WorldWideScience

Sample records for winter snow cover

  1. Monitoring Forsmark. Snow depth, snow water content and ice cover during the winter 2010/2011

    International Nuclear Information System (INIS)

    Wass, Eva

    2011-07-01

    Snow depth and ice cover have been measured and observed during the winter 2010/2011. This type of measurements started in the winter 2002/2003 and has been ongoing since then. In addition to these parameters, the water content of the snow was calculated at each measurement occasion from the weight of a snow sample. Measurements and observations were conducted on a regular basis from the beginning of November 2010 until the middle of April 2011. A persistent snow cover was established in the end of November 2010 and remained until the beginning of April 2011 at the station with longest snow cover duration. The period of ice cover was 160 days in Lake Eckarfjaerden, whereas the sea bay at SFR was ice covered for 135 days

  2. Variability of snow line elevation, snow cover area and depletion in the main Slovak basins in winters 2001–2014

    Directory of Open Access Journals (Sweden)

    Krajčí Pavel

    2016-03-01

    Full Text Available Spatial and temporal variability of snow line (SL elevation, snow cover area (SCA and depletion (SCD in winters 2001–2014 is investigated in ten main Slovak river basins (the Western Carpathians. Daily satellite snow cover maps from MODIS Terra (MOD10A1, V005 and Aqua (MYD10A1, V005 with resolution 500 m are used.

  3. Long-term variability in Northern Hemisphere snow cover and associations with warmer winters

    Science.gov (United States)

    McCabe, Gregory J.; Wolock, David M.

    2010-01-01

    A monthly snow accumulation and melt model is used with gridded monthly temperature and precipitation data for the Northern Hemisphere to generate time series of March snow-covered area (SCA) for the period 1905 through 2002. The time series of estimated SCA for March is verified by comparison with previously published time series of SCA for the Northern Hemisphere. The time series of estimated Northern Hemisphere March SCA shows a substantial decrease since about 1970, and this decrease corresponds to an increase in mean winter Northern Hemisphere temperature. The increase in winter temperature has caused a decrease in the fraction of precipitation that occurs as snow and an increase in snowmelt for some parts of the Northern Hemisphere, particularly the mid-latitudes, thus reducing snow packs and March SCA. In addition, the increase in winter temperature and the decreases in SCA appear to be associated with a contraction of the circumpolar vortex and a poleward movement of storm tracks, resulting in decreased precipitation (and snow) in the low- to mid-latitudes and an increase in precipitation (and snow) in high latitudes. If Northern Hemisphere winter temperatures continue to warm as they have since the 1970s, then March SCA will likely continue to decrease.

  4. Biogeochemical Impact of Snow Cover and Cyclonic Intrusions on the Winter Weddell Sea Ice Pack

    Science.gov (United States)

    Tison, J.-L.; Schwegmann, S.; Dieckmann, G.; Rintala, J.-M.; Meyer, H.; Moreau, S.; Vancoppenolle, M.; Nomura, D.; Engberg, S.; Blomster, L. J.; Hendrickx, S.; Uhlig, C.; Luhtanen, A.-M.; de Jong, J.; Janssens, J.; Carnat, G.; Zhou, J.; Delille, B.

    2017-12-01

    Sea ice is a dynamic biogeochemical reactor and a double interface actively interacting with both the atmosphere and the ocean. However, proper understanding of its annual impact on exchanges, and therefore potentially on the climate, notably suffer from the paucity of autumnal and winter data sets. Here we present the results of physical and biogeochemical investigations on winter Antarctic pack ice in the Weddell Sea (R. V. Polarstern AWECS cruise, June-August 2013) which are compared with those from two similar studies conducted in the area in 1986 and 1992. The winter 2013 was characterized by a warm sea ice cover due to the combined effects of deep snow and frequent warm cyclones events penetrating southward from the open Southern Ocean. These conditions were favorable to high ice permeability and cyclic events of brine movements within the sea ice cover (brine tubes), favoring relatively high chlorophyll-a (Chl-a) concentrations. We discuss the timing of this algal activity showing that arguments can be presented in favor of continued activity during the winter due to the specific physical conditions. Large-scale sea ice model simulations also suggest a context of increasingly deep snow, warm ice, and large brine fractions across the three observational years, despite the fact that the model is forced with a snowfall climatology. This lends support to the claim that more severe Antarctic sea ice conditions, characterized by a longer ice season, thicker, and more concentrated ice are sufficient to increase the snow depth and, somehow counterintuitively, to warm the ice.

  5. Snow cover and extreme winter warming events control flower abundance of some, but not all species in high arctic Svalbard

    DEFF Research Database (Denmark)

    Semenchuk, Philipp R.; Elberling, Bo; Cooper, Elisabeth J.

    2013-01-01

    frequent extreme winter warming events. Flower production of many Arctic plants is dependent on melt out timing, since season length determines resource availability for flower preformation. We erected snow fences to increase snow depth and shorten growing season, and counted flowers of six species over 5......years, during which we experienced two extreme winter warming events. Most species were resistant to snow cover increase, but two species reduced flower abundance due to shortened growing seasons. Cassiope tetragona responded strongly with fewer flowers in deep snow regimes during years without extreme...... events, while Stellaria crassipes responded partly. Snow pack thickness determined whether winter warming events had an effect on flower abundance of some species. Warming events clearly reduced flower abundance in shallow but not in deep snow regimes of Cassiope tetragona, but only marginally for Dryas...

  6. IOD influence on the early winter tibetan plateau snow cover: diagnostic analyses and an AGCM simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Chaoxia; Tozuka, Tomoki; Yamagata, Toshio [The University of Tokyo, Department of Earth and Planetary Science, Graduate School of Science, Tokyo (Japan)

    2012-10-15

    Using diagnostic analyses and an AGCM simulation, the detailed mechanism of Indian Ocean Dipole (IOD) influence on the early winter Tibetan Plateau snow cover (EWTPSC) is clarified. In early winter of pure positive IOD years with no co-occurrence of El Nino, the anomalous dipole diabatic heating over the tropical Indian Ocean excites the baroclinic response in the tropics. Since both baroclinic and barotropic components of the basic zonal wind over the Arabian Peninsula increase dramatically in early winter due to the equatorward retreat of the westerly jet, the baroclinic mode excites the barotropic Rossby wave that propagates northeastward and induces a barotropic cyclonic anomaly north of India. This enables the moisture transport cyclonically from the northern Indian Ocean toward the Tibetan Plateau. The convergence of moisture over the plateau explains the positive influence of IOD on the EWTPSC. In contrast, the basic zonal wind over the Arabian Peninsula is weak in autumn. This is not favorable for excitation of the barotropic Rossby wave and teleconnection, even though the IOD-related diabatic heating anomaly in autumn similar to that in early winter exists. This result explains the insignificant (significant positive) partial correlation between IOD and the autumn (early winter) Tibetan Plateau snow cover after excluding the influence of ENSO. The sensitivity experiment forced by the IOD-related SST anomaly within the tropical Indian Ocean well reproduces the baroclinic response in the tropics, the teleconnection from the Arabian Peninsula, and the increased moisture supply to the Tibetan Plateau. Also, the seasonality of the atmospheric response to the IOD is simulated. (orig.)

  7. Isotope composition of winter precipitation and snow cover in the foothills of the Altai

    Directory of Open Access Journals (Sweden)

    N. S. Malygina

    2017-01-01

    Full Text Available Over the past three decades, several general circulation models of the atmosphere and ocean (atmospheric and oceanic general circulation models  – GCMs have been improved by modeling the hydrological cycle with the use of isotopologues (isotopes of water HDO and H2 18O. Input parameters for the GCM models taking into account changes in the isotope composition of atmospheric precipitation were, above all, the results obtained by the network GNIP – Global Network of Isotopes in Precipitation. At different times, on the vast territory of Russia there were only about 40 simultaneously functioning stations where the sampling of atmospheric precipitation was performed. In this study we present the results of the isotope composition of samples taken on the foothills of the Altai during two winter seasons of 2014/15 and 2015/16. Values of the isotope composition of precipitation changed in a wide range and their maximum fluctuations were 25, 202 and 18‰ for δ18О, dexc and δD, respectively. The weighted-mean values of δ18О and δD of the precipitation analyzed for the above two seasons were close to each other (−21.1 and −158.1‰ for the first season and −21.1 and −161.9‰ for the second one, while dexc values differed significantly. The comparison of the results of isotope analysis of the snow cover integral samples with the corresponding in the time interval the weighted-mean values of precipitation showed high consistency. However, despite the similarity of values of δ18О and δD, calculated for precipitation and snow cover, and the results, interpolated in IsoMAP (from data of the GNIP stations for 1960–2010, the dexc values were close to mean annual values of IsoMAP for only the second winter season. According to the trajectory analysis (the HYSPLIT model, the revealed differences between both, the seasons, and the long-term average values of IsoMAP, were associated with a change of main regions where the air masses

  8. Winter stream temperature in the rain-on-snow zone of the Pacific Northwest: influences of hillslope runoff and transient snow cover

    Directory of Open Access Journals (Sweden)

    J. A. Leach

    2014-02-01

    Full Text Available Stream temperature dynamics during winter are less well studied than summer thermal regimes, but the winter season thermal regime can be critical for fish growth and development in coastal catchments. The winter thermal regimes of Pacific Northwest headwater streams, which provide vital winter habitat for salmonids and their food sources, may be particularly sensitive to changes in climate because they can remain ice-free throughout the year and are often located in rain-on-snow zones. This study examined winter stream temperature patterns and controls in small headwater catchments within the rain-on-snow zone at the Malcolm Knapp Research Forest, near Vancouver, British Columbia, Canada. Two hypotheses were addressed by this study: (1 winter stream temperatures are primarily controlled by advective fluxes associated with runoff processes and (2 stream temperatures should be depressed during rain-on-snow events, compared to rain-on-bare-ground events, due to the cooling effect of rain passing through the snowpack prior to infiltrating the soil or being delivered to the stream as saturation-excess overland flow. A reach-scale energy budget analysis of two winter seasons revealed that the advective energy input associated with hillslope runoff overwhelms vertical energy exchanges (net radiation, sensible and latent heat fluxes, bed heat conduction, and stream friction and hyporheic energy fluxes during rain and rain-on-snow events. Historical stream temperature data and modelled snowpack dynamics were used to explore the influence of transient snow cover on stream temperature over 13 winters. When snow was not present, daily stream temperature during winter rain events tended to increase with increasing air temperature. However, when snow was present, stream temperature was capped at about 5 °C, regardless of air temperature. The stream energy budget modelling and historical analysis support both of our hypotheses. A key implication is that

  9. The value of snow cover

    Science.gov (United States)

    Sokratov, S. A.

    2009-04-01

    Snow is the natural resource, like soil and water. It has specific properties which allow its use not just for skiing but also for houses cooling in summer (Swedish experience), for air fields construction (Arctic and Antarctic), for dams (north of Russia), for buildings (not only snow-houses of some Polar peoples but artistic hotel attracting tourists in Sweden), and as art material (Sapporo snow festival, Finnish events), etc. "Adjustment" of snow distribution and amount is not only rather common practice (avalanche-protection constructions keeping snow on slopes) but also the practice with long history. So-called "snow irrigation" was used in Russia since XIX century to protect winter crop. What is now named "artificial snow production", is part of much larger pattern. What makes it special—it is unavoidable in present climate and economy situation. 5% of national income in Austria is winter tourism. 50% of the economy in Savoy relay on winter tourism. In terms of money this can be less, but in terms of jobs and income involved this would be even more considerable in Switzerland. As an example—the population of Davos is 14000 in Summer and 50000 in Winter. Skiing is growing business. In present time you can find ski slopes in Turkey and Lebanon. To keep a cite suitable for attracting tourists you need certain amount of sunny days and certain amount of snow. The snow cannons are often the only way to keep a place running. On the other hand, more artificial snow does not necessary attract more tourists, while heavy natural snowfall does attract them. Artificial snow making is costly and requires infrastructure (ponds and electric lines) with very narrow range of weather conditions. Related companies are searching for alternatives and one of them can be "weather regulation" by distribution of some chemical components in clouds. It did not happen yet, but can happen soon. The consequences of such interference in Nature is hardly known. The ski tourism is not the

  10. Partial least regression approach to forecast the East Asian winter monsoon using Eurasian snow cover and sea surface temperature

    Science.gov (United States)

    Yu, Lulu; Wu, Zhiwei; Zhang, Renhe; Yang, Xin

    2017-06-01

    Seasonal prediction of the East Asian (EA) winter monsoon (EAWM) is of great significance yet a challenging issue. In this study, three statistical seasonal prediction models for the EAWM are established using three leading modes of the Eurasian snow cover (ESC), the first leading mode of sea surface temperature (SST) and the four leading modes of the combination of the ESC and SST in preceding autumn, respectively. These leading modes are identified by the partial-least square (PLS) regression. The first PLS (PLS1) mode for the ESC features significantly anomalous snow cover in Siberia and Tibetan Plateau regions. The ESC second PLS (PLS2) mode corresponds to large areas of snow cover anomalies in the central Siberia, whereas the third PLS (PLS3) mode a meridional seesaw pattern of ESC. The SST PLS1 mode basically exhibits an El Niño-Southern Oscillation developing phase in equatorial eastern Pacific and significant SST anomalies in North Atlantic. A strong EAWM tends to emerge in a La Niña year concurrent with cold SST anomalies in the North Atlantic, and vice versa. After a 35-year training period (1967-2001), three PLS seasonal prediction models are constructed and the 11-year hindcast is performed for the period of 2002-2012, respectively. The PLS model based on combination of the autumn ESC and SST exhibits the best hindcast skill among the three models, its correlation coefficient between the observation and the hindcast reaching 0.86. This indicates that this physical-based PLS model may provide another practical tool for the EAWM. In addition, the relative contribution of the ESC and SST is also examined by assessing the hindcast skills of the other two PLS models constructed solely by the ESC or SST. Possible physical mechanisms are also discussed.

  11. Indicative properties on snow cover based on the results of experimental studies in the winter 2011/12 in the central part of the East European Plain

    Directory of Open Access Journals (Sweden)

    L. M. Kitaev

    2013-01-01

    Full Text Available Local and regional differences in the snow formation were studied in different landscapes of the central part of the East European Plain – within reserves in the Moscow and Tver’ regions (south-north direction; the study period is the winter 2011/12. The observed increase of snow storage in 1.3–1.5 times in the direction south-north is connected, apparently. The difference in the five-day appearance of snow cover maximum is related to differences in regional winter air temperature. Throughout the snow depth and snow storage in spruce are smaller than in deciduous forest – in the ratio of 0.81 in south area and 0.93 in north area; in spruce the large part of solid precipitation is intercepted by the crowns pine trees. Snow stratigraphy at south areas has four layers, six layers at the north area are more variable in snow density and snow storage. Perhaps, gravitational conversion is more noticeable due to larger snow depth. Snow density and snow storage at the open areas are more heterogeneous than in the forest. This is due to sharp fluctuations in air temperature, wind transport and compaction of snow, evaporation from the snow surface. The stratigraphy of snow also reflects the history of winter changes of air temperature and snow accumulation. Common feature for reserves at south and north is the availability of layers with maximum snow storage in the middle of the snow thickness, which were formed during the air temperature drops to the lowest seasonal values in period with increase of snow depth to maximum. Formation of depth hoar in snow thickness are touched everywhere the bottom and middle layers, respectively, it was formed both before and during the period with minimal air temperature. Thus, the results of experimental studies confirm the significance of the differences of individual components of the landscape setting. Analytical conclusions are largely qualitative in nature due to the lack to date of initial information, and

  12. Winter survival of Scots pine seedlings under different snow conditions.

    Science.gov (United States)

    Domisch, Timo; Martz, Françoise; Repo, Tapani; Rautio, Pasi

    2018-04-01

    Future climate scenarios predict increased air temperatures and precipitation, particularly at high latitudes, and especially so during winter. Soil temperatures, however, are more difficult to predict, since they depend strongly on the fate of the insulating snow cover. 'Rain-on-snow' events and warm spells during winter can lead to thaw-freeze cycles, compacted snow and ice encasement, as well as local flooding. These adverse conditions could counteract the otherwise positive effects of climatic changes on forest seedling growth. In order to study the effects of different winter and snow conditions on young Scots pine (Pinus sylvestris L.) seedlings, we conducted a laboratory experiment in which 80 1-year-old Scots pine seedlings were distributed between four winter treatments in dasotrons: ambient snow cover (SNOW), compressed snow and ice encasement (ICE), flooded and frozen soil (FLOOD) and no snow (NO SNOW). During the winter treatment period and a 1.5-month simulated spring/early summer phase, we monitored the needle, stem and root biomass of the seedlings, and determined their starch and soluble sugar concentrations. In addition, we assessed the stress experienced by the seedlings by measuring chlorophyll fluorescence, electric impedance and photosynthesis of the previous-year needles. Compared with the SNOW treatment, carbohydrate concentrations were lower in the FLOOD and NO SNOW treatments where the seedlings had almost died before the end of the experiment, presumably due to frost desiccation of aboveground parts during the winter treatments. The seedlings of the ICE treatment showed dead needles and stems only above the snow and ice cover. The results emphasize the importance of an insulating and protecting snow cover for small forest tree seedlings, and that future winters with changed snow patterns might affect the survival of tree seedlings and thus forest productivity.

  13. MODIS Snow-Cover Products

    Science.gov (United States)

    Hall, Dorothy K.; Riggs, George A.; Salomonson, Vincent V.; DiGirolamo, Nicole E.; Bayr, Klaus J.; Houser, Paul R. (Technical Monitor)

    2002-01-01

    On December 18, 1999, the Terra satellite was launched with a complement of five instruments including the Moderate Resolution Imaging Spectroradiometer (MODIS). Many geophysical products are derived from MODIS data including global snow-cover products. MODIS snow and ice products have been available through the National Snow and Ice Data Center (NSIDC) Distributed Active Archive Center (DAAC) since September 13, 2000. MODIS snow-cover products represent potential improvement to or enhancement of the currently-available operational products mainly because the MODIS products are global and 500-m resolution, and have the capability to separate most snow and clouds. Also the snow-mapping algorithms are automated which means that a consistent data set may be generated for long-term climate studies that require snow-cover information. Extensive quality assurance (QA) information is stored with the products. The MODIS snow product suite begins with a 500-m resolution, 2330-km swath snow-cover map which is then gridded to an integerized sinusoidal grid to produce daily and 8-day composite tile products. The sequence proceeds to a climate-modeling grid (CMG) product at about 5.6-km spatial resolution, with both daily and 8-day composite products. Each pixel of the CMG contains fraction of snow cover from 40 - 100%. Measured errors of commission in the CMG are low, for example, on the continent of Australia in the spring, they vary from 0.02 - 0.10%. Near-term enhancements include daily snow albedo and fractional snow cover. A case study from March 6, 2000, involving MODIS data and field and aircraft measurements, is presented to show some early validation work.

  14. Effect of summer throughfall exclusion, summer drought, and winter snow cover on methane fluxes in a temperate forest soil

    Science.gov (United States)

    Borken, W.; Davidson, E.A.; Savage, K.; Sundquist, E.T.; Steudler, P.

    2006-01-01

    Soil moisture strongly controls the uptake of atmospheric methane by limiting the diffusion of methane into the soil, resulting in a negative correlation between soil moisture and methane uptake rates under most non-drought conditions. However, little is known about the effect of water stress on methane uptake in temperate forests during severe droughts. We simulated extreme summer droughts by exclusion of 168 mm (2001) and 344 mm (2002) throughfall using three translucent roofs in a mixed deciduous forest at the Harvard Forest, Massachusetts, USA. The treatment significantly increased CH4 uptake during the first weeks of throughfall exclusion in 2001 and during most of the 2002 treatment period. Low summertime CH4 uptake rates were found only briefly in both control and exclusion plots during a natural late summer drought, when water contents below 0.15 g cm-3 may have caused water stress of methanotrophs in the A horizon. Because these soils are well drained, the exclusion treatment had little effect on A horizon water content between wetting events, and the effect of water stress was smaller and more brief than was the overall treatment effect on methane diffusion. Methane consumption rates were highest in the A horizon and showed a parabolic relationship between gravimetric water content and CH4 consumption, with maximum rate at 0.23 g H2O g-1 soil. On average, about 74% of atmospheric CH4 was consumed in the top 4-5 cm of the mineral soil. By contrast, little or no CH4 consumption occurred in the O horizon. Snow cover significantly reduced the uptake rate from December to March. Removal of snow enhanced CH4 uptake by about 700-1000%, resulting in uptake rates similar to those measured during the growing season. Soil temperatures had little effect on CH4 uptake as long as the mineral soil was not frozen, indicating strong substrate limitation of methanotrophs throughout the year. Our results suggest that the extension of snow periods may affect the annual rate

  15. Storing snow for the next winter: Two case studies on the application of snow farming.

    Science.gov (United States)

    Grünewald, Thomas; Wolfsperger, Fabian

    2016-04-01

    Snow farming is the conservation of snow during the warm half-year. This means that large piles of snow are formed in spring in order to be conserved over the summer season. Well-insulating materials such as chipped wood are added as surface cover to reduce melting. The aim of snow farming is to provide a "snow guaranty" for autumn or early winter - this means that a specific amount of snow will definitively be available, independent of the weather conditions. The conserved snow can then be used as basis for the preparation of winter sports grounds such as cross-country tracks or ski runs. This helps in the organization of early winter season sport events such as World Cup races or to provide appropriate training conditions for athletes. We present a study on two snow farming projects, one in Davos (Switzerland) and one in the Martell valley of South Tyrol. At both places snow farming has been used for several years. For the summer season 2015, we monitored both snow piles in order to assess the amount of snow conserved. High resolution terrestrial laser scanning was performed to measure snow volumes of the piles at the beginning and at the end of the summer period. Results showed that only 20% to 30 % of the snow mass was lost due to ablation. This mass loss was surprisingly low considering the extremely warm and dry summer. In order to identify the most relevant drivers of snow melt we also present simulations with the sophisticated snow cover models SNOWPACK and Alpine3D. The simulations are driven by meteorological input data recorded in the vicinity of the piles and enable a detailed analysis of the relevant processes controlling the energy balance. The models can be applied to optimize settings for snow farming and to examine the suitability of new locations, configurations or cover material for future snow farming projects.

  16. Surface energy balance of seasonal snow cover for snow-melt ...

    Indian Academy of Sciences (India)

    This study describes time series analysis of snow-melt, radiation data and energy balance for a seasonal snow cover at Dhundi field station of SASE, which lies in Pir Panjal range of the. N–W Himalaya, for a winter season from 13 January to 12 April 2005. The analysis shows that mean snow surface temperature remains ...

  17. Distributed calibrating snow models using remotely sensed snow cover information

    Science.gov (United States)

    Li, H.

    2015-12-01

    Distributed calibrating snow models using remotely sensed snow cover information Hongyi Li1, Tao Che1, Xin Li1, Jian Wang11. Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China For improving the simulation accuracy of snow model, remotely sensed snow cover data are used to calibrate spatial parameters of snow model. A physically based snow model is developed and snow parameters including snow surface roughness, new snow density and critical threshold temperature distinguishing snowfall from precipitation, are spatially calibrated in this study. The study region, Babaohe basin, located in northwestern China, have seasonal snow cover and with complex terrain. The results indicates that the spatially calibration of snow model parameters make the simulation results more reasonable, and the simulated snow accumulation days, plot-scale snow depth are more better than lumped calibration.

  18. Consistent seasonal snow cover depth and duration variability over ...

    Indian Academy of Sciences (India)

    Decline in consistent seasonal snow cover depth, duration and changing snow cover build- up pattern over the WH in recent decades indicate that WH has undergone considerable climate change and winter weather patterns are changing in the WH. 1. Introduction. Mountainous regions around the globe are storehouses.

  19. Past and future of the Austrian snow cover - results from the CC-Snow project

    Science.gov (United States)

    Strasser, Ulrich; Marke, Thomas; Hanzer, Florian; Ragg, Hansjörg; Kleindienst, Hannes; Wilcke, Renate; Gobiet, Andreas

    2013-04-01

    This study has the goal to simulate the evolution of the Austrian snow cover from 1971 to 2050 by means of a coupled modelling scheme, and to estimate the effect of climate change on the evolution of the natural snow cover. The model outcomes are interepreted with focus on both the future natural snow conditions, and the effects on winter skiing tourism. Therefore the regional temperature-index snow model SNOWREG is applied, providing snow maps with a spatial resolution of 250 m. The model is trained by means of assimilating local measurements and observed natural snow cover patterns. Meteorological forcing consists of the output of four realizations of the ENSEMBLES project for the A1B emission scenario. The meteorological variables are downscaled and error corrected with a quantile based empirical-statistical method on a daily time basis. The control simulation is 1971-2000, and the scenario simulation 2021-2050. Spatial interpolation is performed on the basis of parameter-elevation relations. We compare the four different global/regional climate model combinations and their effect on the snow modelling, and we explain the patterns of the resulting snow cover by means of regional climatological characteristics. The provinces Tirol and Styria serve as test regions, being typical examples for the two climatic subregions of Austria. To support the interpretation of the simulation results we apply indicators which enable to define meaningful measures for the comparison of the different periods and regions. Results show that the mean duration of the snow cover will decrease by 15 to 30 days per winter season, mostly in elevations between 2000 and 2500 m. Above 3000 m the higher winter precipitation can compensate this effect, and mean snow cover duration may even slightly increase. We also investigate the local scale by application of the physically based mountain snow model AMUNDSEN. This model is capable of producing 50 m resolution output maps for indicators

  20. [Snow cover pollution monitoring in Ufa].

    Science.gov (United States)

    Daukaev, R A; Suleĭmanov, R A

    2008-01-01

    The paper presents the results of examining the snow cover polluted with heavy metals in the large industrial town of Ufa. The level of man-caused burden on the snow cover of the conventional parts of the town was estimated and compared upon exposure to a wide range of snow cover pollutants. The priority snow cover pollutants were identified among the test heavy metals.

  1. Assimilation of snow cover and snow depth into a snow model to estimate snow water equivalent and snowmelt runoff in a Himalayan catchment

    Directory of Open Access Journals (Sweden)

    E. E. Stigter

    2017-07-01

    Full Text Available Snow is an important component of water storage in the Himalayas. Previous snowmelt studies in the Himalayas have predominantly relied on remotely sensed snow cover. However, snow cover data provide no direct information on the actual amount of water stored in a snowpack, i.e., the snow water equivalent (SWE. Therefore, in this study remotely sensed snow cover was combined with in situ observations and a modified version of the seNorge snow model to estimate (climate sensitivity of SWE and snowmelt runoff in the Langtang catchment in Nepal. Snow cover data from Landsat 8 and the MOD10A2 snow cover product were validated with in situ snow cover observations provided by surface temperature and snow depth measurements resulting in classification accuracies of 85.7 and 83.1 % respectively. Optimal model parameter values were obtained through data assimilation of MOD10A2 snow maps and snow depth measurements using an ensemble Kalman filter (EnKF. Independent validations of simulated snow depth and snow cover with observations show improvement after data assimilation compared to simulations without data assimilation. The approach of modeling snow depth in a Kalman filter framework allows for data-constrained estimation of snow depth rather than snow cover alone, and this has great potential for future studies in complex terrain, especially in the Himalayas. Climate sensitivity tests with the optimized snow model revealed that snowmelt runoff increases in winter and the early melt season (December to May and decreases during the late melt season (June to September as a result of the earlier onset of snowmelt due to increasing temperature. At high elevation a decrease in SWE due to higher air temperature is (partly compensated by an increase in precipitation, which emphasizes the need for accurate predictions on the changes in the spatial distribution of precipitation along with changes in temperature.

  2. Utilizing Multiple Datasets for Snow Cover Mapping

    Science.gov (United States)

    Tait, Andrew B.; Hall, Dorothy K.; Foster, James L.; Armstrong, Richard L.

    1999-01-01

    Snow-cover maps generated from surface data are based on direct measurements, however they are prone to interpolation errors where climate stations are sparsely distributed. Snow cover is clearly discernable using satellite-attained optical data because of the high albedo of snow, yet the surface is often obscured by cloud cover. Passive microwave (PM) data is unaffected by clouds, however, the snow-cover signature is significantly affected by melting snow and the microwaves may be transparent to thin snow (less than 3cm). Both optical and microwave sensors have problems discerning snow beneath forest canopies. This paper describes a method that combines ground and satellite data to produce a Multiple-Dataset Snow-Cover Product (MDSCP). Comparisons with current snow-cover products show that the MDSCP draws together the advantages of each of its component products while minimizing their potential errors. Improved estimates of the snow-covered area are derived through the addition of two snow-cover classes ("thin or patchy" and "high elevation" snow cover) and from the analysis of the climate station data within each class. The compatibility of this method for use with Moderate Resolution Imaging Spectroradiometer (MODIS) data, which will be available in 2000, is also discussed. With the assimilation of these data, the resolution of the MDSCP would be improved both spatially and temporally and the analysis would become completely automated.

  3. MODIS Snow Cover Recovery Using Variational Interpolation

    Science.gov (United States)

    Tran, H.; Nguyen, P.; Hsu, K. L.; Sorooshian, S.

    2017-12-01

    Cloud obscuration is one of the major problems that limit the usages of satellite images in general and in NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) global Snow-Covered Area (SCA) products in particular. Among the approaches to resolve the problem, the Variational Interpolation (VI) algorithm method, proposed by Xia et al., 2012, obtains cloud-free dynamic SCA images from MODIS. This method is automatic and robust. However, computational deficiency is a main drawback that degrades applying the method for larger scales (i.e., spatial and temporal scales). To overcome this difficulty, this study introduces an improved version of the original VI. The modified VI algorithm integrates the MINimum RESidual (MINRES) iteration (Paige and Saunders., 1975) to prevent the system from breaking up when applied to much broader scales. An experiment was done to demonstrate the crash-proof ability of the new algorithm in comparison with the original VI method, an ability that is obtained when maintaining the distribution of the weights set after solving the linear system. After that, the new VI algorithm was applied to the whole Contiguous United States (CONUS) over four winter months of 2016 and 2017, and validated using the snow station network (SNOTEL). The resulting cloud free images have high accuracy in capturing the dynamical changes of snow in contrast with the MODIS snow cover maps. Lastly, the algorithm was applied to create a Cloud free images dataset from March 10, 2000 to February 28, 2017, which is able to provide an overview of snow trends over CONUS for nearly two decades. ACKNOWLEDGMENTSWe would like to acknowledge NASA, NOAA Office of Hydrologic Development (OHD) National Weather Service (NWS), Cooperative Institute for Climate and Satellites (CICS), Army Research Office (ARO), ICIWaRM, and UNESCO for supporting this research.

  4. Spatiotemporal variability of snow cover and snow water equivalent in the last three decades over Eurasia

    Science.gov (United States)

    Zhang, Yinsheng; Ma, Ning

    2018-04-01

    Changes in the extent and amount of snow cover in Eurasia are of great interest because of their vital impacts on the global climate system and regional water resource management. This study investigated the spatial and temporal variability of the snow cover extent (SCE) and snow water equivalent (SWE) of the continental Eurasia using the Northern Hemisphere Equal-Area Scalable Earth Grid (EASE-Grid) Weekly SCE data for 1972-2006 and the Global Monthly EASE-Grid SWE data for 1979-2004. The results indicated that, in general, the spatial extent of snow cover significantly decreased during spring and summer, but varied little during autumn and winter over Eurasia in the study period. The date at which snow cover began to disappear in spring has significantly advanced, whereas the timing of snow cover onset in autumn did not vary significantly during 1972-2006. The snow cover persistence period declined significantly in the western Tibetan Plateau as well as partial area of Central Asia and northwestern Russia, but varied little in other parts of Eurasia. "Snow-free breaks" (SFBs) with intermittent snow cover in the cold season were principally observed in the Tibetan Plateau and Central Asia, causing a low sensitivity of snow cover persistence period to the timings of snow cover onset and disappearance over the areas with shallow snow. The averaged SFBs were 1-14 weeks during the study period and the maximum intermittence could even reach 25 weeks in certain years. At a seasonal scale, SWE usually peaked in February or March, but fell gradually since April across Eurasia. Both annual mean and annual maximum SWE decreased significantly during 1979-2004 in most parts of Eurasia except for eastern Siberia as well as northwestern and northeastern China. The possible cross-platform inconsistencies between two passive microwave radiometers may cause uncertainties in the detected trends of SWE here, suggesting an urgent need of producing a long-term, more homogeneous SWE

  5. Estimation of the condition of snow cover in Voronezh according to the chemical analysis of water from melted snow

    OpenAIRE

    Prozhorina Tatyana Ivanovna; Bespalova Elena Vladimirovna; Yakunina Nadezhda

    2014-01-01

    Snow cover possesses high sorption ability and represents informative object to identify technogenic pollution of an urban environment. In this article the investigation data of a chemical composition of snow fallen in Voronezh during the winter period of 2014 are given. Relationships between existence of pollutants in snow and the level of technogenic effect are analyzed.

  6. Validation of MODIS snow cover images over Austria

    Directory of Open Access Journals (Sweden)

    J. Parajka

    2006-01-01

    Full Text Available This study evaluates the Moderate Resolution Imaging Spectroradiometer (MODIS snow cover product over the territory of Austria. The aims are (a to analyse the spatial and temporal variability of the MODIS snow product classes, (b to examine the accuracy of the MODIS snow product against in situ snow depth data, and (c to identify the main factors that may influence the MODIS classification accuracy. We use daily MODIS grid maps (version 4 and daily snow depth measurements at 754 climate stations in the period from February 2000 to December 2005. The results indicate that, on average, clouds obscured 63% of Austria, which may significantly restrict the applicability of the MODIS snow cover images to hydrological modelling. On cloud-free days, however, the classification accuracy is very good with an average of 95%. There is no consistent relationship between the classification errors and dominant land cover type and local topographical variability but there are clear seasonal patterns to the errors. In December and January the errors are around 15% while in summer they are less than 1%. This seasonal pattern is related to the overall percentage of snow cover in Austria, although in spring, when there is a well developed snow pack, errors tend to be smaller than they are in early winter for the same overall percent snow cover. Overestimation and underestimation errors balance during most of the year which indicates little bias. In November and December, however, there appears to exist a tendency for overestimation. Part of the errors may be related to the temporal shift between the in situ snow depth measurements (07:00 a.m. and the MODIS acquisition time (early afternoon. The comparison of daily air temperature maps with MODIS snow cover images indicates that almost all MODIS overestimation errors are caused by the misclassification of cirrus clouds as snow.

  7. Effect of snow cover on soil frost penetration

    Science.gov (United States)

    Rožnovský, Jaroslav; Brzezina, Jáchym

    2017-12-01

    Snow cover occurrence affects wintering and lives of organisms because it has a significant effect on soil frost penetration. An analysis of the dependence of soil frost penetration and snow depth between November and March was performed using data from 12 automated climatological stations located in Southern Moravia, with a minimum period of measurement of 5 years since 2001, which belong to the Czech Hydrometeorological institute. The soil temperatures at 5 cm depth fluctuate much less in the presence of snow cover. In contrast, the effect of snow cover on the air temperature at 2 m height is only very small. During clear sky conditions and no snow cover, soil can warm up substantially and the soil temperature range can be even higher than the range of air temperature at 2 m height. The actual height of snow is also important - increased snow depth means lower soil temperature range. However, even just 1 cm snow depth substantially lowers the soil temperature range and it can therefore be clearly seen that snow acts as an insulator and has a major effect on soil frost penetration and soil temperature range.

  8. Snow cover - characteristics and trends for the meteorological mountain stations in Romania

    Science.gov (United States)

    Manea, A.; Ralita, I.; Dumitrescu, Al.; Boroneant, C.

    2009-04-01

    Snow cover represents an important climatological parameter for the specialized analysis because it can provide useful information regarding the climatological evolution of one region, taking into account the variability of the climate. The latest years brought milder winters for Romania. The number of days with snow cover and the depth of snow cover are very important factors for the mountain tourism and the winter sports. This paper presents the trends of the number of days with snow cover and the snow depth over the 1961-2007 period for 18 mountain meteorological stations in Romania. In this case, "mountain station" refers to a station located at an altitude higher than 1000 m.

  9. Influence of snow-cover properties on avalanche dynamics

    Science.gov (United States)

    Steinkogler, W.; Sovilla, B.; Lehning, M.

