combining novel analyses of microstructures in naturally deformed rocks with petrologic data. This conference will bring together experts and students in these research areas with experimentalists and theoreticians studying the same processes. We will discuss and assess where agreement exists on rheological constraints derived at different length/time scales using different techniques - and where new insight is required. To encompass the elements of these topics, speakers and discussion leaders with backgrounds in geodesy, experimental rock deformation, structural geology, earthquake seismology, geodynamics, glaciology, materials science, and mineral physics will be invited to the conference. Thematic sessions will be organized on the dynamics of earthquake rupture, the rheology of the lower crust and coupling with the upper mantle, the measurement and interpretation of seismic attenuation and anisotropy, the dynamics of ice sheets and the coupling of reactive porous flow and brittle deformation for understanding geothermal and chemical

  19. 50 years of mass balance observations at Vernagtferner, Eastern Alps

    Braun, Ludwig; Mayer, Christoph


    The determination and monitoring of the seasonal and annual glacier mass balances of Vernagtferner, Austria, started in 1964 by the Commission of Glaciology, Bavarian Academy of Sciences. Detailed and continuous climate- and runoff measurements complement this mass balance series since 1974. Vernagtferner attracted the attention of scientists since the beginning of the 17th century due to its rapid advances and the resulting glacier lake outburst floods in the Ötztal valley. This is one reason for the first photogrammetric survey in 1889, which was followed by frequent topographic surveys, adding up to more than ten digital elevation models of the glacier until today. By including the known maximum glacier extent at the end of the Little Ice Age in 1845, the geodetic glacier volume balances cover a time span of almost 170 years. The 50 years of glacier mass balance and 40 years of water balance in the drainage basin are therefore embedded in a considerably longer period of glacier evolution, allowing an interpretation within an extended frame of climatology and ice dynamics. The direct mass balance observations cover not only the period of alpine-wide strong glacier mass loss since the beginning of the 1990s. The data also contain the last period of glacier advances between 1970 and 1990. The combination of the observed surface mass exchange and the determined periodic volumetric changes allows a detailed analysis of the dynamic reaction of the glacier over the period of half a century. The accompanying meteorological observations are the basis for relating these reactions to the climatic changes during this period. Vernagtferner is therefore one of the few glaciers in the world, where a very detailed glacier-climate reaction was observed for many decades and can be realistically reconstructed back to the end of the Little Ice Age.

  20. A computationally efficient depression-filling algorithm for digital elevation models, applied to proglacial lake drainage

    Berends, Constantijn J.; van de Wal, Roderik S. W.


    Many processes govern the deglaciation of ice sheets. One of the processes that is usually ignored is the calving of ice in lakes that temporarily surround the ice sheet. In order to capture this process a "flood-fill algorithm" is needed. Here we present and evaluate several optimizations to a standard flood-fill algorithm in terms of computational efficiency. As an example, we determine the land-ocean mask for a 1 km resolution digital elevation model (DEM) of North America and Greenland, a geographical area of roughly 7000 by 5000 km (roughly 35 million elements), about half of which is covered by ocean. Determining the land-ocean mask with our improved flood-fill algorithm reduces computation time by 90 % relative to using a standard stack-based flood-fill algorithm. This implies that it is now feasible to include the calving of ice in lakes as a dynamical process inside an ice-sheet model. We demonstrate this by using bedrock elevation, ice thickness and geoid perturbation fields from the output of a coupled ice-sheet-sea-level equation model at 30 000 years before present and determine the extent of Lake Agassiz, using both the standard and improved versions of the flood-fill algorithm. We show that several optimizations to the flood-fill algorithm used for filling a depression up to a water level, which is not defined beforehand, decrease the computation time by up to 99 %. The resulting reduction in computation time allows determination of the extent and volume of depressions in a DEM over large geographical grids or repeatedly over long periods of time, where computation time might otherwise be a limiting factor. The algorithm can be used for all glaciological and hydrological models, which need to trace the evolution over time of lakes or drainage basins in general.

  1. Physical characteristics of drumlins, with implications for their formation, at an active drumlin field, Múlajökull, Iceland

    McCracken, R. G.; Iverson, N. R.; Benediktsson, Í. Ö.; Schomacker, A.; Johnson, M. D.; Zoet, L.; Hooyer, T.


    The forefield of Múlajökull—a warm-based, surge-type glacier in central Iceland—comprises the only known active drumlin field, with drumlins of similar morphometry to their Pleistocene counterparts but formed under better-known glaciological conditions. Study of till magnetic and till fabrics, till densities and preconsolidation stresses, and drumlin stratigraphy indicates that drumlin relief reflects both erosion and deposition: 1) the package of basal tills that constitutes the drumlins thickens where the forefield has experienced more surging, but uniformities are common on drumlin flanks, 2) attitudes of till layers and patterns of deformation within them indicate till deposition occurred on drumlin slopes rather than prior to drumlinization, and 3) past effective stresses during quiescent periods were highest in interdrumlin areas. These data suggest that erosion occurred during quiescence, rather than during surging, with erosion rates that increased under increasing effective stress. Stratigraphic evidence connecting specific till layers to surge moraines (Johnson et al., 2010, Geology 38, 943-6), on the other hand, indicates that deposition occurred during surges. Such deposition could have resulted from negative flux divergence in a shearing bed, but till fabrics provide no evidence for longitudinally compressive strain. A more likely origin for the basal till is that rapid, uniform bed shear during surging—consistent with the low and relatively uniform effective stresses expected during such periods—generated basal melt rates sufficient to release debris from ice and lodge it onto the bed. This conceptual model of alternating erosion and deposition implies drumlins formed by slow flowing ice elsewhere will be dominantly erosional, whereas drumlins with evidence of deposition may have experienced fast ice flow.

  2. Proglacial lake sediments – a basis for uninterrupted chronicles of the Holocene glacier variations

    M. Y. Alexandrin


    Full Text Available The article covers the origin of paleolimnological method in glaciology, concerns the theoretical background of the approach, and focuses on the principal methods of analysis of the lake sediments and creating the sedimentary age-depth models. Lake sediments can provide a basis for creating uninterrupted reconstructions of the Holocene glacier variations with high resolution. The fundament of paleolimnological method is based on the differences between glacial and non-glacial components of the bottom sediments of proglacial lakes. The glacial signal in the lake sediments was originally distinguished by measuring the organic content of the sediment (normally with loss-on-ignition and the magnetic properties of the sediment. Subsequent methods of analysis could yield more precision and normally include geochemical composition (with the use of high-resolution scanning x-ray fluorescence analysis, use of biogenic indicators (such as pollen and diatoms contained in the sediment and more. Obtaining the most accurate age of the sediment is a crucial question in subsequent application of the sediment parameters for reconstruction of glacier variability. The article covers various methods of dating the lake sediment – radiocarbon, Cs- and Pb-isotope dating, varve counting. Techniques of creating age-depth models are taken into account. A state-of-the-art application of sedimentary properties in paleoglaciology yields a reconstruction of a former equilibrium line altitude – ELA. The article focuses on the basis of the ELA reconstruction approach. Successful examples of reconstructions of glacier variations based on the lake sediments can be found throughout the majority of the glaciated regions of the planet. The article states the most prominent of them and gives an update on the current progress in paleolimnological research in the Caucasus Mountains.

  3. Spatial variability in mass loss of glaciers in the Everest region, central Himalayas, between 2000 and 2015

    King, Owen; Quincey, Duncan J.; Carrivick, Jonathan L.; Rowan, Ann V.


    Region-wide averaging of Himalayan glacier mass change has masked any catchment or glacier-scale variability in glacier recession; thus the role of a number of glaciological processes in glacier wastage remains poorly understood. In this study, we quantify mass loss rates over the period 2000-2015 for 32 glaciers across the Everest region and assess how future ice loss is likely to differ depending on glacier hypsometry. The mean mass balance of all 32 glaciers in our sample was -0.52 ± 0.22 m water equivalent (w.e.) a-1. The mean mass balance of nine lacustrine-terminating glaciers (-0.70 ± 0.26 m w.e. a-1) was 32 % more negative than land-terminating, debris-covered glaciers (-0.53 ± 0.21 m w.e. a-1). The mass balance of lacustrine-terminating glaciers is highly variable (-0.45 ± 0.13 to -0.91 ± 0.22 m w.e. a-1), perhaps reflecting glacial lakes at different stages of development. To assess the importance of hypsometry on glacier response to future temperature increases, we calculated current (Dudh Koshi - 0.41, Tama Koshi - 0.43, Pumqu - 0.37) and prospective future glacier accumulation area Ratios (AARs). IPCC AR5 RCP 4.5 warming (0.9-2.3 °C by 2100) could reduce AARs to 0.29 or 0.08 in the Tama Koshi catchment, 0.27 or 0.17 in the Dudh Koshi catchment and 0.29 or 0.18 in the Pumqu catchment. Our results suggest that glacial lake expansion across the Himalayas could expedite ice mass loss and the prediction of future contributions of glacial meltwater to river flow will be complicated by spatially variable glacier responses to climate change.

  4. Evaluation of the Surface Representation of the Greenland Ice Sheet in a General Circulation Model

    Cullather, Richard I.; Nowicki, Sophie M. J.; Zhao, Bin; Suarez, Max J.


    Simulated surface conditions of the Goddard Earth Observing System model, version 5 (GEOS 5) atmospheric general circulation model (AGCM) are examined for the contemporary Greenland Ice Sheet (GrIS). A surface parameterization that explicitly models surface processes including snow compaction, meltwater percolation and refreezing, and surface albedo is found to remedy an erroneous deficit in the annual net surface energy flux and provide an adequate representation of surface mass balance (SMB) in an evaluation using simulations at two spatial resolutions. The simulated 1980-2008 GrIS SMB average is 24.7+/-4.5 cm yr(- 1) water-equivalent (w.e.) at.5 degree model grid spacing, and 18.2+/-3.3 cm yr(- 1) w.e. for 2 degree grid spacing. The spatial variability and seasonal cycle of the simulation compare favorably to recent studies using regional climate models, while results from 2 degree integrations reproduce the primary features of the SMB field. In comparison to historical glaciological observations, the coarser resolution model overestimates accumulation in the southern areas of the GrIS, while the overall SMB is underestimated. These changes relate to the sensitivity of accumulation and melt to the resolution of topography. The GEOS-5 SMB fields contrast with available corresponding atmospheric models simulations from the Coupled Model Intercomparison Project (CMIP5). It is found that only a few of the CMIP5 AGCMs examined provide significant summertime runoff, a dominant feature of the GrIS seasonal cycle. This is a condition that will need to be remedied if potential contributions to future eustatic change from polar ice sheets are to be examined with GCMs.

  5. Variation of precipitation in Langtang Valley,Himalayas

    ZHANG; Xinping


    Hydrological Sciences, 1997, 42(5): 725-745.[13]Thompson, L. G., Thompson, E. M., Davis, M. E. et al., A 1000 year climatic ice-core record from the Guliya ice cap,China: its relationship to global climate variability, Annals of Glaciology, 1995, 21:175-181.[14]Yao, T. D., Thompson, L. G., Jiao, K. Q. et al., Recent warming as recorded in the Qinghai-Tibetan cryosphere, Annals of Glaciology, 1995,21: 196-200.[15]Yao, T. D., Thompson, L. G., Qin, D. H. et al., Variations in temperature and precipitation in the past 2000 a on the Xizang (Tibet) Plateau Guliya ice core records, Science in China, Ser. B, 1996. 39: 425-433.[16]Stew art, M. K., Stable isotope fractionation due to evaporation and isotopic exchange of falling water drops: application to atmospheric processes and evaporation of lakes, Joumal of Geophysical Research, 1975,80:1133-1146.[17]Zhang, X. P., Xie, Z. Ch., Yao, T. D., Mathematical modeling of variations on stable isotopic ratios in falling raindrops,Acta Meteorologica Sinica, 1998, 12: 213-220.[18]Rozanski, K., Sonntag, C., Munnich, K. O., Factors controlling stable isotope composition of European precipitation, Tellus. 1982, 34: 142-150.[19]Zhang, X. P., Yao, T. D., Mathematical modeling on fractionational process of oxygen isotope in atmospheric precipitation, Joumal of Glaciology and Geocryology (in Chinese), 1994, 16:156-165.[20]Yapp. C. J A model for the relationship between precipitation D/H ratios and precipitation intensity, Joumal of Geophysical Research, 1982, 87(9): 614-620.[21]Ye, D. Zh., Gao, Y. X., Meteorology of the Tibetan Plateau (in Chinese), Beijing: Science Press, 1979, 202-212.[22]Yao, T. D., Thompson, L. G., Qin, D, H. et al., Climatological significance of δ ~O in north Tibetan ice cores, Joumal of Geophysical Research, 1996, 101(29): 531-537.[23]Yao, T. D., Ding, L. F., Pu, J. Ch. et al., The variation of δ180 in snowfall in Tanggula Mountains, the Tibetan Plateau and the relationship with

  6. Glacial recession in the Tropical Andes from the Little Ice Age: the case of Ampato Volcanic Complex (Southern Peru

    Alcalá, J.; Palacios, D.; Zamorano, J. J.


    Europa (Cordillera Cantábrica, NO de España). Análisis morfológico y reconstrucción del avance glaciar histórico. Rev. C & G., 19 (3-4), 79-94. Hastenrath, S. L. (2009): Past glaciation in the tropics. Quaternary Science Reviews, 28: 790-798. Jomelli, V.; Favier, V.; Rabatel, A.; Brunstein, D.; Hoffmann, G.; and Francou, B. (2009): Fluctuations of glaciers in the tropical Andes over the last millennium and palaeoclimatic implications: A review. Palaeogeography, Palaeoclimatology, Palaeoecology, doi: 10.1016/j.palaeo.2008.10.033. Kaser, G., Osmaston, H.A., 2002. Tropical glaciers. Cambridge University Press, Cambridge. Mark, B. (2008): Tracing tropical Andean glaciers over space and time: Some lessons and transdisciplinary implications. Global and Planetary Change, 60: 101-114. Osmaston, H. (2005): Estimates of glacier equilibrium line altitudes by the Area _ Altitude, the Area _ Altitude Balance Ratio and the Area _ Altitude Balance Index Methods and their validation. Quaternary International, 138-139: 22-31. Rabatel, A., Jomelli, V., Naveau, P., Francou, B., Grancher, D. (2005). Dating of Little Ice Age glacier fluctuations in the tropical Andes: Charquini glaciers, Bolivia, 16ºS. C. R. Geoscience, 337: 1311-1322. Rabatel, A., Francou, B., Jomelli, V., Naveau, P., Grancher, D. (2008). A chronology of the Little Ice Age in the tropical Andes of Bolivia (16º S) and its implications for climate reconstruction. Quaternary Research, 70: 198-212. Ramirez, E., Francou, B., Ribstein, P., Descloitres, M., Guerin, R., Mendoza, J., Gallaire, R., Pouyaud, B., Jordan, E., 2001. Small glaciers disappearing in the tropical Andes: a case study in Bolivia: Glaciar Chacaltaya (16°S). Journal of Glaciology 47 (157), 187-194. Soruco, A.; Vincent, C.; Francou, B.; Ribstein, P.; Berger, T.; Sicart, J. E.; Wagnon, P.; Arnaud, Y.; Favier, V.; and Lejeune, Y. (2009): Mass balance of Glacier Zongo, Bolivia, between 1956 and 2006, using glaciological, hydrological and geodetic methods

  7. Temperature and methane records over the last 2 ka in Dasuopu ice core

    PU; Jianchen; (


    [1]Johnsen, S. J., Clauson, H. B., Dansyard, W. et al., Irregular glacial interstadials recoded in a new Greenland ice core, Nature, 1992, 359: 311-312.[2]Grootes, P. M., Stuiver, M., White, J. W. C. et al., Comparison of osygen isotope records from the GISP2 and GRIP Greenland ice cores, Nature, 1993, 366: 552-554.[3]Muller, F., Glaciers and their fluctuations, Nature and Resources, 1980, 16(2): 5-12.[4]Meier, M. F., The contribution of small glaciers to global sea level, Science, 1984, 226: 1418-1421.[5]Kukla, G ., Gavin, J., Summer ice and carbon dioxide, Science, 1981, 214: 497-503.[6]Gornitz, V., Global sea level trend in the past century, Science, 1982, 215: 1611-1614.[7]Rasmusen, R. A., Khalil, M. A. K., Atmospheric methane in the recent and ancient atmospheres: Concentrations, trends and interhemispheric gradient, J. Geophys. Res., 1984, 89(D7): 11599-11605.[8]Blunier, T., Chappellaz, J., Schwander, J. et al., Atmospheric methane record from a Greenland ice core over the last 1000 years, Geoph. Res. Lett., 1993, 20(20): 2219-2222.[9]Zhu, K. Z., Climatic changes in the past 5000 years in China, Science in China, 1973, 26: 1-5.[10]Wu Xiangding, Lin Zhenyao, Some characteristics of the climatic changes during the historical time of Qinghai-Xizang Plateau, Acta Meteorologica Sinica (in Chinese), 1981, 39(1): 90-96.[11]Yao Tangdong, Qin Dahe, Tian Lide et al., Variations in temperature and precipitation in the past 2000a on the Xizang (Tibet) Plateau: Guliya ice core record, Science in China, Ser. D, 1996, 39: 426-433.[12]Yao Tandong, Thompson, L. G ., Trends and features of climatic changes in the past 5000 years recorded by Dunde ice core, Annals of Glaciology, 1992, 16: 470-473.[13]Yao, T. D., Xie Zichu, Climatic Change since the Little Ice Age as recorded in the Dunde Ice Cap, Science in China, Ser. B, 1991, 34(6): 760-767.[14]Yao Tandong, One of the ten science and technology achievements 1997 in China

  8. EDGE (Experiential Discoveries in Geoscience Education) Field Course Provides Alaskan High School and Middle School students with Earth Science and GIS Skills for Science Fair Projects and a College Experience

    Connor, C. L.; Prakash, A.; Brownlee, M.; Nagorski, S.; Walling, R.


    For this outreach project we created watershed scale field activities in the Mendenhall Glacier system in Juneau, Alaska to introduce pre-college students to earth surface processes. These activities were designed to teach field data collection methods and to provide experiences that included exposure to the disciplines of glaciology, hydrology, and geomorphology. Students used their own observations to understand the on-going effects of warming climate in southeastern Alaska. Twenty seven, pre-college students from throughout the state participated in a 5-day, two-credit, introductory college-level course. This course was designed to introduce them to earth science as practiced in the field. Students divided their time between field sessions with data collection and indoor GIS labs. EDGE field excursions enabled students to learn about glacial geomorphology from river rafts, to collect stream discharge and other hydrologic data in local streams, and to integrate glacier recession observations with GPS waypoints collected from observed recessional positions. In labs at the University of Alaska Southeast campus, EDGE students were introduced to the fundamentals of ArcGIS. They downloaded their GPS waypoints onto modern and historic maps. They analyzed their stream flow data and created dynamic maps using their own observations in the field. During Fall 2006 semester, the students will generate earth science projects in their villages and towns that they can complete and present to their peers. EDGE teachers who attended a 10 day workshop in June will mentor their EDGE students. EDGE teachers and students will return to the UAS Juneau campus in March 2007 for a symposium. EGDE students will present their projects to Juneau area undergraduates and Juneau School District K-12 classes. In addition EDGE high school students will have the option to enter and compete in the Southeast Alaska Regional Science Fair held the same weekend. Funding from the National Science

  9. On the late Cenozoic evolution of the Norwegian Arctic continental margin

    Sverre Laberg, Jan; Rydningen, Tom Arne; Lasabuda, Amando


    denudation and landscape formation in this tectonically "passive" setting: 1) The pre-glacial relief controlling the morphology and size of the drainage area, 2) The ice sheet glaciology including the location and size of fast-flowing ice streams where the pre-glacial relief and its bedrock composition exerts a fundamental control, 3) The evolution of the global climate controlling the ice sheet growth and decay as well as its basal properties. For both areas, glacial erosion is interpreted to have amplified the relief of the pre-glacial landscape.