    2012-04-01

    Snow avalanches with the potential of reaching traffic routes and settlements are a permanent winter threat for many mountain communities. Snow safety officers have to take the decision whether to close a road, a railway line or a ski slope. Those decisions are often very difficult as they demand the ability to interpret weather forecasts, to establish their implication for the stability and the structure of the snow cover and to evaluate the influence of the snow cover on avalanche run-out distances. In the operational programme 'Italy-Switzerland, project STRADA' we focus on the effects of snow cover on avalanche dynamics, and thus run-out distance, with the aim to provide a better understanding of this influence and to ultimately develop tools to support snow safety officers in their decision process. We selected five avalanches, measured at the Vallée de la Sionne field site, with similar initial mass and topography but different flow dynamics and run-out distances. Significant differences amongst the individual avalanches could be observed for front and internal velocities, impact pressures, flow regimes, deposition volumes and run-out distances. For each of these avalanches, the prevailing snow conditions at release were reconstructed using field data from local snowpits or were modeled with SNOWPACK. Combining flow dynamical data with snow cover properties shows that erodible snow depth, snow density and snow temperature in the snow pack along the avalanche track are among the decisive variables that appear to explain the observed differences. It is further discussed, how these influencing factors can be quantified and used for improved predictions of site and time specific avalanche hazard.

  10. Central Asian Snow Cover from Hydrometeorological Surveys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Central Asian Snow Cover from Hydrometeorological Surveys data are based on observations made by personnel for three river basins: Amu Darya, Sir Darya, and...

  11. Improving automated disturbance maps using snow-covered landsat time series stacks

    Science.gov (United States)

    Kirk M. Stueve; Ian W. Housman; Patrick L. Zimmerman; Mark D. Nelson; Jeremy Webb; Charles H. Perry; Robert A. Chastain; Dale D. Gormanson; Chengquan Huang; Sean P. Healey; Warren B. Cohen

    2012-01-01

    Snow-covered winter Landsat time series stacks are used to develop a nonforest mask to enhance automated disturbance maps produced by the Vegetation Change Tracker (VCT). This method exploits the enhanced spectral separability between forested and nonforested areas that occurs with sufficient snow cover. This method resulted in significant improvements in Vegetation...

  12. Prevalence of Pure Versus Mixed Snow Cover Pixels across Spatial Resolutions in Alpine Environments

    Directory of Open Access Journals (Sweden)

    David J. Selkowitz

    2014-12-01

    Full Text Available Remote sensing of snow-covered area (SCA can be binary (indicating the presence/absence of snow cover at each pixel or fractional (indicating the fraction of each pixel covered by snow. Fractional SCA mapping provides more information than binary SCA, but is more difficult to implement and may not be feasible with all types of remote sensing data. The utility of fractional SCA mapping relative to binary SCA mapping varies with the intended application as well as by spatial resolution, temporal resolution and period of interest, and climate. We quantified the frequency of occurrence of partially snow-covered (mixed pixels at spatial resolutions between 1 m and 500 m over five dates at two study areas in the western U.S., using 0.5 m binary SCA maps derived from high spatial resolution imagery aggregated to fractional SCA at coarser spatial resolutions. In addition, we used in situ monitoring to estimate the frequency of partially snow-covered conditions for the period September 2013–August 2014 at 10 60-m grid cell footprints at two study areas with continental snow climates. Results from the image analysis indicate that at 40 m, slightly above the nominal spatial resolution of Landsat, mixed pixels accounted for 25%–93% of total pixels, while at 500 m, the nominal spatial resolution of MODIS bands used for snow cover mapping, mixed pixels accounted for 67%–100% of total pixels. Mixed pixels occurred more commonly at the continental snow climate site than at the maritime snow climate site. The in situ data indicate that some snow cover was present between 186 and 303 days, and partial snow cover conditions occurred on 10%–98% of days with snow cover. Four sites remained partially snow-free throughout most of the winter and spring, while six sites were entirely snow covered throughout most or all of the winter and spring. Within 60 m grid cells, the late spring/summer transition from snow-covered to snow-free conditions lasted 17–56 days

  13. Estimation of snow cover distribution in Beas basin, Indian Himalaya ...

    Indian Academy of Sciences (India)

    of snow cover in the study area are snow under vegetation, contaminated snow and patchy snow. To overcome these problems, ... using planetary reflectance), NIR band reflectance and forest/vegetation cover information. The satellite estimated ... exerts an influence on hydropower generation sys- tem, water management ...

  14. MODIS Snow Cover Mapping Decision Tree Technique: Snow and Cloud Discrimination

    Science.gov (United States)

    Riggs, George A.; Hall, Dorothy K.

    2010-01-01

    Accurate mapping of snow cover continues to challenge cryospheric scientists and modelers. The Moderate-Resolution Imaging Spectroradiometer (MODIS) snow data products have been used since 2000 by many investigators to map and monitor snow cover extent for various applications. Users have reported on the utility of the products and also on problems encountered. Three problems or hindrances in the use of the MODIS snow data products that have been reported in the literature are: cloud obscuration, snow/cloud confusion, and snow omission errors in thin or sparse snow cover conditions. Implementation of the MODIS snow algorithm in a decision tree technique using surface reflectance input to mitigate those problems is being investigated. The objective of this work is to use a decision tree structure for the snow algorithm. This should alleviate snow/cloud confusion and omission errors and provide a snow map with classes that convey information on how snow was detected, e.g. snow under clear sky, snow tinder cloud, to enable users' flexibility in interpreting and deriving a snow map. Results of a snow cover decision tree algorithm are compared to the standard MODIS snow map and found to exhibit improved ability to alleviate snow/cloud confusion in some situations allowing up to about 5% increase in mapped snow cover extent, thus accuracy, in some scenes.

  15. Interannual changes in snow cover and its impact on ground surface temperatures in Livingston Island (Antarctica)

    Science.gov (United States)

    Nieuwendam, Alexandre; Ramos, Miguel; Vieira, Gonçalo

    2015-04-01

    In permafrost areas the seasonal snow cover is an important factor on the ground thermal regime. Snow depth and timing are important in ground insulation from the atmosphere, creating different snow patterns and resulting in spatially variable ground temperatures. The aim of this work is to characterize the interactions between ground thermal regimes and snow cover and the influence on permafrost spatial distribution. The study area is the ice-free terrains of northwestern Hurd Peninsula in the vicinity of the Spanish Antarctic Station "Juan Carlos I" and Bulgarian Antarctic Station "St. Kliment Ohridski". Air and ground temperatures and snow thickness data where analysed from 4 sites along an altitudinal transect in Hurd Peninsula from 2007 to 2012: Nuevo Incinerador (25 m asl), Collado Ramos (110 m), Ohridski (140 m) and Reina Sofia Peak (275 m). The data covers 6 cold seasons showing different conditions: i) very cold with thin snow cover; ii) cold with a gradual increase of snow cover; iii) warm with thick snow cover. The data shows three types of periods regarding the ground surface thermal regime and the thickness of snow cover: a) thin snow cover and short-term fluctuation of ground temperatures; b) thick snow cover and stable ground temperatures; c) very thick snow cover and ground temperatures nearly constant at 0°C. a) Thin snow cover periods: Collado Ramos and Ohridski sites show frequent temperature variations, alternating between short-term fluctuations and stable ground temperatures. Nuevo Incinerador displays during most of the winter stable ground temperatures; b) Cold winters with a gradual increase of the snow cover: Nuevo Incinerador, Collado Ramos and Ohridski sites show similar behavior, with a long period of stable ground temperatures; c) Thick snow cover periods: Collado Ramos and Ohridski show long periods of stable ground, while Nuevo Incinerador shows temperatures close to 0°C since the beginning of the winter, due to early snow cover

  16. Forcing the snow-cover model SNOWPACK with forecasted weather data

    Directory of Open Access Journals (Sweden)

    S. Bellaire

    2011-12-01

    Full Text Available Avalanche danger is often estimated based on snow cover stratigraphy and snow stability data. In Canada, single forecasting regions are very large (>50 000 km2 and snow cover data are often not available. To provide additional information on the snow cover and its seasonal evolution the Swiss snow cover model SNOWPACK was therefore coupled with a regional weather forecasting model GEM15. The output of GEM15 was compared to meteorological as well as snow cover data from Mt. Fidelity, British Columbia, Canada, for five winters between 2005 and 2010. Precipitation amounts are most difficult to predict for weather forecasting models. Therefore, we first assess the capability of the model chain to forecast new snow amounts and consequently snow depth. Forecasted precipitation amounts were generally over-estimated. The forecasted data were therefore filtered and used as input for the snow cover model. Comparison between the model output and manual observations showed that after pre-processing the input data the snow depth and new snow events were well modelled. In a case study two key factors of snow cover instability, i.e. surface hoar formation and crust formation were investigated at a single point. Over half of the relevant critical layers were reproduced. Overall, the model chain shows promising potential as a future forecasting tool for avalanche warning services in Canadian data sparse areas and could thus well be applied to similarly large regions elsewhere. However, a more detailed analysis of the simulated snow cover structure is still required.

  17. Deriving Snow Cover Metrics for Alaska from MODIS

    Directory of Open Access Journals (Sweden)

    Chuck Lindsay

    2015-09-01

    Full Text Available Moderate Resolution Imaging Spectroradiometer (MODIS daily snow cover products provide an opportunity for determining snow onset and melt dates across broad geographic regions; however, cloud cover and polar darkness are limiting factors at higher latitudes. This study presents snow onset and melt dates for Alaska, portions of western Canada and the Russian Far East derived from Terra MODIS snow cover daily 500 m grid data (MOD10A1 and evaluates our method for filling data gaps caused by clouds or polar darkness. Pixels classified as cloud or no data were reclassified by: spatial filtering using neighboring pixel values; temporal filtering using pixel values for days before/after cloud cover; and snow-cycle filtering based on a time series assessment of a pixel’s position within snow accumulation, cover or melt periods. During the 2012 snow year, these gap-filling methods reduced cloud pixels from 27.7% to 3.1%. A total of 12 metrics (e.g., date of first and last snow, date of persistent snow cover and periods of intermittence for each pixel were calculated by snow year. A comparison of MODIS-derived snow onset and melt dates with in situ observations from 244 weather stations generally showed an early bias in MODIS-derived dates and an effect of increasing cloudiness exacerbating bias. Our results show that mean regional duration of seasonal snow cover is 179–311 days/year and that snow cover is often intermittent, with 41% of the area experiencing ≥2 snow-covered periods during a snow season. Other regional-scale patterns in the timing of snow onset and melt are evident in the yearly 500 m gridded products publically available at http://static.gina.alaska.edu/NPS_products/MODIS_snow/.

  18. SNOW CLEARING SERVICE WINTER 2001-2002

    CERN Multimedia

    ST-HM Group; Tel. 72202

    2001-01-01

    As usual at this time of the year, the snowing clearing service, which comes under the control of the Transport Group (ST-HM), is preparing for the start of snow-clearing operations (timetable, stand-by service, personnel responsible for driving vehicles and machines, preparation of useful and necessary equipment, work instructions, etc.) in collaboration with the Cleaning Service (ST-TFM) and the Fire Brigade (TIS-FB). The main difficulty for the snow-clearing service is the car parks, which cannot be properly cleared because of the presence of CERN and private vehicles parked there overnight in different parts of the parking areas. The ST-HM Transport Group would therefore like to invite you to park vehicles together in order to facilitate the access of the snow ploughs, thus allowing the car parks to be cleared more efficiently before the personnel arrives for work in the mornings.

  19. Relationship of deer and moose populations to previous winters' snow

    Science.gov (United States)

    Mech, L.D.; McRoberts, R.E.; Peterson, R.O.; Page, R.E.

    1987-01-01

    (1) Linear regression was used to relate snow accumulation during single and consecutive winters with white-tailed deer (Odocoileus virginianus) fawn:doe ratios, mosse (Alces alces) twinning rates and calf:cow ratios, and annual changes in deer and moose populations. Significant relationships were found between snow accumulation during individual winters and these dependent variables during the following year. However, the strongest relationships were between the dependent variables and the sums of the snow accumulations over the previous three winters. The percentage of the variability explained was 36 to 51. (2) Significant relationships were also found between winter vulnerability of moose calves and the sum of the snow accumulations in the current, and up to seven previous, winters, with about 49% of the variability explained. (3) No relationship was found between wolf numbers and the above dependent variables. (4) These relationships imply that winter influences on maternal nutrition can accumulate for several years and that this cumulative effect strongly determines fecundity and/or calf and fawn survivability. Although wolf (Canis lupus L.) predation is the main direct mortality agent on fawns and calves, wolf density itself appears to be secondary to winter weather in influencing the deer and moose populations.

  20. Snow Cover Monitoring Using MODIS Data in Liaoning Province, Northeastern China

    Directory of Open Access Journals (Sweden)

    Yu Lu

    2010-03-01

    Full Text Available This paper presents the results of snow cover monitoring studies in Liaoning Province, northeastern China, using MODIS data. Snow cover plays an important role in both the regional water balance and soil moisture properties during the early spring in northeastern China. In addition, heavy snowfalls commonly trigger hazards such as flooding, caused by rapid snow melt, or crop failure, resulting from fluctuations in soil temperature associated with changes in the snow cover. The latter is a function of both regional, or global, climatic changes, as well as fluctuations in the albedo resulting from variations in the Snow Covered Area (SCA. These impacts are crucial to human activities, especially to those living in middle-latitude areas such as Liaoning Province. Thus, SCA monitoring is currently an important tool in studies of global climate change, particularly because satellite remote sensing data provide timely and efficient snow cover information for large areas. In this study, MODIS L1B data, MODIS Daily Snow Products (MOD10A1 and MODIS 8-day Snow Products (MOD10A2 were used to monitor the SCA of Liaoning Province over the winter months of November–April, 2006–2008. The effects of cloud masking and forest masking on the snow monitoring results were also assessed. The results show that the SCA percentage derived from MODIS L1B data is relatively consistent, but slightly higher than that obtained from MODIS Snow Products. In situ data from 25 snow stations were used to assess the accuracy of snow cover monitoring from the SCA compared to the results from MODIS Snow Products. The studies found that the SCA results were more reliable than MODIS Snow Products in the study area.

  1. ISLSCP II Northern Hemisphere Monthly Snow Cover Extent

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This ISLSCP data set is derived from the National Snow and Ice Data Center (NSIDC) Northern Hemisphere EASE-Grid Weekly Snow Cover and Sea Ice Extent...

  2. ISLSCP II Northern Hemisphere Monthly Snow Cover Extent

    Data.gov (United States)

    National Aeronautics and Space Administration — This ISLSCP data set is derived from the National Snow and Ice Data Center (NSIDC) Northern Hemisphere EASE-Grid Weekly Snow Cover and Sea Ice Extent product which...

  3. [Characteristics of chemical pollution of snow cover in Aktobe areas].

    Science.gov (United States)

    Iskakov, A Zh

    2010-01-01

    The paper gives data on the nature of snow cover pollution in the urbanized areas in relation to the remoteness from the basic sources of ambient air pollution. The total snow content of carcinogens has been estimated.

  4. Snow line analysis in the Romanian Carpathians under the influence of winter warming

    Science.gov (United States)

    Micu, Dana; Cosmin Sandric, Ionut

    2013-04-01

    The Romanian Carpathians are subject to winter warming as statistically proved by station measurements over a 47 year period (1961-2007). Herein, the snow season is considered to last from the 1st of November to the 30th of April, when snowpack usually reaches the highest stability and thickness. This paper investigates the signals of winter temperature and precipitation change at 17 mountain station located above 1,000 m, as being considered the main triggering factors of large fluctuations in snow amount and duration in these mountains. Fewer snowfalls were recorded all over the Romanian Carpathians after the mid 80s and over large mountain areas (including the alpine ones) the frequency of positive temperature extremes became higher (e.g. winter heat waves). Late Fall snowfalls and snowpack onsets (mainly in mid elevation areas, located below 1,700 m) and particularly the shifts towards early Spring snowmelts (at all the sites) were statistically proved to explain the decline of snow cover duration across the Carpathians. However, the sensitivity of snow cover duration to recent winter warming is still blurred in the high elevation areas (above 2,000 m). The trends in winter climate variability observed in the Romanian Carpathians beyond 1,000 m altitude are fairly comparable to those estimated in other European mountain ranges from observational data (e.g. the Swiss Alps, the French Alps and the Tatra Mts.). In relation to the climate change signals derived from observational data provided by low density mountain meteorological network (of about 3.3 stations per km2 in the areas above 1,000 m), the paper analysis the spatial probability and evolution trends of snow line in each winter season across the Romanian Carpathians, based on Landsat satellite data (MSS, TM and ETM+), with sufficiently high spatial (30 to 60 m) and temporal resolutions (850 images), over the 1973-2011 period. The Landsat coverage was considered suitable enough to enable an objective

  5. The effects of changes in snow depth on winter recreation

    Czech Academy of Sciences Publication Activity Database

    Zahradníček, Pavel; Rožnovský, J.; Štěpánek, Petr; Farda, Aleš; Brzezina, J.

    2016-01-01

    Roč. 7, č. 1 (2016), s. 44-54 ISSN 1804-2821 R&D Projects: GA MŠk(CZ) LO1415; GA ČR GA13-04291S; GA ČR(CZ) GA14-12262S Institutional support: RVO:67179843 Keywords : new snow * total snow depth * climate change * climate models * winter recreations Subject RIV: EH - Ecology, Behaviour

  6. Snow cover monitoring in the Kyrgyz Republic through MODIS time series (2000-2010)

    Science.gov (United States)

    Dedieu, J.-P.; Doutreleau, V.; Lessard-Fontaine, A.; Shalpykova, G.

    2012-04-01

    The Kyrgyz Republic is located at the convergence of two mountain systems (Tien Shan and Pamirs) in Central Asia. The region is of great interest all of Central Asia because of its consequent capital in water resources. Theses resources are of importance for electricity production (~15 TWH/year) and irrigation of agricultural land. Over 50% of the 52 km3 of Kyrgyz runoff water irrigates the Syr Darya River which flows over 2200 km from the confluence of Naryn and Kara Darya rivers to the Aral Sea. Around 40% of the Kyrgyz territory lies above 3000m; part of the water resource is cumulated as snow during large periods of the year. Snow cover is thus an important part of the Kyrgyz hydrological cycle. In this already water-stressed region, both climate change and irrigation expansion could trigger a greater scarcity of the resource in the future. One of the major impact could be a modification of the melting season period and the snow melt behavior. The use of passive optical remote sensing data could provide helpful complementary information for hydrological modeling of these effects, but currently, very few scientific publications concerning the Syr Darya headwaters in Kyrgyztan exist. Integrated in the EU-FP7 ACQWA Project (www.acqwa.ch), this study proposes 11 years of snow cover analysis using MODIS snow cover product data. The following parameters are retrieved from MODIS data: Snow Cover Area (SCA), Snow Fraction (FRA), snow cover duration and depletion maps. A Digital Elevation Model (DEM) from the NASA-SRTM database is used to better understand the topographic influence on snow melt behavior and a Land Use database (GlobCover 2009) for the environmental context of snow cover evolution. A statistical analysis of snow cover dynamics is performed on a 2000-2010 8-days temporal resolution dataset. Yearly mean snow cover is 40 ± 5 % and melting runs with 5%.8j-1 average velocity. We observe a greater variation of the inter-annual snow cover extent in winter

  7. Nimbus-7 SMMR Derived Monthly Global Snow Cover and Snow Depth

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set consists of monthly global snow cover and snow depth derived from Nimbus-7 SMMR data for 1978 through 1987. The SMMR data are interpolated for spatial...

  8. Nimbus-7 SMMR Derived Monthly Global Snow Cover and Snow Depth, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set consists of monthly global snow cover and snow depth derived from Nimbus-7 SMMR data for 1978 through 1987. The SMMR data are interpolated for spatial...

  9. Arctic moisture source for Eurasian snow cover variations in autumn

    Science.gov (United States)

    Wegmann, Martin; Orsolini, Yvan; Vázquez Dominguez, Marta; Gimeno Presa, Luis; Nieto, Raquel; Buligyna, Olga; Jaiser, Ralf; Handorf, Dörthe; Rinke, Anette; Dethloff, Klaus; Sterin, Alexander; Brönnimann, Stefan

    2015-04-01

    Global warming is enhanced at high northern latitudes where the Arctic surface air temperature has risen at twice the rate of the global average in recent decades - a feature called Arctic amplification. This recent Arctic warming signal likely results from several factors such as the albedo feedback due to a diminishing cryosphere, enhanced poleward atmospheric and oceanic transport, and change in humidity. The reduction in Arctic sea ice is without doubt substantial and a key factor. Arctic summer sea-ice extent has declined by more than 10% per decade since the start of the satellite era (e.g. Stroeve et al., 2012), culminating in a new record low in September 2012, with the long-term trend largely attributed to anthropogenic global warming. Eurasian snow cover changes have been suggested as a driver for changes in the Arctic Oscillation and might provide a link between sea ice decline in the Arctic during summer and atmospheric circulation in the following winter. However, the mechanism connecting snow cover in Eurasia to sea ice decline in autumn is still under debate. Our analysis focuses at sea ice decline in the Barents-Kara Sea region, which allows us to specify regions of interest for FLEXPART forward and backwards moisture trajectories. Based on Eularian and Lagrangian diagnostics from ERA-INTERIM, we can address the origin and cause of late autumn snow depth variations in a dense (snow observations from 820 land stations), unutilized observational datasets over the Commonwealth of Independent States. Open waters in the Barents and Kara Sea have been shown to increase the diabatic heating of the atmosphere, which amplifies baroclinic cyclones and might induce a remote atmospheric response by triggering stationary Rossby waves (Honda et al. 2009). In agreement with these studies, our results show enhanced storm activity originating at the Barents and Kara with disturbances entering the continent through a small sector from the Barents and Kara Seas

  10. Satellite Snow-Cover Mapping: A Brief Review

    Science.gov (United States)

    Hall, Dorothy K.

    1995-01-01

    Satellite snow mapping has been accomplished since 1966, initially using data from the reflective part of the electromagnetic spectrum, and now also employing data from the microwave part of the spectrum. Visible and near-infrared sensors can provide excellent spatial resolution from space enabling detailed snow mapping. When digital elevation models are also used, snow mapping can provide realistic measurements of snow extent even in mountainous areas. Passive-microwave satellite data permit global snow cover to be mapped on a near-daily basis and estimates of snow depth to be made, but with relatively poor spatial resolution (approximately 25 km). Dense forest cover limits both techniques and optical remote sensing is limited further by cloudcover conditions. Satellite remote sensing of snow cover with imaging radars is still in the early stages of research, but shows promise at least for mapping wet or melting snow using C-band (5.3 GHz) synthetic aperture radar (SAR) data. Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) data beginning with the launch of the first EOS platform in 1998. Digital maps will be produced that will provide daily, and maximum weekly global snow, sea ice and lake ice cover at 1-km spatial resolution. Statistics will be generated on the extent and persistence of snow or ice cover in each pixel for each weekly map, cloudcover permitting. It will also be possible to generate snow- and ice-cover maps using MODIS data at 250- and 500-m resolution, and to study and map snow and ice characteristics such as albedo. been under development. Passive-microwave data offer the potential for determining not only snow cover, but snow water equivalent, depth and wetness under all sky conditions. A number of algorithms have been developed to utilize passive-microwave brightness temperatures to provide information on snow cover and water equivalent. The variability of vegetative Algorithms are being developed to map global snow

  11. Monitoring Areal Snow Cover Using NASA Satellite Imagery

    Science.gov (United States)

    Harshburger, Brian J.; Blandford, Troy; Moore, Brandon

    2011-01-01

    The objective of this project is to develop products and tools to assist in the hydrologic modeling process, including tools to help prepare inputs for hydrologic models and improved methods for the visualization of streamflow forecasts. In addition, this project will facilitate the use of NASA satellite imagery (primarily snow cover imagery) by other federal and state agencies with operational streamflow forecasting responsibilities. A GIS software toolkit for monitoring areal snow cover extent and producing streamflow forecasts is being developed. This toolkit will be packaged as multiple extensions for ArcGIS 9.x and an opensource GIS software package. The toolkit will provide users with a means for ingesting NASA EOS satellite imagery (snow cover analysis), preparing hydrologic model inputs, and visualizing streamflow forecasts. Primary products include a software tool for predicting the presence of snow under clouds in satellite images; a software tool for producing gridded temperature and precipitation forecasts; and a suite of tools for visualizing hydrologic model forecasting results. The toolkit will be an expert system designed for operational users that need to generate accurate streamflow forecasts in a timely manner. The Remote Sensing of Snow Cover Toolbar will ingest snow cover imagery from multiple sources, including the MODIS Operational Snowcover Data and convert them to gridded datasets that can be readily used. Statistical techniques will then be applied to the gridded snow cover data to predict the presence of snow under cloud cover. The toolbar has the ability to ingest both binary and fractional snow cover data. Binary mapping techniques use a set of thresholds to determine whether a pixel contains snow or no snow. Fractional mapping techniques provide information regarding the percentage of each pixel that is covered with snow. After the imagery has been ingested, physiographic data is attached to each cell in the snow cover image. This data

  12. Analysis of the Lake Superior Watershed Seasonal Snow Cover

    National Research Council Canada - National Science Library

    Daly, Steven F; Baldwin, Timothy B; Weyrick, Patricia

    2007-01-01

    Daily estimates of the snow water equivalent (SWE) distribution for the period from 1 December through 30 April for each winter season from 1979 80 through 2002 03 were calculated for the entire Lake Superior watershed...

  13. Estimation of snow cover distribution in Beas basin, Indian Himalaya ...

    Indian Academy of Sciences (India)

    areas of Himalaya, which is at high altitude,. Keywords. Snow cover monitoring; NDSI; AWiFS; reflectance; topographic corrections. J. Earth Syst. Sci. 118, No. 5, October 2009, pp. ... characteristics of snow and vegetation to reduce the errors caused ...... Thakur N and Manoj 2002a Effect of global warming on snow ablation ...

  14. Estimation of snow cover distribution in Beas basin, Indian Himalaya ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 118; Issue 5 ... The satellite estimated snow or non-snow pixel information using proposed methodology was validated with the snow cover information collected at three observatory locations and it was found that the algorithm classify all the sample points correctly ...

  15. How autumn Eurasian snow anomalies affect east asian winter monsoon: a numerical study

    Science.gov (United States)

    Luo, Xiao; Wang, Bin

    2018-03-01

    Previous studies have found that snow Eurasian anomalies in autumn can affect East Asian winter monsoon (EAWM), but the mechanisms remain controversial and not well understood. The possible mechanisms by which Eurasian autumn snow anomalies affect EAWM are investigated by numerical experiments with a coupled general circulation model and its atmospheric general circulation model component. The leading empirical orthogonal function mode of the October-November mean Eurasian snow cover is characterized by a uniform anomaly over a broad region of central Eurasia (40°N-65°N, 60°E-140°E). However, the results from a 150-ensemble mean simulation with snow depth anomaly specified in October and November reveal that the Mongolian Plateau and Vicinity (MPV, 40°-55°N, 80°-120°E) is the key region for autumn snow anomalies to affect EAWM. The excessive snow forcing can significantly enhance EAWM and the snowfall over the northwestern China and along the EAWM front zone stretching from the southeast China to Japan. The physical process involves a snow-monsoon feedback mechanism. The excessive autumn snow anomalies over the MPV region can persist into the following winter, and significantly enhance winter snow anomalies, which increase surface albedo, reduce incoming solar radiation and cool the boundary layer air, leading to an enhanced Mongolian High and a deepened East Asian trough. The latter, in turn, strengthen surface northwesterly winds, cooling East Asia and increasing snow accumulation over the MPV region and the southeastern China. The increased snow covers feedback to EAWM system through changing albedo, extending its influence southeastward. It is also found that the atmosphere-ocean coupling process can amplify the delayed influence of Eurasian snow mass anomaly on EAWM. The autumn surface albedo anomalies, however, do not have a lasting "memory" effect. Only if the albedo anomalies are artificially extended into December and January, will the EAWM be

  16. Hydrological Implications of Covering Wind-Blown Snow Accumulations with Geotextiles on Mount Aragats, Armenia

    Directory of Open Access Journals (Sweden)

    Alexander Nestler

    2014-07-01

    Full Text Available Snow is an excellent water reservoir, naturally storing large quantities of water at time scales from a few days to several months. In summer-dry countries, like Armenia, runoff due to snow melt from mountain regions is highly important for a sustained water supply (irrigation, hydropower. Snow fields on Mount Aragats, Armenia’s highest peak, often persist until July, providing vital amounts of melt water. Artificially managing these wind-driven snow accumulations as a natural water reservoir might have considerable potential. In the context of the Swiss-Armenian joint venture, Freezwater, snow fields are covered with geotextiles in order to delay snow melt long enough to provide additional melt water in the dry season of the year. In this study, we analyze the hydrological effectiveness of the artificial management of the natural snow cover on Mount Aragats based on various field measurements acquired over a three-year period and numerical modeling. Over the winter season, partly more than five meter-thick snow deposits are formed supported by snow redistribution by strong wind. Repeated mappings of snow fields indicate that snow cover patterns remain highly consistent over time. Measurements of ablation below manually applied geotextiles show a considerable reduction of melt rates by more than 50%. Simulations with an energy-balance model and a distributed temperature-index model allow assessing the hydrological effect of artificial snow management for different initial snow depths and elevations and suggest that coverage is needed at a large scale in order to generate a significant impact on discharge.

  17. Alpine snow cover in a changing climate: a regional climate model perspective

    Science.gov (United States)

    Steger, Christian; Kotlarski, Sven; Jonas, Tobias; Schär, Christoph

    2013-08-01

    An analysis is presented of an ensemble of regional climate model (RCM) experiments from the ENSEMBLES project in terms of mean winter snow water equivalent (SWE), the seasonal evolution of snow cover, and the duration of the continuous snow cover season in the European Alps. Two sets of simulations are considered, one driven by GCMs assuming the SRES A1B greenhouse gas scenario for the period 1951-2099, and the other by the ERA-40 reanalysis for the recent past. The simulated SWE for Switzerland for the winters 1971-2000 is validated against an observational data set derived from daily snow depth measurements. Model validation shows that the RCMs are capable of simulating the general spatial and seasonal variability of Alpine snow cover, but generally underestimate snow at elevations below 1,000 m and overestimate snow above 1,500 m. Model biases in snow cover can partly be related to biases in the atmospheric forcing. The analysis of climate projections for the twenty first century reveals high inter-model agreement on the following points: The strongest relative reduction in winter mean SWE is found below 1,500 m, amounting to 40-80 % by mid century relative to 1971-2000 and depending upon the model considered. At these elevations, mean winter temperatures are close to the melting point. At higher elevations the decrease of mean winter SWE is less pronounced but still a robust feature. For instance, at elevations of 2,000-2,500 m, SWE reductions amount to 10-60 % by mid century and to 30-80 % by the end of the century. The duration of the continuous snow cover season shows an asymmetric reduction with strongest shortening in springtime when ablation is the dominant factor for changes in SWE. We also find a substantial ensemble-mean reduction of snow reliability relevant to winter tourism at elevations below about 1,800 m by mid century, and at elevations below about 2,000 m by the end of the century.

  18. The ringed seal's last refuge and the importance of snow cover

    Science.gov (United States)

    Kelly, B. P.; Bitz, C. M.

    2010-12-01

    Ringed seals are strongly adapted to inhabiting seasonal ice cover throughout the Arctic Ocean, marginal seas, and some freshwater lakes. Their distribution has expanded and contracted with northern hemisphere ice cover and is expected to mirror declining ice cover in coming decades. Ringed seals require snow cover to provide shelter from extreme cold and from predators, and the southern extent of their range corresponds to the latitudes to which snow cover—sufficient to form and maintain subnivean lairs—extends. The lairs are especially critical to the survival of pups born and nursed under the snow in late March through May. Snow drifts 50 cm or deeper are necessary for lair occupation, and field measurements indicate that such drifting occurs only where average snow depths (on flat ice) exceed 20 cm. When snow depths are less, ringed seal pups freeze in their lairs and are vulnerable to predation by carnivores and birds. As the climate warms, winter precipitation is expected to increase in the Arctic Ocean, potentially favoring formation and occupation of lairs. At the same time, increasingly late ice formation is expected to decrease the overall accumulation of snow, an effect exacerbated by the high fraction of annual snow fall that occurs in autumn. Early snow melts also contribute to pup mortality and are likely to increase as the climate warms. We forecast April snow depths on Arctic sea ice through the year 2100 in seven runs of CCSM3. Despite predicted increases in winter precipitation in the Arctic, the model forecasted that the accumulation of snow on sea ice will decrease by almost 50% in this century. The timing of the onset of snow melt changes little in the projections, but the shallower snow pack will melt more quickly in the warmer climate. In almost all portions of the range, average snow depths are expected to be less than 20 cm and inadequate for successful rearing of ringed seal young by the end of the century and—in many locations

  19. Snow cover as a source of technogenic pollution of surface water during the snow melting period

    OpenAIRE

    Labuzova Olga; Noskova Tatyana; Lysenko Maria; Ovcharenko Elena; Papina Tatyana

    2016-01-01

    The study of pollutants in melt water of snow cover and snow disposal sites in the city of Barnaul showed that during the snow melting period the surface water is not subjected to significant technogenic impact according to a number of studied indices. The oils content is an exception: it can exceed MAC more than 20 times in river- water due to the melting of city disposal sites. Environmental damage due to an oils input into water resources during the snow melting period...

  20. Consistent seasonal snow cover depth and duration variability over ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 125; Issue 7. Consistent seasonal ... Consistent seasonal snow cover depth and duration, delay days and early melt days of consistent seasonal snow cover at 11 stations spread across different mountain ranges over the WH were analyzed. Mean, maximum and ...

  1. Snow Based Winter Tourism and Kinds of Adaptations to Climate Change

    Science.gov (United States)

    Breiling, M.

    2009-04-01

    Austria is the most intensive winter tourism country in the world with some 4% contribution in the national GNP. Snow based winter tourism became the lead economy of mountain areas, covering two thirds of the country and is by far economically more important than agriculture and forestry. While natural snow was the precondition for the establishment of winter tourism, artificial snow is nowadays the precondition to maintain winter tourism in the current economic intensity. Skiing originally low tech, is developing increasingly into high tech. While skiing was comparatively cheap in previous days due to natural snow, skiing is getting more expensive and exclusive for a higher income class due to the relative high production costs. Measures to adapt to a warmer climate can be divided into three principle types: physical adaptation, technical adaptation - where artificial snow production plays a major role - and social adaptation. It will be discussed under which conditions each adaptation type seems feasible in dependence of the level of warming. In particular physical and technical adaptations are related to major investments. Practically every ski resort has to decide about what is an appropriate, economically cost efficient level of adaptation. Adapting too much reduces profits. Adapting too little does not bring enough income. The optimal level is often not clear. In many cases public subsidies help to collect funds for adaptation and to keep skiing profitable. The possibility to adapt on local, regional or on national scales will depend on the degree of warming, the future price of artificial snow production and the public means foreseen to support the winter tourism industry.

  2. Brilliant Colours from a White Snow Cover

    Science.gov (United States)

    Vollmer, Michael; Shaw, Joseph A

    2013-01-01

    Surprisingly colourful views are possible from sparkling white snow. It is well known that similarly colourful features can exist in the sky whenever appropriate ice crystals are around. However, the transition of light reflection and refraction from ice crystals in the air to reflection and refraction from those in snow on the ground is not…

  3. Cartographic modelling of aerotechnogenic pollution in snow cover in the landscapes of the Kola Peninsula.

    Science.gov (United States)

    Ratkin, N E; Asming, V E; Koshkin, V V

    2001-01-01

    The goal of this work was to develop computational techniques for sulphates, nickel and copper accumulation in the snow in the local pollution zone. The main task was to reveal the peculiarities of formation and pollution of snow cover on the region with complex cross-relief. A digital cartographic model of aerotechnogenic pollution of snow cover in the landscapes of the local zone has been developed, based on five-year experimental data. Data regarding annual emissions from the industrial complex, information about distribution of wind and the sum of precipitation from meteostation "Nikel" for the winter period, allowed the model to ensure: * material presentation in the form of maps of water capacity and accumulation of sulphates, nickel and copper in the snow over any winter period in retrospective; * calculation of water capacity and accumulation of pollutants for watersheds and other natural-territorial complexes; * solution of the opposite problem about the determination of the emissions of sulphates, nickel and copper from the enterprise by measuring snow pollution in datum points. The model can be used in other northern regions of the Russian Federation with similar physical-geographical and climatic conditions. The relationships between the sum of precipitation and water capacity in the landscapes of the same type and also the relationships between pollution content in snow and relief, pollution content in snow and distance from the source of emissions, were used as the basis for the model.

  4. Application of the MODIS “snow cover” product for identification of the snow cover pattern in Gis-Baikal region

    Directory of Open Access Journals (Sweden)

    E. A. Istomina

    2014-01-01

    Full Text Available Validation of remote sensing data MODIS «snow cover» in the period from September to May 2000/01, 2007/08, 2008/09 is realized on the base of weather stations data. Good repeatability of weather stations data and snow cover data is shown (more than 80% when snow depth is exceeds 2 cm. The minimum accuracy is in May and October for the variety of snowfall winters. Remote sensing data give possibility to extend the dot information of hydrometeorological stations network on the spatial snow distribution to the mountainous area of Predbajkalje where ground-based observations are absent. According to remote sensing earlier appearance and later melting of snow in mountain areas were identified. The plains and basins areas are characterized by later appearance and earlier melting of snow.

  5. Modeling the influence of snow cover temperature and water content on wet-snow avalanche runout

    Science.gov (United States)

    Valero, Cesar Vera; Wever, Nander; Christen, Marc; Bartelt, Perry

    2018-03-01

    Snow avalanche motion is strongly dependent on the temperature and water content of the snow cover. In this paper we use a snow cover model, driven by measured meteorological data, to set the initial and boundary conditions for wet-snow avalanche calculations. The snow cover model provides estimates of snow height, density, temperature and liquid water content. This information is used to prescribe fracture heights and erosion heights for an avalanche dynamics model. We compare simulated runout distances with observed avalanche deposition fields using a contingency table analysis. Our analysis of the simulations reveals a large variability in predicted runout for tracks with flat terraces and gradual slope transitions to the runout zone. Reliable estimates of avalanche mass (height and density) in the release and erosion zones are identified to be more important than an exact specification of temperature and water content. For wet-snow avalanches, this implies that the layers where meltwater accumulates in the release zone must be identified accurately as this defines the height of the fracture slab and therefore the release mass. Advanced thermomechanical models appear to be better suited to simulate wet-snow avalanche inundation areas than existing guideline procedures if and only if accurate snow cover information is available.

  6. Monitoring and evaluation of seasonal snow cover in Kashmir valley ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 118; Issue 6 ... Different geographical parameters of these regions were studied to evaluate the influence on snow cover and it was observed that altitude and position of region with respect to mountain range are the deciding factors for retaining the seasonal snow ...

  7. Monitoring and evaluation of seasonal snow cover in Kashmir valley ...

    Indian Academy of Sciences (India)

    in Kashmir valley using remote sensing, GIS and ancillary data. H S Negi∗, N K Thakur, Rajeev Kumar and Manoj Kumar. Snow and Avalanche Study Establishment, Him Parisar, Sector-37A, Chandigarh 160 036, India. ∗ e-mail: negi−hs@yahoo.com. Seasonal snow cover is a vital natural resource in the Himalaya.

  8. Snow cover dynamics and hydrological regime of the Hunza River basin, Karakoram Range, Northern Pakistan

    Directory of Open Access Journals (Sweden)

    A. A. Tahir

    2011-07-01

    Full Text Available A major proportion of flow in the Indus River is contributed by its snow- and glacier-fed river catchments situated in the Himalaya, Karakoram and Hindukush ranges. It is therefore essential to understand the cryosphere dynamics in this area for water resource management. The MODIS MOD10A2 remote-sensing database of snow cover products from March 2000 to December 2009 was selected to analyse the snow cover changes in the Hunza River basin (the snow- and glacier-fed sub-catchment of the Indus River. A database of daily flows for the Hunza River at Dainyor Bridge over a period of 40 yr and climate data (precipitation and temperature for 10 yr from three meteorological stations within the catchment was made available to investigate the hydrological regime in the area. Analysis of remotely sensed cryosphere (snow and ice cover data during the last decade (2000–2009 suggest a rather slight expansion of cryosphere in the area in contrast to most of the regions in the world where glaciers are melting rapidly. This increase in snow cover may be the result of an increase in winter precipitation caused by westerly circulation. The impact of global warming is not effective because a large part of the basin area lies under high altitudes where the temperature remains negative throughout most of the year.

  9. Dynamics of actual aggregation of petroleum products in snow cover

    Science.gov (United States)

    Begunova, L. A.; Kuznetsova, O. V.; Begunov, D. A.; Kuznetsova, A. N.

    2017-11-01

    The paper presents issues of snow cover pollution by petroleum products. Petroleum products content was determined using the fluorimetric method of analysis. The samples of snow were selected on the territory of Angarsk and Irkutsk cities. According to the obtained data, the content of petroleum products in the analyzed samples exceeds the background value up to 6 times. Analysis of the reference data for similar research confirms need for creation of an environmental monitoring centralized system to monitor atmospheric precipitation and, particularly, snow cover.

  10. Modeling the Seasonality of Snow Cover in Naryn Oblast, Kyrgyzstan.

    Science.gov (United States)

    Tomaszewska, M. A.; Henebry, G. M.

    2016-12-01

    Vertical transhumance practiced by herders in the highlands of Kyrgyzstan is strongly affected by timing of snow melt in high-elevation summer pastures. To model snow cover seasonality, we explore a novel approach through the synergistic use of "frost degree-days" obtained from MODIS land surface temperature data and the normalized difference snow index (NDSI) derived from over 16 years of Landsat imagery (2000-2015). From the fitted parameter coefficients of a convex quadratic model linking NDSI to accumulated frost degree-days (AFDD), we calculated two key metrics—the Peak Height of the NDSI and the Thermal Time (in AFDD) to the Peak Height—to examine the interannual variation in the timing of snow cover onset, snow melt, and snow cover duration. We discuss the strengths and limitations of this modeling approach to snow cover seasonality as well as demonstrate how it complements the land surface phenology modeling for understanding climatic influences on the highland pastures of Naryn oblast in Central Kyrgyzstan.

  11. Snow cover as a source of technogenic pollution of surface water during the snow melting period

    Directory of Open Access Journals (Sweden)

    Labuzova Olga

    2016-10-01

    Full Text Available The study of pollutants in melt water of snow cover and snow disposal sites in the city of Barnaul showed that during the snow melting period the surface water is not subjected to significant technogenic impact according to a number of studied indices. The oils content is an exception: it can exceed MAC more than 20 times in river- water due to the melting of city disposal sites. Environmental damage due to an oils input into water resources during the snow melting period can be more than 300000 thousand rubles.

  12. Winter climate extremes and their role for priming SOM decomposition under the snow

    Science.gov (United States)

    Gavazov, Konstantin; Bahn, Michael

    2015-04-01

    The central research question of this project is how soil respiration and soil microbial community composition and activity of subalpine grasslands are affected by extreme winter climate events, such as mid-winter snowmelt and subsequent advanced growing season date. In the scope of this talk, focus will be laid on the assumptions that (1) reduced snow cover leads to intensive freeze-thaw cycles in the soil with larger amplitudes of microbial biomass, DOC and soil CO2 production and efflux over the course of winter, and shifts peak microbial activity to deeper soil layers with limited and recalcitrant substrate; (2) causes a shift in microbial community composition towards decreased fungal/bacterial ratios; and (3) results in a stronger incorporation of labile C in microbial biomass and more pronounced priming effects of soil organic matter turnover. Our findings indicate that snow removal, induces a strong and immediate negative effect on the physiology of soil microbes, impairing them in their capacity for turnover of SOM in the presence of labile substances (priming). This effect however is transient and soil microbes recover within the same winter. The reason for that is that snow removal did not produce any measurable (PLFA) changes in soil microbial community composition. The advanced start of the growing season, as a result of snow removal in mid-winter, granted the bacterial part of the microbial community more active in the uptake of labile substrates and the turnover of SOM than the fungal one. This finding is in line with the concept for a seasonal shift towards bacterial-dominated summer microbial community composition and could bring about implications for the plant-microbe competition for resources at the onset of the growing season.

  13. Quantifying the impacts of snow on surface energy balance through assimilating snow cover fraction and snow depth

    Science.gov (United States)

    Meng, Chunlei

    2017-10-01

    Seasonal snow plays an important part in Earth's climate system. Snow cover regulates the land surface energy balance through altering the albedo of the land surface. To utilize the satellite-retrieved snow cover fraction (SCF) and snow depth (SD) data sufficiently and avoid inconsistency, this paper developed a very simple but robust quality control method to assimilate Fengyun satellite-retrieved SCF and SD simultaneously. The results show that the assimilation method which this paper implemented can not only utilize the satellite-retrieved SCF and SD data sufficiently but also avoid the inconsistency of them. Two experiments were designed and performed to quantify the impacts of snow on land surface energy balance using the integrated urban land model. With the increase of the SCF and SD, the net radiation decreased significantly during the day and increased a little at night; the sensible heat flux decreased significantly during the day; the evapotranspiration and ground heat flux decreased during the day too.

  14. UAS applications in high alpine, snow-covered terrain

    Science.gov (United States)

    Bühler, Y.; Stoffel, A.; Ginzler, C.

    2017-12-01

    Access to snow-covered, alpine terrain is often difficult and dangerous. Hence parameters such as snow depth or snow avalanche release and deposition zones are hard to map in situ with adequate spatial and temporal resolution and with spatial continuous coverage. These parameters are currently operationally measured at automated weather stations and by observer networks. However such isolated point measurements are not able to capture the information spatial continuous and to describe the high spatial variability present in complex mountain topography. Unmanned Aerial Systems (UAS) have the potential to fill this gap by frequently covering selected high alpine areas with high spatial resolution down to ground resolutions of even few millimeters. At the WSL Institute for Snow and Avalanche Research SLF we test different photogrammetric UAS with visual and near infrared bands. During the last three years we were able to gather experience in more than 100 flight missions in extreme terrain. By processing the imagery applying state-of-the-art structure from motion (SfM) software, we were able to accurately document several avalanche events and to photogrammetrically map snow depth with accuracies from 1 to 20 cm (dependent on the flight height above ground) compare to manual snow probe measurements. This was even possible on homogenous snow surfaces with very little texture. A key issue in alpine terrain is flight planning. We need to cover regions at high elevations with large altitude differences (up to 1 km) with high wind speeds (up to 20 m/s) and cold temperatures (down to - 25°C). Only a few UAS are able to cope with these environmental conditions. We will give an overview on our applications of UAS in high alpine terrain that demonstrate the big potential of such systems to acquire frequent, accurate and high spatial resolution geodata in high alpine, snow covered terrain that could be essential to answer longstanding questions in avalanche and snow hydrology

  15. Assessment of Consistencies and Uncertainties between the NASA MODIS and VIIRS Snow-Cover Maps

    Science.gov (United States)

    Hall, D. K.; Riggs, G. A., Jr.; DiGirolamo, N. E.; Roman, M. O.

    2017-12-01

    Snow cover has great climatic and economic importance in part due to its high albedo and low thermal conductivity and large areal extent in the Northern Hemisphere winter, and its role as a freshwater source for about one-sixth of the world's population. The Rutgers University Global Snow Lab's 50-year climate-data record (CDR) of Northern Hemisphere snow cover is invaluable for climate studies, but, at 25-km resolution, the spatial resolution is too coarse to provide accurate snow information at the basin scale. Since 2000, global snow-cover maps have been produced from the MODerate-resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua satellites at 500-m resolution, and from the Suomi-National Polar Program (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) since 2011 at 375-m resolution. Development of a moderate-resolution (375 - 500 m) earth system data record (ESDR) that utilizes both MODIS and VIIRS snow maps is underway. There is a 6-year overlap between the data records. In late 2017 the second in a series of VIIRS sensors will be launched on the Joint Polar Satellite System-1 (JPSS-1), with the JPSS-2 satellite scheduled for launch in 2021, providing the potential to extend NASA's snow-cover ESDR for decades into the future and to create a CDR. Therefore it is important to investigate the continuity between the MODIS and VIIRS NASA snow-cover data products and evaluate whether there are any inconsistencies and biases that would affect their value as CDR. Time series of daily normalized-difference snow index (NDSI) Terra and Aqua MODIS Collection 6 (C6) and NASA VIIRS Collection 1 (C1) snow-cover tile maps (MOD10A1 and VNP10A1) are studied for North America to identify NDSI differences and possible biases between the datasets. Developing a CDR using the MODIS and VIIRS records is challenging. Though the instruments and orbits are similar, differences in bands, viewing geometry, spatial resolution, and cloud- and snow-mapping algorithms

  16. C-Band SAR Imagery for Snow-Cover Monitoring at Treeline, Churchill, Manitoba, Canada

    Directory of Open Access Journals (Sweden)

    Frédérique C. Pivot

    2012-07-01

    Full Text Available RADARSAT and ERS-2 data collected at multiple incidence angles are used to characterize the seasonal variations in the backscatter of snow-covered landscapes in the northern Hudson Bay Lowlands during the winters of 1997/98 and 1998/99. The study evaluates the usefulness of C-band SAR systems for retrieving the snow water equivalent under dry snow conditions in the forest–tundra ecotone. The backscatter values are compared against ground measurements at six sampling sites, which are taken to be representative of the land-cover types found in the region. The contribution of dry snow to the radar return is evident when frost penetrates the first 20 cm of soil. Only then does the backscatter respond positively to changes in snow water equivalent, at least in the open and forested areas near the coast, where 1-dB increases in backscatter for each approximate 5–10 mm of accumulated water equivalent are observed at 20–31° incidence angles. Further inland, the backscatter shows either no change or a negative change with snow accumulation, which suggests that the radar signal there is dominated by ground surface scattering (e.g., fen when not attenuated by vegetation (e.g., forested and transition. With high-frequency ground-penetrating radar, we demonstrate the presence of a 10–20-cm layer of black ice underneath the snow cover, which causes the reduced radar returns (−15 dB and less observed in the inland fen. A correlation between the backscattering and the snow water equivalent cannot be determined due to insufficient observations at similar incidence angles. To establish a relationship between the snow water equivalent and the backscatter, only images acquired with similar incidence angles should be used, and they must be corrected for both vegetation and ground effects.

  17. Aerotechnogenic Monitoring of Urban Environment on Snow Cover Pollution (on the Example of Voronezh City

    Directory of Open Access Journals (Sweden)

    Prozhorina Tatyana Ivanovna

    2014-09-01

    Full Text Available Snow cover is characterized by high sorption ability and represents an informative object in the process of identifying the technogenic pollution of urban environment. The article contains the results of the research on the chemical composition of the snow which fell in Voronezh in the winter period of 2013–2014. The coefficients of chemical elements concentration were calculated to provide objective characteristics of snow cover pollution. The authors analyze the connection between the presence of pollutants in snow and the level of technogenic impact. The obtained ranges of anomaly coefficients among anions reflect the composition of technogenic emissions. The mineralization of snow water reliably characterizes the intensity of anthropogenic impact on the urban environment, and the value of mineralization snow samples ranges from 62,6 (background to 183,9 mg/l. Maximum values of mineralization (more than 150 mg/l are typical for samples taken in transport area. High values of salinity (more than 120 mg/l are observed in snow samples taken in the industrial area, which confirms the high “technogenic pressure” on the urban environment in zones of industrial and transport potential of the city. The investigated functional areas can be arranged in the following series by descending level of contamination: transport area > industrial zone > residential and recreational areas > background territory. The study of the chemical composition of snow cover in the various functional areas of Voronezh allows to conclude that the pH level, mineralization and the content of suspended solids in snow waters characterize the intensity of anthropogenic pressure on the urban environment, and the composition of melt waters indicates the nature of its pollution.

  18. An analysis of snow cover changes in the Himalayan region using MODIS snow products and in-situ temperature data

    NARCIS (Netherlands)

    Maskey, S.; Uhlenbrook, S.; Ojha, S.

    2011-01-01

    Amidst growing concerns over the melting of the Himalayas’ snow and glaciers, we strive to answer some of the questions related to snow cover changes in the Himalayan region covering Nepal and its vicinity using Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover products from 2000 to

  19. Validation of the operational MSG-SEVIRI snow cover product over Austria

    Science.gov (United States)

    Surer, S.; Parajka, J.; Akyurek, Z.

    2014-02-01

    The objective of this study is to evaluate the mapping accuracy of the MSG-SEVIRI operational snow cover product over Austria. The SEVIRI instrument is aboard the geostationary Meteosat Second Generation (MSG) satellite. The snow cover product provides 32 images per day, with a relatively low spatial resolution of 5 km over Austria. The mapping accuracy is examined at 178 stations with daily snow depth observations and compared with the daily MODIS-combined (Terra + Aqua) snow cover product for the period April 2008-June 2012. The results show that the 15 min temporal sampling allows a significant reduction of clouds in the snow cover product. The mean annual cloud coverage is less than 30% in Austria, as compared to 52% for the combined MODIS product. The mapping accuracy for cloud-free days is 89% as compared to 94% for MODIS. The largest mapping errors are found in regions with large topographical variability. The errors are noticeably larger at stations with elevations that differ greatly from those of the mean MSG-SEVIRI pixel elevations. The median of mapping accuracy for stations with absolute elevation difference less than 50 m and more than 500 m is 98.9 and 78.2%, respectively. A comparison between the MSG-SEVIRI and MODIS products indicates an 83% overall agreement. The largest disagreements are found in Alpine valleys and flatland areas in the spring and winter months, respectively.

  20. Springtime warming and reduced snow cover from carbonaceous particles

    Directory of Open Access Journals (Sweden)

    M. G. Flanner

    2009-04-01

    Full Text Available Boreal spring climate is uniquely susceptible to solar warming mechanisms because it has expansive snow cover and receives relatively strong insolation. Carbonaceous particles can influence snow coverage by warming the atmosphere, reducing surface-incident solar energy (dimming, and reducing snow reflectance after deposition (darkening. We apply a range of models and observations to explore impacts of these processes on springtime climate, drawing several conclusions: 1 Nearly all atmospheric particles (those with visible-band single-scatter albedo less than 0.999, including all mixtures of black carbon (BC and organic matter (OM, increase net solar heating of the atmosphere-snow column. 2 Darkening caused by small concentrations of particles within snow exceeds the loss of absorbed energy from concurrent dimming, thus increasing solar heating of snowpack as well (positive net surface forcing. Over global snow, we estimate 6-fold greater surface forcing from darkening than dimming, caused by BC+OM. 3 Equilibrium climate experiments suggest that fossil fuel and biofuel emissions of BC+OM induce 95% as much springtime snow cover loss over Eurasia as anthropogenic carbon dioxide, a consequence of strong snow-albedo feedback and large BC+OM emissions from Asia. 4 Of 22 climate models contributing to the IPCC Fourth Assessment Report, 21 underpredict the rapid warming (0.64°C decade−1 observed over springtime Eurasia since 1979. Darkening from natural and anthropogenic sources of BC and mineral dust exerts 3-fold greater forcing on springtime snow over Eurasia (3.9 W m−2 than North America (1.2 W m−2. Inclusion of this forcing significantly improves simulated continental warming trends, but does not reconcile the low bias in rate of Eurasian spring snow cover decline exhibited by all models, likely because BC deposition trends are negative or near-neutral over much of Eurasia. Improved Eurasian

  1. Design, Development and Testing of Web Services for Multi-Sensor Snow Cover Mapping

    Science.gov (United States)

    Kadlec, Jiri

    to combine volunteer snow reports, cross-country ski track reports and station measurements to fill cloud gaps in the MODIS snow cover product. The method is demonstrated by producing a continuous daily time step snow presence probability map dataset for the Czech Republic region. The ability of the presented methodology to reconstruct MODIS snow cover under cloud is validated by simulating cloud cover datasets and comparing estimated snow cover to actual MODIS snow cover. The percent correctly classified indicator showed accuracy between 80 and 90% using this method. Using crowdsourcing data (volunteer snow reports and ski tracks) improves the map accuracy by 0.7--1.2%. The output snow probability map data sets are published online using web applications and web services. Keywords: crowdsourcing, image analysis, interpolation, MODIS, R statistical software, snow cover, snowpack probability, Tethys platform, time series, WaterML, web services, winter sports.

  2. Preliminary analysis of measured sound propagation over various seasonal snow covers

    Science.gov (United States)

    Albert, Donald G.

    1990-01-01

    Measurements of acoustic pulse propagation in the 5 to 500-Hz frequency band were conducted under various snow cover conditions during the 1989 to 1990 winter in New Hampshire. The objective was to determine the effect of snow cover thickness and other snow properties on the absorption of acoustic pulses. Blank pistol shots were used as the source of the acoustic waves, and geophones and microphones in an 80 m-long linear array served as receivers. Snow thicknesses ranged from 0.05 to 0.35 m, and densities varied from 100 to 350 kg m(sup -3) during the 10 separate measurement days. Preliminary analysis indicates that the peak pulse amplitude decayed in proportion to approx. gamma (sup -1.7) for most conditions and that the acoustic-to-seismic ratios varied from about 4 to 15 x 10(exp -6) m s(sup -1) Pa(sup -1). Theoretical waveforms were calculated for propagation in a homogeneous atmosphere using Attenborough's model of ground impedance. An automatic fitting procedure for the normalized experimental and theoretical waveforms was used to determine the effective flow resistivity of the snow covers, and gave values of 10 to 35 kN s m(sup -4), in agreement with earlier results.

  3. Relationships Between Canopy Openness, Snow Cover and Ground Temperature.

    Science.gov (United States)

    Mattson, L.

    2004-05-01

    Red pine stands, which have undergone varying degrees of thinning and site preparation, are examined with a view to identifying the relationships which exist between canopy openness, snow cover and ground temperature. More specifically, eight red pine stands, which have been intentionally harvested at varying densities within the National Petawawa Research Forest, have been heavily instrumented for detailed measurements of canopy openness, snow cover characteristics, above and subsurface temperature profiles as well as micro-meteorological conditions. Results allow for the specification of relationships between the effect of thinning and site preparation on the soils thermal regime which, in turn, impacts upon the natural regeneration of the pine.

  4. Cloud removal methodology from MODIS snow cover product

    Directory of Open Access Journals (Sweden)

    A. Bárdossy

    2009-07-01

    Full Text Available The Moderate Resolution Imaging Spectroradiometer (MODIS employed by Terra and Aqua satellites provides spatially snow covered data with 500 m and daily temporal resolution. It delivers public domain data in raster format. The main disadvantage of the MODIS sensor is that it is unable to record observations under cloud covered regions. This is why this study focuses on estimating the pixel cover for cloud covered areas where no information is available. Our step to this product involves employing methodology based on six successive steps that estimate the pixel cover using different temporal and spatial information. The study was carried out for the Kokcha River basin located in northeastern part of Afghanistan. Snow coverage in catchments, like Kokcha, is very important where the melt-water from snow dominates the river discharge in vegetation period for irrigation purposes. Since no snow related observations were available from the region, the performance of the proposed methodology was tested using the cloud generated MODIS snow cover data as possible "ground truth" information. The results show successful performances arising from the methods applied, which resulted in all cloud coverage being removed. A validation was carried out for all subsequent steps, to be outlined below, where each step removes progressively more cloud coverage. Steps 2 to 5 (step 1 was not validated performed very well with an average accuracy of between 90–96%, when applied one after another for the selected valid days in this study. The sixth step was the least accurate at 78%, but it led to the removal of all remaining cloud cover.

  5. Influence of snow cover distribution on soil temperature and nutrient dynamics in alpine pedoenvironments

    Directory of Open Access Journals (Sweden)

    Ermanno Zanini

    Full Text Available In Alpine sites snow is present on the ground from six to eight months per year in relation to elevation and exposure. Water is therefore immobilized into the solid state for the greater part of the winter season and released to the ground in a short period during spring snowmelt. In these areas, snow distribution exercises a fundamental role in influencing soil temperature and nutrient dynamics, in particular of nitrogen, with great consequences on plant nutrition. The dormant vegetation period, the low temperatures and the persistent snow cover suggest that soil biological activity is only concentrated during summer. As a matter of fact, soils covered with a consistent snow cover are isolated from the air temperature and can not freeze during winter. A snowpack of sufficient thickness, accumulated early in winter, insulates the ground from the surrounding atmosphere maintaining soil temperature closed to 0 °C during the whole winter season. The elevation of the snow line and the shorter permanence of snow on the ground, as a result of global warming (IPCC, 1996, 2001, might reduce the insulation effect of the snowpack, exposing soils of the mountain belt to lower temperatures and to a greater frequency of freeze/thaw cycles, which might alter organic matter dynamics and soil nutrient availability. Such thermal stresses may determine the lysis of microbial cells and the consequent increase of nitrogen and carbon mineralization by the survived microorganisms. Moreover, the freeze/thaw cycles can determine the exposure of exchange surfaces not available before, with release of organic matter of non-microbial origin, which may become available to surviving microorganisms for respiration. The reduced or absent microbial immobilization may cause the accumulation of remarkable amounts of inorganic nitrogen in soil, potentially leachable during spring snowmelt, when plants have not still started the growing season. Changes of snow distribution in

  6. Observational evidence of changes in global snow and ice cover

    International Nuclear Information System (INIS)

    Barry, R.G.

    1990-01-01

    Sources of observational data on recent variations in the seasonal extent of snow cover and sea ice, of the terminal position and volume of alpine glaciers, and of ground temperature profiles in areas of permafrost are briefly reviewed. Recent evidence of changes in these variables is then examined. The extent of seasonal snow cover in the Northern hemisphere and of sea ice in both hemispheres has fluctuated irregularly over the last 15-20 years with a range of about 10-15% in each case. There is no clear evidence of any recent trends, despite general global warming. In contrast, most glaciers retreated and thinned from before the turn of the century until the 1960s and alaskan permafrost temperatures have risen 2-4 C per century. Recently, glacier advances have been noted, perhaps in response to increased accumulation. Problems of linking climate forcing and snow/ice responses are discussed

  7. Spectral reflectance characteristics of different snow and snow-covered land surface objects and mixed spectrum fitting

    Science.gov (United States)

    Zhang, J.-H.; Zhou, Z.-M.; Wang, P.-J.; Yao, F.-M.; Yang, L.

    2011-01-01

    The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing area. The result showed that for a pure snow spectrum, the snow reflectance peaks appeared from visible to 800 nm band locations; there was an obvious absorption valley of snow spectrum near 1030 nm wavelength. Compared with fresh snow, the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300~1300, 1700~1800 and 2200~2300 nm, the lowest was from the compacted snow and frozen ice. For the vegetation and snow mixed spectral characteristics, it was indicated that the spectral reflectance increased for the snow-covered land types(including pine leaf with snow and pine leaf on snow background), due to the influence of snow background in the range of 350~1300 nm. However, the spectrum reflectance of mixed pixel remained a vegetation spectral characteristic. In the end, based on the spectrum analysis of snow, vegetation, and mixed snow/vegetation pixels, the mixed spectral fitting equations were established, and the results showed that there was good correlation between spectral curves by simulation fitting and observed ones(correlation coefficient R2=0.9509).

  8. Erosion potential of snow cover in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Hana Středová

    2012-01-01

    Full Text Available Amount of water derived from snow and melting rate can be collectively described as the erosion potential of water accumulated in the snow. The erosion potential of snow was calculated for thirty cold periods i.e. 1st November to 30th April (1980/1981 to 2009/2010 based on climatilogical data of fifty stations of Czech hydrometerological station from different climatic conditions according to Climatic region of Estimated Pedological Ecological Unit. Snow erosive potential statistically significantly depends on altitude (r = 0.726**, α = 0.01 and also on climatic region (r = 0.790**, α = 0.01. Mapping expression was based on average values of thirty-year period. Range of snow erosive potential in the map responces to quantile values, quintile values respectively (Q0.2, Q0.4, Q0.6, Q0.8. A map of erosion potential of snow cover for arable land deals with an assumption of arable land incidence. It was determined by excluding forests, built area, land with a slope of 12 ° and areas with an altitude of 700 m.

  9. Tree-Ring Widths and Snow Cover Depth in High Tauern

    Science.gov (United States)

    Falarz, Malgorzata

    2017-12-01

    The aim of the study is to examine the correlation of Norway spruce tree-ring widths and the snow cover depth in the High Tauern mountains. The average standardized tree-ring widths indices for Nowary spruce posted by Bednarz and Niedzwiedz (2006) were taken into account. Increment cores were collected from 39 Norway spruces growing in the High Tauern near the upper limit of the forest at altitude of 1700-1800 m, 3 km from the meteorological station at Sonnblick. Moreover, the maximum of snow cover depth in Sonnblick (3105 m a.s.l.) for each winter season in the period from 1938/39 to 1994/95 (57 winter seasons) was taken into account. The main results of the research are as follows: (1) tree-ring widths in a given year does not reveal statistically significant dependency on the maximum snow cover depth observed in the winter season, which ended this year; (2) however, the tested relationship is statistically significant in the case of correlating of the tree-ring widths in a given year with a maximum snow cover depth in a season of previous year. The correlation coefficient for the entire period of the study is not very high (r=0.27) but shows a statistical significance at the 0.05 level; (3) the described relationship is not stable over time. 30-year moving correlations showed no significant dependencies till 1942 and after 1982 (probably due to the so-called divergence phenomenon). However, during the period of 1943-1981 the values of correlation coefficient for moving 30-year periods are statistically significant and range from 0.37 to 0.45; (4) the correlation coefficient between real and calibrated (on the base of the regression equation) values of maximum snow cover depth is statistically significant for calibration period and not significant for verification one; (5) due to a quite short period of statistically significant correlations and not very strict dependencies, the reconstruction of snow cover on Sonnblick for the period before regular measurements

  10. Assessment of the economic risk for the ski resorts of changes in snow cover duration

    Directory of Open Access Journals (Sweden)

    S. A. Sokratov

    2014-01-01

    Full Text Available Winter tourism that is intensively developed in the Russian Federation in recent years strongly depends on the snow availability and properties in the region. Climate changes exert significant influence on the functioning of mountain ski resorts, especially if they are located in areas with relatively high air temperatures in winter season. At the present time, a snowy cluster of mountain ski resorts is intensively progressing in vicinity of Krasnaya Polyana. This region in the West Caucasus (Russia is characterized by relatively warm climate conditions. The snow cover thickness (of 1% insurance in area of the Aibga mountain range may reach 8.1 m. But the snow cover thickness is not the only characteristic of the mountain skiing attractiveness. According to the Swiss standards a mountain ski resort can be considered reliable if during seven seasons of ten ones the snow cover with minimal thickness of 30–50 cm exists for a time not shorter than 100 days during a period from 1st December till 15th April.According to the forecast, during future decades the calculated amount of solid precipitation should reduce by 25–30% in mountain regions on the south macro-slope of the Great Caucasus. As the calculations show, by 2041–2050 the maximal decade thickness of snow cover will decrease by 29–35% while a number of days with snow – by 35–40%. If this is the case, artificial snow will be needed in addition to the natural one. But, under warm climate conditions using of plants for artificial snow production will require a certain perfecting of the nowadays technologies, and very likely, with use of chemicals. That is why a shadowing of existing mountain ski routes by means of the tree planting along them could be ecologically more promising. As for the mountain ski resorts of the West Caucasus, we should mention a possible weakening of the avalanche activity as a potential positive effect of the climate warming predicted by models.

  11. EVALUATION OF THE URBAN DEVELOPMENT INFLUENCE ON POLLUTION OF SNOW COVER USING GEOINFORMATION AND STATISTICAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    I. D. Korlyakov

    2017-01-01

    Full Text Available The influence of urban development parameters on the pollution of snow with heavy metals and metalloids (HMM has been assessed.The aim of the work is to assess the barrier functions of urban development by means of a joint analysis of data on the content of HMM in the snow cover and the parameters of the artificial relief. The residential area of the Ulan-Ude city was chosen as an object of the study, where 27 snow samples were selected. According to the data of the snow survey in 2014, the total content of HMM in the snow suspension was determined, the priority pollutants of the snow were received and the total indicator of immission at the sampling points was calculated. Data processing in the OpenStreetMap, 2GIS, ArcGis 10.0 and Statistica 7.0 software packages made it possible to determine the main parameters of the buildings near the sampling points. Correlation analysis has shown a significant influence of building parameters on the HMM immission in the snow cover. With an increase in the total and average building area, proximity of buildings to the sampling point, an increase in the immission of most or all HMMs has been observed. The height of houses is a secondary factor which positively affects the immission of Cu and Bi. The maximum correlation links are established in radii of 50, 100 and 150 m. The parameters of development affect the total precipitation of pollutants both in all cardinal directions, and in the south-western, northeast, southeast directions, which can be explained by the wind regime features during the winter season. 

  12. Microwave retrievals of terrestrial precipitation over snow-covered surfaces: A lesson from the GPM satellite

    Science.gov (United States)

    Ebtehaj, A. M.; Kummerow, C. D.

    2017-06-01

    Satellites are playing an ever-increasing role in estimating precipitation over remote areas. Improving satellite retrievals of precipitation requires increased understanding of its passive microwave signatures over different land surfaces. Snow-covered surfaces are notoriously difficult to interpret because they exhibit both emission from the land below and scattering from the ice crystals. Using data from the Global Precipitation Measurement (GPM) satellite, we demonstrate that microwave brightness temperatures of rain and snowfall transition from a scattering to an emission regime from summer to winter, due to expansion of less emissive snow cover. Evidence suggests that the combination of low- (10-19 GHz) and high-frequency (89-166 GHz) channels provides the maximum amount of information for snowfall detection. The results demonstrate that, using a multifrequency matching method, the probability of snowfall detection can even be higher than rainfall—chiefly because of the information content of the low-frequency channels that respond to the (near) surface temperature.

  13. Impact of the snow cover scheme on snow distribution and energy budget modeling over the Tibetan Plateau

    Science.gov (United States)

    Xie, Zhipeng; Hu, Zeyong; Xie, Zhenghui; Jia, Binghao; Sun, Genhou; Du, Yizhen; Song, Haiqing

    2018-02-01

    This paper presents the impact of two snow cover schemes (NY07 and SL12) in the Community Land Model version 4.5 (CLM4.5) on the snow distribution and surface energy budget over the Tibetan Plateau. The simulated snow cover fraction (SCF), snow depth, and snow cover days were evaluated against in situ snow depth observations and a satellite-based snow cover product and snow depth dataset. The results show that the SL12 scheme, which considers snow accumulation and snowmelt processes separately, has a higher overall accuracy (81.8%) than the NY07 (75.8%). The newer scheme performs better in the prediction of overall accuracy compared with the NY07; however, SL12 yields a 15.1% underestimation rate while NY07 overestimated the SCF with a 15.2% overestimation rate. Both two schemes capture the distribution of the maximum snow depth well but show large positive biases in the average value through all periods (3.37, 3.15, and 1.48 cm for NY07; 3.91, 3.52, and 1.17 cm for SL12) and overestimate snow cover days compared with the satellite-based product and in situ observations. Higher altitudes show larger root-mean-square errors (RMSEs) in the simulations of snow depth and snow cover days during the snow-free period. Moreover, the surface energy flux estimations from the SL12 scheme are generally superior to the simulation from NY07 when evaluated against ground-based observations, in particular for net radiation and sensible heat flux. This study has great implications for further improvement of the subgrid-scale snow variations over the Tibetan Plateau.