  10. Volcanological applications of the Kinect sensor

    Tortini, R.; Carn, S. A.


    , particularly where conditions may be unsuitable for the deployment of more costly instruments. K.D. Mankoff, T.A. Russo, B.K. Norris, S. Hossainzadeh, L. Beem, J.I. Walter, and S.M. Tulaczyk, "Kinects as sensors in earth science: glaciological, geomorphological, and hydrological applications". AGU Fall Meeting 2012, San Francisco (USA), poster.

  11. Fifteen Years of ASTER Data on NASA's Terra Platform

    Abrams, M.; Tsu, H.


    The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five instruments operating on NASA's Terra platform. Launched in 1999, ASTER has been acquiring data for 15 years. ASTER is a joint project between Japan's Ministry of Economy, Trade and Industry; and US NASA. Data processing and distribution are done by both organizations; a joint science team helps to define mission priorities. ASTER acquires ~550 images per day, with a 60 km swath width. A daytime acquisition is three visible bands and a backward-looking stereo band with 15 m resolution, six SWIR bands with 30 m resolution, and 5 TIR bands with 90 m resolution. Nighttime TIR-only data are routinely collected. The stereo capability has allowed the ASTER project to produce a global Digital Elevation Model (GDEM) data set, covering the earth's land surfaces from 83 degrees north to 83 degrees south, with 30 m data postings. This is the only (near-) global DEM available to all users at no charge; to date, over 28 million 1-by-1 degree DEM tiles have been distributed. As a general-purpose imaging instrument, ASTER-acquired data are used in numerous scientific disciplines, including: land use/land cover, urban monitoring, urban heat island studies, wetlands studies, agriculture monitoring, forestry, etc. Of particular emphasis has been the acquisition and analysis of data for natural hazard and disaster applications. We have been systematically acquiring images for 15,000 valley glaciers through the USGS Global Land Ice Monitoring from Space Project. The recently published Randolph Glacier Inventory, and the GLIMS book, both relied heavily on ASTER data as the basis for glaciological and climatological studies. The ASTER Volcano Archive is a unique on-line archive of thousands of daytime and nighttime ASTER images of ~1500 active glaciers, along with a growing archive of Landsat images. ASTER was scheduled to target active volcanoes at least 4 times per year, and more frequently for

  12. The down-stress transition from cluster to cone fabrics in experimentally deformed ice

    Qi, Chao; Goldsby, David L.; Prior, David J.


    with low Schmid factors at low stress, to lattice rotation caused by slip primarily on the basal slip system, which causes c-axes to rotate to become parallel to the shortening direction at high stress. Mapping out the transition from cluster (rotation-dominated) to cone (GBM-dominated) CPOs as a function of stress (this study) and temperature (future studies) allows for a robust extrapolation to, and a fundamental understanding of the CPOs formed at, glaciological stresses and temperatures.

  13. 积雪中不溶微粒与Mg~(2+)的沉积特征和相互关系%Study on Deposition Characteristics of Insoluble Microparticles and Mg~(2+) Concentration in Snow Cover and Their Correlation

    尤晓妮; 李忠勤


    It is a part of the PGPI(Program for Processe Investigation) to study the relationship between insoluble microparticles and magnesium,and it was initiated at the Tianshan Glaciological Station in July 2002.In this paper,the vertical distribution and evolution process of insoluble microparticle and magnesium concentration along vertical profiles of snow pits as well as their seasonal variation were studied by weekly sampling from a snow pit(4 130 m a.s.l.,in the percolation zone) on Glacier No.1 in the east Tianshan Mountains from September 2003 to September 2004.The analyzed results of insoluble microparticles and magnesium concentration reveal that their change trends were similar in both surface snow and along vertical snow profiles.In winter,insoluble microparticles and magnesium concentrations in surface snow layer were altered slightly by sublimation and wind erosion.In early summer,as snow melting occurred in the upper part of snow-firn pack,snow meltwater carried microparticles and magnesium to different depths of the underlying snow-firn layers,all the surface elements might be leached out from the upper layers at the end of the ablation season.Correlation coefficient between concentration of insoluble microparticles and magnesium along vertical profiles of snow layer showed a significant negative correlation with temperature.%为了探究不溶微粒和Mg2+在雪冰沉积过程中的相关性,对采自乌鲁木齐河源1号冰川海拔4 130 m处的雪冰样品进行不溶微粒和Mg2+浓度的分析。表层雪中不溶微粒和Mg2+浓度的季节变化具有较好的一致性,在6~8月的降水频发期和局地风盛行时,两者都达到一年中的最大值。粗微粒(直径大于10μm)和Mg2+浓度在雪层剖面中的垂直分布亦具有很好的相似性,表现出相同的演化趋势,暗示两者在后沉积过程中的相关性。这种相关性被证明与同期温度变化呈现出明显的负相关。

  14. South Cascade (USA/North Cascades)

    Bidlake, William R.


    The U.S. Geological Survey has closely monitored this temperate mountain glacier since the late 1950s. During 1958-2007, the glacier retreated about 0.7 km and shrank in area from 2.71 to 1.73 km2, although part of the area change was due to separation of contributing ice bodies from the main glacier. Maximum and average glacier thicknesses are about 170 and 80 m, respectively. Year-to-year variations of snow accumulation amounts on the glacier are largely attributable to the regional maritime climate and fluctuating climate conditions of the North Pacific Ocean. Long-term-average precipitation is about 4500 mm and most of that falls as snow during October through May. Average annual air temperature at 1,900 m altitude (the approximate ELA0) was estimated to be 1.6°C during 2000-2009. Mass balances are computed yearly by the direct glaciological method. Mass balances measured at selected locations are used in an interpolation and extrapolation procedure that computes the mass balance at each point in the glacier surface altitude grid. The resulting mass balance grid is averaged to obtain glacier mass balances. Additionally, the geodetic method has been applied to compute glacier net balances in 1970, 1975, 1977, 1979-80, and 1985-97. Winter snow accumulation on the glacier during 2007/08 and 2008/09 was larger than the long-term (1959-2009) average. The 2007/08 preliminary summer balance (-3510 mm w.e.) was slightly more negative than the long-term average and this yielded a preliminary 2007/08 net balance (-290 mm w.e.), which was less negative than the average for the period of record (-600 mm w.e.). Summer 2009 was uncommonly warm and the preliminary 2008/09 summer balance (-4980 mm w.e.) was more negative than any on record for the glacier. The 2008/09 glacier net balance (-1860 mm w.e.) was among the 10 most negative for the period of net balance record (1953-2009). Material presented here is preliminary in nature and presented prior to final review. These

  15. Glacier Changes in the Nanga Parbat Region, NW Himalaya: A longitudinal study over 160 years (1856-2016)

    Nüsser, Marcus; Schmidt, Susanne


    Against the background of the prominent Himalayan glacier debate of the past decade, global concerns were raised about the severe consequences of detected and expected changes in the South Asian cryosphere. Due to the lack of historical glaciological data in the Himalayan region, studies of glacier changes over long time periods are rare. The present study seeks to analyze and quantify glacier changes in the Nanga Parbat region between 1856 and 2016. Due to the steep topography and great vertical span, the debris-covered glaciers of the mountain massif are largely fed by avalanches of different size. This impact of snow and ice re-distribution by avalanches is often neglected in glacier mass-balances. Therefore, an integrated approach was used to investigate the glacier changes and the impact of avalanches. This approach includes (1) a re-photographic survey with images from several expeditions between 1934 and 2010, (2) mapping during own field surveys between 1992 and 2010, as well as (3) the analyses of remote sensing data (Corona, QuickBird, KompSat, Landsat, etc. and DEM) and (4) historical topographic maps. The re-photographic survey allows for direct comparisons and illustrates glacier changes over a span of seventy years. Changes of glacier lengths were quantified by using remote sensing data and the topographic map of 1934. In order to calculate glacier surface changes, a digital elevation model (DEM) with a spatial resolution of 30 x 30 m2 was derived from the digitized contour lines of the topographic map from 1934 and compared to SRTM-DEM (30 x 30 m2) and ALOS-DSM. Based on remote sensing time-series, avalanche deposits on glaciers were mapped in order to identify their magnitude and frequencies. To calculate the potential glacier catchment, area of steep rock walls and the ratio between accumulation and ablation zones were calculated for each glacier basin. Our field based investigations show that the glaciers in the Rupal Valley are characterized by

  16. Long-term erosion and interglacial period exposure in Western Greenland from meteoric 10Be in ice-bound sediment

    Graly, J. A.; Corbett, L.; Bierman, P. R.; Neumann, T.; Rood, D. H.; Finkel, R. C.


    the Southern Dome of the Greenland Ice Sheet is substantially more effective at eroding subglacial sediment than the ice sheet’s north. The meteoric 10Be data are consistent with models and other evidence suggesting substantial exposure of southern Greenland during the mid-Holocene and Eemian interglacial periods. Reference Cited: Knight, P. G., et al. (2002), Discharge of debris from ice at the margin of the Greenland ice sheet, Journal of Glaciology, 48, 192-198.

  17. All Is Not Lost: The Transition from Order to Disorder in Greenland's Glaciers

    Walker, C. C.; Schmidt, B. E.; Bassis, J. N.


    Iceberg calving is a major process involved in the removal of large volumes of ice from ice sheets to the oceans, but remains relatively poorly understood. The part of the puzzle that remains the least clear is the dynamics involved in the transition between intact glacier ice and rapid fragmentation during calving events. Because calving is a sudden rapid event, it is often the case that what gets captured by satellite observation is the before and after, rather than the exact moment of failure. Here we exploit this fact and use a statistical approach using a collapse model to investigate whether or not there exists a quantifiable critical fracture density, or "critical mass" of closely-spaced fractures, beyond which dynamic fragmentation of the glacier occurs. To do this we study the size distribution of fragments in proglacial mélange, using this information to infer physical properties of the pre-collapsed ice, such as material strength and the energy necessary to create a fragmentation event using methods widely applied in civil and even weapons engineering, but not previously applied in a glaciological context. Characterizing fracture density at different locations and quantifying a critical factor to describe the transition from highly-fractured to collapse/fragmentation region enable us to understand the distribution of observable surface fracture patterns and underlying differences within regions of individual glaciers and between glaciers. This investigation is well-served by the only-recently-available high resolution data over Greenland's glaciers by LandSat, MODIS and Operation IceBridge, among others. While many studies have focused on the propagation of crevasses in the glacier ice as a means of predicting calving, the main goal of this work is to consider the physical transition between the two phases of collapse. As such, our work focuses (1) on the pre-collapse state as characterized by crevasse pattern formation in the glacier, or level of

  18. A Source-to-Sink Perspective on Landscapes and Strata in an Icy World

    Koppes, M. N.; Jaeger, J. M.


    Global climate during the Quaternary Era is distinguished by the transition into a colder, more variable world, dominated by the onset and intensification of glacial conditions. The majority of temperate and high-latitude landscapes, from the land to the deep sea, reflect both a contemporary and more extensive Quaternary glacial influence, including voluminous loess and periglacial terrestrial deposits, scablands carved by meltwater, ice-gouged seafloors, and kilometer-thick continental margin glacial deposits. Whereas on orbital time scales the growth and decay of ice appears to be a global signal, the stratigraphic record of glacier and ice sheet dynamics is created by a combination of allogenic and autogenic processes, including the basal thermal regime, subglacial hydrology, bedrock lithology, and tectonic conditioning. For instance, both sediment and meltwater production vary by orders of magnitude between temperate and polar glacial systems, and between tectonically active and quiescent margins. Documenting the relative roles of each influence on landscape development and strata formation is a fundamental goal of Quaternary geomorphology, glaciology, and glacial sedimentology. The past thirty years have witnessed a wide-ranging effort to document and explain the role that ice plays on shaping the land-ocean-atmosphere interface, led by focused field efforts in glaciated basins to measure/model ice dynamics and glacial erosion rates, and marine programs of seismic reflection profile acquisition, swath bathymetric mapping, and seabed coring and drilling to document the delivery of sediment generated by ice to fjords and continental margins. In this presentation, we review the current state of knowledge on the processes and products associated with glaciation, with a focus on describing the generation, transfer, and accumulation of sediment from land to sea. The specific topics covered include: 1. Contemporary subglacial erosion (models, borehole observations

  19. Regional glacier changes in the Ötztal Alps (Tyrol, Austria) - Results from different remote sensing techniques

    Klug, Christoph; Rieg, Lorenzo; Sailer, Rudolf


    Climate change will pose a variety of challenges in the future, with global sea level rise among the most important ones. Out of all contributions to sea level rise, the contribution from glaciers is the one with the highest uncertainty. This is mainly because only very few and not necessarily representative glaciers are measured regularly. Among others, this limits the validation of extrapolation models. On a regional scale, remote sensing data offer several possibilities for the mapping and monitoring of glaciers. Especially with the advent of very high resolution data, new possibilities can be exploited. The monitoring of glacier area, the calculation of the geodetic glacier mass balances and the tracking of changes in the seasonal snow and firn bodies of glaciers on a regional scale can not only help to enhance the spatial, but also the temporal coverage of observations. The Ötztal Alps in Tyrol, Austria have been a research focus for the University of Innsbruck for several decades. Ongoing glaciological field measurements at two reference glaciers (Hintereisferner and Kesselwandferner) and data from different remote sensing techniques provide a valuable basis for a variety of research. The presented study analyses high-resolution airborne laser scanning (ALS) data, with more than 10 years of annual campaigns on Hintereisferner (2001-2013) and two campaigns covering all of the Ötztal Alps (2006 and 2010) in combination with orthoimages and optical satellite data. Furthermore Pléiades tri-stereo data (2015 and 2016) are available to calculate very high resolution and high quality digital terrain models (DTM). These DTM can be used to extend the time series in combination with the DTM based on ALS data and enable the calculation of the geodetic glacier mass balance for over 150 glaciers within the study area. Furthermore, the optical information (ALS intensity, orthoimages and optical satellite data) is used for surface classification in order to monitor the

  20. Model based historical runoff contribution from an Alpine glacier

    Zoccatelli, Davide; Bonato, Paola; Carturan, Luca; Dalla Fontana, Giancarlo; De Blasi, Fabrizio; Borga, Marco


    The aim of this work is to analyze how climatic variability and glacier retreat impact the water balance of a small (8.5 km2) glaciarised catchment in the Eastern Italia Alps over a 30 year (1983-2013) period. The analysis is carried out by coupling local high quality data and a glacio-hydrological model able to simulate both the glacier and hydrology dynamics. Runoff contribution from glacier ice is related with trends in climatic variables and with glacier retreat. The area analyzed is the headwater of Noce Bianco river basin, lying in the Ortles-Cevedale group and including the La Mare glacier. During the study period the glacier area decreased from 4.7 km2 (50% basin area) to 3.47 km2 (40% basin area). In this area the following observations are available: 30 years of daily meteorological data at high elevation close to the catchment; three DTMs of the glacier, covering the entire period, which enable the calculation of the volume change and geodetic mass balance; direct glaciological mass balance observations over the period 2003-2013; discharge measurement at the catchment outlet over the period 2007-2013. The data availability and the significant shrinking of the glacier during the analyzed period make this catchment ideal for studying the hydrological impacts of glacier retreat. The semi-distributed conceptual model includes a snow and glacier accumulation and ablation module, based on temperature-radiation index and a glacier retreat model. The glacier retreat model allows to use the annual simulated glacier mass balance to update the glacier area (Huss et al., 2010). The model simulations are carried out from 1983 to 2013. We show that the model is able to capture adequately the measured daily discharge, the observed changes in glacier area and their spatial distribution. The contribution of glacier ice meltwater to annual runoff is below 10% in the first decade of simulation. This variable however showed a clear increasing trend, with peaks for single

  1. Morphological dynamics of an englacial channel

    Vatne, Geir; Irvine-Fynn, Tristram D. L.


    Despite an interest in the hydraulic functioning of supraglacial and englacial channels over the last 4 decades, the processes and forms of such ice-bounded streams have remained poorly documented. Recent glaciological research has demonstrated the potential significance of so-called "cut-and-closure" streams, where englacial or subglacial flow paths are created from the long-term incision of supraglacial channels. These flow paths are reported to exhibit step-pool morphology, comprising knickpoints and/or knickzones, exaggerated in dimensions in comparison to supraglacial channels. However, little is known of the development of such channels' morphology. Here, we examine the spatial organisation of step pools and the upstream migration of steps, many of which form knickzones, with repeated surveys over a 10-year period in an englacial conduit in cold-based Austre Brøggerbreen, Svalbard. The observations show upstream step recession to be the dominant process for channel evolution. This is paralleled by an increase in average step height and conduit gradient over time. Characteristic channel-reach types and step-riser forms are consistently observed in each of the morphological surveys reported. We suggest that the formation of steps has a hydrodynamic origin, where step-pool geometry is more efficient for energy dissipation than meanders. The englacial channel system is one in rapid transition towards a quasi-equilibrium form within a decadal timescale. The evolution and recession of knickzones reported here result in the formation of a 37 m deep moulin shaft, suggesting that over time an incising supraglacial channel may evolve towards an englacial channel form exhibiting a stable end-point characterised by a singular vertical descent, which potentially can reach the glacier bed. This challenges the prevailing notions that crevasses or hydrofractures are needed to form deep moulins. Our observations highlight the need to further examine the adjustment processes

  2. The first stages of erosion by ice sheets: Evidence from central Europe

    Hall, A. M.; Migoń, P.


    between blockfield-covered slopes found above Elsterian and Saalian glacial trimlines on summits of granite, gabbro and basalt hills in the Sudetic Foreland and glacially-stripped surfaces at lower elevations implies only limited regeneration of blockfields since 430 and 240 ka. The first stages of roche moutonnée formation are recognised in the exhumation of tor stumps but development of lee-side steps remains very limited. Granite domes retain a pre-glacial morphology and local examples of hill asymmetry are determined by structural, rather than glaciological controls. Development of roches moutonnées and asymmetric and streamlined hills by glacial erosion has not occurred in the Sudetes despite the passage of largely warm-based ice sheets 80-500 m thick that persisted for 5-20 ka.

  3. Backwater rise due to large wood accumulations: Effect of organic fine material

    Schalko, Isabella; Schmocker, Lukas; Weitbrecht, Volker; Boes, Robert M.


    Large wood (logs with a diameter ≥ 0.1 m and a length ≥ 1.0 m) in rivers improves the diversity of morphological structures and flow conditions. It may be transported as single logs or in a bulk, forming a log jam or an accumulation at an obstruction. In a natural river, large wood (LW) accumulations create heterogeneous hydraulic gradients and increase the flow resistance. Besides various ecological benefits, LW accumulations may intensify flood hazard. During flood events, transported LW may accumulate at river infrastructures or is retained intentionally at LW retention structures. In both cases, the accumulation results in an upstream backwater rise and may lead to flooding of the nearby area. Consequently, engineering measures are necessary to mitigate LW accumulation risk. The number of investigations on the role of LW during flood events has substantially increased within the last decades. At the Laboratory of Hydraulics, Hydrology, and Glaciology (VAW) of ETH Zurich, several studies were conducted on LW accumulation probability and rate. Formulae for backwater rise calculation already exist, but the governing parameters are still contradictory. In addition, the effect of organic fine material (e.g. branches or leaves in a LW accumulation) was neglected in all previous studies. In this present study, a series of small-scale and close-to-prototype model tests were conducted to identify the governing parameters on backwater rise due to LW accumulations. During the experiments, the approach flow conditions (inflow flow depth and Froude number) and LW accumulation characteristics (accumulation length, compactness of LW accumulations, LW characteristics, and organic fine material) were varied systematically. The experimental results show that the backwater rise depends mainly on the compactness of LW accumulations, approach flow Froude number, and organic fine material. The study confirms the hypothesis that organic fine material changes the accumulation

  4. Modelling the hydrologic role of glaciers within a Water Evaluation and Planning System (WEAP: a case study in the Rio Santa watershed (Peru

    T. Condom


    Full Text Available For the past 30 years, a process of glacier retreat has been observed in the Andes, raising alarm among regional water resources managers. The purpose of this paper is to develop a model of the role of Andean glaciers in the hydrology of their associated watersheds, which is appropriate for application at a river basin scale, with an eye towards creating an analytical tool that can be used to assess the water management implications of possible future glacier retreat. While the paper delves deeply into our formulation of a glacier module within a water resources management modelling system, the widely subscribed Water Evaluation and Planning System (WEAP, the originality of our work lies less in the domain of glaciology and more in how we apply an existing reduced form representation of glacier evolution within a model of the climate-glacier-hydrology-water management continuum. Key insights gained pertain to appropriate ways to deploy these reduced form representations in a relatively data poor environment and to effectively integrate them into a modelling framework that places glaciers within a wider water management context. The study area is the Rio Santa watershed in Peru which contains many of the expansive glaciers of the singular Cordillera Blanca. The specific objectives of this study included: (i adequately simulating both monitored glacier retreat and observed river flows from the last forty years using historical climate time series as model input; (ii quantifying the proportion of river flow in the Rio Santa produced from melting glaciers during this period; (iii estimating the historical contribution of groundwater accretions to river flows; and (vi reproducing a reasonable simulation of recent hydropower operations in the Rio Santa system. In pursuit objective (i, a split sample calibration-validation of the model was conducted by comparing the simulated glacier area to Landsat images taken in 1987 and 1998 and observed and

  5. Crevassing and calving of glacial ice

    Kenneally, James Patrick

    Calving of ice is a relatively new area of research in the still young field of glaciology. In the short time that calving has been studied, it has been mainly treated as an afterthought, with the predominant mode of thinking being that it will happen so to concern oneself with why is not important. Many studies dealt with observations of calving front positions over time vs. ice velocity in an attempt to quantify the calving rate as the difference between the two, while others have attempted to deduce some empirical relationship between calving rate and variables such as water depth or temperature. This study instead addresses the question of why, where, and when ice will first become crevassed, which is an obviously necessary condition for a later calving event to occur. Previous work examining the causes of calving used ideas put forth from a variety of fields, including civil engineering, materials science, and results from basic physics and mechanics. These theories are re-examined here and presented as part of a larger whole. Important results from the field of fracture mechanics are utilized frequently, and these results can be used as a predictor of ice behavior and intrinsic properties of ice, as well as properties like back stresses induced by local pinning points and resistive shears along glacial ice boundaries. A theory of fracture for a material experiencing creep is also presented with applications to ice shelves and crevasse penetration. Finally, a speculative theory regarding large scale iceberg formation is presented. It is meant mainly as an impetus to further discussion on the topic, with the hope that a model relating crevasse geometries to flow parameters can result in crevasse spacings that could produce the tabular icebergs which are so newsworthy. The primary focus of this thesis is to move away from the "after the fact" studies that are so common in calving research, and instead devote energy to determining what creates the conditions that

  6. Characterization of the upper Arve watershed at Chamonix (French Northern Alp) from an integrated glacial-snow-hydrometeorological point of view

    Isabella, Zin; Delphine, Six; Thomas, Condom; Catherine, Coulaud; Michel, Esteves; Olivier, Laarman; Matthieu, Lafaysse; Thierry, Lebel; Grégoire, Lecourt; Samuel, Morin; Charles, Obled; Antoine, Rabatel; Jesus, Revuelto; Alessandra, Viani; Christian, Vincent; Vincent, Vionnet; Frederic, Gottardi


    The upper Arve watershed (205 km²) is characterized by a high elevational gradient (altitude ranges from 1000 to 4810m asl), a significant glaciated area (about 33% of the total area) and a strong contrast between the bordering Mont Blanc and Aiguilles Rouges massifs in terms of land use , surface conditions and meteorological forcing. While the rainfall regime in the valley is relatively stable during the year, the thermal regime shows strong diurnal and seasonal variability. The hydrological regime of the main stream and its tributaries is dominated by snow and glacier melt, with high flow rates in summer and low flow rates in wintertime, when snowfalls accumulate on the ground. Water transfers from a compartment to another are particularly rapid, with flash floods having lag times of about 4 to 6 hours and significant sediment transport associated with liquid flow rates. Since 2014, a project involving local communities, stackeholders and researchers and aiming at understanding the flood generation processes and their evolution with climatic and environmental changes has been started. The project aims at characterizing the catchment behaviour from an integrated glacial-snow-hydrometeorological point of view and to develop a flood forecasting system for anticipate as much as possible a possible crisis and improve its management. As a part of this project and in the continuity of existing long-term measures in the valley (particularly within the GLACIOCLIM research observing system and the operational Météo-France frameworks) a new instrumentation network has been implemented in order to observe simultaneously the different components of the water cycle (atmospheric, hydrological, snow and glaciological variables) and their spatial, temporal and altitudinal gradients. We will present the instrumental network and the measurement strategy, as well as an analysis of the data collected during the 2014 and 2015 summers, which are quite contrasted from a

  7. Temporal patterns of glacial lake evolution in high-mountain environments

    Mergili, Martin; Emmer, Adam; Viani, Cristina; Huggel, Christian


    Lakes forming at the front of retreating glaciers are characteristic features of high-mountain areas in a warming climate. Typically, lakes shift from the proglacial phase (lake is in direct contact with glacier) to a glacier-detached (no direct contact) and finally to a non-glacial phase (lake catchment is completely deglaciated) of lake evolution. Apart from changing glacier-lake interactions, each stage is characterized by particular features of lake growth, and by the lake's susceptibility to sudden drainage (lake outburst flood). While this concept appears to be valid globally, some mountain areas are rich in dynamically evolving proglacial lakes, while in others most lakes have already shifted to the glacier-detached or even non-glacial phase. In the present contribution we (i) explore and quantify the history of glacial lake formation and evolution over the past up to 70 years; (ii) assess the current situation of selected contrasting mountain areas (eastern and western European Alps, southern and northern Pamir, Cordillera Blanca); and (iii) link the patterns of lake evolution to the prevailing topographic and glaciological characteristics in order to improve the understanding of high-mountain geoenvironmental change. In the eastern Alps we identify only very few lakes in the proglacial stage. While many lakes appeared and dynamically evolved until the 1980s between 2550 m and 2800 m asl, most of them have lost glacier contact until the 2000s, whereas very few new proglacial lakes appeared at the same time. Even though a similar trend is observed in the higher western Alps, a more dynamic glacial lake evolution is observed there. The arid southern Pamir is characterized by a high number of proglacial lakes, mainly around 4500 m asl. There is strong evidence that glacial lake evolution is, after a highly dynamic phase between the 1970s and approx. 2000, decelerating. Few proglacial lakes exist in the higher and more humid, heavily glacierized northern Pamir

  8. Younger Dryas equilibrium line altitudes and precipitation patterns in the Alps

    Kerschner, Hanns; Moran, Andrew; Ivy-Ochs, Susan


    modern values. As winter precipitation was probably much smaller than today, seasonal contrasts were more pronounced. In total, the pattern of YD precipitation change is remarkably similar to precipitation patterns caused by westerly and northwesterly cyclonic airflow during the present-day hydrologic winter (October - March). Kerschner, H., G. Kaser, R. Sailer (2000): Alpine Younger Dryas glaciers as paleo-precipitation gauges. Annals of Glaciology 31, 80-84. Kerschner, H. and S. Ivy-Ochs (2007): Palaeoclimate from glaciers: Examples from the Eastern Alps during the Alpine Lateglacial and early Holocene. Global and Planetary Change 60, 58-71.

  9. Design and Implementation of a Wireless Sensor Network of GPS-enabled Seismic Sensors for the Study of Glaciers and Ice Sheets

    Bilen, S. G.; Anandakrishnan, S.; Urbina, J. V.


    In an effort to provide new and improved geophysical sensing capabilities for the study of ice sheets in Antarctica and Greenland, or to study mountain glaciers, we are developing a network of wirelessly interconnected seismic and GPS sensor nodes (called "geoPebbles"), with the primary objective of making such instruments more capable and cost effective. We describe our design methodology, which has enabled us to develop these state-of-the art sensors using commercial-off-the-shelf hardware combined with custom-designed hardware and software. Each geoPebble is a self-contained, wirelessly connected sensor for collecting seismic measurements and position information. Each node is built around a three-component seismic recorder, which includes an amplifier, filter, and 24-bit analog-to-digital card that can sample up to 10 kHz. Each unit also includes a microphone channel to record the ground-coupled airwave. The timing for each node is available through a carrier-phase measurement of the L1 GPS signal at an absolute accuracy of better than a microsecond. Each geoPebble includes 16 GB of solid-state storage, wireless communications capability to a central supervisory unit, and auxiliary measurements capability (up to eight 10-bit channels at low sample rates). We will report on current efforts to test this new instrument and how we are addressing the challenges imposed by the extreme weather conditions on the Antarctic continent. After fully validating its operational conditions, the geoPebble system will be available for NSF-sponsored glaciology research projects. Geophysical experiments in the polar region are logistically difficult. With the geoPebble system, the cost of doing today's experiments (low-resolution, 2D) will be significantly reduced, and the cost and feasibility of doing tomorrow's experiments (integrated seismic, positioning, 3D, etc.) will be reasonable. Sketch of an experiment with geoPebbles scattered on the surface of the ice sheet. The seismic

  10. From Supernovae To Equatorial Ionosphere, Following a Tortuous Path Through Computer Sciences, Oceanography, and Much, Much More

    de La Beaujardiere, O.


    From as early as I can remember, I always wanted to be a scientist. My interests were oriented towards cataclysmic and catastrophic events. I first wanted to study volcanoes, then earthquakes. As I ended my PhD, my interests had gone a little higher, towards supernovae and the Crab Nebula. This was in Paris. I then immigrated to the US. My first job in the US was in computer sciences. I joined a team who made one of the first computer movies. I then switched fields once more. I went into ionospheric physics, where I stayed for more than 2 decades. I then did two "tours of duty" at National Sciences Foundation. I was first in the Magnetospheric Program. Then I started a multidisciplinary program that covered all sciences related to the arctic - from the bottom o f the ocean to the confines of the magnetosphere, passing through biology, glaciology, etc. Presently, I lead a team of about 20 scientists at the Air Force Research Laboratory. We work on basic and applied ionospheric sciences problems as they relate to communications and navigation. As a woman scientist, the hardest obstacle I had to overcome was probably the permanent guilt of not staying home with my children. I raised 3 boys, and, although they are happy, successful and well adjusted, I continue to feel guilt about not staying home for them, and working so long hours and with so much intensity. When they were small, society was not too accepting of working mothers. In one of my kids' first grade class, he was the only child whose mother was working. As a teenager I also had to overcome rejection from boys who "could not stand" girls who studied science. My own father was not too encouraging to continue studies, warning me that women who are too bright have a hard time finding husbands. One University professor told the class that women were wasting taxpayers' money since they would never put their degree to use. My greatest support was my husband, always there, sharing chores, and understanding my ups

  11. Long-term mass- and energy balance of Kongsvegen glacier, Spitzbergen

    Krismer, Thomas; Obleitner, Friedrich; Kohler, Jack


    We present meteorological and glaciological data from the equilibrium line (ELA) of Kongsvegen glacier (550masl) in Svalbard, covering the period 2000 until 2008. Mean annual air temperatures for the period range from -6.9 to -10.1°C and specific net annual mass balances range from -670 to +281 mm w eq. During some years substantial superimposed ice was formed and even survived the summer. The meteorological data were homogenized and used for input and validation of mass- and energy-balance simulations. The meteorological regime at the ELA is characterized by a coreless winter and summer temperatures around 0°C. Wind conditions are largely determined by katabatic winds and topgraphically channeled upper-air winds. Net short-wave radiation is determined by cloudiness during the polar day and by the seasonal evolution of glacier surface albedo. Long-wave radiation fluxes withdraw energy throughout the year and the mean annual net radiation is almost negligible. The turbulent sensible heat fluxes constitute a comparatively strong and continuous source of energy. The latent heat flux is characterized by prevailing condensation during winter and evaporation during summer. On average, however, the turbulent fluxes provide only a small amount of heat to the glacier. Most of the energy available from the atmosphere is used for summer melt and a small amount goes into heating the near surface ice layers. Similar investigations were performed at the tongue of the glacier (170masl) for a shorter period. Here the conditions are characterized by enhanced input from the atmospheric fluxes and correspondingly increased melt rates. In addition, accumulation is usually small (>50 cm snow) and melt can also occur during winter. We then investigate whether spatially distributed mass balance can be simulated using data measured outside of the glacier. Regression models were developed to derive model input from climate data measured at a nearby research station. These models are

  12. Photographic Snow-cover Monitoring on St Sorlin Glacier, France.

    Gerbaux, M.; Genthon, C.; Dedieu, J.; Balestrieri, J.


    Like most other glaciers in the Alps, the St Sorlin glacier (french Alps, 45.16°N, 6.16°E, 2900 m asl mean elevation and 3km2 of surface area) has been retreating fast in the last 20 years. To understand the meteorological factors responsible for this retreat, and to tentatively predict glaciers evolution in a changing (warming) climate, we use a distributed snow/ice mass and energy balance model derived from the CROCUS snow model (Météo-France). There is no direct meteorological observation on or near St Sorlin glacier yet, and hourly meteorology to force the snow/ice model is obtained from disaggregated meteorological analyses. The model is found to reproduce the St Sorlin mass balance of the last 20 years as obtained from field glaciological measurements and stereophotographic reconstructions. The model is also found to reproduce the interannual variations of the equilibrium line as determined from optical satellite imagery. Because of the albedo feedback involved, it is also important to verify that the summer snow/ice transition on the glacier is correctly simulated. Thus, an automated photographic system was set up facing St Sorlin glacier to monitor the evolution of the snow cover. The system was installed on the 13th of July 2004 and is still in operation at time of abstract writing. Digital photographies are taken every 4 hours, permitting so far at least one non-obstructed (rain, fog) picture per day. The first pictures in the series show an almost fully snow-covered glacier while the latest ones show bare ice up to the highest parts of the glacier. Snow is occasionally deposited during precipitation events but hardly last more than 3 days. Snow line position is deduced from pictures using a DEM with georeferenced points visible on pictures. It should then be compared with the modelled one. The automated photographic system provides not only snow cover to check snow/ice model results at seasonal time-scales, but also qualitative meteorological

  13. The Frozen Ground Data Center: New Data for the International Permafrost Community

    Parsons, M. A.; Zhang, T.


    Permafrost and seasonally frozen ground regions occupy about 24 percent and 60 percent, respectively, of the exposed land surface in the Northern Hemisphere. Data and information on frozen ground collected over many decades and in the future are critical for fundamental process understanding, environmental change detection and impact assessment, model validation, and engineering application in seasonal frost and permafrost regions. However, many of these data sets and information remain widely dispersed and relatively unavailable to the national and international science and engineering community, and some are in danger of being lost permanently. The International Permafrost Association (IPA) has long recognized the inherent and lasting value of data and information and has worked to prioritize and assess permafrost data requirements and to identify critical data sets for scientific and engineering purposes. At the Seventh International Conference on Permafrost in 1998 in Yellowknife, Canada, the first Circumpolar Active-Layer Permafrost System (CAPS) CD-ROM was published and delivered to the Conference delegates. To continue the IPA strategy for data and information management and to meet the requirements by cold regions science, engineering, and modeling community, the World Data Center (WDC) for Glaciology, Boulder in collaboration with the International Arctic Research Center (IARC) has initiated a new Frozen Ground Data Center (FGDC) as a key node in the IPA's Global Geocryological Data (GGD) system. The FGDC has expanded access to the 1998 CAPS data, is expanding data holdings, and is creating a new version of the CD to be distributed at the July 2003 IPA conference in Zurich. The FGDC has improved access to existing data through an online search and order system and availability in the Global Change Master Directory. The FGDC has also expanded and updated current holdings with global and regional permafrost, soil temperature, and soil classification maps in

  14. Global Cryosphere Watch: A New WMO Initiative

    Goodison, B.; Ryabinin, V.; Asrar, G.; Yang, D.


    Legacy of the IPY 2007-2008 will take many forms, and one key legacy for the cryosphere is the development of a WMO Global Cryosphere Watch (GCW), a proposal welcomed by the 15th WMO Congress (May 2007). GCW involves research, monitoring, assessment, product development and prediction. It will cover all aspects of the cryosphere. GCW would contribute to WMO's integrated observing and information systems and the GCOS (Global Climate Observing System), like the Global Atmosphere Watch does. It will be an intergovernmental mechanism for supporting key cryospheric in situ and remote sensing observations implementing the recommendations of the IGOS Cryosphere Theme. GCW will provide reliable, comprehensive observations of the elements of the cryosphere through an integrated observing approach on global and regional scales, in collaboration with other international programmes and agencies. It will work with, and build on existing programs, such as the GTN-G and GTN-P (Global Terrestrial Networks for Glaciers / for Permafrost) and work with external partners such as space agencies and World Data Centers for Glaciology. GCW can provide an integrating mechanism required to ensure better quality data and metadata, comparison of algorithms, the means to provide the scientific community to predict the future state of the cryosphere, facilitate assessment of changes in the cryosphere and their impact, and use this information to aid the detection of climate change, and organize assessments of changes in regional and global components of the cryosphere to support decision making and policy development. GCW is envisioned to include "cold GAW-like stations" - key stations/sites working on a coherently agreed program on monitoring of changes in all components of the cryosphere, producing valuable long- term records, covering key areas of the globe with cryospheric observations. It will help existing elements function better and contribute to a global system, and will help IPY

  15. Glaciers in a changing global climate: first results of worldwide glacier mass balance measurements 2000/2001

    Frauenfelder, R.; Hoelzle, M.; Haeberli, W.


    Glacier signals from mountain areas are key elements of early detection strategies for dealing with possible man-induced climate change. The IPCC Third Assessment Report indeed defines mountain glaciers as one of the best natural indicators of atmospheric warming with the highest reliability ranking. In the chain of processes linking climate and glacier fluctuations, glacier length variation is the indirect/delayed response, whereas glacier mass change is the direct/undelayed reaction. Internationally coordinated long-term monitoring of glaciers started in 1894. The responsibility to collect and publish standardized data has been assumed since 1986 by the World Glacier Monitoring Service (WGMS). This work is primarily being carried out under the auspices of the International Commission on Snow and Ice (ICSI/IAHS) and the Federation of Astronomical and Geophysical Services (FAGS/ICSU). The WGMS maintains data exchange with the ICSU World Data Center A (WDC-A) for Glaciology in Boulder, Colorado. Corresponding data bases and measurement networks form an essential part of the Global Terrestrial Network for Glaciers (GTN-G: operated by the WGMS) as a pilot project within the Global Terrestrial Observing System (GTOS/GCOS). A network of 60 glacier mass balance observations provides information on presently observed rates of change in glacier mass, corresponding acceleration trends and regional distribution patterns. A preliminary calculation of the mass balance observations in 2000/2001 relating to 23 selected data sets provide a mean specific (annual) net balance of -367 mm w.e., 26 % of the observed balances were positive. The corresponding mean in six mountain ranges was -571 mm w.e. Such values indicate that mass losses in 2000/2001 have been less extreme than in the extraordinary years before but are still strongly negative. Over the past two decades glacier melt appears to continue at a considerable and possibly even an accelerating rate. The observed average

  16. Frozen Ground Data Center at NSIDC: New Data and Improved Access

    Yohe, E.; Sheffield, E.; Parsons, M.; Zhang, T.; Barry, R. G.