  14. Evaluation of snow cover and snow depth on the Qinghai–Tibetan Plateau derived from passive microwave remote sensing

    Directory of Open Access Journals (Sweden)

    L. Dai

    2017-08-01

    Full Text Available Snow cover on the Qinghai–Tibetan Plateau (QTP plays a significant role in the global climate system and is an important water resource for rivers in the high-elevation region of Asia. At present, passive microwave (PMW remote sensing data are the only efficient way to monitor temporal and spatial variations in snow depth at large scale. However, existing snow depth products show the largest uncertainties across the QTP. In this study, MODIS fractional snow cover product, point, line and intense sampling data are synthesized to evaluate the accuracy of snow cover and snow depth derived from PMW remote sensing data and to analyze the possible causes of uncertainties. The results show that the accuracy of snow cover extents varies spatially and depends on the fraction of snow cover. Based on the assumption that grids with MODIS snow cover fraction > 10 % are regarded as snow cover, the overall accuracy in snow cover is 66.7 %, overestimation error is 56.1 %, underestimation error is 21.1 %, commission error is 27.6 % and omission error is 47.4 %. The commission and overestimation errors of snow cover primarily occur in the northwest and southeast areas with low ground temperature. Omission error primarily occurs in cold desert areas with shallow snow, and underestimation error mainly occurs in glacier and lake areas. With the increase of snow cover fraction, the overestimation error decreases and the omission error increases. A comparison between snow depths measured in field experiments, measured at meteorological stations and estimated across the QTP shows that agreement between observation and retrieval improves with an increasing number of observation points in a PMW grid. The misclassification and errors between observed and retrieved snow depth are associated with the relatively coarse resolution of PMW remote sensing, ground temperature, snow characteristics and topography. To accurately understand the variation in snow

  15. Reconstructed North American, Eurasian, and Northern Hemisphere Snow Cover Extent, 1915-1997

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains time series of monthly snow cover extent (SCE) for North America, Eurasia, and the Northern Hemisphere from 1915 to 1997, based on snow cover...

  16. Northern Hemisphere EASE-Grid 2.0 Weekly Snow Cover and Sea Ice Extent

    Data.gov (United States)

    National Aeronautics and Space Administration — The Northern Hemisphere EASE-Grid 2.0 Weekly Snow Cover and Sea Ice Extent Version 4 product combine snow cover and sea ice extent at weekly intervals from 23...

  17. Impacts of changing climate and snow cover on the flow regime of Jhelum River, Western Himalayas

    KAUST Repository

    Azmat, Muhammad

    2016-11-17

    This study examines the change in climate variables and snow cover dynamics and their impact on the hydrological regime of the Jhelum River basin in Western Himalayas. This study utilized daily streamflow records from Mangla dam, spanning a time period of 19 years (1995–2013), along with precipitation and temperature data over 52 years (1961–2013) from 12 different climate stations in the catchment. Additionally, moderate-resolution imaging spectroradiometer (MODIS) remote sensing product MOD10A2 was utilized to analyze the change in snow cover dynamics during 2000–2013. The Pearson and Kendall rank correlation tests were used to scrutinize snow cover trends and correlation between temperature, precipitation, snow cover area (SCA) and streamflows records. Basin-wide trend analysis showed a slightly increasing tendency in temperature (τ = 0.098) and precipitation (τ = 0.094), during the years 1961–2013. The changes in streamflow indicated a positive (r > 0.12) relationship with respect to temperature but variable trends (r = −0.45–0.41) with respect to precipitation during both the winter and monsoon seasons. This indicates that temperature has a significant impact on the hydrological regime of the basin. MODIS data-based investigations suggested an expansion in SCA during 2000–2013. The changes in SCA of high-altitude zones (>2000 m a.s.l.) depicted a stronger positive correlation with climate variables and streamflow compared with those obtained for low-altitude regions (<2000 m a.s.l.). Overall, these results signify that high-altitude areas contribute to the streamflow largely in the form of snow- and glacier-melt during the early summer season. The streamflow is then further augmented by monsoon rainfall in the low-elevation regions during late summer.

  18. Improving snow cover mapping in forests through the use of a canopy reflectance model

    International Nuclear Information System (INIS)

    Klein, A.G.; Hall, D.K.; Riggs, G.A.

    1998-01-01

    MODIS, the moderate resolution imaging spectro radiometer, will be launched in 1998 as part of the first earth observing system (EOS) platform. Global maps of land surface properties, including snow cover, will be created from MODIS imagery. The MODIS snow-cover mapping algorithm that will be used to produce daily maps of global snow cover extent at 500 m resolution is currently under development. With the exception of cloud cover, the largest limitation to producing a global daily snow cover product using MODIS is the presence of a forest canopy. A Landsat Thematic Mapper (TM) time-series of the southern Boreal Ecosystem–Atmosphere Study (BOREAS) study area in Prince Albert National Park, Saskatchewan, was used to evaluate the performance of the current MODIS snow-cover mapping algorithm in varying forest types. A snow reflectance model was used in conjunction with a canopy reflectance model (GeoSAIL) to model the reflectance of a snow-covered forest stand. Using these coupled models, the effects of varying forest type, canopy density, snow grain size and solar illumination geometry on the performance of the MODIS snow-cover mapping algorithm were investigated. Using both the TM images and the reflectance models, two changes to the current MODIS snow-cover mapping algorithm are proposed that will improve the algorithm's classification accuracy in forested areas. The improvements include using the normalized difference snow index and normalized difference vegetation index in combination to discriminate better between snow-covered and snow-free forests. A minimum albedo threshold of 10% in the visible wavelengths is also proposed. This will prevent dense forests with very low visible albedos from being classified incorrectly as snow. These two changes increase the amount of snow mapped in forests on snow-covered TM scenes, and decrease the area incorrectly identified as snow on non-snow-covered TM scenes. (author)

  19. Correlated declines in Pacific arctic snow and sea ice cover

    Science.gov (United States)

    Stone, Robert P.; Douglas, David C.; Belchansky, Gennady I.; Drobot, Sheldon

    2005-01-01

    Simulations of future climate suggest that global warming will reduce Arctic snow and ice cover, resulting in decreased surface albedo (reflectivity). Lowering of the surface albedo leads to further warming by increasing solar absorption at the surface. This phenomenon is referred to as “temperature–albedo feedback.” Anticipation of such a feedback is one reason why scientists look to the Arctic for early indications of global warming. Much of the Arctic has warmed significantly. Northern Hemisphere snow cover has decreased, and sea ice has diminished in area and thickness. As reported in the Arctic Climate Impact Assessment in 2004, the trends are considered to be outside the range of natural variability, implicating global warming as an underlying cause. Changing climatic conditions in the high northern latitudes have influenced biogeochemical cycles on a broad scale. Warming has already affected the sea ice, the tundra, the plants, the animals, and the indigenous populations that depend on them. Changing annual cycles of snow and sea ice also affect sources and sinks of important greenhouse gases (such as carbon dioxide and methane), further complicating feedbacks involving the global budgets of these important constituents. For instance, thawing permafrost increases the extent of tundra wetlands and lakes, releasing greater amounts of methane into the atmosphere. Variable sea ice cover may affect the hemispheric carbon budget by altering the ocean–atmosphere exchange of carbon dioxide. There is growing concern that amplification of global warming in the Arctic will have far-reaching effects on lower latitude climate through these feedback mechanisms. Despite the diverse and convincing observational evidence that the Arctic environment is changing, it remains unclear whether these changes are anthropogenically forced or result from natural variations of the climate system. A better understanding of what controls the seasonal distributions of snow and ice

  20. Characteristics of snow cover duration across the northeast United States of America

    Science.gov (United States)

    Leathers, Daniel J.; Luff, Barbara L.

    1997-11-01

    The presence or absence of a snow cover affects a myriad of environmental and societal systems through its modification of the surface radiation balance and its ultimate impact on near-surface air temperatures. Daily snow cover data were collected for a network of 91 stations covering the northeast USA from Maine, south through to West Virginia. The snow cover data along with ancillary temperature, snowfall and precipitation data were used to investigate the characteristics of snow cover duration in this region and the effects of the snow cover on boundary layer climate variables for the snow cover seasons 1948-1949 through to 1987-1988.Results indicate that snow cover duration is variable in both space and time. The duration of a snow cover of 2.5 cm or greater varies from greater than 100 days in northern New England to less than 20 days across areas of Delaware, Maryland and West Virginia. Temporally, snow cover duration for the region as a whole was very short from the late 1940s through to the mid-1950s. From the late 1950s to the end of the period snow cover duration has varied around a consistent mean value. No long-term trends in snow cover duration are apparent in the record for the northeast USA.Principal components analysis and clustering techniques were utilized to isolate spatially coherent regions in which snow cover duration has varied similarly over the period of record. This analysis resulted in the identification of four snow-cover-duration regions across the northeast USA: including (i) the West Virginia area, (ii) the mid-Atlantic from southern New England through to western Pennsylvania, (iii) western and central New York and (iv) northern New England. Snow cover duration is shown to be highly associated with snowfall and temperature but not strongly related to total liquid precipitation. The intra-annual variability of snow cover duration is also investigated for each region.

  1. Relating C-band Microwave and Optical Satellite Observations as A Function of Snow Thickness on First-Year Sea Ice during the Winter to Summer Transition

    Science.gov (United States)

    Zheng, J.; Yackel, J.

    2015-12-01

    The Arctic sea ice and its snow cover have a direct impact on both the Arctic and global climate system through their ability to moderate heat exchange across the ocean-sea ice-atmosphere (OSA) interface. Snow cover plays a key role in the OSA interface radiation and energy exchange, as it controls the growth and decay of first-year sea ice (FYI). However, meteoric accumulation and redistribution of snow on FYI is highly stochastic over space and time, which makes it poorly understood. Previous studies have estimated local-scale snow thickness distributions using in-situ technique and modelling but it is spatially limited and challenging due to logistic difficulties. Moreover, snow albedo is also critical for determining the surface energy balance of the OSA during the critical summer ablation season. Even then, due to persistent and widespread cloud cover in the Arctic at various spatio-temporal scales, it is difficult and unreliable to remotely measure albedo of snow cover on FYI in the optical spectrum. Previous studies demonstrate that only large-scale sea ice albedo was successfully estimated using optical-satellite sensors. However, space-borne microwave sensors, with their capability of all-weather and 24-hour imaging, can provide enhanced information about snow cover on FYI. Daily spaceborne C-band scatterometer data (ASCAT) and MODIS data are used to investigate the the seasonal co-evolution of the microwave backscatter coefficient and optical albedo as a function of snow thickness on smooth FYI. The research focuses on snow-covered FYI near Cambridge Bay, Nunavut (Fig.1) during the winter to advanced-melt period (April-June, 2014). The ACSAT time series (Fig.2) show distinct increase in scattering at melt onset indicating the first occurrence of melt water in the snow cover. The corresponding albedo exhibits no decrease at this stage. We show how the standard deviation of ASCAT backscatter on FYI during winter can be used as a proxy for surface roughness

  2. Combined Study of Snow Depth Determination and Winter Leaf Area Index Retrieval by Unmanned Aerial Vehicle Photogrammetry

    Science.gov (United States)

    Lendzioch, Theodora; Langhammer, Jakub; Jenicek, Michal

    2017-04-01

    A rapid and robust approach using Unmanned Aerial Vehicle (UAV) digital photogrammetry was performed for evaluating snow accumulation over different small localities (e.g. disturbed forest and open area) and for indirect field measurements of Leaf Area Index (LAI) of coniferous forest within the Šumava National Park, Czech Republic. The approach was used to reveal impacts related to changes in forest and snowpack and to determine winter effective LAI for monitoring the impact of forest canopy metrics on snow accumulation. Due to the advancement of the technique, snow depth and volumetric changes of snow depth over these selected study areas were estimated at high spatial resolution (1 cm) by subtracting a snow-free digital elevation model (DEM) from a snow-covered DEM. Both, downward-looking UAV images and upward-looking digital hemispherical photography (DHP), and additional widely used LAI-2200 canopy analyser measurements were applied to determine the winter LAI, controlling interception and transmitting radiation. For the performance of downward-looking UAV images the snow background instead of the sky fraction was used. The reliability of UAV-based LAI retrieval was tested by taking an independent data set during the snow cover mapping campaigns. The results showed the potential of digital photogrammetry for snow depth mapping and LAI determination by UAV techniques. The average difference obtained between ground-based and UAV-based measurements of snow depth was 7.1 cm with higher values obtained by UAV. The SD of 22 cm for the open area seemed competitive with the typical precision of point measurements. In contrast, the average difference in disturbed forest area was 25 cm with lower values obtained by UAV and a SD of 36 cm, which is in agreement with other studies. The UAV-based LAI measurements revealed the lowest effective LAI values and the plant canopy analyser LAI-2200 the highest effective LAI values. The biggest bias of effective LAI was observed

  3. Variability in snow cover phenology in China from 1952 to 2010

    OpenAIRE

    C. Q. Ke; X. C. Li; H. Xie; X. Liu; C. Kou

    2015-01-01

    Daily snow observation data from 672 stations, particularly the 352 stations with over ten annual mean snow cover days (SCD), during 1952–2010 in China, are used in this study. We first examine spatiotemporal variations and trends of SCD, snow cover onset date (SCOD), and snow cover end date (SCED). We then investigate SCD relationships with number of days with temperature below 0 °C (TBZD), mean air temperature (MAT), and Arctic Oscillation (AO) index, the ...

  4. Snow Cover Monitoring Using MODIS Data in Liaoning Province, Northeastern China

    OpenAIRE

    Zhang; Yan; Lu

    2010-01-01

    This paper presents the results of snow cover monitoring studies in Liaoning Province, northeastern China, using MODIS data. Snow cover plays an important role in both the regional water balance and soil moisture properties during the early spring in northeastern China. In addition, heavy snowfalls commonly trigger hazards such as flooding, caused by rapid snow melt, or crop failure, resulting from fluctuations in soil temperature associated with changes in the snow cover. The latter is a fun...

  5. Sensitivity Analysis of Snow Cover to Climate Change Scenarios and Their Impact on Plant Habitats in Alpine Terrain

    Energy Technology Data Exchange (ETDEWEB)

    Keller, F.; Goyette, S.; Beniston, M. [Department of Geosciences, Geography, Fribourg (Switzerland)

    2005-10-01

    In high altitude areas snow cover duration largely determines the length of the growing season of the vegetation. A sensitivity study of snow cover to various scenarios of temperature and precipitation has been conducted to assess how snow cover and vegetation may respond for a very localized area of the high Swiss Alps (2050-2500 m above sea level). A surface energy balance model has been upgraded to compute snow depth and duration, taking into account solar radiation geometry over complex topography. Plant habitat zones have been defined and 23 species, whose photoperiodic preferences were documented in an earlier study, were grouped into each zone. The sensitivity of snowmelt to a change in mean, minimum and maximum temperature alone and a change in mean temperature combined with a precipitation change of +10% in winter and -10% in summer is investigated. A seasonal increase in the mean temperature of 3 to 5 K reduces snow cover depth and duration by more than a month on average. Snow melts two months earlier in the rock habitat zone with the mean temperature scenario than under current climate conditions. This allows the species in this habitat to flower earlier in a warmer climate, but not all plants are able to adapt to such changes.

  6. The seasonal cycle of snow cover, sea ice and surface albedo

    Science.gov (United States)

    Robock, A.

    1980-01-01

    The paper examines satellite data used to construct mean snow cover caps for the Northern Hemisphere. The zonally averaged snow cover from these maps is used to calculate the seasonal cycle of zonally averaged surface albedo. The effects of meltwater on the surface, solar zenith angle, and cloudiness are parameterized and included in the calculations of snow and ice albedo. The data allows a calculation of surface albedo for any land or ocean 10 deg latitude band as a function of surface temperature ice and snow cover; the correct determination of the ice boundary is more important than the snow boundary for accurately simulating the ice and snow albedo feedback.

  7. Influence of snow cover changes on surface radiation and heat balance based on the WRF model

    Science.gov (United States)

    Yu, Lingxue; Liu, Tingxiang; Bu, Kun; Yang, Jiuchun; Chang, Liping; Zhang, Shuwen

    2017-10-01

    The snow cover extent in mid-high latitude areas of the Northern Hemisphere has significantly declined corresponding to the global warming, especially since the 1970s. Snow-climate feedbacks play a critical role in regulating the global radiation balance and influencing surface heat flux exchange. However, the degree to which snow cover changes affect the radiation budget and energy balance on a regional scale and the difference between snow-climate and land use/cover change (LUCC)-climate feedbacks have been rarely studied. In this paper, we selected Heilongjiang Basin, where the snow cover has changed obviously, as our study area and used the WRF model to simulate the influences of snow cover changes on the surface radiation budget and heat balance. In the scenario simulation, the localized surface parameter data improved the accuracy by 10 % compared with the control group. The spatial and temporal analysis of the surface variables showed that the net surface radiation, sensible heat flux, Bowen ratio, temperature and percentage of snow cover were negatively correlated and that the ground heat flux and latent heat flux were positively correlated with the percentage of snow cover. The spatial analysis also showed that a significant relationship existed between the surface variables and land cover types, which was not obviously as that for snow cover changes. Finally, six typical study areas were selected to quantitatively analyse the influence of land cover types beneath the snow cover on heat absorption and transfer, which showed that when the land was snow covered, the conversion of forest to farmland can dramatically influence the net radiation and other surface variables, whereas the snow-free land showed significantly reduced influence. Furthermore, compared with typical land cover changes, e.g., the conversion of forest into farmland, the influence of snow cover changes on net radiation and sensible heat flux were 60 % higher than that of land cover changes

  8. Deriving Snow-Cover Depletion Curves for Different Spatial Scales from Remote Sensing and Snow Telemetry Data

    Science.gov (United States)

    Fassnacht, Steven R.; Sexstone, Graham A.; Kashipazha, Amir H.; Lopez-Moreno, Juan Ignacio; Jasinski, Michael F.; Kampf, Stephanie K.; Von Thaden, Benjamin C.

    2015-01-01

    During the melting of a snowpack, snow water equivalent (SWE) can be correlated to snow-covered area (SCA) once snow-free areas appear, which is when SCA begins to decrease below 100%. This amount of SWE is called the threshold SWE. Daily SWE data from snow telemetry stations were related to SCA derived from moderate-resolution imaging spectro radiometer images to produce snow-cover depletion curves. The snow depletion curves were created for an 80,000 sq km domain across southern Wyoming and northern Colorado encompassing 54 snow telemetry stations. Eight yearly snow depletion curves were compared, and it is shown that the slope of each is a function of the amount of snow received. Snow-cover depletion curves were also derived for all the individual stations, for which the threshold SWE could be estimated from peak SWE and the topography around each station. A stations peak SWE was much more important than the main topographic variables that included location, elevation, slope, and modelled clear sky solar radiation. The threshold SWE mostly illustrated inter-annual consistency.

  9. Changes of snow cover, temperature, and radiative heat balance over the Northern Hemisphere

    Science.gov (United States)

    Groisman, Pavel YA.; Karl, Thomas R.; Knight, Richard W.; Stenchikov, Georgiy L.

    1994-01-01

    Contemporary large-scale changes in satellite-derived snow cover were examined over the Northern Hemisphere extratropical land (NEL) areas. These areas encompass 55% of the land in the Northern Hemisphere. Snow cover (S) transient regions, the 'centers of action' relative to interannual variations of snow cover, were identified for the years 1972-1992. During these years a global retreat in snow cover extent (SE) occurred in the second half of the hydrologic year (April-September). Mean annual SE has decreased by 10% (2.3 x 10(exp 6) sq km). Negative trends account for one-third to one-half of the interannual continental variance of SE. The historical influence of S on the planetary albedo and outgoing longwave radiation (OLR) is investigated. The mean annual response of the S feedback on the radiative balance (RB) is negative and suggests a largescale heat redistribution. During autumn and early winter (up to January), however, the feedback of S on the planetary RB may be positive. Only by February does the cooling effect of S (due to albedo increase) dominate the planetary warming due to reduced OLR over the S. Despite a wintertime maximum in SE, the feedback in spring has the greatest magnitude. The global retreat of spring SE should lead to a positive feedback on temperature. Based on observed records of S, changes in RB are calculated that parallel an observed increase of spring temperature during the past 20 years. The results provide a partial explanation of the significant increase in spring surface air temperature observed over the land areas of the Northern Hemisphere during the past century. The mean SE in years with an El Nino and La Nina were also evaluated. El Nino events are generally accompanied by increased SE over the NEL during the first half of the hydrological year. In the second half of the hydrologic year (spring and summer), the El Nino events are accompanied by a global retreat of SE.

  10. Central Asian Snow Cover from Hydrometeorological Surveys, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides observations of end of month snow depth, snow density, and snow water equivalent from three river basins in Central Asia: Amu Darya, Sir...

  11. Distribution and variability of total mercury in snow cover?a case study from a semi-urban site in Pozna?, Poland

    OpenAIRE

    Siudek, Patrycja

    2016-01-01

    In the present paper, the inter-seasonal Hg variability in snow cover was examined based on multivariate statistical analysis of chemical and meteorological data. Samples of freshly fallen snow cover were collected at the semi-urban site in Pozna? (central Poland), during 3-month field measurements in winter 2013. It was showed that concentrations of atmospherically deposited Hg were highly variable in snow cover, from 0.43 to 12.5?ng?L?1, with a mean value of 4.62?ng?L?1. The highest Hg conc...

  12. Chemical elements contamination of snow cover in region of coal production 'Karazhyra'

    International Nuclear Information System (INIS)

    Evlampieva, E.P.; Panin, M.S.

    2008-01-01

    Peculiarities of space distribution of chemical elements in hardphase and water-soluble falls of snow cover in region of coal deposit 'Karazhyra' are investigated. The maximal, minimal and background areas of elements accumulation in the snow of this region and distribution of their cumulative rates are determined. The main pollutants of snow cover unto background level are revealed.

  13. Snow Precipitation and Snow Cover Climatic Variability for the Period 1971–2009 in the Southwestern Italian Alps: The 2008–2009 Snow Season Case Study

    Directory of Open Access Journals (Sweden)

    Simona Fratianni

    2010-10-01

    Full Text Available Snow cover greatly influences the climate in the Alpine region and is one of the most relevant parameters for the climate change analysis. Nevertheless, snow precipitation variability is a relatively underexplored field of research because of the lack of long-term, continuous and homogeneous time series. After a historical research aiming to recover continuous records, three high quality time series of snow precipitation and snow depth recorded in the southwestern Italian Alps were analyzed. The comparison between the climatological indices over the 30 years reference period 1971–2000 and the decade 2000–2009 outlined a general decrease in the amount of snow precipitation, and a shift in the seasonal distribution of the snow precipitation in the most recent period. In the analysis of the last decade snow seasons characteristics, the attention was focused on the heavy snowfalls that occurred in Piedmont during the 2008–2009 snow season: MODerate resolution Imager Spectroradiometer (MODIS snow cover products were used to evaluate snow cover extension at different times during the snow season, and the results were set in relation to the temperatures.

  14. Global EASE-Grid 8-day Blended SSM/I and MODIS Snow Cover

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set comprises global, 8-day Snow-Covered Area (SCA) and Snow Water Equivalent (SWE) data from 2000 through 2008. Global SWE data are derived from the...

  15. Global EASE-Grid 8-day Blended SSM/I and MODIS Snow Cover, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set comprises global, 8-day Snow-Covered Area (SCA) and Snow Water Equivalent (SWE) data from 2000 through 2008. Global SWE data are derived from the...

  16. Establishing Winter Origins of Migrating Lesser Snow Geese Using Stable Isotopes

    Directory of Open Access Journals (Sweden)

    Viviane Hénaux

    2012-06-01

    Full Text Available Increases in Snow Goose (Chen caerulescens populations and large-scale habitat changes in North America have contributed to the concentration of migratory waterfowl on fewer wetlands, reducing resource availability, and enhancing risks of disease transmission. Predicting wintering locations of migratory individuals is critical to guide wildlife population management and habitat restoration. We used stable carbon (δ13C, nitrogen (δ15N, and hydrogen (δ2H isotope ratios in muscle tissue of wintering Snow Geese to discriminate four major wintering areas, the Playa Lake Region, Texas Gulf Coast, Louisiana Gulf Coast, and Arkansas, and infer the wintering locations of individuals collected later during the 2007 and 2008 spring migrations in the Rainwater Basin (RWB of Nebraska. We predicted the wintering ground derivation of migrating Snow Geese using a likelihood-based approach. Our three-isotope analysis provided an efficient discrimination of the four wintering areas. The assignment model predicted that 53% [95% CI: 37-69] of our sample of Snow Geese from the RWB in 2007 had most likely originated in Louisiana, 38% [23-54] had wintered on Texas Gulf Coast, and 9% [0-20] in Arkansas; the assessment suggested that 89% [73-100] of our 2008 sample had most likely come from Texas Gulf Coast, 9% [0-27] from Louisiana Gulf Coast, and 2% [0-9] from Arkansas. Further segregation of wintering grounds and additional sampling of spring migrating Snow Geese would refine overall assignment and help explain interannual variations in migratory connectivity. The ability to distinguish origins of northbound geese can support the development of spatially-adaptive management strategies for the midcontinent Snow Goose population. Establishing migratory connectivity using isotope assignment techniques can be extended to other waterfowl species to determine critical habitat, evaluate population energy requirements, and inform waterfowl conservation and management

  17. Use of Sentinels to aid the global monitoring of snow cover

    Science.gov (United States)

    Pulliainen, Jouni; Salminen, Miia; Luojus, Kari; Metsämäki, Sari; Lemmetyinen, Juha; Takala, Matias; Cohen, Juval; Böttcher, Kristine

    2014-05-01

    Earth observation instruments onboard Sentinel satellites provide a unique opportunity for the monitoring and investigation of global snow processes. The issue of the possible decay of seasonal snow cover is highly relevant for climate research. In addition to water cycle, the extent and amount of snow affects to surface albedo, and indirectly to carbon cycling. The latter issue includes snow-induced changes in permafrost regions (active layer characteristics), as well as the effect of snow (melt) to vegetation growth and soil respiration. Recent advances in ESA DUE GlobSnow project have shown that by combining data from optical satellite sensors and passive microwave instruments advanced Climate Data Records (CDR) on seasonal snow cover can be produced, extending to time periods of over 30 years. The combined snow cover products provide information both on Snow Extent (SE) and Snow Water Equivalent (SWE) on a daily basis. The applicable instruments providing historical data for CDR generation include such microwave radiometers as SMMR, AMSR and SSMI/I, and such optical sensors as AVHRR, AATSR and VIIRS. Sentinel 3, especially its SLSTR instrument, is a prominent tool for expanding the snow CDR for forthcoming years. The developed global snow cover monitoring methodology, demonstrated and discussed here, derives the SWE information from passive microwave data (accompanied with in situ observations of snow depth at synoptic weather stations). The snow extent and fractional snow cover (FSC) on ground is derived from optical satellite data, in order to accurately map the continental line of seasonal snow cover, and to map regions of ephemeral snow cover. An advanced feature in the developed methodology is the provision of uncertainty information on snow cover characteristics associated with each individual satellite data footprint on ground and moment of time. In addition to assisting the generation and extension of the global snow cover CDR, Sentinel missions provide

  18. Research on snow cover monitoring of Northeast China using Fengyun Geostationary Satellite

    Science.gov (United States)

    Wu, Tong; Gu, Lingjia; Ren, Ruizhi; Zhou, TIngting

    2017-09-01

    Snow cover information has great significance for monitoring and preventing snowstorms. With the development of satellite technology, geostationary satellites are playing more important roles in snow monitoring. Currently, cloud interference is a serious problem for obtaining accurate snow cover information. Therefore, the cloud pixels located in the MODIS snow products are usually replaced by cloud-free pixels around the day, which ignores snow cover dynamics. FengYun-2(FY-2) is the first generation of geostationary satellite in our country which complements the polar orbit satellite. The snow cover monitoring of Northeast China using FY-2G data in January and February 2016 is introduced in this paper. First of all, geometric and radiometric corrections are carried out for visible and infrared channels. Secondly, snow cover information is extracted according to its characteristics in different channels. Multi-threshold judgment methods for the different land types and similarity separation techniques are combined to discriminate snow and cloud. Furthermore, multi-temporal data is used to eliminate cloud effect. Finally, the experimental results are compared with the MOD10A1 and MYD10A1 (MODIS daily snow cover) product. The MODIS product can provide higher resolution of the snow cover information in cloudless conditions. Multi-temporal FY-2G data can get more accurate snow cover information in cloudy conditions, which is beneficial for monitoring snowstorms and climate changes.

  19. Effects of sowing time on pink snow mould, leaf rust and winter damage in winter rye varieties in Finland

    Directory of Open Access Journals (Sweden)

    M. SERENIUS

    2008-12-01

    Full Text Available Disease infection in relation to sowing time of winter rye (Secale cereale was studied in southern Finland in order to compare overwintering capacity of modern rye varieties and to give recommendations for rye cultivation. This was done by using three sowing times and four rye varieties in field trials conducted at three locations in 1999–2001. The early sown rye (beginning of August was severely affected by diseases caused by Puccinia recondita and Microdochium nivale, whereas postponing sowing for two weeks after the recommended sowing time resulted in considerably less infection. The infection levels of diseases differed among rye varieties. Finnish rye varieties Anna and Bor 7068 were more resistant to snow mould and more winter hardy than the Polish variety Amilo, or the German hybrid varieties Picasso and Esprit. However, Amilo was the most resistant to leaf rust. In the first year snow mould appeared to be the primary cause of winter damage, but in the second year the winter damage was positively correlated with leaf rust. No significant correlation between frit fly infestation and winter damage or disease incidence of snow mould or leaf rust was established. The late sowing of rye (in the beginning of September is recommended in Finland, particularly with hybrid varieties, to minimize the need for chemical plant protection in autumn.;

  20. Representation of vegetation effects on the snow-covered albedo in the Noah land surface model with multiple physics options

    OpenAIRE

    S. Park; S. K. Park

    2015-01-01

    Snow albedo plays a critical role in calculating the energy budget, but parameterization of the snow surface albedo is still under great uncertainty. It varies with snow grain size, snow cover thickness, snow age, forest shading factor and other variables. Snow albedo of forest is typically lower than that of short vegetation; thus snow albedo is dependent on the spatial distributions of characteristic land cover and on the canopy density and structure. In the No...

  1. Disentangling the mechanisms behind winter snow impact on vegetation activity in northern ecosystems.

    Science.gov (United States)

    Wang, Xiaoyi; Wang, Tao; Guo, Hui; Liu, Dan; Zhao, Yutong; Zhang, Taotao; Liu, Qiang; Piao, Shilong

    2018-04-01

    Although seasonal snow is recognized as an important component in the global climate system, the ability of snow to affect plant production remains an important unknown for assessing climate change impacts on vegetation dynamics at high-latitude ecosystems. Here, we compile data on satellite observation of vegetation greenness and spring onset date, satellite-based soil moisture, passive microwave snow water equivalent (SWE) and climate data to show that winter SWE can significantly influence vegetation greenness during the early growing season (the period between spring onset date and peak photosynthesis timing) over nearly one-fifth of the land surface in the region north of 30 degrees, but the magnitude and sign of correlation exhibits large spatial heterogeneity. We then apply an assembled path model to disentangle the two main processes (via changing early growing-season soil moisture, and via changing the growth period) in controlling the impact of winter SWE on vegetation greenness, and suggest that the "moisture" and "growth period" effect, to a larger extent, result in positive and negative snow-productivity associations, respectively. The magnitude and sign of snow-productivity association is then dependent upon the relative dominance of these two processes, with the "moisture" effect and positive association predominating in Central, western North America and Greater Himalaya, and the "growth period" effect and negative association in Central Europe. We also indicate that current state-of-the-art models in general reproduce satellite-based snow-productivity relationship in the region north of 30 degrees, and do a relatively better job of capturing the "moisture" effect than the "growth period" effect. Our results therefore work towards an improved understanding of winter snow impact on vegetation greenness in northern ecosystems, and provide a mechanistic basis for more realistic terrestrial carbon cycle models that consider the impacts of winter snow

  2. Winter fidelity and apparent survival of lesser snow goose populations in the Pacific flyway

    Science.gov (United States)

    Williams, C.K.; Samuel, M.D.; Baranyuk, Vasily V.; Cooch, E.G.; Kraege, Donald K.

    2008-01-01

    The Beringia region of the Arctic contains 2 colonies of lesser snow geese (Chen caerulescens caerulescens) breeding on Wrangel Island, Russia, and Banks Island, Canada, and wintering in North America. The Wrangel Island population is composed of 2 subpopulations from a sympatric breeding colony but separate wintering areas, whereas the Banks Island population shares a sympatric wintering area in California, USA, with one of the Wrangel Island subpopulations. The Wrangel Island colony represents the last major snow goose population in Russia and has fluctuated considerably since 1970, whereas the Banks Island population has more than doubled. The reasons for these changes are unclear, but hypotheses include independent population demographics (survival and recruitment) and immigration and emigration among breeding or wintering populations. These demographic and movement patterns have important ecological and management implications for understanding goose population structure, harvest of admixed populations, and gene flow among populations with separate breeding or wintering areas. From 1993 to 1996, we neckbanded molting birds at their breeding colonies and resighted birds on the wintering grounds. We used multistate mark-recapture models to evaluate apparent survival rates, resighting rates, winter fidelity, and potential exchange among these populations. We also compared the utility of face stain in Wrangel Island breeding geese as a predictor of their wintering area. Our results showed similar apparent survival rates between subpopulations of Wrangel Island snow geese and lower apparent survival, but higher emigration, for the Banks Island birds. Males had lower apparent survival than females, most likely due to differences in neckband loss. Transition between wintering areas was low (<3%), with equal movement between northern and southern wintering areas for Wrangel Island birds and little evidence of exchange between the Banks and northern Wrangel Island

  3. Frost flower chemical signature in winter snow on Vestfonna ice cap, Nordaustlandet, Svalbard

    Directory of Open Access Journals (Sweden)

    E. Beaudon

    2009-07-01

    Full Text Available The chemistry of snow and ice cores from Svalbard is influenced by variations in local sea ice margin and distance to open water. Snow pits sampled at two summits of Vestfonna ice cap (Nordaustlandet, Svalbard, exhibit spatially heterogeneous soluble ions concentrations despite similar accumulation rates, reflecting the importance of small-scale weather patterns on this island ice cap. The snow pack on the western summit shows higher average values of marine ions and a winter snow layer that is relatively depleted in sulphate. One part of the winter snow pack exhibits a [SO42-/Na+] ratio reduced by two thirds compared with its ratio in sea water. This low sulphate content in winter snow is interpreted as the signature of frost flowers, which are formed on young sea ice when offshore winds predominate. Frost flowers have been described as the dominant source of sea salt to aerosol and precipitation in ice cores in coastal Antarctica but this is the first time their chemical signal has been described in the Arctic. The eastern summit does not show any frost flower signature and we interpret the unusually dynamic ice transport and rapid formation of thin ice on the Hinlopen Strait as the source of the frost flowers.

  4. Western Italian Alps Monthly Snowfall and Snow Cover Duration

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set consists of snow observations for 18 stations in the western Italian Alps. Two types of data are included: monthly snowfall amounts and monthly snow...

  5. Winter fidelity and apparent survival of lesser snow goose populations in the Pacific flyway

    Science.gov (United States)

    Williams, C.K.; Samuel, M.D.; Baranyuk, Vasily V.; Cooch, E.G.; Kraege, Donald K.

    2008-01-01

    The Beringia region of the Arctic contains 2 colonies of lesser snow geese (Chen caerulescens caerulescens) breeding on Wrangel Island, Russia, and Banks Island, Canada, and wintering in North America. The Wrangel Island population is composed of 2 subpopulations from a sympatric breeding colony but separate wintering areas, whereas the Banks Island population shares a sympatric wintering area in California, USA, with one of the Wrangel Island subpopulations. The Wrangel Island colony represents the last major snow goose population in Russia and has fluctuated considerably since 1970, whereas the Banks Island population has more than doubled. The reasons for these changes are unclear, but hypotheses include independent population demographics (survival and recruitment) and immigration and emigration among breeding or wintering populations. These demographic and movement patterns have important ecological and management implications for understanding goose population structure, harvest of admixed populations, and gene flow among populations with separate breeding or wintering areas. From 1993 to 1996, we neckbanded molting birds at their breeding colonies and resighted birds on the wintering grounds. We used multistate mark-recapture models to evaluate apparent survival rates, resighting rates, winter fidelity, and potential exchange among these populations. We also compared the utility of face stain in Wrangel Island breeding geese as a predictor of their wintering area. Our results showed similar apparent survival rates between subpopulations of Wrangel Island snow geese and lower apparent survival, but higher emigration, for the Banks Island birds. Males had lower apparent survival than females, most likely due to differences in neckband loss. Transition between wintering areas was low (exchange between the Banks and northern Wrangel Island populations. Face staining was an unreliable indicator of wintering area. Our findings suggest that northern and southern

  6. [Evaluation of pollution of an urban area by level of heavy metals in snow cover].

    Science.gov (United States)

    Stepanova, N V; Khamitova, R Ia; Petrova, R S

    2003-01-01

    The goal of this study was to systematize various methodological approaches to evaluating the contamination of the snow cover with heavy metals (HM) by using Kazan, an industrial city with diversified industry, as an example. The findings suggest that it is necessary to characterize the contamination of the snow cover by the actual entrance of an element per area unit of the snow cover for a definite period of time rather than by the concentration of TM in the volume unit of snow water (mg/l), which minimizes the uncertainties with spatial and temporary snow cover variations. The index of the maximum allowable entrance, which is of practical value, may be used to objectively calibrate the pollution of the snow cover, by estimating the amount of a coming element and its toxicity.

  7. Estimation of snow line elevation changes from MODIS snow cover data

    Science.gov (United States)

    Parajka, Juraj; Bezak, Nejc; Burkhart, John; Holko, Ladislav; Hundecha, Yeshewa; Krajči, Pavel; Mangini, Walter; Molnar, Peter; Sensoy, Aynur; Riboust, Phillippe; Rizzi, Jonathan; Thirel, Guillaume; Arheimer, Berit

    2017-04-01

    This contribution evaluates changes in snowline elevation during snowmelt runoff events in selected basins from Austria, France, Norway, Slovakia, Slovenia, Sweden, Switzerland and Turkey. The main objectives are to investigate the spatial and temporal differences in regional snowline elevation (RSLE) across Europe and to discuss the factors which control its change. The analysis is performed in two steps. In the first, the regional snowline elevation is processed from daily MODIS snow cover data (MOD10A1) by using the methodology of Krajčí et al., (2014). In the second step, the changes in RSLE are analysed for selected flood events in the period 2000-2015. The snowmelt runoff events are extracted from Catalogue of identified flood peaks from GRDC dataset (FLOOD TYPE experiment) available at http://www.water-switch-on.eu/sip-webclient/byod/#/resource/12056. The results will be discussed in terms of: (a) availability and potential of MODIS snow cover data for identifying RSLE changes during snowmelt runoff events, (b) spatial and temporal patterns of RSLE changes across Europe and (c) factor controlling the RSLE change. The analysis is performed as an experiment in Virtual Water Science Laboratory of SWITCH-ON Project (http://www.water-switch-on.eu/). All data, tools and results of the analysis will be open and accessible through the Spatial Information Platform of the Project (http://www.water-switch-on.eu/sip-webclient/byod/). We believe that such strategy will allow to improve and forward comparative research and cooperation between different partners in hydrology (Ceola et al., 2015). References Ceola, S., Arheimer, B., Baratti, E., Blöschl, G., Capell, R., Castellarin, A., Freer, J., Han, D., Hrachowitz, M., Hundecha, Y., Hutton, C., Lindström, G., Montanari, A., Nijzink, R., Parajka, J., Toth, E., Viglione, A., and Wagener, T.: Virtual laboratories: new opportunities for collaborative water science, Hydrol. Earth Syst. Sci., 19, 2101-2117, doi:10

  8. Field investigations of apparent optical properties of ice cover in Finnish and Estonian lakes in winter 2009

    Directory of Open Access Journals (Sweden)

    Ruibo Lei

    2011-03-01

    Full Text Available A field programme on light conditions in ice-covered lakes and optical properties of lake ice was performed in seven lakes of Finland and Estonia in February–April 2009. On the basis of irradiance measurements above and below ice, spectral reflectance and transmittance were determined for the ice sheet; time evolution of photosynthetically active radiation (PAR transmittance was examined from irradiance recordings at several levels inside the ice sheet. Snow cover was the dominant factor for transmission of PAR into the lake water body. Reflectance was 0.74–0.92 in winter, going down to 0.18–0.22 in the melting season. The bulk attenuation coefficient of dry snow was 14–25 m–1; the level decreased as the spring was coming. The reflectance and bulk attenuation coefficient of snow-free ice were 0.1–0.4 and 1–5 m–1. Both were considerably smaller than those of snow cover. Seasonal evolution of light transmission was mainly due to snow melting. Snow and ice cover not only depress the PAR level in a lake but also influence the spectral and directional distribution of light.

  9. Distribution and variability of total mercury in snow cover-a case study from a semi-urban site in Poznań, Poland.

    Science.gov (United States)

    Siudek, Patrycja

    2016-12-01

    In the present paper, the inter-seasonal Hg variability in snow cover was examined based on multivariate statistical analysis of chemical and meteorological data. Samples of freshly fallen snow cover were collected at the semi-urban site in Poznań (central Poland), during 3-month field measurements in winter 2013. It was showed that concentrations of atmospherically deposited Hg were highly variable in snow cover, from 0.43 to 12.5 ng L -1 , with a mean value of 4.62 ng L -1 . The highest Hg concentration in snow cover coincided with local intensification of fossil fuel burning, indicating large contribution from various anthropogenic sources such as commercial and domestic heating, power generation plants, and traffic-related pollution. Moreover, the variability of Hg in collected snow samples was associated with long-range transport of pollutants, nocturnal inversion layer, low boundary layer height, and relatively low air temperature. For three snow episodes, Hg concentration in snow cover was attributed to southerly advection, suggesting significant contribution from the highly polluted region of Poland (Upper Silesia) and major European industrial hotspots. However, the peak Hg concentration was measured in samples collected during predominant N to NE advection of polluted air masses and after a relatively longer period without precipitation. Such significant contribution to the higher Hg accumulation in snow cover was associated with intensive emission from anthropogenic sources (coal combustion) and atmospheric conditions in this area. These results suggest that further measurements are needed to determine how the Hg transformation paths in snow cover change in response to longer/shorter duration of snow cover occurrence and to determine the interactions between mercury and absorbing carbonaceous aerosols in the light of climate change.

  10. No evidence of widespread decline of snow cover on the Tibetan Plateau over 2000-2015.

    Science.gov (United States)

    Wang, Xiaoyue; Wu, Chaoyang; Wang, Huanjiong; Gonsamo, Alemu; Liu, Zhengjia

    2017-11-07

    Understanding the changes in snow cover is essential for biological and hydrological processes in the Tibetan Plateau (TP) and its surrounding areas. However, the changes in snow cover phenology over the TP have not been well documented. Using Moderate Resolution Imaging Spectroradiometer (MODIS) daily snow products and the Interactive Multi-sensor Snow and Ice Mapping System (IMS) data, we reported daily cloud-free snow cover product over the Tibetan Plateau (TP) for 2000-2015. Snow cover start (SCS), melt (SCM) and duration (SCD) dates were calculated for each hydrological year, and their spatial and temporal variations were analyzed with elevation variations. Our results show no widespread decline in snow cover over the past fifteen years and the trends of snow cover phenology over the TP has high spatial heterogeneity. Later SCS, earlier SCM, and thus decreased SCD mainly occurred in the areas with elevation below 3500 m a.s.l., while regions in central and southwestern edges of the TP showed advanced SCS, delayed SCM and consequently longer SCD. The roles of temperature and precipitation on snow cover penology varied in different elevation zones, and the impact of both temperature and precipitation strengthened as elevation increases.

  11. Variability in snow cover phenology in China from 1952 to 2010

    OpenAIRE

    Ke, Chang-Qing; Li, Xiu-Cang; Xie, Hongjie; Ma, Dong-Hui; Liu, Xun; Kou, Cheng

    2016-01-01

    Daily snow observation data from 672 stations in China, particularly the 296 stations with over 10 mean snow cover days (SCDs) in a year during the period of 1952–2010, are used in this study. We first examine spatiotemporal variations and trends of SCDs, snow cover onset date (SCOD), and snow cover end date (SCED). We then investigate the relationships of SCDs with number of days with temperature below 0 °C (TBZD), mean air temperature (MAT), and Arctic Oscillation (AO) index....

  12. Laws of distribution of the snow cover on the greater Caucasus (Soviet Union)

    Science.gov (United States)

    Gurtovaya, Y. Y.; Sulakvelidze, G. K.; Yashina, A. V.

    1985-01-01

    The laws of the distribution of the snow cover on the mountains of the greater Caucasus are discussed. It is shown that an extremely unequal distribution of the snow cover is caused by the complex orography of this territory, the diversity of climatic conditions and by the difference in altitude. Regions of constant, variable and unstable snow cover are distinguished because of the clearly marked division into altitude layers, each of which is characterized by climatic differences in the nature of the snow accumulation.

  13. Effects of Planting of Calluna Vulgaris for Stable Snow Accumulation in Winter

    Science.gov (United States)

    Ibuki, R.; Harada, K.

    2017-12-01

    Recent year climate of the winter season is changing and the period of snow accumulation is reduced compared with before. It affects the management of the ski resort. Snowfall had occurred in December 2016, but the snow accumulated after January 2017 at the ski resort located in the Pacific Ocean side of the Northeast region of Japan. This situation is thought to be originated from two reasons, one is snow thawing, another is to be blown away by the strong monsoon wind. We are considering utilizing planting to stabilize snow accumulation. Currently building rock gardens with shrubs, mainly Calluna Vulgaris in the ski resort for attracting customers in the summer. These are difficult to raise in the lowlands of Japan because they are too hot, but because of their good growth in relatively low-temperature highlands, it is rare for local residents to appreciate the value of these. In addition, it is excellent in low temperature resistance, and it will not die even under the snow. We investigated the pressure resistance performance due to snowfall and the appropriateness of growth under the weather conditions of the area. Regarding Calluna Vulgaris, Firefly, the plants were not damaged even under snow more than 1 m. In addition, three years have passed since planting, relatively good growth is shown, and the stock has been growing every year. Based on these results, we plan to stabilize the snow accumulation by carrying out planting of Calluna vulgaris inside the slope. The growth of the Calluna species is gentle and the tree height grows only about 50 cm even if 15 years have passed since planting. Therefore, it is considered that the plant body is hard to put out their head on the snow surface during the ski season. Next season will monitor the snow accumulation around the planting area through the snow season.

  14. Removal of snow cover inhibits spring growth of Arctic ice algae through physiological and behavioral effects

    DEFF Research Database (Denmark)

    Lund-Hansen, L.C.; Hawes, Ian; Sorrell, Brian Keith

    2014-01-01

    The snow cover of Arctic sea ice has recently decreased, and climate models forecast that this will continue and even increase in future. We therefore tested the effect of snow cover on the optical properties of sea ice and the biomass, photobiology, and species composition of sea ice algae at Ka...

  15. Boreal snow cover variations induced by aerosol emissions in the middle of the 21st century

    Science.gov (United States)

    Ménégoz, M.; Krinner, G.; Balkanski, Y.; Cozic, A.; Boucher, O.; Ciais, P.

    2012-11-01

    We used a coupled climate-chemistry model to quantify the impacts of aerosols on snow cover both for the present-day and for the middle of the 21st century. Black carbon (BC) deposition over continents induces a reduction in the Mean Number of Days With Snow at the Surface (MNDWS) that ranges from 0 to 10 days over large areas of Eurasia and Northern America for the present-day relative to the pre-industrial period. This is mainly due to BC deposition during the spring, a period of the year when the remaining of snow accumulated during the winter is exposed to both strong solar radiation and large amount of aerosol deposition induced themselves by a high level of transport of particles from polluted areas. North of 30° N, this deposition flux represents 222 Gg BC month-1 on average from April to June in our simulation. A large reduction in BC emissions is expected in the future in the Radiative Concentration Pathway (RCP) scenarios. Considering this scenario in our simulation leads to a decrease in the spring BC deposition down to 110 Gg month-1 in the 2050s in the RCP8.5 scenario. However, despite the reduction of the aerosol impact on snow, the MNDWS is strongly reduced by 2050, with a decrease ranging from 10 to 100 days from pre-industrial values over large parts of the Northern Hemisphere. This reduction is essentially due to temperature increase, which is quite strong in the RCP8.5 scenario in the absence of climate mitigation policies. Moreover, the projected sea-ice retreat in the next decades will open new routes for shipping in the Arctic. However, a large increase in shipping emissions in the Arctic by the mid 21st century does not lead to significant changes of BC deposition over snow-covered areas in our simulation. Therefore, the MNDWS is clearly not affected through snow darkening effects associated to these Arctic ship emissions. In an experiment without nudging toward atmospheric reanalyses, we simulated however some changes of the MNDWS

  16. Sensitivity of the French Alps snow cover to the variation of climatic variables

    Directory of Open Access Journals (Sweden)

    E. Martin

    Full Text Available In order to study the sensitivity of snow cover to changes in meteorological variables at a regional scale, a numerical snow model and an analysis system of the meteorological conditions adapted to relief were used. This approach has been successfully tested by comparing simulated and measured snow depth at 37 sites in the French Alps during a ten year data period. Then, the sensitivity of the snow cover to a variation in climatic conditions was tested by two different methods, which led to very similar results. To assess the impact of a particular "doubled CO2" scenario, coherent perturbations were introduced in the input data of the snow model. It was found that although the impact would be very pronounced, it would also be extremely differentiated, dependent on the internal state of the snow cover. The most sensitive areas are the elevations below 2400 m, especially in the southern part of the French Alps.

  17. Slip resistance of winter footwear on snow and ice measured using maximum achievable incline.

    Science.gov (United States)

    Hsu, Jennifer; Shaw, Robert; Novak, Alison; Li, Yue; Ormerod, Marcus; Newton, Rita; Dutta, Tilak; Fernie, Geoff

    2016-05-01

    Protective footwear is necessary for preventing injurious slips and falls in winter conditions. Valid methods for assessing footwear slip resistance on winter surfaces are needed in order to evaluate footwear and outsole designs. The purpose of this study was to utilise a method of testing winter footwear that was ecologically valid in terms of involving actual human testers walking on realistic winter surfaces to produce objective measures of slip resistance. During the experiment, eight participants tested six styles of footwear on wet ice, on dry ice, and on dry ice after walking over soft snow. Slip resistance was measured by determining the maximum incline angles participants were able to walk up and down in each footwear-surface combination. The results indicated that testing on a variety of surfaces is necessary for establishing winter footwear performance and that standard mechanical bench tests for footwear slip resistance do not adequately reflect actual performance. Practitioner Summary: Existing standardised methods for measuring footwear slip resistance lack validation on winter surfaces. By determining the maximum inclines participants could walk up and down slopes of wet ice, dry ice, and ice with snow, in a range of footwear, an ecologically valid test for measuring winter footwear performance was established.

  18. Short Communication A vetch winter cover crop can improve ...

    African Journals Online (AJOL)

    A high nitrogen (N) fertiliser requirement can be a deterrent to the adoption of conservation agriculture (CA). A field trial was carried out to test whether a high biomass-yielding vetch (Vicia dasycarpa L.) winter cover crop can be used to improve N response and profitability of a subsequent maize (Zea mays L.) crop under ...

  19. Feasibility of winter cover crop production under rainfed conditions ...

    African Journals Online (AJOL)

    Low winter rainfall poses a challenge to production of high biomass from cover crops, which is necessary for the success of conservation agriculture systems in the Eastern Cape Province of South Africa. An experiment was conducted to evaluate the adaptability of white oats (Avena sativa), grazing vetch (Vicia dasycarpa), ...

  20. The stepwise discriminant algorithm for snow cover mapping based on FY-3/MERSI data

    Science.gov (United States)

    Han, Tao; Wang, Dawei; Jiang, Youyan; Wang, Xiaowei

    2013-10-01

    Medium Resolution Spectral Imager (MERSI) on board China's new generation polar orbit meteorological satellite FY- 3A provides a new data source for snow monitoring in large area. As a case study, the typical snow cover of Qilian Mountains in northwest China was selected in this paper to develop the algorithm to map snow cover using FY- 3A/MERSI. By analyzing the spectral response characteristics of snow and other surface elements, as well as each channel image quality on FY-3A/MERSI, the widely used Normalized Difference Snow Index (NDSI) was defined to be computed from channel 2 and channel 7 for this satellite data. Basing on NDSI, a tree-structure prototype version of snow identification model was proposed, including five newly-built multi-spectral indexes to remove those pixels such as forest, cloud shadow, water, lake ice, sand (salty land), or cloud that are usually confused with snow step by step, especially, a snow/cloud discrimination index was proposed to eliminate cloud, apart from use of cloud mask product in advance. Furthermore, land cover land use (LULC) image has been adopted as auxiliary dataset to adjust the corresponding LULC NDSI threshold constraints for snow final determination and optimization. This model is composed as the core of FY-3A/MERSI snow cover mapping flowchart, to produce daily snow map at 250m spatial resolution, and statistics can be generated on the extent and persistence of snow cover in each pixel for time series maps. Preliminary validation activities of our snow identification model have been undertaken. Comparisons of the 104 FY- 3A/MERSI snow cover maps in 2010-2011 snow season with snow depth records from 16 meteorological stations in Qilian Mountains region, the sunny snow cover had an absolute accuracy of 92.8%. Results of the comparison with the snow cover identified from 6 Terra/MODIS scenes showed that they had consistent pixels about 85%. When the two satellite resultant snow cover maps compared with the 6

  1. Snow cover dynamics in the Catalan Pyrenees range using remote sensing data from 2002 to 2008 period

    Science.gov (United States)

    Cea, C.; Cristóbal, J.; Pons, X.

    2009-04-01

    Snow cover dynamics in the Catalan Pyrenees range using remote sensing data from 2002 to 2008 period. C. Cea (1), J. Cristóbal (1), X. Pons (1, 2) (1) Department of Geography. Autonomous University of Barcelona. Cerdanyola del Vallès, 08193. Cristina.Cea@uab.cat, (2) Center for Ecological Research and Forestry Applications (CREAF) Cerdanyola del Vallès, 08193. Water resources and its management are essential in many alpine mountainous areas. Snow cover monitoring in the Mediterranean zone requires obtaining accurate snow cartography to estimate the volume of water derived from snow melting and species distribution modelling. Snow data is usually obtained by field campaigns, but to obtain a spatial and temporal cover of enough detail and quality it is necessary collect an important number of data. However, when a continuous surface is needed, Remote Sensing could provide better snow cover estimation due to its spatial and temporal resolution. The aim of this study is to map snow cover and analyse its spatial and temporal dynamics using medium and coarse remote sensing data at a regional scale over an heterogeneous area, the Catalan Pyrenees (NE of the Iberian Peninsula). The seasonal snow cover period is from October to June. In this period, regular snowfalls usually take place from December to April, although during the rest of the period, punctual but important episodes of snowfalls are frequent. To perform this analysis, a set of 96 Landsat images (36 Landsat-5 TM and 60 Landsat-7 ETM+) of path 197 and 198 and rows 31 and 32 from January 2002 to April 2007, and 90 Terra-MODIS images from October 2007 to July 2008, with a different percentage of cloudiness, have been chosen. The computation of the Landsat-5 TM and Landsat-7 ETM+ data used in snow cover mapping has been carried out by means of the following methodologies. Images have been geometrically corrected by means of techniques based on first order polynomials taking into account the effect of the relief

  2. Consistent seasonal snow cover depth and duration variability over ...

    Indian Academy of Sciences (India)

    of biodiversity, global ecosystem and global hydro- logical cycle (Robinson ... climate change impacts assessment, water resources ...... Brown R D and Braaten R O 1998 Spatial and temporal vari- ability of Canadian monthly snow depths; Atmos. Ocean. 36 37–54. Cayan D R 1996 Interannual climate variability and snow.

  3. Prolongation of soil frost resulting from reduced snow cover increases nitrous oxide emissions from boreal forest soil

    Energy Technology Data Exchange (ETDEWEB)

    Maljanen, M.; Martikainen, P.J. (Univ. of Kuopio, Dept. of Environmental Science (Finland)); Alm, J.; Repo, T. (Finnish Forest Research Inst., Joensuu Research Centre (Finland))

    2010-07-01

    Emission rates of the greenhouse gas, nitrous oxide (N{sub 2}O), from northern upland forest soils are generally low. According to recent climate scenarios, the snow cover in the boreal region is predicted to decrease and which will result in lower soil temperatures. In this study, we investigated whether lower soil temperatures during winter can also trigger N{sub 2}O emissions from boreal forest soils with originally low N{sub 2}O emissions, as has earlier been shown for northern agricultural soils with higher N{sub 2}O emissions. We measured the N{sub 2}O emissions from a spruce forest in eastern Finland where the soil temperature was changed by manipulating snow-pack thickness and using insulating covers. The effects of the treatments on methane (CH{sub 4}) and carbon dioxide (CO{sub 2}) fluxes were also studied for comparative purposes. The results show that there can be an increase in N{sub 2}O emissions and CO{sub 2} production rate from boreal upland forest soils resulting from a thinner snow cover that causes a prolongation of soil frost. Reducing the snow pack thickness had only minor effects on the CH{sub 4} fluxes. (orig.)

  4. Changing Arctic snow cover: A review of recent developments and assessment of future needs for observations, modelling, and impacts

    DEFF Research Database (Denmark)

    Bokhorst, Stef; Pedersen, Stine Højlund; Brucker, Ludovic

    2016-01-01

    Snow is a critically important and rapidly changing feature of the Arctic. However, snow-cover and snowpack conditions change through time pose challenges for measuring and prediction of snow. Plausible scenarios of how Arctic snow cover will respond to changing Arctic climate are important for i...

  5. Changing Arctic snow cover: A review of recent developments and assessment of future needs for observations, modelling, and impacts

    NARCIS (Netherlands)

    Bokhorst, Stef; Pedersen, Stine Højlund; Brucker, Ludovic; Anisimov, Oleg; Bjerke, Jarle W.; Brown, Ross D.; Ehrich, Dorothee; Essery, Richard L. H.; Heilig, Achim; Ingvander, Susanne; Johansson, Cecilia; Johansson, Margareta; Jónsdóttir, Ingibjörg Svala; Inga, Niila; Luojus, Kari; Macelloni, Giovanni; Mariash, Heather; Mclennan, Donald; Rosqvist, Gunhild Ninis; Sato, Atsushi; Savela, Hannele; Schneebeli, Martin; Sokolov, Aleksandr; Sokratov, Sergey A.; Terzago, Silvia; Vikhamar-schuler, Dagrun; Williamson, Scott; Qiu, Yubao; Callaghan, Terry V.

    2016-01-01

    Snow is a critically important and rapidly changing feature of the Arctic. However, snow-cover and snowpack conditions change through time pose challenges for measuring and prediction of snow. Plausible scenarios of how Arctic snow cover will respond to changing Arctic climate are important for

  6. Snow Cover Variability in the Black Forest Region as an Example of a German Low Mountain Range under the Influence of Climate Change

    Science.gov (United States)

    Schoenbein, J.; Schneider, C.

    2003-04-01

    of 10 cm is likely to be shortened by 20 days per winter season until 2025 in the Black Forest. That is to say snow cover duration in the summit region will be shortened by one third in comparison to the snow cover duration in the 1990s. Regions below 800 m altitude a.s.l. will no longer regularly receive a snow cover lasting for at least a fortnight during the winter season. The analysis was extended to allow for the possibilities of artificial snowing within skiing resorts. Based on air temperature and air humidity data the mean seasonal number of days suitable for artificial snowing was calculated depending on region and altitude. The conditions for operating artificial snow production units are much better within more continental toned climates in the east of Germany than in the southern and western parts of the country. Together with a digital elevation model (DEM) of Germany the data within a Geographic Information System (GIS)serves to identify key regions of possible investments into winter sport facilities.

  7. Trace element distribution in the snow cover from an urban area in central Poland.

    Science.gov (United States)

    Siudek, Patrycja; Frankowski, Marcin; Siepak, Jerzy

    2015-05-01

    This work presents the first results from winter field campaigns focusing on trace metals and metalloid chemistry in the snow cover from an urbanized region in central Poland. Samples were collected between January and March 2013 and trace element concentrations were determined using GF-AAS. A large inter-seasonal variability depending on anthropogenic emission, depositional processes, and meteorological conditions was observed. The highest concentration (in μg L(-1)) was reported for Pb (34.90), followed by Ni (31.37), Zn (31.00), Cu (13.71), Cr (2.36), As (1.58), and Cd (0.25). In addition, several major anthropogenic sources were identified based on principal component analysis (PCA), among which the most significant was the activity of industry and coal combustion for residential heating. It was stated that elevated concentrations of some trace metals in snow samples were associated with frequent occurrence of south and southeast advection of highly polluted air masses toward the sampling site, suggesting a large impact of regional urban/industrial pollution plumes.

  8. Some relationships among air, snow, and soil temperatures and soil frost

    Science.gov (United States)

    George Hart; Howard W. Lull

    1963-01-01

    Each winter gives examples of the insulating properties of snow cover. Seeds and soil fauna are protected from the cold by snow. Underground water pipes are less likely to freeze under snow cover. And, according to many observers, the occurrence, penetration, and thaw of soil frost are affected by snow cover. The depth of snow necessary to protect soil from freezing...

  9. Response of alpine vegetation growth dynamics to snow cover phenology on the Tibetan Plateau

    Science.gov (United States)

    Wang, X.; Wu, C.

    2017-12-01

    Alpine vegetation plays a crucial role in global energy cycles with snow cover, an essential component of alpine land cover showing high sensitivity to climate change. The Tibetan Plateau (TP) has a typical alpine vegetation ecosystem and is rich of snow resources. With global warming, the snow of the TP has undergone significant changes that will inevitably affect the growth of alpine vegetation, but observed evidence of such interaction is limited. In particular, a comprehensive understanding of the responses of alpine vegetation growth to snow cover variability is still not well characterized on TP region. To investigate this, we calculated three indicators, the start (SOS) and length (LOS) of growing season, and the maximum of normalized difference vegetation index (NDVImax) as proxies of vegetation growth dynamics from the Moderate Resolution Imaging Spectroradiometer (MODIS) data for 2000-2015. Snow cover duration (SCD) and melt (SCM) dates were also extracted during the same time frame from the combination of MODIS and the Interactive Multi-sensor Snow and Ice Mapping System (IMS) data. We found that the snow cover phenology had a strong control on alpine vegetation growth dynamics. Furthermore, the responses of SOS, LOS and NDVImax to snow cover phenology varied among plant functional types, eco-geographical zones, and temperature and precipitation gradients. The alpine steppes showed a much stronger negative correlation between SOS and SCD, and also a more evidently positive relationship between LOS and SCD than other types, indicating a longer SCD would lead to an earlier SOS and longer LOS. Most areas showed positive correlation between SOS and SCM, while a contrary response was also found in the warm but drier areas. Both SCD and SCM showed positive correlations with NDVImax, but the relationship became weaker with the increase of precipitation. Our findings provided strong evidences between vegetation growth and snow cover phenology, and changes in

  10. Winter precipitation and snow accumulation drive the methane sink or source strength of Arctic tussock tundra.

    Science.gov (United States)

    Blanc-Betes, Elena; Welker, Jeffrey M; Sturchio, Neil C; Chanton, Jeffrey P; Gonzalez-Meler, Miquel A

    2016-08-01

    Arctic winter precipitation is projected to increase with global warming, but some areas will experience decreases in snow accumulation. Although Arctic CH4 emissions may represent a significant climate forcing feedback, long-term impacts of changes in snow accumulation on CH4 fluxes remain uncertain. We measured ecosystem CH4 fluxes and soil CH4 and CO2 concentrations and (13) C composition to investigate the metabolic pathways and transport mechanisms driving moist acidic tundra CH4 flux over the growing season (Jun-Aug) after 18 years of experimental snow depth increases and decreases. Deeper snow increased soil wetness and warming, reducing soil %O2 levels and increasing thaw depth. Soil moisture, through changes in soil %O2 saturation, determined predominance of methanotrophy or methanogenesis, with soil temperature regulating the ecosystem CH4 sink or source strength. Reduced snow (RS) increased the fraction of oxidized CH4 (Fox) by 75-120% compared to Ambient, switching the system from a small source to a net CH4 sink (21 ± 2 and -31 ± 1 mg CH4  m(-2)  season(-1) at Ambient and RS). Deeper snow reduced Fox by 35-40% and 90-100% in medium- (MS) and high- (HS) snow additions relative to Ambient, contributing to increasing the CH4 source strength of moist acidic tundra (464 ± 15 and 3561 ± 97 mg CH4  m(-2)  season(-1) at MS and HS). Decreases in Fox with deeper snow were partly due to increases in plant-mediated CH4 transport associated with the expansion of tall graminoids. Deeper snow enhanced CH4 production within newly thawed soils, responding mainly to soil warming rather than to increases in acetate fermentation expected from thaw-induced increases in SOC availability. Our results suggest that increased winter precipitation will increase the CH4 source strength of Arctic tundra, but the resulting positive feedback on climate change will depend on the balance between areas with more or less snow accumulation than they are currently

  11. Timing and Statistics of Autumn and Spring Annual Snow Cover for the Northern Hemisphere, 1972 to 2000

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Snow and Ice Data Center hosts a time-series data set comprising annual snow cover data for the Northern Hemisphere (covering land primarily over 45...

  12. MEaSUREs Northern Hemisphere Terrestrial Snow Cover Extent Daily 25km EASE-Grid 2.0 V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set offers users 25 km Northern Hemisphere snow cover extent represented by four different variables. Three of the snow cover variables are derived from...

  13. MODIS/Aqua Near Real Time (NRT) Snow Cover 5-Min L2 Swath 500m, Version 006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS/Aqua Near Real Time (NRT) Snow Cover 5-Min L2 Swath 500m (MYD10_L2) data set contains snow cover and Quality Assessment (QA) data, latitudes and longitudes...

  14. Snow cover dynamics and water balance in complex high alpine terrain

    Science.gov (United States)

    Warscher, Michael; Kraller, Gabriele; Kunstmann, Harald; Strasser, Ulrich; Franz, Helmut

    2010-05-01

    The water balance in high alpine regions in its full complexity is so far insufficiently understood. High altitudinal gradients, a strong variability of meteorological variables in time and space, complex hydrogeological situations, unquantified lateral snow transport processes and heterogenous snow cover dynamics result in high uncertainties in the quantification of the water balance. To achieve interpretable modeling results we have complemented the deterministic hydrological model WaSiM-ETH with the high-alpine specific snow model AMUNDSEN. The integration of the new snow module was done to improve the modeling of water fluxes influenced by the dynamics of the snow cover, which greatly affect the water cycle in high alpine regions. To enhance the reproduction of snow deposition and ablation processes, the new approach calculates the energy balance of the snow cover considering the terrain-dependent radiation fluxes, the interaction between tree canopy and snow cover as well as lateral snow transport processes. The test site for our study is the Berchtesgaden National Park which is characterized by an extreme topography with mountain ranges covering an altitude from 607 to 2713 m.a.s.l. About one quarter of the investigated catchment area, which comprises 433 km² in total, is terrain steeper than 35°. Due to water soluble limestone being predominant in the region, a high number of subsurface water pathways (karst) exist. The results of several tracer experiments and extensive data of spring observations provide additional information to meet the challenge of modeling the unknown subsurface pathways and the complex groundwater system of the region. The validation of the new snow module is based on a dense network of meteorological stations which have been adapted to measure physical properties of the snow cover like snow water equivalent and liquid water content. We will present first results which show that the integration of the new snow module generates a

  15. Complex responses of spring alpine vegetation phenology to snow cover dynamics over the Tibetan Plateau, China.

    Science.gov (United States)

    Wang, Siyuan; Wang, Xiaoyue; Chen, Guangsheng; Yang, Qichun; Wang, Bin; Ma, Yuanxu; Shen, Ming

    2017-09-01

    Snow cover dynamics are considered to play a key role on spring phenological shifts in the high-latitude, so investigating responses of spring phenology to snow cover dynamics is becoming an increasingly important way to identify and predict global ecosystem dynamics. In this study, we quantified the temporal trends and spatial variations of spring phenology and snow cover across the Tibetan Plateau by calibrating and analyzing time series of the NOAA AVHRR-derived normalized difference vegetation index (NDVI) during 1983-2012. We also examined how snow cover dynamics affect the spatio-temporal pattern of spring alpine vegetation phenology over the plateau. Our results indicated that 52.21% of the plateau experienced a significant advancing trend in the beginning of vegetation growing season (BGS) and 34.30% exhibited a delaying trend. Accordingly, the snow cover duration days (SCD) and snow cover melt date (SCM) showed similar patterns with a decreasing trend in the west and an increasing trend in the southeast, but the start date of snow cover (SCS) showed an opposite pattern. Meanwhile, the spatial patterns of the BGS, SCD, SCS and SCM varied in accordance with the gradients of temperature, precipitation and topography across the plateau. The response relationship of spring phenology to snow cover dynamics varied within different climate, terrain and alpine plant community zones, and the spatio-temporal response patterns were primarily controlled by the long-term local heat-water conditions and topographic conditions. Moreover, temperature and precipitation played a profound impact on diverse responses of spring phenology to snow cover dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. A technigue exploitation about anti-slide tire polyploid on ice-snow road in winter

    Science.gov (United States)

    Xiaojie, Qi; Qiang, Wang; Zhao, Yang; Yunlong, Wang; Guotian, Wang; Degang, Lv

    2017-04-01

    Present studies focus on improving anti-slide property of tyes on ice-snow road by changing material modification of tyre tread and designing groove. However, the basic reason causing starting slide, long braking distance, turning slide slip and so on of tyres used in winter is that tyre tread materials are unitary and homogenous rubber composite which can’t coordinate driving demands of tyres in winter under muti-work condition, and can’t exert their best property when starting, braking and sliding slip. In order to improve comprehensive anti-slide property of tyres, this paper discusses about changing structure, shape and distribution proportion among haploid materials of tyre tread rubber. Polyploid bubber tyre tread technique based on artificial neural network which is in favor of starting, braking and anti-slide slip is optimized and combined. Friction feature and anti-slide mechanism on ice-snow road of polyploid rubber tyre tread are studied using testing technique of low-temperature cabin and computer simulation. A set high anti-slide theories and realizing method systems of polyploid rubber composite formed from basic theory, models and technique method are developped which will be applied into solving anti-slide problem of winter tyres, provide theory instruction for studies on high anti-slide winter tyres, and promote development of application and usage safety of winter tyres.

  17. Spatial and Temporal Characteristics of Snow Cover in the Tizinafu Watershed of the Western Kunlun Mountains

    Directory of Open Access Journals (Sweden)

    Jiangfeng She

    2015-03-01

    Full Text Available The Tizinafu watershed has a complex mountainous terrain in the western Kunlun Mountains; little study has been done on the spatial and temporal characteristics of snow cover in the region. Daily snow cover data of 10 hydrological years (October 2002 to September 2012 in the watershed were generated by combining MODIS Terra (MOD10A1 and Aqua (MYD10A1 snow cover products and employing a nine-day temporal filter for cloud reduction. The accuracy and window size of the temporal filter were assessed using a simulation approach. Spatial and temporal characteristics of snow cover in the watershed were then analyzed. Our results showed that snow generally starts melting in March and reaches the minimum in early August in the watershed. Snow cover percentages (SCPs in all five elevation zones increase consistently with the rise of elevation. Slope doesn’t play a major role in snow cover distribution when it exceeds 10°. The largest SCP difference is between the south and the other aspects and occurs between mid-October and mid-November with decreasing SCP, indicating direct solar radiation may cause the reduction of snow cover. While both the mean snow cover durations (SCDs of the hydrological years and of the snowmelt seasons share a similar spatial pattern to the topography of the watershed, the coefficient of variation of the SCDs exhibits an opposite spatial distribution. There is a significant correlation between annual mean SCP and annual total stream flow, indicating that snowmelt is a major source of stream runoff that might be predictable with SCP.

  18. An Automated Approach for Mapping Persistent Ice and Snow Cover over High Latitude Regions

    Directory of Open Access Journals (Sweden)

    David J. Selkowitz

    2015-12-01

    Full Text Available We developed an automated approach for mapping persistent ice and snow cover (glaciers and perennial snowfields from Landsat TM and ETM+ data across a variety of topography, glacier types, and climatic conditions at high latitudes (above ~65°N. Our approach exploits all available Landsat scenes acquired during the late summer (1 August–15 September over a multi-year period and employs an automated cloud masking algorithm optimized for snow and ice covered mountainous environments. Pixels from individual Landsat scenes were classified as snow/ice covered or snow/ice free based on the Normalized Difference Snow Index (NDSI, and pixels consistently identified as snow/ice covered over a five-year period were classified as persistent ice and snow cover. The same NDSI and ratio of snow/ice-covered days to total days thresholds applied consistently across eight study regions resulted in persistent ice and snow cover maps that agreed closely in most areas with glacier area mapped for the Randolph Glacier Inventory (RGI, with a mean accuracy (agreement with the RGI of 0.96, a mean precision (user’s accuracy of the snow/ice cover class of 0.92, a mean recall (producer’s accuracy of the snow/ice cover class of 0.86, and a mean F-score (a measure that considers both precision and recall of 0.88. We also compared results from our approach to glacier area mapped from high spatial resolution imagery at four study regions and found similar results. Accuracy was lowest in regions with substantial areas of debris-covered glacier ice, suggesting that manual editing would still be required in these regions to achieve reasonable results. The similarity of our results to those from the RGI as well as glacier area mapped from high spatial resolution imagery suggests it should be possible to apply this approach across large regions to produce updated 30-m resolution maps of persistent ice and snow cover. In the short term, automated PISC maps can be used to

  19. An automated approach for mapping persistent ice and snow cover over high latitude regions

    Science.gov (United States)

    Selkowitz, David J.; Forster, Richard R.