    Permafrost and seasonally frozen ground regions occupy about 24% and 60%, respectively, of the exposed land surface in the Northern Hemisphere. Frozen ground data and information are critical for understanding fundamental cold regions processes, detecting environmental change, assessing climate impacts, validating models, and for engineering applications. However, much of the information collected over past decades, and currently being collected, remains widely dispersed and unavailable to the science, engineering, and modeling communities. To meet the requirements of these users for data and information management, the International Permafrost Association (IPA) developed the Global Geocryological Data (GGD) system, an internationally distributed system linking investigators and data centers around the world. The World Data Center (WDC) for Glaciology at Boulder and the National Snow and Ice Data Center (NSIDC), in collaboration with the International Arctic Research Center (IARC), have established the Frozen Ground Data Center (FGDC) as a central node of the GGD. The FGDC identifies, archives, documents, and distributes data related to permafrost and seasonally frozen ground. The FGDC currently holds over 100 data sets and information products and contains detailed metadata records describing over 100 additional data sets available at other GGD nodes around the world. The data center has improved access to these data through an online search and order system and availability in the Global Change Master Directory. The FGDC's holdings include summary data, metadata, and maps describing the Circumpolar Active Layer Monitoring (CALM) program sites, and comprehensive metadata describing the IPA's Global Terrestrial Network for Permafrost (GTN-P) boreholes. The FGDC also holds site metadata and photos from the Arctic Coastal Dynamics (ACD) program, as well as products of the Permafrost and Climate in Europe (PACE) program, and the IPA's Southern Hemisphere Working Group

  17. Geodetic Imaging of Glacio-Seismotectonic Processes in Southern Alaska

    Sauber, J.; Bruhn, R.; Forster, R.; Hofton, M.


    velocities and SAR images to infer the large scale sub-ice structures that form the structural framework of the Seward-Bagley Basins. The new lidar, InSAR, and STEEP results provide constraints that enable us to critically re-evaluate alternate models of the nature of tectonics and structures hidden beneath the ice originally proposed by Ford et al [2003] . Ford, A.L., R.R. Forster, and R.L. Bruhn, 2003, Ice surface velocity patterns on Seward Glacier, Alaska/Yukon, and their implications for regional tectonics in the Saint Elias Mountains, Annals of Glaciology, 36, 21-28.

  18. Dartmouth College Earth Sciences Mobile Field Program

    Meyer, E. E.; Osterberg, E. C.; Dade, W. B.; Sonder, L. J.; Renshaw, C. E.; Kelly, M. A.; Hawley, R. L.; Chipman, J. W.; Mikucki, J.; Posmentier, E. S.; Moore, J. R.


    For the last 50 years the Department of Earth Sciences at Dartmouth College has offered a term-long, undergraduate field program, informally called "the Stretch". A student typically enrolls during fall quarter of his or her junior year soon after choosing a major or minor. The program thus provides valuable field context for courses that a student will take during the remainder of his or her undergraduate career. Unlike many traditional field camps that focus on one particular region, the Stretch is a mobile program that currently travels through Western North America, from the Canadian Rockies to the Grand Canyon. The program spans two and a half months, during which time undergraduates, graduate TAs, and faculty live, work, and learn collaboratively. Dartmouth College faculty members sequentially teach individual 1- to 2-week segments that focus on their interests and expertise; currently, there are a total of eight segments led by eleven faculty members. Consequently, topics are diverse and include economic geology, geobiology, geomorphology, glaciology, glacial geology, geophysics, hydrogeology, paleontology, stratigraphy, structure and tectonics, and volcanology. The field localities are equally varied, including the alpine glaciers of western Alberta, the national parks of Montana, Wyoming and Utah, the eastern Sierra Nevada, the southern Great Basin, and highlight such classic geological field locales as Sheep Mountain in Wyoming's Bighorn Basin, Death Valley, and the Grand Canyon. Overall, the program aims to: 1) give students a broad perspective on the timing and nature of the processes that resulted in the landscape and underlying geology of western North America; and 2) introduce students to a wide variety of geological environments, field techniques, and research equipment. Students emerge from the program with wide-ranging exposure to active research questions as well as a working knowledge of core field skills in the earth sciences. Stretch students

  19. Quantarctica: A Unique, Open, Standalone GIS Package for Antarctic Research and Education

    Roth, George; Matsuoka, Kenichi; Skoglund, Anders; Melvær, Yngve; Tronstad, Stein


    The Norwegian Polar Institute has developed Quantarctica (, an open GIS package for use by the international Antarctic community. Quantarctica includes a wide range of cartographic basemap layers, geophysical and glaciological datasets, and satellite imagery in standardized open file formats with a consistent Antarctic map projection and customized layer and labeling styles for quick, effective cartography. Quantarctica's strengths as an open science platform lie in 1) The complete, ready-to-use data package which includes full-resolution, original-quality vector and raster data, 2) A policy for freely-redistributable and modifiable data including all metadata and citations, and 3) QGIS, a free, full-featured, modular, offline-capable open-source GIS suite with a rapid and active development and support community. The Quantarctica team is actively incorporating more up-to-date, peer-reviewed, freely distributable pan-Antarctic geospatial datasets for the next version release in 2017. As part of this ongoing development, we are investigating the best approaches for quickly and seamlessly distributing new and updated data to users, storing datasets in efficient, open file formats while maintaining full data integrity, and coexisting with numerous online data portals in a way that most actively benefits the Antarctic community. A recent survey of Quantarctica users showed broad geographical adoption among Antarctic Treaty countries, including those outside the large US and UK Antarctic programs. Maps and figures produced by Quantarctica have also appeared in open-access journals and outside of the formal scientific community on popular science and GIS blogs. Our experience with the Quantarctica project has shown the tremendous value of education and outreach, not only in promoting open software, data formats, and practices, but in empowering Antarctic science groups to more effectively use GIS and geospatial data. Open practices are

  20. State of the Earth’s cryosphere at the beginning of the 21st century : glaciers, global snow cover, floating ice, and permafrost and periglacial environments: Chapter A in Satellite image atlas of glaciers of the world

    Williams, Richard S.; Ferrigno, Jane G.; Williams, Richard S., Jr.; Ferrigno, Jane G.


    This chapter is the tenth in a series of 11 book-length chapters, collectively referred to as “this volume,” in the series U.S. Geological Survey Professional Paper 1386, Satellite Image Atlas of Glaciers of the World. In the other 10 chapters, each of which concerns a specific glacierized region of Earth, the authors used remotely sensed images, primarily from the Landsat 1, 2, and 3 series of spacecraft, in order to analyze that glacierized region and to monitor changes in its glaciers. Landsat images, acquired primarily during the period 1972 through 1981, were used by an international team of glaciologists and other scientists to study the various glacierized regions and (or) to discuss related glaciological topics. In each glacierized region, the present distribution of glaciers within its geographic area is compared, wherever possible, with historical information about their past areal extent. The atlas provides an accurate regional inventory of the areal extent of glacier ice on our planet during the 1970s as part of an expanding international scientific effort to measure global environmental change on the Earth’s surface. However, this chapter differs from the other 10 in its discussion of observed changes in all four elements of the Earth’s cryosphere (glaciers, snow cover, floating ice, and permafrost) in the context of documented changes in all components of the Earth System. Human impact on the planet at the beginning of the 21st century is pervasive. The focus of Chapter A is on changes in the cryosphere and the importance of long-term monitoring by a variety of sensors carried on Earth-orbiting satellites or by a ground-based network of observatories in the case of permafrost. The chapter consists of five parts. The first part provides an introduction to the Earth System, including the interrelationships of the geosphere (cryosphere, hydrosphere, lithosphere, and atmosphere), the biosphere, climate processes, biogeochemical cycles, and the

  1. The Greenland Analogue Project (GAP). Literature review of hydrogeology/ hydrogeochemistry

    Wallroth, Thomas; Lokrantz, Hanna; Rimsa, Andrius (Bergab Consulting Geologists, Goeteborg (Sweden))


    This report is produced as part of the Greenland Analogue Project (GAP), carried out as a collaboration project with the Canadian Nuclear Waste Management Organization (NWMO), Posiva Oy and the Swedish Nuclear Fuel and Waste Management Co (SKB). The overall aim of the project is to improve the current understanding of hydrogeological and hydrogeochemical processes associated with continental-scale glacial periods including with the presence of permafrost and the advance/retreat of ice sheets. The project will focus on studying how an ice sheet affects groundwater flow and water chemistry around a deep geological repository in crystalline bedrock. The Greenland Analogue Project consists of three active sub-projects (A-C) with individual objectives. Field studies are conducted in the Kangerlussuaq region, in central Western Greenland. Sub-projects A and B collectively aim at improving the understanding of ice sheet hydrology by combining investigations on surface water processes with ice sheet drilling and instrumentation. In sub-project C, the penetration of glacial melt water into the bedrock, groundwater flow and the chemical composition of water will be studied. Main planned activities in sub-project C include drilling of a deep borehole in front of the ice sheet, in which different downhole surveys, sampling and monitoring will be carried out. The primary aim of this report is to review available information about hydrogeology and hydrogeochemistry in central Western Greenland, with special emphasis on the area around Kangerlussuaq. The relevant information about this area is however very limited, and it was decided to extend the review to briefly include studies made in other regions with similar conditions in terms of geology, climate and glaciology. The number of published studies made in other areas with glaciers, ice sheets or permafrost is very large, and the review and list of references in this report is far from complete. It is also obvious that both

  2. Proceedings of the Fourth Glacier Bay Science Symposium

    Piatt, John F.; Gende, Scott M.


    Foreword Glacier Bay was established as a National Monument in 1925, in part to protect its unique character and natural beauty, but also to create a natural laboratory to examine evolution of the glacial landscape. Today, Glacier Bay National Park and Preserve is still a place of profound natural beauty and dynamic landscapes. It also remains a focal point for scientific research and includes continuing observations begun decades ago of glacial processes and terrestrial ecosystems. In recent years, research has focused on glacial-marine interactions and ecosystem processes that occur below the surface of the bay. In October 2004, Glacier Bay National Park convened the fourth in a series of science symposiums to provide an opportunity for researchers, managers, interpreters, educators, students and the general public to share knowledge about Glacier Bay. The Fourth Glacier Bay Science Symposium was held in Juneau, Alaska, rather than at the Park, reflecting a desire to maximize attendance and communication among a growing and diverse number of stakeholders interested in science in the park. More than 400 people attended the symposium. Participants provided 46 oral presentations and 41 posters covering a wide array of disciplines including geology, glaciology, oceanography, wildlife and fisheries biology, terrestrial and marine ecology, socio-cultural research and management issues. A panel discussion focused on the importance of connectivity in Glacier Bay research, and keynote speakers (Gary Davis and Terry Chapin) spoke of long-term monitoring and ecological processes. These proceedings include 56 papers from the symposium. A summary of the Glacier Bay Science Plan-itself a subject of a meeting during the symposium and the result of ongoing discussions between scientists and resource managers-also is provided. We hope these proceedings illustrate the diversity of completed and ongoing scientific studies, conducted within the Park. To this end, we invited all

  3. Mass balance and hydrological contribution of glaciers in northern and central Chile

    MacDonell, Shelley; Vivero, Sebastian; McPhee, James; Ayala, Alvaro; Pellicciotti, Francesca; Campos, Cristian; Caro, Dennys; Ponce, Rodrigo


    Water is a critical resource in the northern and central regions of Chile, as the area supports more than 40% of the country's population, and the regional economy depends on agricultural production and mining, which are two industries that rely heavily on a consistent water supply. Due to relatively low rates of rainfall, meltwater from snow and ice bodies in the highland areas provides a key component of the annual water supply in these areas. Consequently, accurate estimates of the rates of ablation of the cryosphere (i.e. snow and ice) are crucial for predicting current supply rates, and future projections. Whilst snow is generally a larger contributor of freshwater, during periods of drought, glaciers provide a significant source. This study aims to determine the contribution of glaciers to two catchments in northern and central Chile during a 2.5 year period, which largely consisted of extreme dry periods, but also included the recent El Niño event. This study combined field and modelling studies to understand glacier and rock glacier contributions in the Tapado (30°S), Yeso (33°S) catchments. In the field we undertook glaciological mass balance monitoring of three glaciers, monitored albedo and snow line changes using automatic cameras for three glaciers, measured discharge continuously at several points, installed six automatic weather stations and used thermistors to monitor thermal regime changes of two rock glaciers. The combination of these datasets where used to drive energy balance and hydrological models to estimate the contribution of ice bodies to streamflow in the two studied catchments. Over the course of the study all glaciers maintained a negative mass balance, however glaciers in central Chile lost more mass, which is due to the higher melt rates experienced due to lower elevations and higher temperatures. Areas free of debris generally contributed more to streamflow than sediment covered regions, and snow generally contributed more over

  4. Impact of sublimation losses in the mass balance of glaciers in semi-arid mountain regions

    Ayala, Alvaro; Pellicciotti, Francesca; Burlando, Paolo; MacDonell, Shelley; McPhee, James


    restricted to wind-exposed sites above 5000 m. Our results help to understand and identify the mechanisms that control the glacier mass balance in this region and provide a base line for glaciological and hydrological future simulations.

  5. Recent Increases in Snow Accumulation and Decreases in Sea-Ice Concentration Recorded in a Coastal NW Greenland Ice Core

    Osterberg, E. C.; Thompson, J. T.; Wong, G. J.; Hawley, R. L.; Kelly, M. A.; Lutz, E.; Howley, J.; Ferris, D. G.


    A significant rise in summer temperatures over the past several decades has led to widespread retreat of the Greenland Ice Sheet (GIS) margin and surrounding sea ice. Recent observations from geodetic stations and GRACE show that ice mass loss progressed from South Greenland up to Northwest Greenland by 2005 (Khan et al., 2010). Observations from meteorological stations at the U.S. Thule Air Force Base, remote sensing platforms, and climate reanalyses indicate a 3.5C mean annual warming in the Thule region and a 44% decrease in summer (JJAS) sea-ice concentrations in Baffin Bay from 1980-2010. Mean annual precipitation near Thule increased by 12% over this interval, with the majority of the increase occurring in fall (SON). To improve projections of future ice loss and sea-level rise in a warming climate, we are currently developing multi-proxy records (lake sediment cores, ice cores, glacial geologic data, glaciological models) of Holocene climate variability and cryospheric response in NW Greenland, with a focus on past warm periods. As part of our efforts to develop a millennial-length ice core paleoclimate record from the Thule region, we collected and analyzed snow pit samples and short firn cores (up to 20 m) from the coastal region of the GIS (2Barrel site; 76.9317 N, 63.1467 W) and the summit of North Ice Cap (76.938 N, 67.671 W) in 2011 and 2012, respectively. The 2Barrel ice core was sampled using a continuous ice core melting system at Dartmouth, and subsequently analyzed for major anion and trace element concentrations and stable water isotope ratios. Here we show that the 2Barrel ice core spanning 1990-2010 records a 25% increase in mean annual snow accumulation, and is positively correlated (r = 0.52, p<0.01) with ERA-Interim precipitation. The 2Barrel annual sea-salt Na concentration is strongly correlated (r = 0.5-0.8, p<0.05) with summer and fall sea-ice concentrations in northern Baffin Bay near Thule (Figure 1). We hypothesize that the positive

  6. Premonsoon Aerosol Characterization and Radiative Effects Over the Indo-Gangetic Plains: Implications for Regional Climate Warming

    Gautam, Ritesh; Hsu, N. Christina; Lau, K.-M.


    /decade) and underscores the potential role of enhanced aerosol solar absorption in the maximum warming localized over the western Himalayas (0.26 C/decade f 0.09 C/decade) that significantly exceed the entire HKHT and global warming rates. We believe the accelerated warming rates reported here are critical to both the South Asian summer monsoon and hydro-glaciological resource variability in the Himalayan-Hindu Kush snowpack and therefore to the densely populated downstream regions.

  7. Elevation and mass change of the Echaurren Norte Glacier (Central Andes, Chile) from 1955 to 2015.

    Farías, David; Vivero, Sebastián; Casassa, Gino; Seehaus, Thorsten; Braun, Matthias H.


    The Echaurren Norte Glacier (33°34'S 70°07'W) is a small mountain glacier located at the upper Maipo basin, approximately 80 km to Santiago de Chile. The glacier has the longest surface mass balance record in South America (1975 to 2016). The measurements are carried out by DGA (water directory of Chile) using the direct glaciological method. The surface mass balance show continuous negative values, but exceptional positive mass balances were identified during ENSO periods. The aim of our study is complement the in-situ observations on Echaurren Norte Glacier with the geodetic mass balance measurements for the period 1955 to 2015. Our database comprises digital elevation models (DEM) from historical cartography based on aerial photographs (1955), SRTM (2000) and Lidar data. In addition, we mapped changes in glacier extent using aerial photography and multi-mission satellite data. TanDEM-X (2012-2015) and SRTM data will be used to investigate surrounding glaciers that have not such extensive and detailed coverage as Echaurren Norte Glacier. The aerial photographs from 1955 were scanned from the original negative using a photogrammetric scanner and processed on a digital photogrammetric workstation (DPW) and georeferenced with the aid of GCPs derived from the Lidar dataset. The TanDEM-X data was processed using differential interferometry using SRTM C-band DEM as reference. Differences resulting from X- and C-band penetration are considered comparing X- and C-band SRTM data. All DEMs were laterally and vertically co-registered to each other. Error assessment was done over stable ground. Our preliminary results indicate an elevation change of -42.2 m ± 4 m (1955-2015) for Echaurren Norte Glacier. The estimated averaged annual mass balance is -0.59 m water equivalent for the period 1955-2015 using a density of 0.85 kg/cm3 for volume to mass conversion. Significant changes of the surface cover were identified, with a considerable increase of the debris cover, in

  8. A new 100-m Digital Elevation Model of the Antarctic Peninsula derived from ASTER Global DEM: methods and accuracy assessment

    A. J. Cook


    Full Text Available A high resolution surface topography Digital Elevation Model (DEM is required to underpin studies of the complex glacier system on the Antarctic Peninsula. A complete DEM with better than 200 m pixel size and high positional and vertical accuracy would enable mapping of all significant glacial basins and provide a dataset for glacier morphology analyses. No currently available DEM meets these specifications. We present a new 100-m DEM of the Antarctic Peninsula (63–70° S, based on ASTER Global Digital Elevation Model (GDEM data. The raw GDEM products are of high-quality on the rugged terrain and coastal-regions of the Antarctic Peninsula and have good geospatial accuracy, but they also contain large errors on ice-covered terrain and we seek to minimise these artefacts. Conventional data correction techniques do not work so we have developed a method that significantly improves the dataset, smoothing the erroneous regions and hence creating a DEM with a pixel size of 100 m that will be suitable for many glaciological applications. We evaluate the new DEM using ICESat-derived elevations, and perform horizontal and vertical accuracy assessments based on GPS positions, SPOT-5 DEMs and the Landsat Image Mosaic of Antarctica (LIMA imagery. The new DEM has a mean elevation difference of −4 m (± 25 m RMSE from ICESat (compared to −13 m mean and ±97 m RMSE for the original ASTER GDEM, and a horizontal error of less than 2 pixels, although elevation accuracies are lower on mountain peaks and steep-sided slopes. The correction method significantly reduces errors on low relief slopes and therefore the DEM can be regarded as suitable for topographical studies such as measuring the geometry and ice flow properties of glaciers on the Antarctic Peninsula. The DEM is available for download from the NSIDC website: (GTN-G, WGI, RGI, DCW, GLIMS, WGMS, GCOS - What's all this about? (Invited)

    Paul, F.; Raup, B. H.; Zemp, M.