    2016-01-01

    We developed an automated approach for mapping persistent ice and snow cover (glaciers and perennial snowfields) from Landsat TM and ETM+ data across a variety of topography, glacier types, and climatic conditions at high latitudes (above ~65°N). Our approach exploits all available Landsat scenes acquired during the late summer (1 August–15 September) over a multi-year period and employs an automated cloud masking algorithm optimized for snow and ice covered mountainous environments. Pixels from individual Landsat scenes were classified as snow/ice covered or snow/ice free based on the Normalized Difference Snow Index (NDSI), and pixels consistently identified as snow/ice covered over a five-year period were classified as persistent ice and snow cover. The same NDSI and ratio of snow/ice-covered days to total days thresholds applied consistently across eight study regions resulted in persistent ice and snow cover maps that agreed closely in most areas with glacier area mapped for the Randolph Glacier Inventory (RGI), with a mean accuracy (agreement with the RGI) of 0.96, a mean precision (user’s accuracy of the snow/ice cover class) of 0.92, a mean recall (producer’s accuracy of the snow/ice cover class) of 0.86, and a mean F-score (a measure that considers both precision and recall) of 0.88. We also compared results from our approach to glacier area mapped from high spatial resolution imagery at four study regions and found similar results. Accuracy was lowest in regions with substantial areas of debris-covered glacier ice, suggesting that manual editing would still be required in these regions to achieve reasonable results. The similarity of our results to those from the RGI as well as glacier area mapped from high spatial resolution imagery suggests it should be possible to apply this approach across large regions to produce updated 30-m resolution maps of persistent ice and snow cover. In the short term, automated PISC maps can be used to rapidly

  20. Assessment of dynamic probabilistic methods for mapping snow cover in Québec Canada

    Science.gov (United States)

    De Seve, D.; Perreault, L.; Vachon, F.; Guay, F.; choquette, Y.

    2012-04-01

    Hydro-Quebec is the leader in electricity production in North America and uses hydraulic resources to generate 97% of its overall production where snow represents 30% of its annual energy reserve. Information on snow cover extent (SC) and snow water equivalent (SWE) is crucial for hydrological forecasting, particularly in Nordic regions where a majority of total precipitations falls as snow. Accurate estimation of the spatial distribution of snow cover variables is required to measure the extent of this resource but snow surveys are expensive due to inaccessibility factors and to the large extent nature of the Quebec geography. Consequently, the follow-up of snowmelt is particularly challenging for operational forecasting resulting in the need to develop a new approach to assist forecasters. For improved understanding of the dynamics of snow melting over watersheds and to generate optimized power production, Hydro-Québec's Research Institute (IREQ) has developed expertise in in-situ, remote sensing monitoring and statistical treatment of such data. The main goal of this Hydro-Quebec project is to develop an automatic and dynamic snow mapping system providing a daily snow map by merging remote sensing (AVHRR and SSMI) and in situ data. This paper focuses on the work accomplished on passive microwave SSM/I data to follow up snow cover. In our problematic, it is highly useful to classify snow, more specifically during the snowmelt period. The challenge is to be able to discriminate ground from wet snow as it will react as a black body, therefore, adding noise to global brightness temperature. Two dynamic snow classifiers were developed and tested. For this purpose, channels at 19 and 37 GHz in vertical polarization have been used to feed each model. SWE values from gamma ray in situ stations (GMON) and data snow depth from ultrasonic sensor (SR50) were used to validate the output models. The first algorithm is based on a standard K-mean clustering approach, combined

  1. Numerical study of fracture arrest on snow cover

    Directory of Open Access Journals (Sweden)

    B. Frigo

    2010-10-01

    Full Text Available Under the hypothesis of a perfectly brittle phenomenon, avalanche triggering can be investigated numerically by means of Linear Elastic Fracture Mechanics (LEFM. Since, however, the real phenomenon is intrinsically dynamical, another aspect to investigate is represented by dynamic fracture propagation. In this paper, we model dynamic crack propagation into a dry snow slab and we investigate the possibility to arrest the crack propagation through the presence of weak zones distributed along the extension of the snow slope. Assuming that the weak layer is almost collapsed, we simulate the efficiency of artificial voids in the slab to arrest fracture propagation, into the framework of Dynamical Fracture Mechanics. We put forward here a new philosophy for the use of artificial discontinuities (void into the snowpack able to perform as crack arresters distributed along the snow slope area: the target is to split a large avalanche slab into smaller slabs, causing small avalanches to propagate with less catastrophic effects.

  2. Optimizing winter/snow removal operations in MoDOT St. Louis district : includes outcome based evaluation of operations.

    Science.gov (United States)

    2011-10-01

    The objective of this project was to develop fleet location, route decision, material selection, and treatment procedures for winter snow removal operations to improve MoDOTs services and lower costs. This work uses a systematic, heuristic-based o...

  3. Satellite-observed snow cover variations over the Tibetan Plateau for the period 2001-2014

    Science.gov (United States)

    Long, D.; Chen, X.

    2016-12-01

    Snow is an integral component of the global climate system. Owing to its high albedo and thermal and water storage properties, snow has important linkages and feedbacks through its influence on surface energy and moisture fluxes, clouds, precipitation, hydrology, and atmospheric circulation. As the "Roof of the World" and the "Third Pole" with the highest mountains in middle latitudes, the Tibetan Plateau (TP) is one of the most hot spots in climate change and hydrological studies, in which seasonal snow cover is a critical aspect. Unlike large-scale snow cover and regional-scale glaciers over other cryospheric regions, changes in snow cover over the TP has been largely unknown due mostly to the quality of observations. Based on improved MODIS daily snow cover products, this study aims to quantify the distribution and changes in snow cover over the TP for the period 2001 to 2014. Results show that the spatial distribution of changes in snow cover fraction (SCF) over the 14-year study period exhibited a general negative trend over the TP driven primarily by increasing land surface temperature (LST), except some areas of the upper Golden-Sanded River and upper Brahmaputra River basins. However, decreased LST and increased precipitation in the accumulation season (September to the following February) resulted in increased SCF in the accumulation season, coinciding with large-scale cold snaps and heavy snowfall events at middle latitudes. Detailed analyses of the intra-annual variability of SCF in the TP regions show an increase in SCF in the accumulation season but a decrease in SCF in the melting season (March to August), indicating that the intra-annual amplitude of SCF increased during the study period and more snow cover was released as snowmelt in the spring season.

  4. Global Snow-Cover Evolution from Twenty Years of Satellite Passive Microwave Data

    Science.gov (United States)

    Mognard, N.M.; Kouraev, A.V.; Josberger, E.G.

    2003-01-01

    Starting in 1979 with the SMMR (Scanning Multichannel Microwave Radiometer) instrument onboard the satellite NIMBUS-7 and continuing since 1987 with the SSMI (Special Sensor Microwave Imager) instrument on board the DMSP (Defence Meteorological Satellite Program) series, more then twenty years of satellite passive microwave data are now available. This dataset has been processed to analyse the evolution of the global snow cover. This work is part of the AICSEX project from the 5th Framework Programme of the European Community. The spatio-temporal evolution of the satellite-derived yearly snow maximum extent and the timing of the spring snow melt were estimated and analysed over the Northern Hemisphere. Significant differences between the evolution of the yearly maximum snow extent in Eurasia and in North America were found. A positive correlation between the maximum yearly snow cover extent and the ENSO index was obtained. High interannual spatio-temporal variability characterises the timing of snow melt in the spring. Twenty-year trends in the timing of spring snow melt have been computed and compared with spring air temperature trends for the same period and the same area. In most parts of Eurasia and in the central and western parts of North America the tendency has been for earlier snow melt. In northeastern Canada, a large area of positive trends, where snow melt timing starts later than in the early 1980s, corresponds to a region of positive trends of spring air temperature observed over the same period.

  5. Automated Webcam Monitoring of Fractional Snow Cover in Northern Boreal Conditions

    Directory of Open Access Journals (Sweden)

    Ali Nadir Arslan

    2017-07-01

    Full Text Available Fractional snow cover (FSC is an important parameter to estimate snow water equivalent (SWE and surface albedo important to climatic and hydrological applications. The presence of forest creates challenges to retrieve FSC accurately from satellite data, as forest canopy can block the sensor’s view of snow cover. In addition to the challenge related to presence of forest, in situ data of FSC—necessary for algorithm development and validation—are very limited. This paper investigates the estimation of FSC using digital imagery to overcome the obstacle caused by forest canopy, and the possibility to use this imagery in the validation of FSC derived from satellite data. FSC is calculated here using an algorithm based on defining a threshold value according to the histogram of an image, to classify a pixel as snow-covered or snow-free. Images from the MONIMET camera network, producing a continuous image series in Finland, are used in the analysis of FSC. The results obtained from automated image analysis of snow cover are compared with reference data estimated by visual inspection of same images. The results show the applicability and usefulness of digital imagery in the estimation of fractional snow cover in forested areas, with a Root Mean Squared Error (RMSE in the range of 0.1–0.3 (with the full range of 0–1.

  6. Organic compounds and suspended matter in the White Sea snow-ice cover

    International Nuclear Information System (INIS)

    Nemirovskaya, I.; Shevchenko, V.

    2008-01-01

    The pollution of the White Sea snow-ice cover was estimated by examining the distribution of organic compounds, including oil and pyrogenic hydrocarbons. Ice and snow cores were taken from Chupa Bay and the Kandalaksha Gulf in the Cape Kartesh area in the spring of 2004 and from the mouth of the Severnaya Dvina River in the spring of 2005, 2006, and 2007. This paper presented data on the lipid content, aliphatic hydrocarbons (AHC), polycyclic aromatic hydrocarbons (PAH) and suspended particulate matter in snow, ice and under-ice water. This paper focused on organic compounds and suspended matter (SM) concentrations in the sea snow-ice cover and described the ice forming conditions and interactions of the substances with ice, snow and sub-ice water. The amount of particulate matter and organic compounds in the snow increased sharply near industrial centres. The concentration of compounds decreased further away from these centres, suggesting that most pollutants are deposited locally. The study revealed that organic compounds concentrate in barrier zones, such as snow-ice and water-ice, depending on the source of pollution. There was no obvious evidence of petrogenic sources of PAHs in particulate matter from the White Sea snow-ice cover. The SM and organic compounds accumulated in layers characterized by local depositional processes. The zones remained biogeochemically active even under low temperature conditions, but the accumulation of both SM and organic compounds was at its highest during the initial stage of ice formation. 16 refs., 2 tabs., 4 figs

  7. CLPX-Satellite: EO-1 Hyperion Surface Reflectance, Snow-Covered Area, and Grain Size

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of apparent surface reflectance, subpixel snow-covered area and grain size collected from the Hyperion hyperspectral imager. The Hyperion...

  8. NOAA Climate Data Record (CDR) of Northern Hemisphere (NH) Snow Cover Extent (SCE), Version 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This NOAA Climate Data Record (CDR) is a record for the Northern Hemisphere (NH) Snow Cover Extent (SCE) spanning from October 4, 1966 to present, updated monthly...

  9. NOAA JPSS Visible Infrared Imaging Radiometer Suite (VIIRS) Snow Cover Environmental Data Record (EDR) from NDE

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a high quality operational Environmental Data Record (EDR) of snow cover from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument...

  10. Space-time analysis of snow cover change in the Romanian Carpathians (2001-2016)

    Science.gov (United States)

    Micu, Dana; Cosmin Sandric, Ionut

    2017-04-01

    Snow cover is recognized as an essential climate variable, highly sensitive to the ongoing climate warming, which plays an important role in regulating mountain ecosystems. Evidence from the existing weather stations located above 800 m over the last 50 years points out that the climate of the Romanian Carpathians is visibly changing, showing an ongoing and consistent warming process. Quantifying and attributing the changes in snow cover on various spatial and temporal scales have a great environmental and socio-economic importance for this mountain region. The study is revealing the inter-seasonal changes in the timing and distribution of snow cover across the Romanian Carpathians, by combining gridded snow data (CARPATCLIM dataset, 1961-2010) and remote sensing data (2001-2016) in specific space-time assessment at regional scale. The geostatistical approach applied in this study, based on a GIS hotspot analysis, takes advantage of all the dimensions in the datasets, in order to understand the space-time trends in this climate variable at monthly time-scale. The MODIS AQUA and TERRA images available from 2001 to 2016 have been processed using ArcGIS for Desktop and Python programming language. All the images were masked out with the Carpathians boundary. Only the pixels with snow have been retained for analysis. The regional trends in snow cover distribution and timing have been analysed using Space-Time cube with ArcGIS for Desktop, according with Esri documentation using the Mann-Kendall trend test on every location with data as an independent bin time-series test. The study aimed also to assess the location of emerging hotspots of snow cover change in Carpathians. These hotspots have been calculated using Getis-Ord Gi* statistic for each bin using Hot Spot Analysis implemented in ArcGIS for Desktop. On regional scale, snow cover appear highly sensitive to the decreasing trends in air temperatures and land surface temperatures, combined with the decrease in

  11. Dynamics of snow cover characteristics exerting influence on stability of the Svalbard permafrost

    Directory of Open Access Journals (Sweden)

    N. I. Osokin

    2016-01-01

    Full Text Available Climate variations result in changes of the snow cover characteristics which have a certain influence upon thermal state and stability of permafrost. Analysis of data of meteorological station Barentsburg (Svalbard and our own observations has revealed small change in the snow cover thickness for the period 1984–2015. At the same time, duration of the snow cover presence has shortened by 8%. In recent years, more than 60% of the snow cover thickness was formed during the early third of the cold season which adversely affects a rate of the ground freezing. Durations of thaws increased from 12 to 22 days, and the rainfall amount decreased during the cold period from 60 to 120 mm. The largest increase in the thaw duration (by a factor of 7 and decrease of the rainfall amount (by a factor of 8 fall on January and February. Summing up of the thaw duration and the rainfall amount for the 5‑year periods demonstrated significant growth of both. It should be noted also that, according to data of the Barentsburg station and our ones, in a few last years, these parameters reached anomalously high values. Appearance of anomalous values of the snow cover thickness as well as of the dates of its onset became more frequent. For the last decade, recurrence of anomalous values of the snow cover thickness increased: one event for 2.4 years before 2000, and one occurrence of anomalous thickness for 1.4 years since 2001. The later onset of snow cover resulted in shortening of duration of its presence. Occurrence of anomalous duration of the snow cover presence was observed once for 4.3 years before 2001, and once for 3.3 years after 2000.

  12. Using Gridded Snow Covered Area and Snow-Water Equivalence Spatial Data Sets to Improve Snow-Pack Depletion Simulation in a Continental Scale Hydrologic Model

    Science.gov (United States)

    Risley, J. C.; Tracey, J. A.; Markstrom, S. L.; Hay, L.

    2014-12-01

    Snow cover areal depletion curves were used in a continuous daily hydrologic model to simulate seasonal spring snowmelt during the period between maximum snowpack accumulation and total melt. The curves are defined as the ratio of snow-water equivalence (SWE) divided by the seasonal maximum snow-water equivalence (Ai) (Y axis) versus the percent snow cover area (SCA) (X axis). The slope of the curve can vary depending on local watershed conditions. Windy sparsely vegetated high elevation watersheds, for example, can have a steeper slope than lower elevation forested watersheds. To improve the accuracy of simulated runoff at ungaged watersheds, individual snow cover areal depletion curves were created for over 100,000 hydrologic response units (HRU) in the continental scale U.S. Geological Survey (USGS) National Hydrologic Model (NHM). NHM includes the same components of the USGS Precipitation-Runoff-Modeling System (PRMS), except it uses consistent land surface characterization and model parameterization across the U.S. continent. Weighted-mean daily time series of 1-kilometer gridded SWE, from Snow Data Assimilation System (SNODAS), and 500-meter gridded SCA, from Moderate Resolution Imaging Spectroradiometer (MODIS), for 2003-2014 were computed for each HRU using the USGS Geo Data Portal. Using a screening process, pairs of SWE/Ai and SCA from the snowmelt period of each year were selected. SCA values derived from imagery that did not have any cloud cover and were >0 and <100 percent were selected. Unrealistically low and high SCA values that were paired with high and low SWE/Ai ratios, respectively, were removed. Second order polynomial equations were then fit to the remaining pairs of SWE/Ai and SCA to create a unique curve for each HRU. Simulations comparing these new curves with an existing single default curve in NHM will be made to determine if there are significant improvements in runoff.

  13. Describing macro-scale structure of the snow cover by a dynamic-stochastic model

    Directory of Open Access Journals (Sweden)

    A. N. Gelfan

    2015-01-01

    Full Text Available Possibilities to investigate the spatial structure of snow cover by means of dynamic-stochastic model are discussed in this article. Basin of the Cheboksary reservoir (area of 376 500 sq.km was used as an example. Results of numerical experiments show that our dynamic-stochastic model of the snow cover formation reproduces a snow field structure with adequate accuracy. The fractal dimensions of the modeled fields are in good correspondence with respective dimensions of fields obtained from data of the in situ observations.

  14. Evaluation of gridded snow water equivalent and satellite snow cover products for mountain basins in a hydrologic model

    Science.gov (United States)

    Dressler, K.A.; Leavesley, G.H.; Bales, R.C.; Fassnacht, S.R.

    2006-01-01

    The USGS precipitation-runoff modelling system (PRMS) hydrologic model was used to evaluate experimental, gridded, 1 km2 snow-covered area (SCA) and snow water equivalent (SWE) products for two headwater basins within the Rio Grande (i.e. upper Rio Grande River basin) and Salt River (i.e. Black River basin) drainages in the southwestern USA. The SCA product was the fraction of each 1 km2 pixel covered by snow and was derived from NOAA advanced very high-resolution radiometer imagery. The SWE product was developed by multiplying the SCA product by SWE estimates interpolated from National Resources Conservation Service snow telemetry point measurements for a 6 year period (1995-2000). Measured SCA and SWE estimates were consistently lower than values estimated from temperature and precipitation within PRMS. The greatest differences occurred in the relatively complex terrain of the Rio Grande basin, as opposed to the relatively homogeneous terrain of the Black River basin, where differences were small. Differences between modelled and measured snow were different for the accumulation period versus the ablation period and had an elevational trend. Assimilating the measured snowfields into a version of PRMS calibrated to achieve water balance without assimilation led to reduced performance in estimating streamflow for the Rio Grande and increased performance in estimating streamflow for the Black River basin. Correcting the measured SCA and SWE for canopy effects improved simulations by adding snow mostly in the mid-to-high elevations, where satellite estimates of SCA are lower than model estimates. Copyright ?? 2006 John Wiley & Sons, Ltd.

  15. Snow cover, freeze-thaw, and the retention of nutrients in an oceanic mountain ecosystem

    NARCIS (Netherlands)

    Wipf, Sonja; Sommerkorn, Martin; Stutter, Marc I.; Wubs, E. R. Jasper; van der Wal, René

    2015-01-01

    As the climate warms, winters with less snow and therefore more soil freeze-thaw cycles are likely to become more frequent in oceanic mountain areas. It is a concern that this might impair the soil's ability to store carbon and nutrients, and lead to increased leaching losses of dissolved C and

  16. Modelling snow cover duration improves predictions of functional and taxonomic diversity for alpine plant communities.

    Science.gov (United States)

    Carlson, Bradley Z; Choler, Philippe; Renaud, Julien; Dedieu, Jean-Pierre; Thuiller, Wilfried

    2015-11-01

    Quantifying relationships between snow cover duration and plant community properties remains an important challenge in alpine ecology. This study develops a method to estimate spatial variation in energy availability in the context of a topographically complex, high-elevation watershed, which was used to test the explanatory power of environmental gradients both with and without snow cover in relation to taxonomic and functional plant diversity. Snow cover in the French Alps was mapped at 15-m resolution using Landsat imagery for five recent years, and a generalized additive model (GAM) was fitted for each year linking snow to time and topography. Predicted snow cover maps were combined with air temperature and solar radiation data at daily resolution, summed for each year and averaged across years. Equivalent growing season energy gradients were also estimated without accounting for snow cover duration. Relationships were tested between environmental gradients and diversity metrics measured for 100 plots, including species richness, community-weighted mean traits, functional diversity and hyperspectral estimates of canopy chlorophyll content. Accounting for snow cover in environmental variables consistently led to improved predictive power as well as more ecologically meaningful characterizations of plant diversity. Model parameters differed significantly when fitted with and without snow cover. Filtering solar radiation with snow as compared without led to an average gain in R(2) of 0·26 and reversed slope direction to more intuitive relationships for several diversity metrics. The results show that in alpine environments high-resolution data on snow cover duration are pivotal for capturing the spatial heterogeneity of both taxonomic and functional diversity. The use of climate variables without consideration of snow cover can lead to erroneous predictions of plant diversity. The results further indicate that studies seeking to predict the response of alpine

  17. Retrospective forecasts of the upcoming winter season snow accumulation in the Inn headwaters (European Alps)

    Science.gov (United States)

    Förster, Kristian; Hanzer, Florian; Stoll, Elena; Scaife, Adam A.; MacLachlan, Craig; Schöber, Johannes; Huttenlau, Matthias; Achleitner, Stefan; Strasser, Ulrich

    2018-02-01

    This article presents analyses of retrospective seasonal forecasts of snow accumulation. Re-forecasts with 4 months' lead time from two coupled atmosphere-ocean general circulation models (NCEP CFSv2 and MetOffice GloSea5) drive the Alpine Water balance and Runoff Estimation model (AWARE) in order to predict mid-winter snow accumulation in the Inn headwaters. As snowpack is hydrological storage that evolves during the winter season, it is strongly dependent on precipitation totals of the previous months. Climate model (CM) predictions of precipitation totals integrated from November to February (NDJF) compare reasonably well with observations. Even though predictions for precipitation may not be significantly more skilful than for temperature, the predictive skill achieved for precipitation is retained in subsequent water balance simulations when snow water equivalent (SWE) in February is considered. Given the AWARE simulations driven by observed meteorological fields as a benchmark for SWE analyses, the correlation achieved using GloSea5-AWARE SWE predictions is r = 0.57. The tendency of SWE anomalies (i.e. the sign of anomalies) is correctly predicted in 11 of 13 years. For CFSv2-AWARE, the corresponding values are r = 0.28 and 7 of 13 years. The results suggest that some seasonal prediction of hydrological model storage tendencies in parts of Europe is possible.

  18. Retrospective forecasts of the upcoming winter season snow accumulation in the Inn headwaters (European Alps

    Directory of Open Access Journals (Sweden)

    K. Förster

    2018-02-01

    Full Text Available This article presents analyses of retrospective seasonal forecasts of snow accumulation. Re-forecasts with 4 months' lead time from two coupled atmosphere–ocean general circulation models (NCEP CFSv2 and MetOffice GloSea5 drive the Alpine Water balance and Runoff Estimation model (AWARE in order to predict mid-winter snow accumulation in the Inn headwaters. As snowpack is hydrological storage that evolves during the winter season, it is strongly dependent on precipitation totals of the previous months. Climate model (CM predictions of precipitation totals integrated from November to February (NDJF compare reasonably well with observations. Even though predictions for precipitation may not be significantly more skilful than for temperature, the predictive skill achieved for precipitation is retained in subsequent water balance simulations when snow water equivalent (SWE in February is considered. Given the AWARE simulations driven by observed meteorological fields as a benchmark for SWE analyses, the correlation achieved using GloSea5-AWARE SWE predictions is r  =  0.57. The tendency of SWE anomalies (i.e. the sign of anomalies is correctly predicted in 11 of 13 years. For CFSv2-AWARE, the corresponding values are r  =  0.28 and 7 of 13 years. The results suggest that some seasonal prediction of hydrological model storage tendencies in parts of Europe is possible.

  19. Threshold temperatures mediate the impact of reduced snow cover on overwintering freeze-tolerant caterpillars

    Science.gov (United States)

    Marshall, Katie E.; Sinclair, Brent J.

    2012-01-01

    Decreases in snow cover due to climate change could alter the energetics and physiology of ectothermic animals that overwinter beneath snow, yet how snow cover interacts with physiological thresholds is unknown. We applied numerical simulation of overwintering metabolic rates coupled with field validation to determine the importance of snow cover and freezing to the overwintering lipid consumption of the freeze-tolerant Arctiid caterpillar Pyrrharctia isabella. Caterpillars that overwintered above the snow experienced mean temperatures 1.3°C lower than those below snow and consumed 18.36 mg less lipid of a total 68.97-mg reserve. Simulations showed that linear temperature effects on metabolic rate accounted for only 30% of the difference in lipid consumption. When metabolic suppression by freezing was included, 93% of the difference between animals that overwintered above and below snow was explained. Our results were robust to differences in temperature sensitivity of metabolic rate, changes in freezing point, and the magnitude of metabolic suppression by freezing. The majority of the energy savings was caused by the non-continuous reduction in metabolic rate due to freezing, the first example of the importance of temperature thresholds in the lipid use of overwintering insects.

  20. Surface energy balance of seasonal snow cover for snow-melt ...

    Indian Academy of Sciences (India)

    ... surface at this station received a mean short wave radiation of 430 W m−2, out of which 298 W m−2 was re flected back by the snow surface with mean albedo value of 0.70. The high average temperature and more absorption of solar radiation resulted in higher thermal state of the snowpack which was further responsible ...

  1. Multi-decadal evolution of ice/snow covers in the Mont-Blanc massif (France)

    Science.gov (United States)

    Guillet, Grégoire; Ravanel, Ludovic

    2017-04-01

    Dynamics and evolution of the major glaciers of the Mont-Blanc massif have been vastly studied since the XXth century. Ice/snow covers on steep rock faces as part of the cryosphere however remain poorly studied with only qualitative descriptions existing. The study of ice/snow covers is primordial to further understand permafrost degradation throughout the Mont-Blanc massif and to improve safety and prevention for mountain sports practitioners. This study focuses on quantifying the evolution of ice/snow covers surface during the past century using a specially developed monoplotting tool using Bayesian statistics and Markov Chain Monte Carlo algorithms. Combining digital elevation models and photographs covering a time-span of 110 years, we calculated the ice/snow cover surface for 3 study sites — North faces of the Tour Ronde (3792 m a.s.l.) and the Grandes Jorasses (4208 m a.s.l.) and Triangle du Tacul (3970 m a.s.l.) — and deduced the evolution of their area throughout the XXth century. First results are showing several increase/decrease periods. The first decrease in ice/snow cover surface occurs between the 1940's and the 1950's. It is followed by an increase up to the 1980's. Since then, ice/snow covers show a general decrease in surface which is faster since the 2010's. Furthermore, the gain/loss during the increase/decrease periods varies with the considered ice/snow cover, making it an interesting cryospheric entity of its own.

  2. Snow cover setting-up dates in the north of Eurasia: relations and feedback to the macro-scale atmospheric circulation

    Directory of Open Access Journals (Sweden)

    V. V. Popova

    2014-01-01

    values –0.82 ÷ –0.85 in 1973–1994 (Fig. 4, а, б. Results of numerical experiments on simulation of observed October snow cover anomaly in 1976 and its impact on Northern Hemisphere sea level pressure in winter months approved potential ability of abrupt increase of albedo caused by snow cover onset to influence on weakening of westerly and negative temperature anomalies in North Eurasia (Fig. 5. Evidently, based on observational data and results of modeling one should conclude that autumn snow cover anomalies in North are able to effect on macro-scale circulation regime in winter, but in condition of weakening of other major factors influencing on circulation, for example sea surface temperature over the oceans. In any case, correlation analysis of earth observations shows that snow cover extent anomalies could not be recognized as cause of negative AO anomalies and severe winters in North Eurasia in last decade.

  3. Biomass and nutrient cycling by winter cover crops

    Directory of Open Access Journals (Sweden)

    Jana Koefender

    Full Text Available ABSTRACT Cover crops are of fundamental importance for the sustainability of the no-tillage system, to ensure soil coverage and to provide benefits for the subsequent crop. The objective of this study was to evaluate the production of biomass and the content and accumulation of nutrients by winter cover crops. The experimental design used in the experiment was a randomized complete block with four replications and six treatments: oilseed radish, vetch, black oats, vetch + black oats, vetch + oilseed radish and fallow. Black oat, oilseed radish in single cultivation and black oat + vetch and vetch + oilseed radish intercroppings showed higher dry matter production. Vetch + oilseed radish intercropping demonstrates higher performance regarding cycling of nutrients, with higher accumulations of N, P, K, Ca, Mg, S, Cu, Zn, Fe, Na and B.

  4. An Evaluation of High-Resolution Regional Climate Model Simulated Snow Cover Using Satellite Data (With Implications for the Simulated Snow-Albedo Feedback)

    Science.gov (United States)

    Minder, J. R.; Letcher, T.

    2015-12-01

    Snow cover often exhibits large spatial variability over mountainous regions where variations in elevation, aspect, vegetation, winds, and orographic precipitation all modulate snow cover. Under climate change, reductions in mountain snow cover are likely to substantially amplify regional warming via the snow-albedo feedback. To capture this important feedback it is crucial that regional climate models (RCMs) adequately simulate spatial and temporal variations in snow cover. Snow cover simulated by high-resolution RCMs over the central Rocky Mountains of the United States is evaluated. RCM simulations were conducted using the Weather Research and Forecasting (WRF) model on a 4 km horizontal grid forced by reanalysis boundary conditions over a seven-year time period. A pair of simulations is considered that differ in the domain size (regional vs. continental) and the land surface model (Noah vs. Noah-MP) employed. RCM output is compared with high-resolution gridded satellite analyses of surface albedo and fractional snow cover derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). Results reveal that both RCMs are generally successful at reproducing the observed seasonal cycle and interannual variability of snow extent over the high terrain of the Rockies. However, in simulations using the Noah land surface model (LSM), sub-grid scale fractional snow covered area of grid cells containing snow is systematically too high compared to observations, often exceeding observations by more than 0.2. This bias in fractional snow cover leads to a substantial positive bias in regional surface albedo. Simulations using the Noah-MP LSM produce more realistic variations in fractional snow cover and surface albedo, likely due to its more-realistic treatment of canopy effects. We quantify how differences in simulated snow cover affect the strength of the snow-albedo feedback under climate change. Both RCMs were used to conduct representative 7-year simulations of a

  5. Snow cover detection and snow depth algorithms for the Global Change Observation Mission (GCOM) AMSR2 instrument using AMSR-E/AMSR2 measurements

    Science.gov (United States)

    Lee, Y. K.; Kongoli, C.; Key, J. R.

    2014-12-01

    Snow is one of the most dynamic hydrological variables on the Earth surface playing a key role in the global energy and water budget. The ability to detect global snow cover and measure snow depth in near all weather conditions has been demonstrated with satellite microwave measurements. The Advanced Microwave Scanning Radiometer 2 (AMSR2), launched on May 18, 2012 onboard SHIZUKU, is included in A-train group of satellites and will replace the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) instrument. The similarity of channels between AMSR-E and AMSR2 makes AMSR2 instrument a successor of AMSR-E instrument. This study will evaluate the suite of AMSR2 algorithms that are being developed for the operational retrieval of snow cover detection and snow depth using AMSR-E and AMSR2 data. AMSR-E data spans 10 years from June 2002 to September 2011; AMSR2 data spans 2 years from August 2012 to May 2014. The snow cover detection algorithm is based on the operational NOAA's heritage microwave algorithm with snow climatology tests and wet snow filtering as new enhancements. The SD algorithm is adopted from the current version of the operational NASA AMSR-E SWE algorithm. The 24- and 4-km IMS snow cover and in-situ SYNOP and COOP snow depth are used as references for the evaluation. More details about the reference data and evaluation results will be discussed.

  6. Ensemble-based assimilation of fractional snow-covered area satellite retrievals to estimate the snow distribution at Arctic sites

    Science.gov (United States)

    Aalstad, Kristoffer; Westermann, Sebastian; Vikhamar Schuler, Thomas; Boike, Julia; Bertino, Laurent

    2018-01-01

    With its high albedo, low thermal conductivity and large water storing capacity, snow strongly modulates the surface energy and water balance, which makes it a critical factor in mid- to high-latitude and mountain environments. However, estimating the snow water equivalent (SWE) is challenging in remote-sensing applications already at medium spatial resolutions of 1 km. We present an ensemble-based data assimilation framework that estimates the peak subgrid SWE distribution (SSD) at the 1 km scale by assimilating fractional snow-covered area (fSCA) satellite retrievals in a simple snow model forced by downscaled reanalysis data. The basic idea is to relate the timing of the snow cover depletion (accessible from satellite products) to the peak SSD. Peak subgrid SWE is assumed to be lognormally distributed, which can be translated to a modeled time series of fSCA through the snow model. Assimilation of satellite-derived fSCA facilitates the estimation of the peak SSD, while taking into account uncertainties in both the model and the assimilated data sets. As an extension to previous studies, our method makes use of the novel (to snow data assimilation) ensemble smoother with multiple data assimilation (ES-MDA) scheme combined with analytical Gaussian anamorphosis to assimilate time series of Moderate Resolution Imaging Spectroradiometer (MODIS) and Sentinel-2 fSCA retrievals. The scheme is applied to Arctic sites near Ny-Ålesund (79° N, Svalbard, Norway) where field measurements of fSCA and SWE distributions are available. The method is able to successfully recover accurate estimates of peak SSD on most of the occasions considered. Through the ES-MDA assimilation, the root-mean-square error (RMSE) for the fSCA, peak mean SWE and peak subgrid coefficient of variation is improved by around 75, 60 and 20 %, respectively, when compared to the prior, yielding RMSEs of 0.01, 0.09 m water equivalent (w.e.) and 0.13, respectively. The ES-MDA either outperforms or at least

  7. Ensemble-based assimilation of fractional snow-covered area satellite retrievals to estimate the snow distribution at Arctic sites

    Directory of Open Access Journals (Sweden)

    K. Aalstad

    2018-01-01

    Full Text Available With its high albedo, low thermal conductivity and large water storing capacity, snow strongly modulates the surface energy and water balance, which makes it a critical factor in mid- to high-latitude and mountain environments. However, estimating the snow water equivalent (SWE is challenging in remote-sensing applications already at medium spatial resolutions of 1 km. We present an ensemble-based data assimilation framework that estimates the peak subgrid SWE distribution (SSD at the 1 km scale by assimilating fractional snow-covered area (fSCA satellite retrievals in a simple snow model forced by downscaled reanalysis data. The basic idea is to relate the timing of the snow cover depletion (accessible from satellite products to the peak SSD. Peak subgrid SWE is assumed to be lognormally distributed, which can be translated to a modeled time series of fSCA through the snow model. Assimilation of satellite-derived fSCA facilitates the estimation of the peak SSD, while taking into account uncertainties in both the model and the assimilated data sets. As an extension to previous studies, our method makes use of the novel (to snow data assimilation ensemble smoother with multiple data assimilation (ES-MDA scheme combined with analytical Gaussian anamorphosis to assimilate time series of Moderate Resolution Imaging Spectroradiometer (MODIS and Sentinel-2 fSCA retrievals. The scheme is applied to Arctic sites near Ny-Ålesund (79° N, Svalbard, Norway where field measurements of fSCA and SWE distributions are available. The method is able to successfully recover accurate estimates of peak SSD on most of the occasions considered. Through the ES-MDA assimilation, the root-mean-square error (RMSE for the fSCA, peak mean SWE and peak subgrid coefficient of variation is improved by around 75, 60 and 20 %, respectively, when compared to the prior, yielding RMSEs of 0.01, 0.09 m water equivalent (w.e. and 0.13, respectively. The ES-MDA either

  8. Changing Arctic Snow Cover: A Review of Recent Developments and Assessment of Future Needs for Observations, Modelling, and Impacts

    Science.gov (United States)

    Bokhorst, Stef; Pedersen, Stine Hojlund; Brucker, Ludovic; Anisimov, Oleg; Bjerke, Jarle W.; Brown, Ross D.; Ehrich, Dorothee; Essery, Richard L. H.; Heilig, Achim; Ingvander, Susanne; hide

    2016-01-01

    Snow is a critically important and rapidly changing feature of the Arctic. However, snow-cover and snowpack conditions change through time pose challenges for measuring and prediction of snow. Plausible scenarios of how Arctic snow cover will respond to changing Arctic climate are important for impact assessments and adaptation strategies. Although much progress has been made in understanding and predicting snow-cover changes and their multiple consequences, many uncertainties remain. In this paper, we review advances in snow monitoring and modelling, and the impact of snow changes on ecosystems and society in Arctic regions. Interdisciplinary activities are required to resolve the current limitations on measuring and modelling snow characteristics through the cold season and at different spatial scales to assure human well-being, economic stability, and improve the ability to predict manage and adapt to natural hazards in the Arctic region.

  9. Changing Snow Cover and Stream Discharge in the Western United States - Wind River Range, Wyoming

    Science.gov (United States)

    Hall, Dorothy K.; Foster, James L.; DiGirolamo, Nicolo E.; Barton, Jonathan S.; Riggs, George A.

    2011-01-01

    Earlier onset of springtime weather has been documented in the western United States over at least the last 50 years. Because the majority (>70%) of the water supply in the western U.S. comes from snowmelt, analysis of the declining spring snowpack has important implications for the management of water resources. We studied ten years of Moderate-Resolution Imaging Spectroradiometer (MODIS) snow-cover products, 40 years of stream discharge and meteorological station data and 30 years of snow-water equivalent (SWE) SNOw Telemetry (SNOTEL) data in the Wind River Range (WRR), Wyoming. Results show increasing air temperatures for.the 40-year study period. Discharge from streams in WRR drainage basins show lower annual discharge and earlier snowmelt in the decade of the 2000s than in the previous three decades. Changes in streamflow may be related to increasing air temperatures which are probably contributing to a reduction in snow cover, although no trend of either increasingly lower streamflow or earlier snowmelt was observed within the decade of the 2000s. And SWE on 1 April does not show an expected downward trend from 1980 to 2009. The extent of snow cover derived from the lowest-elevation zone of the WRR study area is strongly correlated (r=0.91) with stream discharge on 1 May during the decade of the 2000s. The strong relationship between snow cover and streamflow indicates that MODIS snow-cover maps can be used to improve management of water resources in the drought-prone western U.S.

  10. The bright side of snow cover effects on PV production - How to lower the seasonal mismatch between electricity supply and demand in a fully renewable Switzerland

    Science.gov (United States)

    Kahl, Annelen; Dujardin, Jérôme; Dupuis, Sonia; Lehning, Michael

    2017-04-01

    One of the major problems with solar PV in the context of a fully renewable electricity production at mid-latitudes is the trend of higher production in summer and lower production in winter. This trend is most often exactly opposite to demand patterns, causing a seasonal mismatch that requires extensive balancing power from other production sources or large storage capacities. Which possibilities do we have to bring PV production into closer correlation with demand? This question motivated our research and in response we investigated the effects of placing PV panels at different tilt angles in regions with extensive snow cover to increase winter production from ground reflected short wave radiation. The aim of this project is therefore to quantify the effect of varying snow cover duration (SCD) and of panel tilt angle on the annual total production and on production during winter months when electricity is most needed. We chose Switzerland as ideal test site, because it has a wide range of snow cover conditions and a high potential for renewable electricity production. But methods can be applied to other regions of comparable conditions for snow cover and irradiance. Our analysis can be separated into two steps: 1. A systematic, GIS and satellite-based analysis for all of Switzerland: We use time series of satellite-derived irradiance, and snow cover characteristics together with land surface cover types and elevation information to quantify the environmental conditions and to estimate potential production and ideal tilt angles. 2. A scenario-based analysis that contrasts the production patterns of different placement scenarios for PV panels in urban, rural and mountainous areas. We invoke a model of a fully renewable electricity system (including Switzerland's large hydropower system) at national level to compute the electricity import and storage capacity that will be required to balance the remaining mismatch between production and demand to further illuminate

  11. Variations in snow cover seasonality across the Kyrgyz Republic from 2000 to 2016 revealed through MODIS Terra and Aqua snow products

    Science.gov (United States)

    Tomaszewska, M. A.; Henebry, G. M.

    2017-12-01

    The vertical transhumance practiced by herders in the highlands of Kyrgyzstan is vulnerable to environmental change. Herd movements and pasture conditions are both affected by spatial and temporal variations in snow cover and the timing of snowmelt. Early growing season soil moisture conditions affect the phenology and growth of vegetation, especially in the high elevation pastures used for summer forage. To evaluate snow seasonality, we examined three snow cover variables—the first day of snow (FDoS), the last day of snow (LDoS), and the duration of snow cover (DoSC) over 17 years based on 8-day snow product from MODIS Terra and Aqua (MOD/MYD10A2) across the Kyrgyz Republic (KYR). To track the "snow season" efficiently in the presence of snow-capped peaks, we start each snow season at day of year (DOY) 169, approximately the summer solstice, and extend to DOY 168 of the following year. To track the interannual variation of these variables, we applied two nonparametric statistics: the Mann-Kendall trend test and the Theil-Sen linear trend estimator. Our preliminary results focusing on four rayons in two oblasts indicate both large swaths of positive and negative significant trends over the different regions of the country. Positive trends in FDoS, meaning later snow arrival, were detected in parts of central KYR. Negative trends in FDoS meaning earlier arrival were detected at lower elevations in southwestern KYR. Earlier snowmelt (negative trend in LDoS) in eastern KYR resulted in a shorter snow season (negative trend in DoSC); in contrast, later snowmelt in southwestern KYR (positive trend in LDoS) resulted in a longer period of snow cover (positive trend of DoSC). We extend the analysis to the entire country and explore the influence of terrain attribites (elevation, slope, and aspect) and MODIS IGBP land cover type (MCD12Q1) on trends in snow cover seasonality. Additionally, we ran the trend tests for the Terra and Aqua snow products separately to evaluate

  12. Fractional Snow Cover Mapping by Artificial Neural Networks and Support Vector Machines

    Science.gov (United States)

    Çiftçi, B. B.; Kuter, S.; Akyürek, Z.; Weber, G.-W.

    2017-11-01

    Snow is an important land cover whose distribution over space and time plays a significant role in various environmental processes. Hence, snow cover mapping with high accuracy is necessary to have a real understanding for present and future climate, water cycle, and ecological changes. This study aims to investigate and compare the design and use of artificial neural networks (ANNs) and support vector machines (SVMs) algorithms for fractional snow cover (FSC) mapping from satellite data. ANN and SVM models with different model building settings are trained by using Moderate Resolution Imaging Spectroradiometer surface reflectance values of bands 1-7, normalized difference snow index and normalized difference vegetation index as predictor variables. Reference FSC maps are generated from higher spatial resolution Landsat ETM+ binary snow cover maps. Results on the independent test data set indicate that the developed ANN model with hyperbolic tangent transfer function in the output layer and the SVM model with radial basis function kernel produce high FSC mapping accuracies with the corresponding values of R = 0.93 and R = 0.92, respectively.

  13. Precipitation and snow cover in the Himalaya: from reanalysis to regional climate simulations

    Directory of Open Access Journals (Sweden)

    M. Ménégoz

    2013-10-01

    Full Text Available We applied a Regional Climate Model (RCM to simulate precipitation and snow cover over the Himalaya, between March 2000 and December 2002. Due to its higher resolution, our model simulates a more realistic spatial variability of wind and precipitation than those of the reanalysis of the European Centre of Medium range Weather Forecast (ECMWF used as lateral boundaries. In this region, we found very large discrepancies between the estimations of precipitation provided by reanalysis, rain gauges networks, satellite observations, and our RCM simulation. Our model clearly underestimates precipitation at the foothills of the Himalaya and in its eastern part. However, our simulation provides a first estimation of liquid and solid precipitation in high altitude areas, where satellite and rain gauge networks are not very reliable. During the two years of simulation, our model resembles the snow cover extent and duration quite accurately in these areas. Both snow accumulation and snow cover duration differ widely along the Himalaya: snowfall can occur during the whole year in western Himalaya, due to both summer monsoon and mid-latitude low pressure systems bringing moisture into this region. In Central Himalaya and on the Tibetan Plateau, a much more marked dry season occurs from October to March. Snow cover does not have a pronounced seasonal cycle in these regions, since it depends both on the quite variable duration of the monsoon and on the rare but possible occurrence of snowfall during the extra-monsoon period.

  14. Global warming in the context of 2000 years of Australian alpine temperature and snow cover.

    Science.gov (United States)

    McGowan, Hamish; Callow, John Nikolaus; Soderholm, Joshua; McGrath, Gavan; Campbell, Micheline; Zhao, Jian-Xin

    2018-03-13

    Annual resolution reconstructions of alpine temperatures are rare, particularly for the Southern Hemisphere, while no snow cover reconstructions exist. These records are essential to place in context the impact of anthropogenic global warming against historical major natural climate events such as the Roman Warm Period (RWP), Medieval Climate Anomaly (MCA) and Little Ice Age (LIA). Here we show for a marginal alpine region of Australia using a carbon isotope speleothem reconstruction, warming over the past five decades has experienced equivalent magnitude of temperature change and snow cover decline to the RWP and MCA. The current rate of warming is unmatched for the past 2000 years and seasonal snow cover is at a minimum. On scales of several decades, mean maximum temperatures have undergone considerable change ≈ ± 0.8 °C highlighting local scale susceptibility to rapid temperature change, evidence of which is often masked in regional to hemisphere scale temperature reconstructions.

  15. Black carbon and mineral dust in snow cover on the Tibetan Plateau

    Science.gov (United States)

    Zhang, Yulan; Kang, Shichang; Sprenger, Michael; Cong, Zhiyuan; Gao, Tanguang; Li, Chaoliu; Tao, Shu; Li, Xiaofei; Zhong, Xinyue; Xu, Min; Meng, Wenjun; Neupane, Bigyan; Qin, Xiang; Sillanpää, Mika

    2018-02-01

    Snow cover plays a key role for sustaining ecology and society in mountainous regions. Light-absorbing particulates (including black carbon, organic carbon, and mineral dust) deposited on snow can reduce surface albedo and contribute to the near-worldwide melting of snow and ice. This study focused on understanding the role of black carbon and other water-insoluble light-absorbing particulates in the snow cover of the Tibetan Plateau (TP). The results found that the black carbon, organic carbon, and dust concentrations in snow cover generally ranged from 202 to 17 468 ng g-1, 491 to 13 880 ng g-1, and 22 to 846 µg g-1, respectively, with higher concentrations in the central to northern areas of the TP. Back trajectory analysis suggested that the northern TP was influenced mainly by air masses from Central Asia with some Eurasian influence, and air masses in the central and Himalayan region originated mainly from Central and South Asia. The relative biomass-burning-sourced black carbon contributions decreased from ˜ 50 % in the southern TP to ˜ 30 % in the northern TP. The relative contribution of black carbon and dust to snow albedo reduction reached approximately 37 and 15 %, respectively. The effect of black carbon and dust reduced the snow cover duration by 3.1 ± 0.1 to 4.4 ± 0.2 days. Meanwhile, the black carbon and dust had important implications for snowmelt water loss over the TP. The findings indicate that the impacts of black carbon and mineral dust need to be properly accounted for in future regional climate projections, particularly in the high-altitude cryosphere.

  16. Linkages between Snow Cover Seasonality, Terrain, and Land Surface Phenology in the Highland Pastures of Kyrgyzstan

    Science.gov (United States)

    Henebry, Geoffrey; Tomaszewska, Monika; Kelgenbaeva, Kamilya

    2017-04-01

    In the highlands of Kyrgyzstan, vertical transhumance is the foundation of montane agropastoralism. Terrain attributes, such as elevation, slope, and aspect, affect snow cover seasonality, which is a key influence on the timing of plant growth and forage availability. Our study areas include the highland pastures in Central Tien Shan mountains, specifically in the rayons of Naryn and At-Bashy in Naryn oblast, and Alay and Chong-Alay rayons in Osh oblast. To explore the linkages between snow cover seasonality and land surface phenology as modulated by terrain and variations in thermal time, we use 16 years (2001-2016) of Landsat surface reflectance data at 30 m resolution with MODIS land surface temperature and snow cover products at 1 km and 500 m resolution, respectively, and two digital elevation models, SRTM and ASTER GDEM. We model snow cover seasonality using frost degree-days and land surface phenology using growing degree-days as quadratic functions of thermal time: a convex quadratic (CxQ) model for land surface phenology and a concave quadratic (CvQ) model for snow cover seasonality. From the fitted parameter coefficients, we calculated phenometrics, including "peak height" and "thermal time to peak" for the CxQ models and "trough depth" and "thermal time to trough" for the CvQ models. We explore how these phenometrics change as a function of elevation and slope-aspect interactions and due to interannual variability. Further, we examine how snow cover duration and timing affects the subsequent peak height and thermal time to peak in wetter, drier, and normal years.

  17. Mapping snow cover using multi-source satellite data on big data platforms

    Science.gov (United States)

    Lhermitte, Stef

    2017-04-01

    Snowmelt is an important and dynamically changing water resource in mountainous regions around the world. In this framework, remote sensing data of snow cover data provides an essential input for hydrological models to model the water contribution from remote mountain areas and to understand how this water resource might alter as a result of climate change. Traditionally, however, many of these remote sensing products show a trade-off between spatial and temporal resolution (e.g., 16-day Landsat at 30m vs. daily MODIS at 500m resolution). With the advent of Sentinel-1 and 2 and the PROBA-V 100m products this trade-off can partially be tackled by having data that corresponds more closely to the spatial and temporal variations in snow cover typically observed over complex mountain areas. This study provides first a quantitative analysis of the trade-offs between the state-of-the-art snow cover mapping methodologies for Landsat, MODIS, PROBA-V, Sentinel-1 and 2 and applies them on big data platforms such as Google Earth Engine (GEE), RSS (ESA Research Service & Support) CloudToolbox, and the PROBA-V Mission Exploitation Platform (MEP). Second, it combines the different sensor data-cubes in one multi-sensor classification approach using newly developed spatio-temporal probability classifiers within the big data platform environments. Analysis of the spatio-temporal differences in derived snow cover areas from the different sensors reveals the importance of understanding the spatial and temporal scales at which variations occur. Moreover, it shows the importance of i) temporal resolution when monitoring highly dynamical properties such as snow cover and of ii) differences in satellite viewing angles over complex mountain areas. Finally, it highlights the potential and drawbacks of big data platforms for combining multi-source satellite data for monitoring dynamical processes such as snow cover.

  18. Combining MOD10A1 and MYD10A1 Images For Snow Cover Area Monitoring

    Science.gov (United States)

    Tekeli, A. E.

    2008-12-01

    MOD10A1 and MYD10A1 daily snow cover maps at 500 m resolution are available from MODIS sensors on Terra and Aqua satellites. Aqua obtains the image of same region approximately three hours after Terra over Turkey region. MODIS is an optic sensor and cloud cover degrades the usability of derived snow cover maps. Moreover, spectral similarity between clouds and snow complicates their separability in visible imagery. Fortunately, dynamic behavior of clouds enables their discrimination from snow stationary on the surface. Combined use of MOD10A1 and MYD10A1 images mostly reduces the cloud cover present in one image alone and provides better representation of surface snow cover. Comparison of merged images with in situ data indicated higher hit ratios. The individual comparison of MOD10A1 and MYD10A1 images with ground data each yielded 31% hit ratio whereas, the merged images provided 38%. One-day shifts in comparisons increased hit ratios to 52 % and 46% whereas and two-day shifts gave 77 % and 79 % for MOD10A1 and MYD10A1 respectively. Merged maps yielded 54% and 83% for one and two day shifts. The improvement provided by the merging technique is found to be 7% for the present day, 7 % for one- day and 5% for two-day shifts for the whole season. Monthly decomposition resulted 25% improvement as the maximum. The snow cover product obtained by merging Terra and Aqua satellites provided higher hit ratios, as expected.

  19. Hydrological Modelling and data assimilation of Satellite Snow Cover Area using a Land Surface Model, VIC

    Science.gov (United States)

    Naha, Shaini; Thakur, Praveen K.; Aggarwal, S. P.

    2016-06-01

    The snow cover plays an important role in Himalayan region as it contributes a useful amount to the river discharge. So, besides estimating rainfall runoff, proper assessment of snowmelt runoff for efficient management and water resources planning is also required. A Land Surface Model, VIC (Variable Infiltration Capacity) is used at a high resolution grid size of 1 km. Beas river basin up to Thalot in North West Himalayas (NWH) have been selected as the study area. At first model setup is done and VIC has been run in its energy balance mode. The fluxes obtained from VIC has been routed to simulate the discharge for the time period of (2003-2006). Data Assimilation is done for the year 2006 and the techniques of Data Assimilation considered in this study are Direct Insertion (D.I) and Ensemble Kalman Filter (EnKF) that uses observations of snow covered area (SCA) to update hydrologic model states. The meteorological forcings were taken from 0.5 deg. resolution VIC global forcing data from 1979-2006 with daily maximum temperature, minimum temperature from Climate Research unit (CRU), rainfall from daily variability of NCEP and wind speed from NCEP-NCAR analysis as main inputs and Indian Meteorological Department (IMD) data of 0.25 °. NBSSLUP soil map and land use land cover map of ISRO-GBP project for year 2014 were used for generating the soil parameters and vegetation parameters respectively. The threshold temperature i.e. the minimum rain temperature is -0.5°C and maximum snow temperature is about +0.5°C at which VIC can generate snow fluxes. Hydrological simulations were done using both NCEP and IMD based meteorological Forcing datasets, but very few snow fluxes were obtained using IMD data met forcing, whereas NCEP based met forcing has given significantly better snow fluxes throughout the simulation years as the temperature resolution as given by IMD data is 0.5°C and rainfall resolution of 0.25°C. The simulated discharge has been validated using observed

  20. Investigation of snow cover dust pollution by contact and satellite observations

    Science.gov (United States)

    Raputa, Vladimir F.; Yaroslavtseva, Tatyana V.

    2015-11-01

    The problems of reconstructing the snow cover pollution fields from dusting, point, linear and area sources according to ground and satellite observations are considered. Using reconstruction models, the methods of the combined analysis of the characteristic images of snow cover pollution haloes in the vicinity of sources of dust and contact data observations have been developed. On the basis of the numerical data analysis of ground monitoring and satellite imagery, the stable quantitative regularities between the fields of dust fallouts and the intensity of a change of tones of gray in the radial directions relative to the main sources are identified.

  1. Lessons learned from the snow emergency management of winter season 2008-2009 in Piemonte

    Science.gov (United States)

    Bovo, Dr.; Pelosini, Dr.; Cordola, Dr.

    2009-09-01

    The winter season 2008-2009 has been characterized by heavy snowfalls over the whole Piemonte, in the Western Alps region. The snowfalls have been exceptional because of their earliness, persistence and intensity. The impact on the regional environment and territory has been relevant, also from the economical point of view, as well as the effort of the people involved in the forecasting, prevention and fighting actions. The environmental induced effects have been shown until late spring. The main critical situations have been arisen from the snowfalls earliness in season, the several snow precipitation events over the plains, the big amount of snow accumulation on the ground, as well as the anomaly with respect to the last 30 years climatic trend of snow conditions in Piemonte. The damage costs to the public property caused by the snowfalls have been estimated by the Regione Piemonte to be 470 million euros, giving evidence of the real emergency dimension of the event, never occurred during the last 20 years. The technical support from the Regional Agency for Environmental Protection of Regione Piemonte (Arpa Piemonte) to the emergency management allowed to analyse and highlight the direct and induced effects of the heavy snowfalls, outlining risk scenarios characterized by different space and time scales. The risk scenarios deployment provided a prompt recommendation list, both for the emergency management and for the natural phenomena evolution surveillance planning to assure the people and property safety. The risk scenarios related to the snow emergency are different according to the geographical and anthropic territory aspects. In the mountains, several natural avalanche releases, characterized frequently by a large size, may affect villages, but they may also interrupt the main and secondary roads both down in the valleys and small villages road access, requiring a long time for the complete and safe snow removal and road re-opening. The avalanches often

  2. Monitoring of carbon isotope composition of snow cover for Tomsk region

    Science.gov (United States)

    Akulov, P. A.; Volkov, Y. V.; Kalashnikova, D. A.; Markelova, A. N.; Melkov, V. N.; Simonova, G. V.; Tartakovskiy, V. A.

    2016-11-01

    This article shows the potential of using δ13C values of pollutants in snow pack to study the human impact on the environment of Tomsk and its surroundings. We believe that it is possible to use a relation between the isotope compositions of a fuel and black carbon for establishing the origin of the latter. The main object of our investigation was dust accumulated by the snow pack in the winter of 2015-2016. The study of dust samples included the following steps: determination of the total carbon content in snow pack samples of Tomsk and its surroundings, extraction of black carbon from the dust, as well as the determination of δ13C values of the total and black carbon accumulated in the snow pack. A snow survey was carried out on the 26th of January and on the 18th of March. The relative carbon content in the dust samples was determined by using an EA Flash 2000 element analyzer. It varied from 3 to 24%. The maximum carbon content was in the dust samples from areas of cottage building with individual heating systems. The δ13C values of the total and black carbon were determined by using a DELTA V Advantage isotope mass spectrometer (TomTsKP SB RAS). The isotope composition of black carbon corresponded to that of the original fuel. This fact allowed identifying the origin of black carbon in some areas of Tomsk.

  3. Assimilation of MODIS Snow Cover Fraction Observations into the NASA Catchment Land Surface Model

    Directory of Open Access Journals (Sweden)

    Ally M. Toure

    2018-02-01

    Full Text Available The NASA Catchment land surface model (CLSM is the land model component used for the Modern-Era Retrospective Analysis for Research and Applications (MERRA. Here, the CLSM versions of MERRA and MERRA-Land are evaluated using snow cover fraction (SCF observations from the Moderate Resolution Imaging Spectroradiometer (MODIS. Moreover, a computationally-efficient empirical scheme is designed to improve CLSM estimates of SCF, snow depth, and snow water equivalent (SWE through the assimilation of MODIS SCF observations. Results show that data assimilation (DA improved SCF estimates compared to the open-loop model without assimilation (OL, especially in areas with ephemeral snow cover and mountainous regions. A comparison of the SCF estimates from DA against snow cover estimates from the NOAA Interactive Multisensor Snow and Ice Mapping System showed an improvement in the probability of detection of up to 28% and a reduction in false alarms by up to 6% (relative to OL. A comparison of the model snow depth estimates against Canadian Meteorological Centre analyses showed that DA successfully improved the model seasonal bias from −0.017 m for OL to −0.007 m for DA, although there was no significant change in root-mean-square differences (RMSD (0.095 m for OL, 0.093 m for DA. The time-average of the spatial correlation coefficient also improved from 0.61 for OL to 0.63 for DA. A comparison against in situ SWE measurements also showed improvements from assimilation. The correlation increased from 0.44 for OL to 0.49 for DA, the bias improved from −0.111 m for OL to −0.100 m for DA, and the RMSD decreased from 0.186 m for OL to 0.180 m for DA.

  4. Estimation of the spatiotemporal dynamics of snow covered area by using cellular automata models

    Science.gov (United States)

    Pardo-Igúzquiza, Eulogio; Collados-Lara, Antonio-Juan; Pulido-Velazquez, David

    2017-07-01

    Given the need to consider the cryosphere in water resources management for mountainous regions, the purpose of this paper is to model the daily spatially distributed dynamics of snow covered area (SCA) by using calibrated cellular automata models. For the operational use of the calibrated model, the only data requirements are the altitude of each cell of the spatial discretization of the area of interest and precipitation and temperature indexes for the area of interest. For the calibration step, experimental snow covered area data are needed. Potential uses of the model are to estimate the snow covered area when satellite data are absent, or when they provide a temporal resolution different from the operational resolution, or when the satellite images are useless because they are covered by clouds or because there has been a sensor failure. Another interesting application is the simulation of SCA dynamics for the snow covered area under future climatic scenarios. The model is applied to the Sierra Nevada mountain range, in southern Spain, which is home to significant biodiversity, contains important water resources in its snowpack, and contains the most meridional ski resort in Europe.

  5. Boreal and temperate snow cover variations induced by black carbon emissions in the middle of the 21st century

    Science.gov (United States)

    Ménégoz, M.; Krinner, G.; Balkanski, Y.; Cozic, A.; Boucher, O.; Ciais, P.

    2013-03-01

    We used a coupled climate-chemistry model to quantify the impacts of aerosols on snow cover north of 30° N both for the present-day and for the middle of the 21st century. Black carbon (BC) deposition over continents induces a reduction in the mean number of days with snow at the surface (MNDWS) that ranges from 0 to 10 days over large areas of Eurasia and Northern America for the present-day relative to the pre-industrial period. This is mainly due to BC deposition during the spring, a period of the year when the remaining of snow accumulated during the winter is exposed to both strong solar radiation and a large amount of aerosol deposition induced themselves by a high level of transport of particles from polluted areas. North of 30° N, this deposition flux represents 222 Gg BC month-1 on average from April to June in our simulation. A large reduction in BC emissions is expected in the future in all of the Representative Concentration Pathway (RCP) scenarios. In particular, considering the RCP8.5 in our simulation leads to a decrease in the spring BC deposition down to 110 Gg month-1 in the 2050s. However, despite the reduction of the aerosol impact on snow, the MNDWS is strongly reduced by 2050, with a decrease ranging from 10 to 100 days from present-day values over large parts of the Northern Hemisphere. This reduction is essentially due to temperature increase, which is quite strong in the RCP8.5 scenario in the absence of climate mitigation policies. Moreover, the projected sea-ice retreat in the next decades will open new routes for shipping in the Arctic. However, a large increase in shipping emissions in the Arctic by the mid-21st century does not lead to significant changes of BC deposition over snow-covered areas in our simulation. Therefore, the MNDWS is clearly not affected through snow darkening effects associated with these Arctic ship emissions. In an experiment without nudging toward atmospheric reanalyses, we simulated however some changes of

  6. Cadmium content in snow cover on the Pavlodar territory of the Republic of Kazakhstan

    International Nuclear Information System (INIS)

    Azhaev, G.S.; Panin, M.S.

    2008-01-01

    In the present report results of Cadmium concentration determination in aqueous and solid phases of snow cover on the Pavlodar territory of the Republic of Kazakhstan are presented. Cadmium content was tested with atomic absorption method on spectrophotometer of Perkin Elmer Company, model 403 with thermal-electric analyser HGA-74 and deuterium background corrector. Average concentration of cadmium in solid phase of snow goes up to 3.2 mg/kg, in aqueous phase - 2.1 mkg/dm 3 . That is respectively 22.9 and 13.1 times higher than background level. The cadmium concentration level in aqueous and solid phases of snow cover on the different areas of Pavlodar city is unequal. That indicates the specific character of different manufacturing enterprises, their anthropogenic impact on the environment and purification efficiency of emissions

  7. [Monitoring of the chemical composition of snow cover pollution in the Moscow region].

    Science.gov (United States)

    Ermakov, A A; Karpova, E A; Malysheva, A G; Mikhaylova, R I; Ryzhova, I N

    2014-01-01

    Monitoring of snow cover pollution as an indicator of ambient air pollution in 20 districts in the Moscow region during 2009-2013 was performed. The identification with a quantitative assessment of a wide array of organic compounds and the control of the main physical and chemical and inorganic indices of snow water pollution were carried out. More than 60 organic substances for most of which there are no the hygienic standards were established. The assessment of pollution levels of basic inorganic indices was given by means of the comparing them with the average values in the snow cover in the European territory of Russia and natural content in areas not been exposed to human impact.

  8. Automated mapping of persistent ice and snow cover across the western U.S. with Landsat

    Science.gov (United States)

    Selkowitz, David J.; Forster, Richard R.

    2016-01-01

    We implemented an automated approach for mapping persistent ice and snow cover (PISC) across the conterminous western U.S. using all available Landsat TM and ETM+ scenes acquired during the late summer/early fall period between 2010 and 2014. Two separate validation approaches indicate this dataset provides a more accurate representation of glacial ice and perennial snow cover for the region than either the U.S. glacier database derived from US Geological Survey (USGS) Digital Raster Graphics (DRG) maps (based on aerial photography primarily from the 1960s–1980s) or the National Land Cover Database 2011 perennial ice and snow cover class. Our 2010–2014 Landsat-derived dataset indicates 28% less glacier and perennial snow cover than the USGS DRG dataset. There are larger differences between the datasets in some regions, such as the Rocky Mountains of Northwest Wyoming and Southwest Montana, where the Landsat dataset indicates 54% less PISC area. Analysis of Landsat scenes from 1987–1988 and 2008–2010 for three regions using a more conventional, semi-automated approach indicates substantial decreases in glaciers and perennial snow cover that correlate with differences between PISC mapped by the USGS DRG dataset and the automated Landsat-derived dataset. This suggests that most of the differences in PISC between the USGS DRG and the Landsat-derived dataset can be attributed to decreases in PISC, as opposed to differences between mapping techniques. While the dataset produced by the automated Landsat mapping approach is not designed to serve as a conventional glacier inventory that provides glacier outlines and attribute information, it allows for an updated estimate of PISC for the conterminous U.S. as well as for smaller regions. Additionally, the new dataset highlights areas where decreases in PISC have been most significant over the past 25–50 years.

  9. Changes in snow cover over China in the 21st century as simulated by a high resolution regional climate model

    International Nuclear Information System (INIS)

    Shi Ying; Gao Xuejie; Wu Jia; Giorgi, Filippo

    2011-01-01

    On the basis of the climate change simulations conducted using a high resolution regional climate model, the Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model, RegCM3, at 25 km grid spacing, future changes in snow cover over China are analyzed. The simulations are carried out for the period of 1951–2100 following the IPCC SRES A1B emission scenario. The results suggest good performances of the model in simulating the number of snow cover days and the snow cover depth, as well as the starting and ending dates of snow cover to the present day (1981–2000). Their spatial distributions and amounts show fair consistency between the simulation and observation, although with some discrepancies. In general, decreases in the number of snow cover days and the snow cover depth, together with postponed snow starting dates and advanced snow ending dates, are simulated for the future, except in some places where the opposite appears. The most dramatic changes are found over the Tibetan Plateau among the three major snow cover areas of Northeast, Northwest and the Tibetan Plateau in China.

  10. Peculiarities of hydrocarbon distribution in the snow-ice cover of different regions of the white sea

    Science.gov (United States)

    Nemirovskaya, I. A.

    2014-03-01

    This paper presents data on the content of hydrocarbons (HCs) in the snow-ice cover of the coastal regions of the Dvina and Kandalaksha gulfs, White Sea, in 2008-2012 in comparison with the content of organic carbon, lipids, and the suspension. The accumulation of HCs in the snow-ice cover depends on the degree of pollution of the atmosphere, formation conditions of ice, and intensity of biogeochemical processes at the ice-water boundary. Thus, the highest concentrations in the water basin of Arkhangelsk are identified in snow and in the upper part of the ice. The peculiarities of formation of the snow-ice cover in Rugozero Bay of the Kandalaksha Gulf leads to the concentration of HCs in different snow and ice layers. The decreased HC content in the snow-ice cover of the White Sea, in comparison with previous studies, is caused by recession of industrial production in recent years.

  11. The role of surface energy fluxes in pan-Arctic snow cover changes

    International Nuclear Information System (INIS)

    Shi Xiaogang; Lettenmaier, Dennis P; Groisman, Pavel Ya; Dery, Stephen J

    2011-01-01

    We analyze snow cover extent (SCE) trends in the National Oceanic and Atmospheric Administration's (NOAA) northern hemisphere weekly satellite SCE data using the Mann-Kendall trend test and find that North American and Eurasian snow cover in the pan-Arctic have declined significantly in spring and summer over the period of satellite record beginning in the early 1970s. These trends are reproduced, both in trend direction and statistical significance, in reconstructions using the variable infiltration capacity (VIC) hydrological model. We find that spring and summer surface radiative and turbulent fluxes generated in VIC have strong correlations with satellite observations of SCE. We identify the role of surface energy fluxes and determine which is most responsible for the observed spring and summer SCE recession. We find that positive trends in surface net radiation (SNR) accompany most of the SCE trends, whereas modeled latent heat (LH) and sensible heat (SH) trends associated with warming on SCE mostly cancel each other, except for North America in spring, and to a lesser extent for Eurasia in summer. In spring over North America and summer in Eurasia, the SH contribution to the observed snow cover trends is substantial. The results indicate that ΔSNR is the primary energy source and ΔSH plays a secondary role in changes of SCE. Compared with ΔSNR and ΔSH, ΔLH has a minor influence on pan-Arctic snow cover changes.

  12. River flow regime and snow cover of the Pamir Alay (Central Asia) in a changing climate

    NARCIS (Netherlands)

    Chevallier, P.; Pouyaud, B.; Mojaisky, M.; Bolgov, M.; Olsson, O.; Bauer, M.; Froebrich, J.

    2014-01-01

    The Vakhsh and Pyandj rivers, main tributaries of the Amu Darya River in the mountainous region of the Pamir Alay, play an important role in the water resources of the Aral Sea basin (Central Asia). In this region, the glaciers and snow cover significantly influence the water cycle and flow regime,

  13. Snow cover variability in a forest ecotone of the Oregon Cascades via MODIS Terra products

    Science.gov (United States)

    Tihomir Sabinov Kostadinov; Todd R. Lookingbill

    2015-01-01

    Snowcover pattern and persistence have important implications for planetary energy balance, climate sensitivity to forcings, and vegetation structure, function, and composition. Variability in snow cover within mountainous regions of the Pacific Northwest, USA is attributable to a combination of anthropogenic climate change and climate oscillations. However,...

  14. Snow Cover and Precipitation Impacts on Dry Season Streamflow in the Lower Mekong Basin

    Science.gov (United States)

    Cook, Benjamin I.; Bell, A. R.; Anchukaitis, K. J.; Buckley, B. M.

    2012-01-01

    Climate change impacts on dry season streamflow in the Mekong River are relatively understudied, despite the fact that water availability during this time is critically important for agricultural and ecological systems. Analyses of two gauging stations (Vientiane and Kratie) in the Lower Mekong Basin (LMB) show significant positive correlations between dry season (March through May, MAM) discharge and upper basin snow cover and local precipitation. Using snow cover, precipitation, and upstream discharge as predictors, we develop skillful regression models for MAM streamflow at Vientiane and Kratie, and force these models with output from a suite of general circulation model (GCM) experiments for the twentieth and twenty-first centuries. The GCM simulations predict divergent trends in snow cover (decreasing) and precipitation (increasing) over the twenty-first century, driving overall negligible long-term trends in dry season streamflow. Our study demonstrates how future changes in dry season streamflow in the LMB will depend on changes in snow cover and precipitation, factors that will need to be considered when assessing the full basin response to other climatic and non-climatic drivers.

  15. Improved identification of clouds and ice/snow covered surfaces in SCIAMACHY observations

    Directory of Open Access Journals (Sweden)

    J. M. Krijger

    2011-10-01

    Full Text Available In the ultra-violet, visible and near infra-red wavelength range the presence of clouds can strongly affect the satellite-based passive remote sensing observation of constituents in the troposphere, because clouds effectively shield the lower part of the atmosphere. Therefore, cloud detection algorithms are of crucial importance in satellite remote sensing. However, the detection of clouds over snow/ice surfaces is particularly difficult in the visible wavelengths as both clouds an snow/ice are both white and highly reflective. The SCIAMACHY Polarisation Measurement Devices (PMD Identification of Clouds and Ice/snow method (SPICI uses the SCIAMACHY measurements in the wavelength range between 450 nm and 1.6 μm to make a distinction between clouds and ice/snow covered surfaces, specifically developed to identify cloud-free SCIAMACHY observations. For this purpose the on-board SCIAMACHY PMDs are used because they provide higher spatial resolution compared to the main spectrometer measurements. In this paper we expand on the original SPICI algorithm (Krijger et al., 2005a to also adequately detect clouds over snow-covered forests which is inherently difficult because of the similar spectral characteristics. Furthermore the SCIAMACHY measurements suffer from degradation with time. This must be corrected for adequate performance of SPICI over the full SCIAMACHY time range. Such a correction is described here. Finally the performance of the new SPICI algorithm is compared with various other datasets, such as from FRESCO, MICROS and AATSR, focusing on the algorithm improvements.