    In a large collaborative effort, the glaciological community has compiled a new and spa-tially complete global dataset of glacier outlines, the so-called Randolph Glacier Inventory or RGI. Despite its regional shortcomings in quality (e.g. in regard to geolocation, gener-alization, and interpretation), this dataset was heavily used for global-scale modelling ap-plications (e.g. determination of total glacier volume and glacier contribution to sea-level rise) in support of the forthcoming 5th Assessment Report (AR5) of Working Group I of the IPCC. The RGI is a merged dataset that is largely based on the GLIMS database and several new datasets provided by the community (both are mostly derived from satellite data), as well as the Digital Chart of the World (DCW) and glacier attribute information (location, size) from the World Glacier Inventory (WGI). There are now two key tasks to be performed, (1) improving the quality of the RGI in all regions where the outlines do not met the quality required for local scale applications, and (2) integrating the RGI in the GLIMS glacier database to improve its spatial completeness. While (1) requires again a huge effort but is already ongoing, (2) is mainly a technical issue that is nearly solved. Apart from this technical dimension, there is also a more political or structural one. While GLIMS is responsible for the remote sensing and glacier inventory part (Tier 5) of the Global Terrestrial Network for Glaciers (GTN-G) within the Global Climate Observing System (GCOS), the World Glacier Monitoring Service (WGMS) is collecting and dis-seminating the field observations. Along with new global products derived from satellite data (e.g. elevation changes and velocity fields) and the community wish to keep a snap-shot dataset such as the RGI available, how to make all these datasets available to the community without duplicating efforts and making best use of the very limited financial resources available must now be discussed. This

  9. Thicknesses and volumes of glaciers in the Andes of Peru estimated with satellite data and digital terrain information

    Torres, Judith; Colonia, Daniel; Haeberli, Wilfried; Giráldez, Claudia; Frey, Holger; Huggel, Christian


    The glaciers in the tropical Andes of Peru have been melting at an unprecedented rate in recent years and generally after the Little Ice Age, a cold period that lasted from the 16th to the 19th century. Knowledge of glacier thicknesses and volumes is necessary for evaluating possible future scenarios of glacier shrinkage and of water supply to the Andean populations under conditions of continued warming. Calculation of glacier volumes for 19 mountain ranges in Perú has been based on two ice- thickness modeling methods including an area-related approach with different parameterizations and a slope-dependent approach. Both methods allow for rapid treatment of regional data obtained from satellite imagery and a Digital Elevation Model, integrated into a Geographic Information System. In addition, glacier outlines were obtained from the glacier inventory compiled by the Unit of Glaciology and Water Resources (UGRH) - National Water Authority (ANA) that used satellite imagery (ASTER, SPOT and LISS III from 2003 to 2010) and topographic information acquired from the cartography of the National Geographical Institute (IGN). The volume-area scaling approach resulted in glacier volume of 35.00 km3 and a total volume of 34.39 km3 resulted from the slope-dependent thickness with a thickness approximately 30 m. Estimated results also show a loss of the total ice surface ~42% and glacier volume loss about ~38% in both methods based on the first Glacier Inventory of Peru (from aerial photographs 1962 -1970) performed by HIDRANDINA SA. The results also indicate that volume estimations are subject to large uncertainties. Field measurements of glacier thickness are scarce and locally restricted due to rugged topography, high altitude and heavy crevassing of glaciers. Possibilities of calibrating and validating the applied model approaches are therefore limited. New possibilities nevertheless come into play with slope-dependent approaches, which lead beyond area-related average

  10. Generation of Digital Surface Models from satellite photogrammetry: the DSM-OPT service of the ESA Geohazards Exploitation Platform (GEP)

    Stumpf, André; Michéa, David; Malet, Jean-Philippe


    The continuously increasing fleet of agile stereo-capable very-high resolution (VHR) optical satellites has facilitated the acquisition of multi-view images of the earth surface. Theoretical revisit times have been reduced to less than one day and the highest spatial resolution which is commercially available amounts now to 30 cm/pixel. Digital Surface Models (DSM) and point clouds computed from such satellite stereo-acquisitions can provide valuable input for studies in geomorphology, tectonics, glaciology, hydrology and urban remote sensing The photogrammetric processing, however, still requires significant expertise, computational resources and costly commercial software. To enable a large Earth Science community (researcher and end-users) to process easily and rapidly VHR multi-view images, the work targets the implementation of a fully automatic satellite-photogrammetry pipeline (i.e DSM-OPT) on the ESA Geohazards Exploitation Platform (GEP). The implemented pipeline is based on the open-source photogrammetry library MicMac [1] and is designed for distributed processing on a cloud-based infrastructure. The service can be employed in pre-defined processing modes (i.e. urban, plain, hilly, and mountainous environments) or in an advanced processing mode (i.e. in which expert-users have the possibility to adapt the processing parameters to their specific applications). Four representative use cases are presented to illustrate the accuracy of the resulting surface models and ortho-images as well as the overall processing time. These use cases consisted of the construction of surface models from series of Pléiades images for four applications: urban analysis (Strasbourg, France), landslide detection in mountainous environments (South French Alps), co-seismic deformation in mountain environments (Central Italy earthquake sequence of 2016) and fault recognition for paleo-tectonic analysis (North-East India). Comparisons of the satellite-derived topography to airborne

  11. Nye Lecture: Water Under Ice: Curiosities, Complexities, and Catastrophes

    Clarke, G. K.


    Meltwater beneath glaciers and ice sheets activates some of the most curious and impressive phenomena known to glaciology. These range from the generation of miniscule electrokinetic currents by water flow through subglacial sediment to massive outburst floods that rearrange landscapes and deliver freshwater pulses to the ocean. The source of this water varies but is some mix of surface water and water melted from the glacier base by geothermal and frictional heating. The outflow of subglacial water is somewhat affected by bed topography but the dominant influence is from gradients in ice overburden pressure and thus from the surface topography of the ice sheet. Upslope water flow is possible and large adverse bed slopes are required before topographic water traps can exist. As a consequence, subglacial topographic basins tend to be leaky and less than 5% of the area of the contemporary Antarctic Ice Sheet provides suitable habitat for subglacial lakes. Following a variety of subglacial pathways, water can migrate toward the ice margins, either as a liquid or as refrozen meltwater accreted to the ice base. The morphology of the subglacial water system is thought to comprise a combination of sheet-like, channel-like, and vein-like elements, all of which lend themselves to mathematical representation. Water transport processes need not operate in a steady fashion and morphological switching between sheet-like and channel-like endmembers is linked to spectacular events such as glacier surges and outburst floods. Large outbursts of proglacially or subglacially-stored meltwater, the classic Icelandic j{ö}kulhaups, continue to occur in glaciated regions of the world and much larger floods were released during the Late Pleistocene--Early Holocene deglaciation of the Northern Hemisphere. Whether large subglacial lakes like Lake Vostok, Earth's seventh largest lake, have similar potential for delivering cataclysmic floods remains uncertain. The recent detection of a small

  12. MACS-Himalaya: A photogrammetric aerial oblique camera system designed for highly accurate 3D-reconstruction and monitoring in steep terrain and under extreme illumination conditions

    Brauchle, Joerg; Berger, Ralf; Hein, Daniel; Bucher, Tilman


    aerial imagery. These data are used in the fields of natural hazards, geomorphology and glaciology (see Thompson et al., CR4.3). In the presentation the camera system is introduced and examples and applications from the Nepal campaign are given.

  13. FOSREM - Fibre-Optic System for Rotational Events&Phenomena Monitoring

    Jaroszewicz, Leszek; Krajewski, Zbigniew; Kurzych, Anna; Kowalski, Jerzy; Teisseyre, Krzysztof


    their vicinity. In geodetic, geomorphological and glaciological survey, joint measurement of tilt and seismic phenomena using a set of three FOSREM devices oriented in perpendicular planes would enable to collect very important information.

  14. High altitude environmental monitoring: the SHARE project and CEOP-HE

    Tartari, G.


    Mountain areas above 2,500 m a.s.l. constitute about 25% of the Earth's surface and play a fundamental role in the global water balance, while influencing global climate and atmospheric circulation systems. Several millions, including lowlanders, are directly affected by the impacts of climate change on glaciers and water resource distribution. Mountains and high altitude plateaus are subject to the highest rate of temperature increase (e.g., Tibetan Plateau) and are recognized as particularly vulnerable to the effects of climate change. In spite of this, the number of permanent monitoring sites in the major environmental networks decreases with altitude. On a sample of two hundred high altitude automatic weather stations located above 2,500 m a.s.l., less than 20% are over 4,000 m, while there are only 24 stations in the world that could be considered "complete" high altitude observatories. Furthermore, entire mountain areas are left uncovered, creating significant data gaps which make reliable modelling and forecasting nearly impossible. In response to these problems, Ev-K2-CNR has developed the project SHARE (Stations at High Altitude for Research on the Environment) with the support of the Italian government and in collaboration with UNEP. This integrated environmental monitoring and research project aims to improve knowledge on the local, regional and global consequences of climate change in mountain regions and on the influence of high elevations on climate, atmospheric circulation and hydrology. SHARE today boasts a network of 13 permanent monitoring stations between 2,165 m and 8,000 m. Affiliated researchers have produced over 150 scientific publications in atmospheric sciences, meteorology and climate, glaciology, limnology and paleolimnology and geophysics. SHARE network data is also contributed to international programs (UNEP-ABC, WMO-GAW, WCRP-GEWEX-CEOP, NASA-AERONET, ILTER, EU-EUSAAR, EU-ACCENT). Within this context, the CEOP-High Elevations (CEOP

  15. International Field School on Permafrost: Yenisei, Russian Federation - 2013

    Nyland, K. E.; Streletskiy, D. A.; Grebenets, V. I.


    's Department of Cryolithology and Glaciology. This course and others like it are extremely important to support and advertise to a wider audience of students studying the cryosphere because of its unique multidisciplinary nature and the hands-on experience it provides. However, this course not only provides students with an excellent field education, but also the opportunity to network and build strong relationships among their peers within the field. And hopefully these student friendships and working relationships built by this field school will continue and will foster future international research collaborations.

  16. The role of glaciers in stream flow from the Nepal Himalaya

    Alford, D.; Armstrong, R.


    Recent concerns related to the potential impacts of the retreat of Himalayan glaciers on the hydrology of rivers originating in the catchment basins of the Himalaya have been accompanied by few analyses describing the role of glaciers in the hydrologic regime of these mountains. This is, at least in part, a result of the relative inaccessibility of the glaciers of the Himalaya, at altitudes generally between 4000-7000 m, and the extreme logistical difficulties of: 1) reaching the glaciers, and 2) conducting meaningful research once they have been reached. It is apparent that an alternative to traditional "Alpine" glaciology is required in the mountains of the Hindu Kush-Himalaya region. The objectives of the study discussed here have been to develop methodologies that will begin to quantify the role of complete glacier systems in the hydrologic regime of the Nepal Himalaya, and to develop estimates of the potential impact of a continued retreat of these glacier, based on the use of disaggregated low-altitude data bases, topography derived from satellite imagery, and simple process models of water and energy exchange in mountain regions. While the extent of mesoscale variability has not been established by studies to date, it is clear that the dominant control on the hydrologic regime of the tributaries to the Ganges Basin from the eastern Himalaya is the interaction between the summer monsoon and the 8000 m of topographic relief represented by the Himalayan wall. All the available evidence indicates that the gradient of specific runoff with altitude resulting from this interaction is moderately to strongly curvilinear, with maximum runoff occurring at mid-altitudes, and minima at the altitudinal extremes. At the upper minimum of this gradient, Himalayan glaciers exist in what has been characterized as an "arctic desert". The methodologies developed for this study involve the relationship between area-altitude distributions of catchment basins and glaciers, based on

  17. The importance of strain localisation in shear zones

    Bons, Paul D.; Finch, Melanie; Gomez-Rivas, Enrique; Griera, Albert; Llorens, Maria-Gema; Steinbach, Florian; Weikusat, Ilka


    are, however, ephemeral and best seen in movies. In the final microstructure they are very difficult to discern. We present movies that show that in all cases the distribution of both strain rate and of finite strain is much more heterogeneous than the finite microstructure tends to show. Bons, P.D., et al. (2008) Lecture Notes in Earth Sciences, 106 Griera, A. et al. (2011) Geology, 39, 275-278 Griera, A., et al. (2013) Tectonophysics, 587, 4-29 Griera, A., et al. Geotectonic Research, 97, 37-39 Lebensohn, R.A. (2001) Acta Materialia, 49, 2723-2737 Llorens, M.G. (2015)) Numerical simulation of deformation microstructures and folds in polar ice and ductile rocks. PhD-thesis, Tübingen Univ. Llorens, M.G., et al. (in press) Journal of Glaciology

  18. A Cryosphere Monitoring Project in the Himalayas

    Stumm, D.; Mool, P. K.; Shresta, A. B.; Joshi, S. P.; Bajracharya, S. R.; Kayastha, R. B.; Devkota, L. P.; Bajracharya, O. R.


    time snow cover data for the entire Hindu Kush-Himalayas. The Cryosphere Knowledge Hub will be realised with a interactive web-based platform, regular bulletin board services and workshops to ensure knowledge sharing especially within the Hindu Kush-Himalayan region. Capacity building of Nepalese organisations is implemented by the setup of a MSc programme for Research in Glaciology at Kathmandu University for twenty students, which are trained together with staff from governmental organisations in field measurements, glacio-hydrological modelling and remote sensing techniques. The integrative approach of the project ensures a long-term and sustainable monitoring of the cryosphere on several strategic levels.

  19. Thermofluidodynamic modelling of the Adamello Glacier in a future climate scenario. Will the largest Italian glacier disappear by 2080?

    Ranzi, Roberto; Svanera, Eros; Baroni, Carlo; Barontini, Stefano; Caronna, Paolo; Grossi, Giovanna; Salvatore, Maria Cristina


    A thermofluidodynamic model was applied to the study case of the Adamello glacier (17,24 km2, after ASTER 2003 data), located in the Central Alps. The dynamic of the glacier was first simulated in the current climate conditions (1996-2007) and then using future climate projection resulting from the PCM A1b scenarios. Using the finite element code Elmer the dynamic equations were solved for the velocity field and the free surface elevation. The glacier was modelled with a 3D mesh composed by 28050 nodes and subdivided into 10 vertical layers. Elevation of the free surface and bedrock recorded in 1991 and in 1996 were used as boundary and initial conditions. For each simulated year a top surface temperature of -7.5 °C was considered for the winter semester in the ablation season the glacier's temperature was set to 0°C. During melting a fixed bottom velocity was applied to simulate the slip behaviour. As a Neumann boundary condition on the glacier's top surface the seasonal mass balance estimated from the energy-balance over the 1995-2009 period was assumed, with a mean value of -1.4 m/a. The reliability of the energy balance was verified with point measurement at ablation stakes over two ablation seasons, with runoff data and remote sensing. The maximum simulated surface velocities of the order of 100 m/a, a value consistent with observations of speed of some ablation stakes. In order to assess the validity of the results, the change in the thickness of the glacier observed between 1998 and 2007 (DEM difference) was compared to the simulated change in the free surface elevation. Another useful application of the modeling result is the identification of the ice divide of 5 glaciological units in the Sarca and Oglio subbasins, separated from a hydrological point of view, which is not a trivial task to be performed in the field. Another verification is done comparing the simulated glacier's extent in the year 2015 starting from 1996 initial conditions. The simulation

  1. Numerical experiments of dynamical processes during the 2011-2013 surge of the Bering-Bagley Glacier System, using a full-Stokes finite element model

    Trantow, Thomas

    current model. Documentation of the effects that altering glaciological parameters and boundary conditions have on ice rheology in a large complex glacial system comes as secondary result. Simulations have yet to reveal any quasi-cyclic behavior or natural surge initiation.

  2. Application of a 1-Dimensional Viscoelastic Bending Beam Model to the Buoyant Terminus of Lake-Calving Mendenhall Glacier, Southeast Alaska

    Boyce, E.; Motyka, R. J.; Bueler, E.


    less so for lake-calving glaciers. Reeh, N., E. L. Christensen, C. Mayer, O. B. Olesen, 2003. Tidal bending of glaciers: a linear viscoelastic approach. Annals of Glaciology 37(1), 83-89.

  3. Interior flow re-organization along the great Byrd-Totten ice divide of East Antarctica: evidence from radar layer disruptions

    Cavitte, M. G. P.; Blankenship, D. D.; Young, D. A.; Siegert, M. J.; Le Meur, E.; Chappellaz, J. A.


    Interior flow re-organization is an essential component in our understanding of the temporality and magnitude of sea-level variations, especially in non-marine portions of the East Antarctic ice sheet where most of the "sea-level rise potential" is stored. Internal structure in these regions can be evaluated using internal layers from radar sounding, which can be traced over hundreds of kilometers using airborne surveys. The exceptional acuity of phase-coherent radar surveys gives both vertical resolution and horizontal continuity to radar layers that makes them extremely useful for constraining glaciological models and contributing to ice core site selection as well as understanding transient ice sheet behavior. Specifically, when well dated, these ice layers can give us high resolution snapshots into temporal and spatial ice evolution including tributary penetration of ice divides. Present areas of tributary flow reaching into the interior are well constrained through remote sensing techniques, while evidence of such transient behavior in previous glacial cycles has long since been buried by subsequent accumulation. In these cases, radar imaging is the only technique useful for identifying buried episodes of transient ice flow as anomalous yet depth consistent layer disruptions. We focus on the great Byrd-Totten ice divide in the East Antarctic interior, between the Vostok and EPICA Dome C ice core sites, to identify periods of tributary encroachment. Several layers tracked between the two sites are used to correlate their chronologies and accurately date the horizons (M. Cavitte et al, in prep.). A strong advantage in using radar for the dating of these events is its negligible contribution to age uncertainties: radar uncertainties are of the order of hundreds of years, a factor of ten smaller than traditional ice core dating techniques. Combining the age-depth stratigraphy obtained for the area and visual identifications of tributary intrusions gives a

  4. Glacier outburst floods from Ghulkin Glacier, upper Hunza Valley, Pakistan

    Richardson, S. D.; Quincey, D. J.


    Outburst floods from Ghulkin Glacier in 2008 caused localised damage to properties, land and infrastructure of Ghulkin village and to the Karakoram Highway in the upper Hunza Valley of northern Pakistan. The unexpected nature of the floods highlights a poor understanding of glacial flood potential related to advancing glaciers in the Karakoram. Here we describe the Ghulkin floods and examine the broader glaciological controls on flood generation. Ghulkin Glacier is an active mountain glacier, its steep (up to 12˚ ), debris-covered snout bound by a continuous latero-terminal moraine. Three separate outburst floods during May and June 2008 exited the right lateral moraine close to the glacier terminus, resulting in two separate flood paths; one flowing down the existing outwash fan that resulted in no damage and the other flowing directly through properties and land of Ghulkin village. In 2008, the snout of Ghulkin Glacier was overriding its terminal moraine, and local villagers report an associated increase in debris flows and rock fall since 2005. High surface velocities (of the order of 50 m a-1) near the terminus are associated with the current period of advance, and an increase in the number and size of transient supraglacial lakes during the melt season has been observed. Assessment of the processes and characteristics of the summer 2008 floods provides a conceptual model for local glacier hazards associated with advancing mountain glaciers in the Karakoram. Crevasses and seracs associated with the high flow velocities have steep, debris-free ice cliffs that melt rapidly during the summer ablation season and provide a route for the meltwater to enter the englacial drainage system. Meltwater is stored temporarily in supraglacial, and probably englacial, settings; whilst drainage is facilitated by the formation of new, or re-organisation of existing, conduits under the active ice conditions. The steep glacier surface gradient and active ice results in

  5. GAMBIT--Gamburtsev Aerogeophysical Mapping of Bedrock and Ice Targets During IPY

    Studinger, M.; Finn, C. A.; Bell, R. E.; Gogineni, S.; Hayden, L.; Braaten, D.


    Antarctica is a key element in Earth's climatic and geodynamic systems, yet on the eve of the 50th anniversary of the International Geophysical Year, we lack fundamental geologic and geophysical data from the deep interior of this vast continent. Despite the central role that Antarctica has played in shaping the present global environment, fundamental, first-order parameters such as ice volume and stratigraphy, bedrock elevation, lithology, structure, age, and tectonic history remain poorly known over large portions of the continent, including the Gamburtsev Subglacial Mountains. Given the extensive ice cover, airborne geophysical data is the best and most cost-effective method to characterize broad areas of sub-ice basement and expand our knowledge of Antarctica. Under a program entitled, GAMBIT--Gamburtsev Aerogeophysical Mapping of Bedrock and Ice Targets, we propose to conduct airborne gravity, magnetic and radar surveys over the Gamburtsev Subglacial Mountains, a priority for geophysical and drilling studies by the solid Earth and glaciology communities for many years. This proposal will help develop long-range aerogeophysical capabilities and provide data to the Antarctic community within a year after collection to help answer fundamental science questions of global significance. By integrating these with international efforts during the IPY, we can maximize and broaden the use of all data sets. Specifically, we propose to image the East Antarctic ice sheet and bedrock with airborne geophysical surveys through the GAMBIT project in order to: 1) determine ice volume for mass balance calculations and identify internal layers reflecting the accumulation history of the East Antarctic ice sheet in the Gamburtsev Subglacial Mountains region; 2) characterize the gravity, magnetic, and elevation signatures of the East Antarctic crustal basement of the Gamburtsev Subglacial Mountains; 3) integrate these data with existing and new data collected during IPY over

  6. Ice sheet systems and sea level change.

    Rignot, E. J.


    Modern views of ice sheets provided by satellites, airborne surveys, in situ data and paleoclimate records while transformative of glaciology have not fundamentally changed concerns about ice sheet stability and collapse that emerged in the 1970's. Motivated by the desire to learn more about ice sheets using new technologies, we stumbled on an unexplored field of science and witnessed surprising changes before realizing that most were coming too fast, soon and large. Ice sheets are integrant part of the Earth system; they interact vigorously with the atmosphere and the oceans, yet most of this interaction is not part of current global climate models. Since we have never witnessed the collapse of a marine ice sheet, observations and exploration remain critical sentinels. At present, these observations suggest that Antarctica and Greenland have been launched into a path of multi-meter sea level rise caused by rapid climate warming. While the current loss of ice sheet mass to the ocean remains a trickle, every mm of sea level change will take centuries of climate reversal to get back, several major marine-terminating sectors have been pushed out of equilibrium, and ice shelves are irremediably being lost. As glaciers retreat from their salty, warm, oceanic margins, they will melt away and retreat slower, but concerns remain about sea level change from vastly marine-based sectors: 2-m sea level equivalent in Greenland and 23-m in Antarctica. Significant changes affect 2/4 marine-based sectors in Greenland - Jakobshavn Isb. and the northeast stream - with Petermann Gl. not far behind. Major changes have affected the Amundsen Sea sector of West Antarctica since the 1980s. Smaller yet significant changes affect the marine-based Wilkes Land sector of East Antarctica, a reminder that not all marine-based ice is in West Antarctica. Major advances in reducing uncertainties in sea level projections will require massive, interdisciplinary efforts that are not currently in place

  7. Hydroelastic analysis of ice shelves under long wave excitation

    Papathanasiou, Theodosios; Karperaki, Angeliki; Theotokoglou, Efstathios; Belibassakis, Kostas


    . References [1] Brunt K. M. et al., 'Antarctic ice shelf calving triggered by the Honsu (Japan) Earthquake and tsunami, March 2011', Journal of Glaciology, 57(205), 785-788, 2011. [2] Stoker J. J. Water Waves, the Mathematical Theory with Applications. Interscience Publishers, inc., New York, 1957. [3] Sturova I. V., 'Time-dependent response of a heterogeneous elastic plate floating on shallow water of variable depth', J. Fluid Mech., 637, 305-325, 2009. [4] Kienzler R., Herrmann G., 'An Elementary Theory of Defective Beams', Acta Mechanica, 62, 37-46, 1986.

  8. Modern Process Studies in Kongsfjord, Svalbard: Arctic Geoscience Research Experience for U.S. Undergraduates (Svalbard REU)

    Powell, R. D.; Brigham-Grette, J.


    The Svalbard REU (Research Experience for Undergraduates) program focuses on understanding how high latitude glaciers, meltwater streams, and sedimentation in lakes and fjords respond to changing climate. Since summer of 2004, six under-graduate students have been selected to participate in the summer field program. Students work on individual projects and in close conjunction with faculty advisors and other student researchers. They formulate their own research questions, develop their project, and complete their field research during a five-week program on Svalbard, Norway. Following the summer program, students complete their projects at their home institution during the following academic year as a senior thesis. A spring symposium brings all participants back together again with their final results. The most recent field season was completed in Kongsfjord (79N) showing that the contemporary studies of tidewater glacier margins provide an unparalleled opportunity for introducing motivated third year undergraduate students to the challenges and rewards of polar geoscientific field research. Rates of rapid change in this high-latitude Arctic environment emphasize the complexity of the Earth System at the interface of the ocean, atmosphere and cryosphere. Given background information in glacial and marine geology, glaciology, hydrology, climatology and fjord oceanography not routinely offered in undergraduate curricula, students develop the science questions to be addressed and establish a field plan for instrumentation and sampling. Working together in small boats in one of the most challenging natural environments, the students expand their leadership skills, learn the value of teamwork and collaborative data sharing while maintaining a strong sense of ownership over their individual science projects. The rigors of studying an actively calving tidewater glacier also builds on their outdoor skills, especially when it is necessary to improvise and become

  9. Uncertainty quantification of Antarctic contribution to sea-level rise using the fast Elementary Thermomechanical Ice Sheet (f.ETISh) model

    Bulthuis, Kevin; Arnst, Maarten; Pattyn, Frank; Favier, Lionel


    Uncertainties in sea-level rise projections are mostly due to uncertainties in Antarctic ice-sheet predictions (IPCC AR5 report, 2013), because key parameters related to the current state of the Antarctic ice sheet (e.g. sub-ice-shelf melting) and future climate forcing are poorly constrained. Here, we propose to improve the predictions of Antarctic ice-sheet behaviour using new uncertainty quantification methods. As opposed to ensemble modelling (Bindschadler et al., 2013) which provides a rather limited view on input and output dispersion, new stochastic methods (Le Maître and Knio, 2010) can provide deeper insight into the impact of uncertainties on complex system behaviour. Such stochastic methods usually begin with deducing a probabilistic description of input parameter uncertainties from the available data. Then, the impact of these input parameter uncertainties on output quantities is assessed by estimating the probability distribution of the outputs by means of uncertainty propagation methods such as Monte Carlo methods or stochastic expansion methods. The use of such uncertainty propagation methods in glaciology may be computationally costly because of the high computational complexity of ice-sheet models. This challenge emphasises the importance of developing reliable and computationally efficient ice-sheet models such as the f.ETISh ice-sheet model (Pattyn, 2015), a new fast thermomechanical coupled ice sheet/ice shelf model capable of handling complex and critical processes such as the marine ice-sheet instability mechanism. Here, we apply these methods to investigate the role of uncertainties in sub-ice-shelf melting, calving rates and climate projections in assessing Antarctic contribution to sea-level rise for the next centuries using the f.ETISh model. We detail the methods and show results that provide nominal values and uncertainty bounds for future sea-level rise as a reflection of the impact of the input parameter uncertainties under

  10. Relationships Between GIS-Based Erosion Indices and Relief Production in the Karakoram Himalaya

    Bishop, M. P.; Shroder, J. F.; Bush, A. B.; Copland, L.; Owen, L. A.


    maximum estimates of valley incision near K2 average > 1.5 cm / yr. Paleoclimate simulations and glaciological parameter estimates support the interpretation of periodic monsoon-enhanced, high-magnitude glacial erosion in these zones. We conclude that climate forcing and glacier positive-feedback mechanisms can generate significant relief at high altitudes, as deep glacier erosion removes lithospheric mass, whereas high peaks and ridge-lines are protected by permafrost and cold-based ice.

  11. Climatic controls and climate proxy potential of Lewis Glacier, Mt Kenya

    Prinz, Rainer; Nicholson, Lindsey; Gurgiser, Wolfgang; Mölg, Thomas; Kaser, Georg


    Glaciers in the tropics can provide information about regional climate, its dynamics, and its evolution over decadal and centennial time scales, if their interaction with the atmosphere is understood, and their changes are documented or reconstructed. The glaciers on Mount Kenya capture a climate signal from the mid troposphere at about 5 km a.s.l., where our knowledge of climate change is scarce and controversial. We use in-situ meteorological and glaciological observations to optimize and validate a physically-based, process-orientated energy and mass balance model to quantify the exchange processes between the glacier surface and the atmosphere above and to explore the sensitivity of energy and mass exchanges to changing climatic conditions. Currently the glacier loses mass due to the imbalance between insufficient accumulation and enhanced melt, because radiative energy gains cannot be compensated by turbulent energy sinks. Exchanging model input data with synthetic climate scenarios, which were sampled from the meteorological measurements and account for coupled climatic variable perturbations, reveal that the current mass balance is most sensitive to changes in atmospheric moisture (via its impact on solid precipitation, cloudiness and surface albedo). Scenarios with lower air temperatures are drier and associated with lower accumulation and increased net radiation due to reduced cloudiness and albedo. Hence, similar to the glaciers of nearby Kilimanjaro, the recession of Lewis Glacier is not because of increased air temperatures, but because of decreased atmospheric moisture. If the climate scenarios currently producing positive mass balances are applied to Lewis Glacier's late 19th century maximum extent (L19), negative mass balances are the result, meaning that the conditions required sustaining the glacier in its L19 extent are not reflected in today's climate observations. Alternatively, a balanced mass budget for the L19 extent can be explained by

  12. Greenland Ice sheet mass balance from satellite and airborne altimetry

    Khan, S. A.; Bevis, M. G.; Wahr, J. M.; Wouters, B.; Sasgen, I.; van Dam, T. M.; van den Broeke, M. R.; Hanna, E.; Huybrechts, P.; Kjaer, K.; Korsgaard, N. J.; Bjork, A. A.; Kjeldsen, K. K.


    ., 116, D24121 Janssens, I., and P. Huybrechts (2000). The treatment of meltwater retention in mass-balance parameterisations of the Greenland ice sheet. Annals of Glaciology 31, 133-140

  13. Possible sea sediments due to glaciofluvial activity in Elysium Planitia, Mars

    Nussbaumer, J.

    conditions to their geographic and stratigraphic positions, we intend to develop a geologic history of the central Elysium region. Ackowledgements for helpful contributions: D. Burr, J. Skinner, R. Williams References: [1] Tomei, K. (2004), Scriptum Publishers, 312 pp. [2] Burr et al. (2006) LPS XXXVII, #1367. [3] Evans, D. (2005), Hodder Arnold, 544pp. [4] Sharp M. J. (1984) Journal of Glaciology 82-93.

  14. Premonsoon Aerosol Characterization and Radiative Effects Over the Indo-Gangetic Plains: Implications for Regional Climate Warming

    Gautam, Ritesh; Hsu, N. Christina; Lau, K.-M.


    /decade) and underscores the potential role of enhanced aerosol solar absorption in the maximum warming localized over the western Himalayas (0.26 C/decade f 0.09 C/decade) that significantly exceed the entire HKHT and global warming rates. We believe the accelerated warming rates reported here are critical to both the South Asian summer monsoon and hydro-glaciological resource variability in the Himalayan-Hindu Kush snowpack and therefore to the densely populated downstream regions.

  15. Linking the spatial variability of glacier mass loss to fjord geometry

    Porter, D. F.; Tinto, K. J.; Boghosian, A.; Cochran, J. R.; Csatho, B. M.; Bell, R. E.


    There is compelling evidence of increasing mass loss of the ice sheets using a diverse set of observations, including increased thinning rates measured from both airborne and satellite altimeters, elevated mass fluxes resulting from the acceleration of outlet glaciers, and mass changes measured directly from satellite gravimetry. A dominant characteristic of observed change in Greenland outlet glaciers is that it is locally random. Numerous studies have revealed a high degree of spatial and temporal variability of outlet glacier mass change. Modeling studies suggest that increased ocean temperatures may be responsible for the observed glacial retreat in Greenland through increased basal melting, leading to increased calving rates, terminus retreat, glacier speedup, and eventually thinning of inland ice. Knowledge of fjord geometry is crucial for ice-ocean interaction because the availability of ocean heat to the ice will be restricted by narrow sills and shallow grounding lines. We investigate whether the variability in observed changes among Greenland glaciers can be partially explained by variation in fjord geometry. Using statistical techniques commonly employed to detect patterns in complex spatial data, we objectively show that mass change in Greenland tidewater glaciers between 2003 and 2009 is indeed mostly spatially incoherent. Except for a few clusters of similar change in the NW and Scoresby Sund regions, there is significant glacier-scale variability in mass loss rates. To understand the drivers of this local variability, we compare fjord bathymetries from all regions of Greenland, modeled using airborne gravimetry measurements from NASA Operation IceBridge flights, to estimates of glaciological change. Specifically, we investigate the correlation between water depths at the grounding line and the dynamic mass loss of tidewater glaciers. In theory, a deep grounding line will allow greater interaction with the warm Atlantic Water observed in most fjords

  16. Mass balance and near-surface ice temperature structure of Baishui Glacier No.1 in Mt.Yulong

    DU Jiankuo; HE Yuanqing; LI Shuang; WANG Shijin; NIU Hewen; XIN Huijuan; PU Tao


    The accumulation and ablation of a glacier directly reflect its mass income and wastage,and ice temperature indicates glacier's climatic and dynamic conditions.Glaciological studies at Baishui Glacier No.1 in Mt.Yulong are important for estimating recent changes of the cryosphere in Hengduan Mountains.Increased glacier ablation and higher ice temperatures can cause the incidents of icefall.Therefore,it is important to conduct the study of glacier mass balance and ice temperature,but there are few studies in relation to glacier's mass balance and active-layer temperature in China's monsoonal temperate glacier region.Based on the field observations of mass balance and glacier temperature at Baishui Glacier No.1,its accumulation,ablation,net balance and near-surface ice temperature structure were analyzed and studied in this paper.Results showed that the accumulation period was ranged from October to the following mid-May,and the ablation period occurred from mid-May to October,suggesting that the ablation period of temperate glacier began about 15 days earlier than that of continental glaciers,while the accumulation period began about 15 days later.The glacier ablation rate was 6.47 cm d-1 at an elevation of 4600 m between June 23 and August 30,and it was 7.4 cm d-1 at 4800 m between June 26 and July 11 in 1982,moreover,they respectively increased to 9.2 cm d-1 and 10.8 cm d-1 in the corresponding period and altitude in 2009,indicating that glacier ablation has greatly intensified in the past years.The temperature of the main glacier body was close to melting point in summer,and it dropped from the glacier surface and reached a minimum value at a depth of 4-6 m in the ablation zone.The temperature then rose to around melting point with the depth increment.In winter,the ice temperature rose gradually with the increasing depth,and close to melting point at the depth of 10 m.Compared with the data from 1982,the glacier temperature has risen in the ablation zone in

  17. The effects of climate uncertainty on the stability of the Antarctic ice sheet during the mid-Pliocene warm period

    Bernales, Jorge; Häfliger, Tonio; Rogozhina, Irina; Thomas, Maik


    . Dynamic behaviour of the East Antarctic ice sheet during Pliocene warmth. Nature Geoscience 6.9 (2013): 765-769. [2] Sato, T., and Greve, R. Sensitivity experiments for the Antarctic ice sheet with varied sub-ice-shelf melting rates. Annals of Glaciology 53.60 (2012): 221-228. [3] Haywood, A. M., et al. Large-scale features of Pliocene climate: results from the Pliocene Model Intercomparison Project. Clim. Past 9 (2013): 191-209.

  18. Glacier surface melt characterization and trend analysis (1992-2011) in the Russian High Arctic from combined resolution-enhanced scatterometer and passive microwave data

    Zhao, M.; Ramage, J. M.; Semmens, K. A.


    Global warming has been pronounced in the remote glacierized archipelagoes (Severnaya Zemlya, Novaya Zemlya and Franz Josef Land) of the Russian High Arctic (RHA) and its effect on the low altitude, high latitude small ice caps needs examination. The timing and spatial variability of snow melt onset, duration and intensity are key factors influencing mass balance and the ice marginal hydrological system as well as important indicators of glacial response to anthropogenic and natural forcings. Characterization and trend analysis of RHA glacier melt behaviors provide insight about assessing the mass loss rate under recent Arctic climate change. However, due to the harsh environment, long term records of glaciological data for RHA are limited, necessitating the application of remotely sensed data to accomplish the research. The high sensitivity to liquid water and the ability to penetrate non-precipitating clouds enables microwave remote sensing to detect glacier surface melt. The appearance of melt water in snow dramatically decreases the returned scatterometer radar signal from active microwave sensors and sharply augments passive microwave emission. Based on this feature, we combined resolution-enhanced ERS-1/2 C-band (1992-2000), QuickSCAT Ku-band (2000-2009), ASCAT C-band (2009-2011) scatterometer data and SSMI 37 GHz (1995-2007) vertically polarized passive microwave products from Brigham Young University and analyzed glacier surface melt trends from 1992 to 2011 with a spatial resolution downscaled to 4.45km. We concatenated scatterometer derived melt behaviors by overlapping years and refined the results based on passive microwave data. Cross-validation shows that melt timing to be consistent between the active and passive sensors. Trend analysis (α < 0.005) reveals that the average glacier surface melt onset date occurs earlier by approximately 0.85 days/year in Severnaya Zemlya which outpaced the mean advancing rate in the pan-Arctic. Surrounded by ocean

  19. Monitoring of a debris-covered and avalanche-fed glacier in the Eastern Italian Alps using ground-based SfM-MVS

    Piermattei, Livia; Carturan, Luca; Cazorzi, Federico; Colucci, Renato R.; Dalla Fontana, Giancarlo; Forte, Emanuele


    The Montasio Occidentale glacier is a 0.07 km2 wide, avalanche-fed glacier located at very low-altitude (1860-2050 m a.s.l.) in the Eastern Italian Alps. The glacier is still active and shows a detectable mass transfer from the accumulation area to the lower ablation area, which is covered by a thick debris mantle. Geometric changes and mass balance have been monitored starting in 2010, combining glaciological methods and high-resolution geodetic surveying with a terrestrial laser scanner (TLS). The TLS technique has proved to be very effective in determining the volume change of this glacier, but presents several limitations as high costs, high level of specialized training and low portability. On the other hand, the recent improvements in close-range photogrammetric techniques like the Structure from Motion (SfM), combined with dense image matching algorithms as Multi View Stereo (MVS), make them competitive for high quality 3D models production. The purpose of this work was to apply ground-based photogrammetric surveys for the monitoring of the annual mass balance and surface processes of Montasio Occidentale glacier. A consumer-grade SLR camera and the SfM-MVS software PhotoScan were used to detect the changes in the surface topography of the glacier from 2012 to 2014. Different data acquisition settings were tested, in order to optimize the quality and the spatial coverage of the 3D glacier model. The accuracy of the image-based 3D models was estimated in stable areas outside the glacier, using the TLS 3D model as reference. A ground penetrating radar (GPR) survey was carried out in 2014, simultaneously to the photogrammetric survey, that was used to compare the snow height estimations obtained by photogrammetry with those obtained by geophysics. The achieved results indicate that the resolution and accuracy of the 3D models generated by the SfM-MVS technique are comparable with those obtained from TLS surveys. Consequently, almost identical volumetric changes

  20. Graduate training in Earth science across borders and disciplines: ArcTrain -"Processes and impacts of climate change in the North Atlantic Ocean and the Canadian Arctic"

    Stein, Rüdiger; Kucera, Michal; Walter, Maren; de Vernal, Anne


    Due to a complex set of feedback processes collectively known as "polar amplification", the Arctic realm is expected to experience a greater-than-average response to global climate forcing. The cascades of feedback processes that connect the Arctic cryosphere, ocean and atmosphere remain incompletely constrained by observations and theory and are difficult to simulate in climate models. Our capacity to predict the future of the region and assess the impacts of Arctic change processes on global and regional environments hinges on the availability of interdisciplinary experts with strong international experience and understanding of the science/society interface. This is the basis of the International Research Training Group "Processes and impacts of climate change in the North Atlantic Ocean and the Canadian Arctic - ArcTrain", which was initiated in 2013. ArcTrain aims to educate PhD students in an interdisciplinary environment that combines paleoclimatology, physical oceanography, remote sensing and glaciology with comprehensive Earth system modelling, including sea-ice and ice-sheet components. The qualification program for the PhD students includes joint supervision, mandatory research residences at partner institutions, field courses on land and on sea (Floating University), annual meetings and training workshops and a challenging structured training in expert skills and transferrable skills. Its aim is to enhance the career prospects and employability of the graduates in a challenging international job market across academic and applied sectors. ArcTrain is a collaborative project at the University of Bremen and the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven. The German part of the project is designed to continue for nine years and educate three cohorts of twelve PhD students each. The Canadian partners comprise a consortium of eight universities led by the GEOTOP cluster at the Université du Québec à Montréal and including

  1. Airborne laser altimetry survey of Glaciar Tyndall, Patagonia

    Keller, Kristian; Casassa, Gino; Rivera, Andrés; Forsberg, Rene; Gundestrup, Niels


    The first airborne laser altimetry measurements of a glacier in South America are presented. Data were collected in November of 2001 over Glaciar Tyndall, Torres del Paine National Park, Chilean Patagonia, onboard a Twin Otter airplane of the Chilean Air Force. A laser scanner with a rotating polygon-mirror system together with an Inertial Navigation System (INS) were fixed to the floor of the aircraft, and used in combination with two dual-frequency GPS receivers. Together, the laser-INS-GPS system had a nominal accuracy of 30 cm after data processing. On November 23rd, a total of 235 km were flown over the ablation area of Glaciar Tyndall, with 5 longitudinal tracks with a mean swath width of 300 m, which results in a point spacing of approximately 2 m both along and across track. A digital elevation model (DEM) generated using the laser altimetry data was compared with a DEM produced from a 1975 map (1:50,000 scale — Instituto Geográfico Militar (IGM), Chile). A mean thinning of - 3.1 ± 1.0 m a - 1 was calculated for the ablation area of Glaciar Tyndall, with a maximum value of - 7.7 ± 1.0 m a - 1 at the calving front at 50 m a.s.l. and minimum values of between - 1.0 and - 2.0 ± 1.0 m a - 1 at altitudes close to the equilibrium line altitude (900 m a.s.l.). The thinning rates derived from the airborne survey were similar to the results obtained by means of ground survey carried out at ˜ 600 m of altitude on Glaciar Tyndall between 1975 and 2002, yielding a mean thinning of - 3.2 m a - 1 [Raymond, C., Neumann, T.A., Rignot, E., Echelmeyer, K.A., Rivera, A., Casassa, G., 2005. Retreat of Tyndall Glacier, Patagonia, over the last half century. Journal of Glaciology 173 (51), 239-247.]. A good agreement was also found between ice elevation changes measured with laser data and previous results obtained with Shuttle Radar Topography Mission (SRTM) data. We conclude that airborne laser altimetry is an effective means for accurately detecting glacier elevation

  2. Construction of Late Pleistocene Laurentide Ice History on Earth with Composite Rheology

    Wu, P. P. C.; van der Wal, W.; Steffen, H.; Wang, H.


    A good ice thickness history model is essential in the study of Glacial Isostatic Adjustment (GIA), its effects on coastal engineering, water resource management, fault stability and intraplate earthquakes, monitor global climate change, etc... Ice history models can be constructed based on glaciology and climate data only, but Peltier mainly used GIA observations and simple ice physics to construct global models ICE-4G, 5G & 6G where the main uncertainty is the ice thickness in Antarctica and western Laurentide during the last glacial maximum. One should note that most of the ice models constructed this way are based on the assumption that mantle rheology is linear and that rheology varies in the radial direction only. However, surface geology and seismic tomography show that Earth properties also vary strongly in the lateral direction. Moreover, high temperature creep experiments on mantle rocks show that mantle flow is better described by composite rheology since both diffusion (linear) and dislocation (nonlinear) creep operate in the mantle at the same time. The aim of our study is to construct global ice history models that are consistent with composite rheology and lateral heterogeneity. Thus we use the Coupled Poisson-Finite Element method to model GIA in a spherical, self-gravitating viscoelastic Earth with composite rheology and lateral heterogeneity. We shall follow the approach of Peltier and use GIA observations and simple ice physics as constraints to our ice model. The limitation of using sea level data is that they only lie near the coast and thus there is little constraint on ice thickness inland. To overcome this, we will use gravity rate-of-change data from GRACE with the effect of hydrology accurately removed using GPS observations (rather than GIA models which introduce large uncertainties). However, these data only give the current-day rate-of-change, which is more than 8,000 years after the end of deglaciation. To further constrain our ice

  3. Three-Dimensional Animation Technology: a New Interactive Model Designed for the Teaching of Cryospheric Science

    Porter, P. R.; Marunchak, A.


    One of the key challenges facing educators in the cryospheric sciences is to explain to students the processes that operate and the landforms that exist in relatively unfamiliar glacial environments. In many cases these environments are also largely inaccessible which can hinder field-based teaching. This is particularly the case for en-glacial and sub-glacial hydrology and the closely related topic of sub-glacial glacier dynamics, yet a full understanding of these subject areas is pivotal to overall student understanding of glaciology. An ability to visualise these unfamiliar and inaccessible environments offers a potentially powerful tool to assist student conceptualisation and comprehension. To address this we have developed a three-dimensional interactive 'virtual glacier' simulation model. Based on standards and technology established by the rapidly evolving video gaming industry, the user is presented with an interactive real-time three-dimensional environment designed to accurately portray multiple aspects of glacial environments. The user can move in all directions in the fore-field area, on the glacier surface and within en-glacial and sub-glacial drainage networks. Descent into the glacier hydrological system is via a moulin, from which the user can explore en-glacial channels linking to this moulin and ultimately descend into the sub-glacial drainage system. Various sub-glacial drainage network morphologies can then be 'explored' to aid conceptualisation and understanding and the user can navigate through drainage networks both up- and down-glacier and ultimately emerge at the portal into the fore-field environment. Interactive icons relating to features of interest are presented to the user throughout the model, prompting multimedia dialogue boxes to open. Dialogue box content (e.g. text, links to online resources, videos, journal papers, etc.) is fully customisable by the educator. This facilitates the use of the model at different academic levels

  4. Derivation of deformation characteristics in fast-moving glaciers

    Herzfeld, Ute C.; Clarke, Garry K. C.; Mayer, Helmut; Greve, Ralf


    Crevasse patterns are the writings in a glacier's history book—the movement, strain and deformation frozen in ice. Therefore by analysis of crevasse patterns we can learn about the ice-dynamic processes which the glacier has experienced. Direct measurement of ice movement and deformation is time-consuming and costly, in particular for large glaciers; typically, observations are lacking when sudden changes occur. Analysis of crevasse patterns provides a means to reconstruct past and ongoing deformation processes mathematically. This is especially important for fast-moving ice. Ice movement and deformation are commonly described and analyzed using continuum mechanics and measurements of ice velocities or strain rates. Here, we present a different approach to the study of ice deformation based on principles of structural geology. Fast ice movement manifests itself in the occurrence of crevasses. Because crevasses remain after the deformation event and may be transported, overprinted or closed, their analysis based on aerial videography and photography or satellite data gives information on past deformation events and resulting strain states. In our treatment, we distinguish (A) continuously fast-moving glaciers and ice streams, and (B) surge-type glaciers, based on observations of two prototypes, Jakobshavns Isbræ, Greenland, for (A), and Bering Glacier, Alaska, during the 1993-1995 surge, for (B). Classes of ice-deformation types are derived from aerial images of ice surfaces using structural geology, i.e. structural glaciology. For each type, the deformation gradient matrix is formed. Relationships between invariants used in structural geology and continuum mechanics and the singular value decomposition are established and applied to ice-surface classification. Deformation during a surge is mostly one of the extensional deformation types. Continuously, or infinitesimally repeated, deformation acting in continuously fast-moving ice causes different typical

  5. Persistent Surface River on Nansen Ice Shelf Drains Meltwater Preventing Collapse for Decades

    Bell, R. E.; Chu, W.; Kingslake, J.; Das, I.; Tedesco, M.; Tinto, K. J.; Zappa, C. J.; Frezzotti, M.


    Meltwater ponding on the surface of Antarctic ice shelves has been advanced as the trigger for their collapse through loading and hydrofracturing. While ponding was associated with the Larsen B Ice Shelf collapse, draining meltwater off an ice shelf could limit the destructive role of increasing surface melt in the future. In this regard, we present the first evidence of the presence and evolution of a persistent active network of streams, ponds, and rivers on the Nansen Ice Shelf, Antarctica. This active drainage system has delivered meltwater into the Ross Sea since at least 1908, reducing the volume of water seasonally stored on the ice surface and protecting the ice shelf from collapsing. We integrated early 20th century observations with modern airborne and satellite imagery to identify three distinct surface hydrology systems on the Nansen Ice Shelf. Near the calving front, surface meltwater coalesces into surface streams and ponds that grow over days to weeks, eventually connecting to a shear margin river that drains at a large waterfall into the Ross Sea. Between 1989 and 2016, the shear margin river drained into a rift associated with a large calving event in 2016. The second system forms close to the grounding line where surface meltwater drains into regions of rifted mélange, possibly explaining the low salinity of the ice drilled in these regions. This surface meltwater is injected into the ice shelf cavity through the mélange and may foster basal melting beneath the shear margins. The third system develops on the steeper Priestly Glacier flow where surface melt is produced adjacent to exposed bedrock and moraines and then is transported by surface streams that terminate in firn-covered regions. Ice shelf hydrology is spatially complex, sensitive to glaciological and climatic conditions, and evolves seasonally. Surface streams that coalesce melt and rivers that export water off the ice shelf will limit the damage from ponding-induced hydrofracturing

  6. Evolution and hazard analysis of high-mountain lakes in the Cordillera Vilcabamba (Southern Peru) from 1991 to 2014

    Guardamino, Lucía; Drenkhan, Fabian


    In recent decades, glaciers in high-mountain regions have experienced unprecedented glacier retreat since the Little Ice Age (LIA). This development triggers the formation and growth of glacier lakes, which in combination with changes in glacier parameters might produce more frequent conditions for the occurrence of disasters, such as Glacier Lake Outburst Floods (GLOF). Facing such a scenario, the analysis of changing lake characteristics and identification of new glacier lakes are imperative in order to identify and reduce potential hazards and mitigate or prevent future disasters for adjacent human settlements. In this study, we present a multi-temporal analysis with Landsat TM 5 and OLI 8 images between 1991 and 2014 in the Cordillera Vilcabamba region (Southern Peru), a remote area with difficult access and climate and glaciological in-situ data scarcity. A semi-automatic model was developed using the band ratios Normalized Difference Snow Index (NDSI) and Normalized Difference Water Index (NDWI) in order to identify glacier and lake area changes. Results corroborate a strong glacier area reduction of about 51% from 1991 (200.3 km²) to 2014 (98.4 km²). At the same time, the number of lakes (total lake surface) has increased at an accelerated rate, from 0.77% (0.48%) in 1991 to 2.31% (2.49%) in 2014. In a multiple criteria analysis to identify potential hazards, 90 out of a total of 329 lakes in 2014 have been selected for further monitoring. Additionally, 29 population centers have been identified as highly exposed to lake related hazards from which 25 indicate a distance less than 1 km to an upstream lake and four are situated in a channel of potential debris flow. In these areas human risks are particularly high in view of a low HDI below Peru's average and hence pronounced vulnerability. We suggest more future research on measurements and monitoring of glacier and lake characteristics in these remote high-mountain regions, which include comprehensive risk

  7. Snow cover as an indicator of cumulative land pollution

    V. R. Alekseev


    Full Text Available A reliable technique has been devised for a simultaneous total and serial retrospective assessment of the ever increasing pollution of lands from aerospace images and from benchmark ground-based observations which permit calculations of the negative human impact on the environment for the particular regions, river drainage basins, states, and for the planet Earth as a whole. Use is made of the glacio-indication approach to the study of polluted territories around cities and transport routes that has come to be known as the «ProcUsmethod». An assessment of the land pollution across the globe was made for 221 administrative entities. Calculations were done for 193 states and 41 trust territories. The total area of polluted lands on the continents was estimated at 13 606 thousand km2 (10% of the Earth’s land surface. The heaviest pollution corresponds to West Europe (44.5% of its area, Micronesia (33.3%, and to the countries within the Caribbean basin (31.1%; the worst levels of land pollution correspond to Australia with New Zealand (2.1%, Melanesia (3.1%, and to Central Africa (3.8%. The most heavily polluted states are China (with the polluted area of 2400 thou km2, India (1460 thou km2, the USA (1156 thou km2, Russia (683 thou km2 and Brazil (657 thou km2.The findings, obtained by the Russian scientists V.G. Prokacheva and V.F. Usachev over the course of the last 30 years, are recognized as a fundamental contribution to glaciology and geoecology. The ProcUs method, suggested by Russian scientists, offers strong possibilities of obtaining quantitative indicators and studying spatiotemporal variability of pollutants. It is recommended that the method should be expanded and sophisticated on the basis of special-purpose ground-truth pilot observations to be used in implementing the Earth’s global ecological monitoring program.

  8. Thermal relations leading to the formation of gaseous phase within the ice covering lakes and ponds

    Hruba, J.; Kletetschka, G.


    When cutting the ice from the lakes and ponds gaseous phase displays often ubiquitous bubble textures along the ice thickness. The occurrence of bubbles (enclosures filled with the gas) in ice relates to a content of the dissolved gas in the lake/pond water prior to freezing over the surface. When water freezes, dissolved gases are rejected and redistributed at the ice-water interface, depending on the saturation ratio between the gas and water. If the concentration of dissolved gases surpasses a critical value (as freezing progresses), the water at the interface becomes supersaturated, and gas bubbles nucleate and grow to a visible size along the interface. The bubbles generated at the ice-water interface are either incorporated into the ice crystal as the water-ice interface advances, thus forming gas pores in the ice, or released from the interface. If there is incorporation or release is determined by several factors. The bubbles nucleated at the advancing ice-water interface may be characterized by concentration, shape, and size, which depend on growth rate of ice, the amount of gases dissolved in water, and the particulate content of water. Our work focused on the relation between growth rates of the ice and the occurrence of bubbles in the pond ice. We monitored the temperature of the ice formed under natural conditions over the pond Dolní Tušimy in Mokrovraty, Czech Republic. Distinct layers of gas bubbles were observed when the ice samples have been retrieved. These layers may relate to fast growth rates of ice. In this case the maximum growth rates were about 1 μm/s. The results were compared with similar work done (Bari and Hallett, 1974; Carte 1961; Yoshimura et al., 2008). This comparison showed distinction that may be due to different methods of ice formation (laboratory condition vs. natural conditions). References: Bari, S.A., Hallett, J. (1974): Nucleation and Growth of Bubbles at an Ice-Water Interface. Journal of Glaciology, Vol. 13, No. 69, p

  9. Snow zonation on Hielo Patagónico Sur, Southern Patagonia, derived from Landsat 5 TM data

    De Angelis, Hernán; Rau, Frank; Skvarca, Pedro


    Hielo Patagónico Sur (HPS), an icefield in Southern Patagonia, is the largest temperate ice mass in the southern hemisphere. Despite continued research efforts during the last decade many glaciological variables, especially mass balance, are still poorly known. This is partly because access to the icefield is difficult due to remoteness and persistent harsh weather conditions. Therefore, remote sensing appears to be a more suitable tool for the acquisition of data. In this work we present a remote sensing study of snow zonation on HPS using Landsat 5 Thematic Mapper data acquired on 12 March 2001. By using image processing and classification techniques, proved to be useful in other glaciated regions, we map for the first time the extent and occurrence of major snow zones on the whole HPS. We separate between two classes of ice and three classes of snow. Ice facies are classified as bare or debris (i.e. dirt) covered ice, covering 2454 km 2 and 777 km 2 respectively, or 18.4% and 5.8% of the icefield on the day of image acquisition. Snow types are classified according to spectral differences in the images, following the glacier facies concept. Two of the three snow cover types are interpreted to represent differences in snow grain size within a fairly homogeneous snow pack whereas the third one is interpreted to represent the slush zone. A first order altitudinal control on the distribution of these snow facies is evident. In addition, our results show that snow accumulation on HPS is markedly controlled by the interaction of strong west-northwest snow-bearing winds and the rough mountainous terrain. In order of decreasing altitude we find that the two snow facies and the slush facies occupy 3819 km 2, 3292 km 2 and 2295 km 2 respectively, or 28.6%, 24.6% and 17.2% of the icefield, on the day of image acquisition. Estimates of equilibrium line altitude using our results yield values of 800-900 m above sea level for the western side and 1500-1600 m above sea level

  10. Critical Approach to Methods of Glacier Reconstruction in High Asia and Discussion of the Probability of a Qinghai-Xizang (Tibetan) Inland Ice

    Matthias Kuhle


    This overview discusses old and new results as to the controversy on the past glacier extension in High Asia, which has been debated for 35 years now. This paper makes an attempt to come closer to a solution. H.v. Wissmann's interpretation(1959) of a small-scale glaciation contrasts with M.Kuhle's reconstruction (1974) of a large-scale glaciation with a 2.4 million km2 extended Qinghai-Xizang (Tibetan) inland glaciation and a Himalaya-Karakorum icestream network. Both opinions find support but also contradiction in the International and Chinese literature (Academia Sinica). The solution of this question is of supraregional importance because of the subtropical position of the concerned areas. In case of large albedo-intensive ice surfaces, a global cooling would be the energetical consequence and, furthermore, a breakdown of the summer monsoon. The current and interglacial heat-low above the very effective heating panel of the Qinghai-Xizang (Tibetan) Plateau exceeding 4000 m, which gives rise to this monsoon circulation, would be replaced by the cold-high of an inland ice. In addition, the plate-tectonically created Pleistocene history of the uplift of High Asia - should the occasion arise up to beyond the snowline (ELA) -would attain a paleoclimatically great, perhaps global importance. In case of a heavy superimposed ice load,the question would come up as to the glacio-isostatic interruption of this primary uplift. The production of the loesses sedimentated in NE-China and their very probable glacial genesis as well as an eustatic lowering of the sea-level by 5 to 7 m in the maximum case of glaciation are immediately tied up with the question of glaciation we want to discuss. Not the least, the problems of biotopes of the sanctuary-centres of flora and fauna, i.e., interglacial re-settlement, are also dependent on it. On the basis of this Quaternary-geomorphological-glaciological connection, future contributions are requested on the past glaciation, the current

  11. Groundwater flow modelling under ice sheet conditions in Greenland (phase II)

    Jaquet, Olivier; Namar, Rabah; Siegel, Pascal [In2Earth Modelling Ltd, Lausanne (Switzerland); Jansson, Peter [Dept. of Physical Geography and Quaternary Geology, Stockholm Univ., Stockholm (Sweden)


    Within the framework of the GAP project, this second phase of geosphere modelling has enabled the development of an improved regional model that has led to a better representation of groundwater flow conditions likely to occur under ice sheet conditions. New data in relation to talik geometry and elevation, as well as to deformation zones were integrated in the geosphere model. In addition, more realistic hydraulic properties were considered for geosphere modelling; they were taken from the Laxemar site in Sweden. The geological medium with conductive deformation zones was modelled as a 3D continuum with stochastically hydraulic properties. Surface and basal glacial meltwater rates provided by a dynamic ice sheet model were assimilated into the groundwater flow model using mixed boundary conditions. The groundwater flow system is considered to be governed by infiltration of glacial meltwater in heterogeneous faulted crystalline rocks in the presence of permafrost and taliks. The characterisation of the permafrost-depth distribution was achieved using a coupled description of flow and heat transfer under steady state conditions. Using glaciological concepts and satellite data, an improved stochastic model was developed for the description at regional scale for the subglacial permafrost distribution in correlation with ice velocity and bed elevation data. Finally, the production of glacial meltwater by the ice sheet was traced for the determination of its depth and lateral extent. The major improvements are related to the type and handling of the subglacial boundary conditions. The use of meltwater rates provided by an ice sheet model applied as input to a mixed boundary condition enables to produce a more plausible flow field in the Eastern part of the domain, in comparison to previous modelling results (Jaquet et al. 2010). In addition, the integration of all potential taliks within the modelled domain provides a better characterisation of the likely groundwater

  12. Assessment of methods for mapping snow cover from MODIS

    Rittger, Karl; Painter, Thomas H.; Dozier, Jeff


    Characterization of snow is critical for understanding Earth’s water and energy cycles. Maps of snow from MODIS have seen growing use in investigations of climate, hydrology, and glaciology, but the lack of rigorous validation of different snow mapping methods compromises these studies. We examine three widely used MODIS snow products: the “binary” (i.e., snow yes/no) global snow maps that were among the initial MODIS standard products; a more recent standard MODIS fractional snow product; and another fractional snow product, MODSCAG, based on spectral mixture analysis. We compare them to maps of snow obtained from Landsat ETM+ data, whose 30 m spatial resolution provides nearly 300 samples within a 500 m MODIS nadir pixel. The assessment uses 172 images spanning a range of snow and vegetation conditions, including the Colorado Rocky Mountains, the Upper Rio Grande, California’s Sierra Nevada, and the Nepal Himalaya. MOD10A1 binary and fractional fail to retrieve snow in the transitional periods during accumulation and melt while MODSCAG consistently maintains its retrieval ability during these periods. Averaged over all regions, the RMSE for MOD10A1 fractional is 0.23, whereas the MODSCAG RMSE is 0.10. MODSCAG performs the most consistently through accumulation, mid-winter and melt, with median differences ranging from -0.16 to 0.04 while differences for MOD10A1 fractional range from -0.34 to 0.35. MODSCAG maintains its performance over all land cover classes and throughout a larger range of land surface properties. Characterizing snow cover by spectral mixing is more accurate than empirical methods based on the normalized difference snow index, both for identifying where snow is and is not and for estimating the fractional snow cover within a sensor’s instantaneous field-of-view. Determining the fractional value is particularly important during spring and summer melt in mountainous terrain, where large variations in snow, vegetation and soil occur over

  13. Penn State geoPebble system: Design,Implementation, and Initial Results

    Urbina, J. V.; Anandakrishnan, S.; Bilen, S. G.; Fleishman, A.; Burkett, P.


    current efforts to test this new instrument system and how we are addressing the challenges imposed by the extreme weather conditions on the Antarctic continent. After fully validating its operational conditions, the geoPebble system will be available for NSF-sponsored glaciology research projects.

  14. Photogrammetry on glaciers: Old and new knowledge

    Pfeffer, W. T.; Welty, E.; O'Neel, S.


    In the past few decades terrestrial photogrammetry has become a widely used tool for glaciological research, brought about in part by the proliferation of high-quality, low-cost digital cameras, dramatic increases in image-processing power of computers, and very innovative progress in image processing, much of which has come from computer vision research and from the computer gaming industry. At present, glaciologists have developed their capacity to gather images much further than their ability to process them. Many researchers have accumulated vast inventories of imagery, but have no efficient means to extract the data they desire from them. In many cases these are single-image time series where the processing limitation lies in the paucity of methods to obtain 3-dimension object space information from measurements in the 2-dimensional image space; in other cases camera pairs have been operated but no automated means is in hand for conventional stereometric analysis of many thousands of image pairs. Often the processing task is further complicated by weak camera geometry or ground control distribution, either of which will compromise the quality of 3-dimensional object space solutions. Solutions exist for many of these problems, found sometimes among the latest computer vision results, and sometimes buried in decades-old pre-digital terrestrial photogrammetric literature. Other problems, particularly those arising from poorly constrained or underdetermined camera and ground control geometry, may be unsolvable. Small-scale, ground-based photography and photogrammetry of glaciers has grown over the past few decades in an organic and disorganized fashion, with much duplication of effort and little coordination or sharing of knowledge among researchers. Given the utility of terrestrial photogrammetry, its low cost (if properly developed and implemented), and the substantial value of the information to be had from it, some further effort to share knowledge and methods

  15. Arrest of Avalanche Propagation by Discontinuities on Snow Cover

    Frigo, B.; Chiaia, B.


    results are supported also by other investigations, which suggested that increased spatial variability in the snow cover leads to a lower release probability of snow avalanches. The above studies are based on very different approaches, such as cellular automata (Kronholm and Birkeland, 2005) and statistical renormalization (Chiaia and Frigo, 2009) models, but come to the same conclusion, i.e. that the presence of randomly distributed weak zones increase the global robustness and toughness of the snow slope. From a practical engineering viewpoint, results could be used towards a new idea of active avalanche protection, based on the presence of natural (e.g., trees) or artificial objects throughout the slope, able to create low deposition zones as discontinuities in the snow cover. Key words: snow avalanche, fracture mechanics, crack arrester. References Chiaia, B., Cornetti, P., Frigo, B., 2008. Triggering of dry snow slab avalanches: Stress versus fracture mechanical approach Cold Reg. Sci. Technol. 53 170-178. Chiaia, B., Frigo, B., 2009, A scale-invariant model for snow slab-avalanches, J. Stat. Phys., submitted Föhn, P.M.B., Camponovo, C., Krüsi, G., 1998. Mechanical and structural properties of weak snow layers measured in situ. Annals of Glaciology 26, 1-6. Jamieson, J.B., Johnston, C.D., 1992. A fracture-arrest model for unconfined dry slab avalanches. Canadian Geotechnical Journal, 29, 61-66. Jamieson, B., Johnston, C.D., 2001. Evaluation of shear frame test for weak snowpack layers. Annals of Glaciology 32, 59-69. Kirchner, H.O.K., Michot, G., Schweizer, J., 2002. Fracture toughness of snow in shear and tension. Scripta Materialia 46, 425-429. Kronholm, K., Birkeland, K. W., 2005. Integrating spatial patterns into a snow avalanche cellular automata model, Geophysical Research Letters 32, L19504. McClung, D. M. 1979. Shear fracture precipitated by strain softening as a mechanism of dry slab avalanche release, J. Geophys. Res. 84(B7) 3519-3526. Schweizer, J., 1999

  16. Symmetry distribution of cities in China

    YE; Danian


    , central Asia, Geol. Soc. Amer. Bull., 1996, 108: 1004-1021.[12]Allen, M. B., Vincents, S. J., Wheeler, P. J., Late cenozoic tectonics of the Kepingtoge thrust zone: Interaction between the Tianshan and the Tarim Basin, northwest China,Tectonics, 1999, 18: 639-654.[13]Burchfiel, B. C., Brown, E. T., Deng Qidong et al., Crustal shortening on the margins of the Tianshan, Xinjiang, China, 2000, (unpublished).[14]Brown, E, T., Boarles, D. C., Barchfiel, B. C. et al., Estimation of slip rates in the southern Tianshan using cosmic ray ex-posure dates of abandoned alluvial fans, Geol, Soc. Amer. Bull., 1998, 110: 377-386.[15]Yin, A., Nie, S., Craig, P. et al., Late cenozoic tectonic evolution of the southern Chinese Tainshan, Tectonics, 1998, 17: 1-27.[16]Hubert-Ferrari, A., Suppe, J., Wang, X. et al., 18 kyr, 120 kyr and 5 Myr shortening rates along the front of the southern Tianshan Mountain (China), Geol.Soc.America, Abstracts, 1999.[17]Shi Yafeng, Zheng Benxing, Su Zhen et al., Study of Quaternary glaciation in Mts. Tomur-Hantengri area, Tianshan, Jour-nal of Glaciology and Cryopedology (in Chinese), 1984,6: 1-14.[18]Shi Yafeng, Tang Macang, Ma Yuzhen, Linkage between the second uplifting of the Qinghai-Tibetan Plateau and the ini-tiation of the Asian, Science in China, Ser. D, 1999, 42(3): 303-312.[19]Zheng Benxing, Glacial geomorphological map (1:200000)of Mt.Tomar Region, Tianshan, Annals of Glaciology, 1986, 8: 209.

  17. Glacier mass balance in high-arctic areas with anomalous gravity

    Sharov, A.; Rieser, D.; Nikolskiy, D.


    All known glaciological models describing the evolution of Arctic land- and sea-ice masses in changing climate treat the Earth's gravity as horizontally constant, but it isn't. In the High Arctic, the strength of the gravitational field varies considerably across even short distances under the influence of a density gradient, and the magnitude of free air gravity anomalies attains 100 mGal and more. On long-term base, instantaneous deviations of gravity can have a noticeable effect on the regime and mass budget of glaciological objects. At best, the gravity-induced component of ice mass variations can be determined on topographically smooth, open and steady surfaces, like those of arctic planes, regular ice caps and landfast sea ice. The present research is devoted to studying gravity-driven impacts on glacier mass balance in the outer periphery of four Eurasian shelf seas with a very cold, dry climate and rather episodic character of winter precipitation. As main study objects we had chosen a dozen Russia's northernmost insular ice caps, tens to hundreds of square kilometres in extent, situated in a close vicinity of strong gravity anomalies and surrounded with extensive fields of fast and/or drift ice for most of the year. The supposition about gravitational forcing on glacioclimatic settings in the study region is based on the results of quantitative comparison and joint interpretation of existing glacier change maps and available data on the Arctic gravity field and solid precipitation. The overall mapping of medium-term (from decadal to half-centennial) changes in glacier volumes and quantification of mass balance characteristics in the study region was performed by comparing reference elevation models of study glaciers derived from Russian topographic maps 1:200,000 (CI = 20 or 40 m) representing the glacier state as in the 1950s-1980s with modern elevation data obtained from satellite radar interferometry and lidar altimetry. Free-air gravity anomalies were


    唐学远; 孙波; 崔祥斌


    , glaciology research has achieved a number of quantitative results by relating millennial-timescale subglacial geomorphology with the paleo-ice stream.In this review concerning the Antarctic ice sheet, we summarize the phys-ical mechanism of the internal layer and its benefit to glaciology, and evaluate its application to the following:(1) siting and dating of deep ice cores, (2) ice sheet dynamics, (3) ice sheet mass balance, (4) ice sheet stability, and (5) the subglacial environment.In addition, based on our understanding of internal isochronous layers, we outline a number of challenges to be addressed in the future.(1) The development and testing of numerical ice-sheet models with more elaborate frameworks that include the structure of internal layers, such as their temporal and spatial variations.(2) The identification of ice mass change based on the internal layers using the current Antarctic ice sheet as the initial conditions.(3) The increase of observations of the subglacial environment, to obtain higher resolution quantitative images of the isochronous layer structure and ice deformation.

  19. Estimation of the shortening rate since late Pleistocene in the Aksu area on the southern flank of the Tianshan, China

    WANG; Xin


    , central Asia, Geol. Soc. Amer. Bull., 1996, 108: 1004-1021.[12]Allen, M. B., Vincents, S. J., Wheeler, P. J., Late cenozoic tectonics of the Kepingtoge thrust zone: Interaction between the Tianshan and the Tarim Basin, northwest China,Tectonics, 1999, 18: 639-654.[13]Burchfiel, B. C., Brown, E. T., Deng Qidong et al., Crustal shortening on the margins of the Tianshan, Xinjiang, China, 2000, (unpublished).[14]Brown, E, T., Boarles, D. C., Barchfiel, B. C. et al., Estimation of slip rates in the southern Tianshan using cosmic ray ex-posure dates of abandoned alluvial fans, Geol, Soc. Amer. Bull., 1998, 110: 377-386.[15]Yin, A., Nie, S., Craig, P. et al., Late cenozoic tectonic evolution of the southern Chinese Tainshan, Tectonics, 1998, 17: 1-27.[16]Hubert-Ferrari, A., Suppe, J., Wang, X. et al., 18 kyr, 120 kyr and 5 Myr shortening rates along the front of the southern Tianshan Mountain (China), Geol.Soc.America, Abstracts, 1999.[17]Shi Yafeng, Zheng Benxing, Su Zhen et al., Study of Quaternary glaciation in Mts. Tomur-Hantengri area, Tianshan, Jour-nal of Glaciology and Cryopedology (in Chinese), 1984,6: 1-14.[18]Shi Yafeng, Tang Macang, Ma Yuzhen, Linkage between the second uplifting of the Qinghai-Tibetan Plateau and the ini-tiation of the Asian, Science in China, Ser. D, 1999, 42(3): 303-312.[19]Zheng Benxing, Glacial geomorphological map (1:200000)of Mt.Tomar Region, Tianshan, Annals of Glaciology, 1986, 8: 209.

  20. Impact of Po Valley emissions on the highest glacier of the Eastern European Alps

    J. Gabrieli


    Full Text Available In June 2009, we conducted the first extensive glaciological survey of Alto dell'Ortles, the uppermost glacier of Mt. Ortles (3905 m a.s.l., the highest summit of the Eastern European Alps. This section of the Alps is located in a rain shadow and is characterized by the lowest precipitation rate in the entire Alpine arc. Mt. Ortles offers a unique opportunity to test deposition mechanisms of chemical species that until now were studied only in the climatically-different western sector. We analyzed snow samples collected on Alto dell'Ortles from a 4.5 m snow-pit at 3830 m a.s.l., and we determined a large suite of trace elements and ionic compounds that comprise the atmospheric deposition over the past two years.

    Trace element concentrations measured in snow samples are extremely low with mean concentrations at pg g−1 levels. Only Al and Fe present median values of 1.8 and 3.3 ng g−1, with maximum concentrations of 21 and 25 ng g−1. The median crustal enrichment factor (EFc values for Be, Rb, Sr, Ba, U, Li, Al, Ca, Cr, Mn, Fe, Co, Ga and V are lower than 10 suggesting that these elements originated mainly from soil and mineral aerosol. EFc higher than 100 are reported for Zn (118, Ag (135, Bi (185, Sb (401 and Cd (514, demonstrating the predominance of non-crustal depositions and suggesting an anthropogenic origin.

    Our data show that the physical stratigraphy and the chemical signals of several species were well preserved in the uppermost snow of the Alto dell'Ortles glacier. A clear seasonality emerges from the data as the summer snow is more affected by anthropogenic and marine contributions while the winter aerosol flux is dominated by crustal sources. For trace elements, the largest mean EFc seasonal variations are displayed by V (with a factor of 3.8, Sb (3.3, Cu (3.3, Pb (2.9, Bi (2.8, Cd (2.1, Zn (1.9, Ni (1.8, Ag (1.8, As (1.7 and Co (1.6.

    When trace species ratios in local

  1. AirBase - A database of 160,000 aerial photos of Greenland 1930-1980s

    Korsgaard, Niels; Weng, Willy L.; Kjær, Kurt H.


    Beginning in the 1930s Danish survey agencies and US military organizations conducted large-scale aerial photograph surveys of Greenland for mapping purposes (1), eventuating in the recording of more than 160,000 photographs. Glaciological researchers have used this amazing resource of multi-decadal observations of the Greenlandic cryosphere for many decades (e.g. (2), (3), (4)). In recent years this information has been synthesized with modern remote sensing data resulting in a range of published research and data sets ((5), (6), (7), (8)). Today, the historical aerial photographs are stored at the SDFE (Agency for Data Supply and Effiency), the successor agency for the institutions doing the surveying and mapping of Greenland where the material is accessible to researchers and general public alike. The digitized flightline maps and databases necessary for the creation of this data for this work was made available by the SDFE, and it the past and present work with this database we present here. Based on digitized flight line maps, the database contains geocoded metadata such as recording dates, camera and film roll canister, connecting the database with the analog archive material. Past work concentrated on bulk digitization, while the focus of the current work is to improve positional accuracy, completeness, and refinements for web publication. (1) Nielsen, A., Olsen, J. & Weng, W. L. Grønlands opmåling og kortlægning. Landinspektøren 37 (1995). (2) Weidick A. Frontal variations at Upernaviks Isstrøm in the last 100 years. Medd. fra Dansk Geol. Forening. Vol. 14 (1958. (3) Bauer, A., Baussart, M., Carbonnell, M., Kasser, P. Perroud, P. & Renaud, A. Missions aériennes de reconnaissance au Groenland 1957-1958. Observations aériennes et terrestres, exploitation des photographies aériennes, détermination des vitesses des glaciers vêlant dans Disko Bugt et Umanak Fjord. Meddelelser om Grønland 173(3) (1968a. (4) Rignot, E. Box, J.E., Burgess, E. & Hanna, E

  2. Use of the SAR (Synthetic Aperture Radar) P band for detection of the Moche and Lambayeque canal networks in the Apurlec region, Perù

    Ilaria Pannaccione Apa, Maria; Santovito, Maria Rosaria; Pica,