  16. NOAA JPSS Visible Infrared Imaging Radiometer Suite (VIIRS) Snow Cover/Depth (SCD) Snow Fraction Environmental Data Record (EDR) from IDPS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a high quality operational Environmental Data Record (EDR) of Snow Cover/Depth Fraction (SCF) from the Visible Infrared Imaging Radiometer...

  17. A long-term assessment of the variability in winter use of dense conifer cover by female white-tailed deer.

    Directory of Open Access Journals (Sweden)

    Glenn D Delgiudice

    Full Text Available Long-term studies allow capture of a wide breadth of environmental variability and a broader context within which to maximize our understanding of relationships to specific aspects of wildlife behavior. The goal of our study was to improve our understanding of the biological value of dense conifer cover to deer on winter range relative to snow depth and ambient temperature.We examined variation among deer in their use of dense conifer cover during a 12-year study period as potentially influenced by winter severity and cover availability. Female deer were fitted with a mixture of very high frequency (VHF, n = 267 and Global Positioning System (GPS, n = 24 collars for monitoring use of specific cover types at the population and individual levels, respectively. We developed habitat composites for four study sites. We fit multinomial response models to VHF (daytime data to describe population-level use patterns as a function of snow depth, ambient temperature, and cover availability. To develop alternative hypotheses regarding expected spatio-temporal patterns in the use of dense conifer cover, we considered two sets of competing sub-hypotheses. The first set addressed whether or not dense conifer cover was limiting on the four study sites. The second set considered four alternative sub-hypotheses regarding the potential influence of snow depth and ambient temperature on space use patterns. Deer use of dense conifer cover increased the most with increasing snow depth and most abruptly on the two sites where it was most available, suggestive of an energy conservation strategy. Deer use of dense cover decreased the most with decreasing temperatures on the sites where it was most available. At all four sites deer made greater daytime use (55 to >80% probability of use of open vegetation types at the lowest daily minimum temperatures indicating the importance of thermal benefits afforded from increased exposure to solar radiation. Date

  18. Capabilities of scatterometer for detection of diurnal thaw and refreeze of snow cover

    Science.gov (United States)

    Bartsch, A.; Naeimi, V.; Wagner, W.

    2009-04-01

    Microwave sensors with short wavelengths such as SeaWinds Quikscat (Ku-band) are sensitive to changes at snow surfaces due to thaw. Especially scatterometer can provide several measurements per day at high latitudes. Diurnal differences are investigated in a range of studies since they indicate exactly when snowmelt is taking place. Large changes in backscatter between morning and evening acquisitions are characteristic for the snowmelt period, when freezing takes place over night and thawing of the surface during the day. A change from volume to surface scattering occurs in case of melting. The actual number of dates of snow thaw is of most interest for glacier mass balance studies but the final disappearance of snow together with the length of spring thaw is required in regions with seasonal snow cover. When significant changes due to freeze/thaw cycling cease, closed snow cover also disappears. The exact day of year of beginning and end of freeze/thaw cycling can be clearly determined using QuikScat with consideration of long-term noise in order to exclude unnatural effects and changes in soil moisture and snow pack characteristics. SeaWinds Quikscat measurements are available since 1999. The first entire snowmelt period on the northern hemisphere is covered in 2000. A further scatteromter which provides the necessary observation intervals at high latitudes is the Metop ASCAT. It acquires data with %80 daily global coverage but at a longer wavelength (C-band) and different incidence angles since 2007. Comparison examples showing the capabilities of the two different sensors for the purpose of snowmelt detection are presented for high latitude regions and mountainous terrain at mid latitudes (Alps).

  19. MODIS/Terra Near Real Time (NRT) Snow Cover 5-Min L2 Swath 500m, Version 6

    Data.gov (United States)

    National Aeronautics and Space Administration — MODIS/Terra Near Real Time (NRT) Snow Cover 5-Min L2 Swath 500m (MOD10_L2) contains snow cover and quality assurance (QA) data, latitudes, and longitudes in HDF-EOS...

  20. Dust pollution of snow cover in the industrial areas of Tomsk city (Western Siberia, Russia)

    OpenAIRE

    Talovskaya, Anna Valerievna; Filimonenko, Ekaterina Anatolievna; Osipova, Nina Aleksandrovna; Yazikov, Yegor (Egor) Grigoryevich; Nadeina, Louise Vasilievna

    2016-01-01

    This article describes the results of long-term monitoring (2007-2014) of snow cover pollution in the territory of Tomsk city. Snow samples were collected in the territory of Tomsk. Determination of dust load level was carried out by comparing with the background and reference values. It has been determined that the north-east and central parts of Tomsk are the most contaminated areas, where brickworks, coal and gas-fired thermal power plant are located. The analysis of long-term dynamics sho...

  1. Timing and Statistics of Autumn and Spring Annual Snow Cover for the Northern Hemisphere, 1972 to 2000, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set comprises a time series of annual snow cover data for the Northern Hemisphere (covering land primarily above 45 degrees North) from 1972 to 2000. Data...

  2. Dust pollution of snow cover in the industrial areas of Tomsk city (Western Siberia, Russia)

    Science.gov (United States)

    Talovskaya, A. V.; Filimonenko, E. A.; Osipova, N. A.; Yazikov, E. G.; Nadeina, L. V.

    2016-03-01

    This article describes the results of long-term monitoring (2007-2014) of snow cover pollution in the territory of Tomsk city. Snow samples were collected in the territory of Tomsk. Determination of dust load level was carried out by comparing with the background and reference values. It has been determined that the north-east and central parts of Tomsk are the most contaminated areas, where brickworks, coal and gas-fired thermal power plant are located. The analysis of long-term dynamics showed a dust load decrease in the vicinity of coal and gas-fired thermal power plant due to upgrading of the existing dust collecting systems. During the monitoring period the high dust load in the vicinity of brickworks did not change. The lowest value of the dust load on snow cover was detected in the vicinity of the petrochemical plant and concrete product plants. The near and far zones of dust load on snow cover were determined with the reference to the location of the studied plants.

  3. Variability in snow cover phenology in China from 1952 to 2010

    Science.gov (United States)

    Ke, Chang-Qing; Li, Xiu-Cang; Xie, Hongjie; Ma, Dong-Hui; Liu, Xun; Kou, Cheng

    2016-02-01

    Daily snow observation data from 672 stations in China, particularly the 296 stations with over 10 mean snow cover days (SCDs) in a year during the period of 1952-2010, are used in this study. We first examine spatiotemporal variations and trends of SCDs, snow cover onset date (SCOD), and snow cover end date (SCED). We then investigate the relationships of SCDs with number of days with temperature below 0 °C (TBZD), mean air temperature (MAT), and Arctic Oscillation (AO) index. The results indicate that years with a positive anomaly of SCDs for the entire country include 1955, 1957, 1964, and 2010, and years with a negative anomaly of SCDs include 1953, 1965, 1999, 2002, and 2009. The reduced TBZD and increased MAT are the main reasons for the overall late SCOD and early SCED since 1952. This explains why only 12 % of the stations show significant shortening of SCDs, while 75 % of the stations show no significant change in the SCDs trends. Our analyses indicate that the distribution pattern and trends of SCDs in China are very complex and are not controlled by any single climate variable examined (i.e. TBZD, MAT, or AO), but a combination of multiple variables. It is found that the AO has the maximum impact on the shortening trends of SCDs in the Shandong peninsula, Changbai Mountains, Xiaoxingganling, and north Xinjiang, while the combined TBZD and MAT have the maximum impact on the shortening trends of SCDs in the Loess Plateau, Tibetan Plateau, and Northeast Plain.

  4. Changing snow cover in tundra ecosystems tips the Arctic carbon balance

    Science.gov (United States)

    Zona, D.; Hufkens, K.; Gioli, B.; Kalhori, A. A. M.; Oechel, W. C.

    2014-12-01

    The Arctic environment has witnessed important changes due to global warming, resulting in increased surface air temperatures and rain events which both exacerbate snow cover deterioration (Semmens et al, 2013; Rennert et al, 2009; White et al, 2007; Min et al, 2008; Sharp et al, 2013; Schaeffer et al, 2013). Snow cover duration is declining by almost 20% per decade, a far higher rate than model estimates (Derksen and Brown, 2012). Concomitant with increasing temperatures and decreasing snow cover duration, the length of the arctic growing season is reported to have increased by 1.1 - 4.9 days per decade since 1951 (Menzel et al, 2006), and, plant productivity and CO2 uptake from arctic vegetation are strongly influenced by changes in growing season length (Myneni et al., 1997; Schaefer et al., 2005; Euskirchen et al., 2006). Based on more than a decade of eddy flux measurements in Arctic tundra ecosystems across the North slope of Alaska, and remotely sensed snow cover data, we show that earlier snow melt in the spring increase C uptake while an extended snow free period in autumn is associated with a higher C loss. Here we present the impacts of changes in snow cover dynamics between spring and autumn in arctic tundra ecosystems on the carbon dynamics and net C balance of the Alaskan Arctic. ReferencesDerksen, C., Brown R. (2012) Geophys. Res. Lett., doi:10.1029/2012GL053387 Euskirchen, E.S., et al. (2006) Glob. Change Biol., 12, 731-750. Menzel, A., et al. 2006. Glob. Change Biol., 12, 1969-1976. Min SK, Zhang X, Zweirs F (2008) Science 320: 518-520. Rennert K J, Roe G, Putkonen J and Bitz C M (2009) J. Clim. 22 2302-15. Schaefer, K., Denning A.S., Leonard O. (2005) Global Biogeochem. Cycles, 19, GB3017. Schaeffer, S. M., Sharp, E., Schimel, J. P. & Welker, J. M. (2013). Soil- plant N processes in a High Arctic ecosystem, NW Greenland are altered by long-term experimental warming and higher rainfall. Glob. Change Biol., 11, 3529-39. doi: 10.1111/gcb.12318

  5. Effect of land cover change on snow free surface albedo across the continental United States

    Science.gov (United States)

    Wickham, J.; Nash, M.S.; Barnes, Christopher A.

    2016-01-01

    Land cover changes (e.g., forest to grassland) affect albedo, and changes in albedo can influence radiative forcing (warming, cooling). We empirically tested albedo response to land cover change for 130 locations across the continental United States using high resolution (30 m-×-30 m) land cover change data and moderate resolution (~ 500 m-×-500 m) albedo data. The land cover change data spanned 10 years (2001 − 2011) and the albedo data included observations every eight days for 13 years (2001 − 2013). Empirical testing was based on autoregressive time series analysis of snow free albedo for verified locations of land cover change. Approximately one-third of the autoregressive analyses for woody to herbaceous or forest to shrub change classes were not significant, indicating that albedo did not change significantly as a result of land cover change at these locations. In addition, ~ 80% of mean differences in albedo arising from land cover change were less than ± 0.02, a nominal benchmark for precision of albedo measurements that is related to significant changes in radiative forcing. Under snow free conditions, we found that land cover change does not guarantee a significant albedo response, and that the differences in mean albedo response for the majority of land cover change locations were small.

  6. POLSCAT Ku-Band Radar Remote Sensing of Terrestrial Snow Cover

    Science.gov (United States)

    Yueh, Simon; Cline, Donald; Elder, Kelly

    2008-01-01

    Characteristics of the POLSCAT data acquired from five sets of aircraft flights in the winter months of 2006-2008 for the second Cold Land Processes Experiment (CLPX-II) in Colorado are described in this paper. The data showed the response of the Ku-band radar echoes to snowpack changes for various types of background vegetation in the study site in north central Colorado. We observed about 0.15 to 0.5 dB increases in backscatter for every 1 cm of snow water equivalent (SWE) accumulation for areas with short vegetation. Based on a simplified radiative transfer model, the change detection technique is used to convert the temporal change of radar backscatter into SWE accumulation for dry snow conditions. The resulting SWE accumulation estimates are consistent with the in-situ SWE measurements, with about 2 to 3 cm Root-Mean-Square (RMS) difference for regions with sagebrush or pasture.

  7. Snow Cover, Snowmelt Timing and Stream Power in the Wind River Range, Wyoming

    Science.gov (United States)

    Hall, Dorothy K.; Foster, James L.; DiGirolamo, Nicolo E.; Riggs, George A.

    2011-01-01

    Earlier onset of springtime weather, including earlier snowmelt, has been documented in the western United States over at least the last 50 years. Because the majority (is greater than 70%) of the water supply in the western U.S. comes from snowmelt, analysis of the declining spring snowpack (and shrinking glaciers) has important implications for the management of streamflow. The amount of water in a snowpack influences stream discharge which can also influence erosion and sediment transport by changing stream power, or the rate at which a stream can do work, such as move sediment and erode the stream bed. The focus of this work is the Wind River Range (WRR) in west-central Wyoming. Ten years of Moderate-Resolution Imaging Spectroradiometer (MODIS) snow-cover, cloud-gap-filled (CGF) map products and 30 years of discharge and meteorological station data are studied. Streamflow data from streams in WRR drainage basins show lower annual discharge and earlier snowmelt in the decade of the 2000s than in the previous three decades, though no trend of either lower streamflow or earlier snowmelt was observed within the decade of the 2000s. Results show a statistically-significant trend at the 95% confidence level (or higher) of increasing weekly maximum air temperature (for three out of the five meteorological stations studied) in the decade of the 1970s, and also for the 40-year study period as a whole. The extent of snow-cover (percent of basin covered) derived from the lowest elevation zone (2500-3000 m) of the WRR, using MODIS CGF snow-cover maps, is strongly correlated with maximum monthly discharge on 30 April, where Spearman's Rank correlation, rs,=0.89 for the decade of the 2000s. We also investigated stream power for Bull Lake Creek above Bull Lake; and found a trend (significant at the 90% confidence level) toward reduced stream power from 1970 to 2009. Observed changes in streamflow and stream power may be related to increasing weekly maximum air temperature

  8. Overview of NASA's MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS) snow-cover Earth System Data Records

    Science.gov (United States)

    Riggs, George A.; Hall, Dorothy K.; Román, Miguel O.

    2017-10-01

    Knowledge of the distribution, extent, duration and timing of snowmelt is critical for characterizing the Earth's climate system and its changes. As a result, snow cover is one of the Global Climate Observing System (GCOS) essential climate variables (ECVs). Consistent, long-term datasets of snow cover are needed to study interannual variability and snow climatology. The NASA snow-cover datasets generated from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua spacecraft and the Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) are NASA Earth System Data Records (ESDR). The objective of the snow-cover detection algorithms is to optimize the accuracy of mapping snow-cover extent (SCE) and to minimize snow-cover detection errors of omission and commission using automated, globally applied algorithms to produce SCE data products. Advancements in snow-cover mapping have been made with each of the four major reprocessings of the MODIS data record, which extends from 2000 to the present. MODIS Collection 6 (C6; https://nsidc.org/data/modis/data_summaries) and VIIRS Collection 1 (C1; https://doi.org/10.5067/VIIRS/VNP10.001) represent the state-of-the-art global snow-cover mapping algorithms and products for NASA Earth science. There were many revisions made in the C6 algorithms which improved snow-cover detection accuracy and information content of the data products. These improvements have also been incorporated into the NASA VIIRS snow-cover algorithms for C1. Both information content and usability were improved by including the Normalized Snow Difference Index (NDSI) and a quality assurance (QA) data array of algorithm processing flags in the data product, along with the SCE map. The increased data content allows flexibility in using the datasets for specific regions and end-user applications. Though there are important differences between the MODIS and VIIRS instruments (e.g., the VIIRS 375

  9. Overview of NASA's MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS snow-cover Earth System Data Records

    Directory of Open Access Journals (Sweden)

    G. A. Riggs

    2017-10-01

    Full Text Available Knowledge of the distribution, extent, duration and timing of snowmelt is critical for characterizing the Earth's climate system and its changes. As a result, snow cover is one of the Global Climate Observing System (GCOS essential climate variables (ECVs. Consistent, long-term datasets of snow cover are needed to study interannual variability and snow climatology. The NASA snow-cover datasets generated from the Moderate Resolution Imaging Spectroradiometer (MODIS on the Terra and Aqua spacecraft and the Suomi National Polar-orbiting Partnership (S-NPP Visible Infrared Imaging Radiometer Suite (VIIRS are NASA Earth System Data Records (ESDR. The objective of the snow-cover detection algorithms is to optimize the accuracy of mapping snow-cover extent (SCE and to minimize snow-cover detection errors of omission and commission using automated, globally applied algorithms to produce SCE data products. Advancements in snow-cover mapping have been made with each of the four major reprocessings of the MODIS data record, which extends from 2000 to the present. MODIS Collection 6 (C6; https://nsidc.org/data/modis/data_summaries and VIIRS Collection 1 (C1; https://doi.org/10.5067/VIIRS/VNP10.001 represent the state-of-the-art global snow-cover mapping algorithms and products for NASA Earth science. There were many revisions made in the C6 algorithms which improved snow-cover detection accuracy and information content of the data products. These improvements have also been incorporated into the NASA VIIRS snow-cover algorithms for C1. Both information content and usability were improved by including the Normalized Snow Difference Index (NDSI and a quality assurance (QA data array of algorithm processing flags in the data product, along with the SCE map. The increased data content allows flexibility in using the datasets for specific regions and end-user applications. Though there are important differences between the MODIS and VIIRS instruments (e

  10. Overview of NASA's MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS) snow-cover Earth System Data Records

    Science.gov (United States)

    Riggs, George A.; Hall, Dorothy K.; Roman, Miguel O.

    2017-01-01

    Knowledge of the distribution, extent, duration and timing of snowmelt is critical for characterizing the Earth's climate system and its changes. As a result, snow cover is one of the Global Climate Observing System (GCOS) essential climate variables (ECVs). Consistent, long-term datasets of snow cover are needed to study interannual variability and snow climatology. The NASA snow-cover datasets generated from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua spacecraft and the Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) are NASA Earth System Data Records (ESDR). The objective of the snow-cover detection algorithms is to optimize the accuracy of mapping snow-cover extent (SCE) and to minimize snow-cover detection errors of omission and commission using automated, globally applied algorithms to produce SCE data products. Advancements in snow-cover mapping have been made with each of the four major reprocessings of the MODIS data record, which extends from 2000 to the present. MODIS Collection 6 (C6) and VIIRS Collection 1 (C1) represent the state-of-the-art global snow cover mapping algorithms and products for NASA Earth science. There were many revisions made in the C6 algorithms which improved snow-cover detection accuracy and information content of the data products. These improvements have also been incorporated into the NASA VIIRS snow cover algorithms for C1. Both information content and usability were improved by including the Normalized Snow Difference Index (NDSI) and a quality assurance (QA) data array of algorithm processing flags in the data product, along with the SCE map.The increased data content allows flexibility in using the datasets for specific regions and end-user applications.Though there are important differences between the MODIS and VIIRS instruments (e.g., the VIIRS 375m native resolution compared to MODIS 500 m), the snow detection algorithms and data

  11. Subpixel Snow Cover Mapping from MODIS Data by Nonparametric Regression Splines

    Science.gov (United States)

    Akyurek, Z.; Kuter, S.; Weber, G. W.

    2016-12-01

    Spatial extent of snow cover is often considered as one of the key parameters in climatological, hydrological and ecological modeling due to its energy storage, high reflectance in the visible and NIR regions of the electromagnetic spectrum, significant heat capacity and insulating properties. A significant challenge in snow mapping by remote sensing (RS) is the trade-off between the temporal and spatial resolution of satellite imageries. In order to tackle this issue, machine learning-based subpixel snow mapping methods, like Artificial Neural Networks (ANNs), from low or moderate resolution images have been proposed. Multivariate Adaptive Regression Splines (MARS) is a nonparametric regression tool that can build flexible models for high dimensional and complex nonlinear data. Although MARS is not often employed in RS, it has various successful implementations such as estimation of vertical total electron content in ionosphere, atmospheric correction and classification of satellite images. This study is the first attempt in RS to evaluate the applicability of MARS for subpixel snow cover mapping from MODIS data. Total 16 MODIS-Landsat ETM+ image pairs taken over European Alps between March 2000 and April 2003 were used in the study. MODIS top-of-atmospheric reflectance, NDSI, NDVI and land cover classes were used as predictor variables. Cloud-covered, cloud shadow, water and bad-quality pixels were excluded from further analysis by a spatial mask. MARS models were trained and validated by using reference fractional snow cover (FSC) maps generated from higher spatial resolution Landsat ETM+ binary snow cover maps. A multilayer feed-forward ANN with one hidden layer trained with backpropagation was also developed. The mutual comparison of obtained MARS and ANN models was accomplished on independent test areas. The MARS model performed better than the ANN model with an average RMSE of 0.1288 over the independent test areas; whereas the average RMSE of the ANN model

  12. Winter severity determines functional trait composition of phytoplankton in seasonally ice-covered lakes.

    Science.gov (United States)

    Özkundakci, Deniz; Gsell, Alena S; Hintze, Thomas; Täuscher, Helgard; Adrian, Rita

    2016-01-01

    How climate change will affect the community dynamics and functionality of lake ecosystems during winter is still little understood. This is also true for phytoplankton in seasonally ice-covered temperate lakes which are particularly vulnerable to the presence or absence of ice. We examined changes in pelagic phytoplankton winter community structure in a north temperate lake (Müggelsee, Germany), covering 18 winters between 1995 and 2013. We tested how phytoplankton taxa composition varied along a winter-severity gradient and to what extent winter severity shaped the functional trait composition of overwintering phytoplankton communities using multivariate statistical analyses and a functional trait-based approach. We hypothesized that overwintering phytoplankton communities are dominated by taxa with trait combinations corresponding to the prevailing winter water column conditions, using ice thickness measurements as a winter-severity indicator. Winter severity had little effect on univariate diversity indicators (taxon richness and evenness), but a strong relationship was found between the phytoplankton community structure and winter severity when taxon trait identity was taken into account. Species responses to winter severity were mediated by the key functional traits: motility, nutritional mode, and the ability to form resting stages. Accordingly, one or the other of two functional groups dominated the phytoplankton biomass during mild winters (i.e., thin or no ice cover; phototrophic taxa) or severe winters (i.e., thick ice cover; exclusively motile taxa). Based on predicted milder winters for temperate regions and a reduction in ice-cover durations, phytoplankton communities during winter can be expected to comprise taxa that have a relative advantage when the water column is well mixed (i.e., need not be motile) and light is less limiting (i.e., need not be mixotrophic). A potential implication of this result is that winter severity promotes different

  13. Assessing winter cover crop nutrient uptake efficiency using a water quality simulation model

    Science.gov (United States)

    Yeo, In-Young; Lee, Sangchui; Sadeghi, Ali M.; Beeson, Peter C.; Hively, W. Dean; McCarty, Greg W.; Lang, Megan W.

    2013-01-01

    Winter cover crops are an effective conservation management practice with potential to improve water quality. Throughout the Chesapeake Bay Watershed (CBW), which is located in the Mid-Atlantic US, winter cover crop use has been emphasized and federal and state cost-share programs are available to farmers to subsidize the cost of winter cover crop establishment. The objective of this study was to assess the long-term effect of planting winter cover crops at the watershed scale and to identify critical source areas of high nitrate export. A physically-based watershed simulation model, Soil and Water Assessment Tool (SWAT), was calibrated and validated using water quality monitoring data and satellite-based estimates of winter cover crop species performance to simulate hydrological processes and nutrient cycling over the period of 1991–2000. Multiple scenarios were developed to obtain baseline information on nitrate loading without winter cover crops planted and to investigate how nitrate loading could change with different winter cover crop planting scenarios, including different species, planting times, and implementation areas. The results indicate that winter cover crops had a negligible impact on water budget, but significantly reduced nitrate leaching to groundwater and delivery to the waterways. Without winter cover crops, annual nitrate loading was approximately 14 kg ha−1, but it decreased to 4.6–10.1 kg ha−1 with winter cover crops resulting in a reduction rate of 27–67% at the watershed scale. Rye was most effective, with a potential to reduce nitrate leaching by up to 93% with early planting at the field scale. Early planting of winter cover crops (~30 days of additional growing days) was crucial, as it lowered nitrate export by an additional ~2 kg ha−1 when compared to late planting scenarios. The effectiveness of cover cropping increased with increasing extent of winter cover crop implementation. Agricultural fields with well-drained soils

  14. Snow Cover and Vegetation-Induced Decrease in Global Albedo From 2002 to 2016

    Science.gov (United States)

    Li, Qiuping; Ma, Mingguo; Wu, Xiaodan; Yang, Hong

    2018-01-01

    Land surface albedo is an essential parameter in regional and global climate models, and it is markedly influenced by land cover change. Variations in the albedo can affect the surface radiation budget and further impact the global climate. In this study, the interannual variation of albedo from 2002 to 2016 was estimated on the global scale using Moderate Resolution Imaging Spectroradiometer (MODIS) datasets. The presence and causes of the albedo changes for each specific region were also explored. From 2002 to 2016, the MODIS-based albedo decreased globally, snow cover declined by 0.970 (percent per pixel), while the seasonally integrated normalized difference vegetation index increased by 0.175. Some obvious increases in the albedo were detected in Central Asia, northeastern China, parts of the boreal forest in Canada, and the temperate steppe in North America. In contrast, noticeable decreases in the albedo were found in the Siberian tundra, Europe, southeastern Australia, and northeastern regions of North America. In the Northern Hemisphere, the greening trend at high latitudes made more contribution to the decline in the albedo. However, the dramatic fluctuation of snow-cover at midlatitudes predominated in the change of albedo. Our analysis can help to understand the roles that vegetation and snow cover play in the variation of albedo on global and regional scales.

  15. Satellite Based Probabilistic Snow Cover Extent Mapping (SCE) at Hydro-Québec

    Science.gov (United States)

    Teasdale, Mylène; De Sève, Danielle; Angers, Jean-François; Perreault, Luc

    2016-04-01

    Over 40% of Canada's water resources are in Quebec and Hydro-Quebec has developed potential to become one of the largest producers of hydroelectricity in the world, with a total installed capacity of 36,643 MW. The Hydro-Québec fleet park includes 27 large reservoirs with a combined storage capacity of 176 TWh, and 668 dams and 98 controls. Thus, over 98% of all electricity used to supply the domestic market comes from water resources and the excess output is sold on the wholesale markets. In this perspective the efficient management of water resources is needed and it is based primarily on a good river flow estimation including appropriate hydrological data. Snow on ground is one of the significant variables representing 30% to 40% of its annual energy reserve. More specifically, information on snow cover extent (SCE) and snow water equivalent (SWE) is crucial for hydrological forecasting, particularly in northern regions since the snowmelt provides the water that fills the reservoirs and is subsequently used for hydropower generation. For several years Hydro Quebec's research institute ( IREQ) developed several algorithms to map SCE and SWE. So far all the methods were deterministic. However, given the need to maximize the efficient use of all resources while ensuring reliability, the electrical systems must now be managed taking into account all risks. Since snow cover estimation is based on limited spatial information, it is important to quantify and handle its uncertainty in the hydrological forecasting system. This paper presents the first results of a probabilistic algorithm for mapping SCE by combining Bayesian mixture of probability distributions and multiple logistic regression models applied to passive microwave data. This approach allows assigning for each grid point, probabilities to the set of the mutually exclusive discrete outcomes: "snow" and "no snow". Its performance was evaluated using the Brier score since it is particularly appropriate to

  16. Improvement of a snow albedo parameterization in the Snow-Atmosphere-Soil Transfer model: evaluation of impacts of aerosol on seasonal snow cover

    Science.gov (United States)

    Zhong, Efang; Li, Qian; Sun, Shufen; Chen, Wen; Chen, Shangfeng; Nath, Debashis

    2017-11-01

    The presence of light-absorbing aerosols (LAA) in snow profoundly influence the surface energy balance and water budget. However, most snow-process schemes in land-surface and climate models currently do not take this into consideration. To better represent the snow process and to evaluate the impacts of LAA on snow, this study presents an improved snow albedo parameterization in the Snow-Atmosphere-Soil Transfer (SAST) model, which includes the impacts of LAA on snow. Specifically, the Snow, Ice and Aerosol Radiation (SNICAR) model is incorporated into the SAST model with an LAA mass stratigraphy scheme. The new coupled model is validated against in-situ measurements at the Swamp Angel Study Plot (SASP), Colorado, USA. Results show that the snow albedo and snow depth are better reproduced than those in the original SAST, particularly during the period of snow ablation. Furthermore, the impacts of LAA on snow are estimated in the coupled model through case comparisons of the snowpack, with or without LAA. The LAA particles directly absorb extra solar radiation, which accelerates the growth rate of the snow grain size. Meanwhile, these larger snow particles favor more radiative absorption. The average total radiative forcing of the LAA at the SASP is 47.5 W m-2. This extra radiative absorption enhances the snowmelt rate. As a result, the peak runoff time and "snow all gone" day have shifted 18 and 19.5 days earlier, respectively, which could further impose substantial impacts on the hydrologic cycle and atmospheric processes.

  17. Potential feedbacks between snow cover, soil moisture and surface energy fluxes in Southern Norway

    Science.gov (United States)

    Brox Nilsen, Irene; Tallaksen, Lena M.; Stordal, Frode

    2017-04-01

    At high latitudes, the snow season has become shorter during the past decades because snowmelt is highly sensitive to a warmer climate. Snowmelt influences the energy balance by changing the albedo and the partitioning between latent and sensible heat fluxes. It further influences the water balance by changing the runoff and soil moisture. In a previous study, we identified southern Norway as a region where significant temperature changes in summer could potentially be explained by land-atmosphere interactions. In this study we hypothesise that changes in snow cover would influence the summer surface fluxes in the succeeding weeks or months. The exceptionally warm summer of 2014 was chosen as a test bed. In Norway, evapotranspiration is not soil moisture limited, but energy limited, under normal conditions. During warm summers, however, such as in 2014, evapotranspiration can be restricted by the available soil moisture. Using the Weather Research and Forecasting (WRF) model we replace the initial ground conditions for 2014 with conditions representative of a snow-poor spring and a snow-rich spring. WRF was coupled to Noah-MP at 3 km horizontal resolution in the inner domain, and the simulations covered mid-May through September 2014. Boundary conditions used to force WRF were taken from the Era-Interim reanalysis. Snow, runoff, soil moisture and soil temperature observational data were provided by the Norwegian Water Resources and Energy Directorate for validation. The validation shows generally good agreement with observations. Preliminary results show that the reduced snowpack, hereafter "sim1" increased the air temperature by up to 5 K and the surface temperature by up to 10 K in areas affected by snow changes. The increased snowpack, hereafter "sim2", decreased the air and surface temperature by the same amount. These are weekly mean values for the first eight simulation weeks from mid May. Because of the higher net energy available ( 100 Wm-2) in sim 1, both

  18. Assessing the thermal dissipation sap flux density method for monitoring cold season water transport in seasonally snow-covered forests.

    Science.gov (United States)

    Chan, Allison M; Bowling, David R

    2017-07-01

    Productivity of conifers in seasonally snow-covered forests is high before and during snowmelt when environmental conditions are optimal for photosynthesis. Climate change is altering the timing of spring in many locations, and changes in the date of transition from winter dormancy can have large impacts on annual productivity. Sap flow methods provide a promising approach to monitor tree activity during the cold season and the winter-spring and fall-winter transitions. Although sap flow techniques have been widely used, cold season results are generally not reported. Here we examine the feasibility of using the Granier thermal dissipation (TD) sap flux density method to monitor transpiration and dormancy of evergreen conifers during the cold season. We conducted a laboratory experiment which demonstrated that the TD method reliably detects xylem water transport (when it occurs) both at near freezing temperature and at low flow rate, and that the sensors can withstand repeated freeze-thaw events. However, the dependence between sensor output and water transport rate in these experiments differed from the established TD relation. In field experiments, sensors installed in two Abies forests lasted through two winters and a summer with low failure. The baseline (no-flow) sensor output varied considerably with temperature during the cold season, and a new baseline algorithm was developed to accommodate this variation. The Abies forests differed in elevation (2070 and 2620 m), and there was a clear difference in timing of initiation and cessation of transpiration between them. We conclude that the TD method can be reliably used to examine water transport during cold periods with associated low flow conditions. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Snow cover dynamics in Andean watersheds of Chile (32.0-39.5° S) during the years 2000-2016

    Science.gov (United States)

    Stehr, Alejandra; Aguayo, Mauricio

    2017-10-01

    Andean watersheds present important snowfall accumulation mainly during the winter, which melts during the spring and part of the summer. The effect of snowmelt on the water balance can be critical to sustain agriculture activities, hydropower generation, urban water supplies and wildlife. In Chile, 25 % of the territory between the region of Valparaiso and Araucanía comprises areas where snow precipitation occurs. As in many other difficult-to-access regions of the world, there is a lack of hydrological data of the Chilean Andes related to discharge, snow courses, and snow depths, which complicates the analysis of important hydrological processes (e.g. water availability). Remote sensing provides a promising opportunity to enhance the assessment and monitoring of the spatial and temporal variability of snow characteristics, such as the snow cover area (SCA) and snow cover dynamic (SCD). With regards to the foregoing questions, the objective of the study is to evaluate the spatiotemporal dynamics of the SCA at five watersheds (Aconcagua, Rapel, Maule, Biobío and Toltén) located in the Chilean Andes, between latitude 32.0 and 39.5° S, and to analyse its relationship with the precipitation regime/pattern and El Niño-Southern Oscillation (ENSO) events. Those watersheds were chosen because of their importance in terms of their number of inhabitants, and economic activities depending on water resources. The SCA area was obtained from MOD10A2 for the period 2000-2016, and the SCD was analysed through a number of statistical tests to explore observed trends. In order to verify the SCA for trend analysis, a validation of the MOD10A2 product was done, consisting of the comparison of snow presence predicted by MODIS with ground observations. Results indicate that there is an overall agreement of 81 to 98 % between SCA determined from ground observations and MOD10A2, showing that the MODIS snow product can be taken as a feasible remote sensing tool for SCA estimation in

  20. Snow cover and End of Summer Snowline statistics from a simple stochastic model

    Science.gov (United States)

    Petrelli, A.; Crouzy, B.; Perona, P.

    2012-04-01

    One essential parameter characterizing snow cover statistics is the End Of Summer Snowline (EOSS), which is also a good indicator of actual climatic trends in mountain regions. EOSS is usually modelled by means of spatially distributed physically based models, and typically require heavy parameterization. In this paper we validate the simple stochastic model proposed by Perona et al. (2007), by showing that the snow cover statistics and the position of EOSS can in principle be explained by only four essential (meteorological) parameters. Perona et al. (2007) proposed a model accounting for stochastic snow accumulation in the cold period, and deterministic melting dynamics in the warm period, and studied the statistical distribution of the snowdepth on the long term. By reworking the ensemble average of the steady state evolution equation we single out a relationship between the snowdepth statistics (including the position of EOSS) and the involved parameters. The validation of the established relationship is done using 50 years of field data from 73 Swiss stations located above 2000 m a.s.l. First an estimation of the meteorological parameters is made. Snow height data are used as a precipitation proxy, using temperature data to estimate SWE during the precipitation event. Thresholds are used both to separate accumulation from actual precipitation and wind transport phenomena, and to better assess summer melting rate, considered to be constant over the melting period according to the simplified model. First results show that data for most of the weather stations actually scales with the proposed relationship. This indicates that, on the long term, the effect of spatial and temporal noise masks most of the process detail so that minimalist models suffice to obtain reliable statistics. Future works will test the validity of this approach at different spatial scales, e.g., regional, continental and planetary. Reference: P. Perona, A. Porporato, and L. Ridolfi, "A

  1. Retrieval of the ultraviolet effective snow albedo during 1998 winter campaign in the French Alps.

    Science.gov (United States)

    Smolskaia, Irina; Masserot, Dominique; Lenoble, Jacqueline; Brogniez, Colette; de la Casinière, Alain

    2003-03-20

    A measurement campaign was carried out in February 1998 at Briançon Station, French Alps (44.9 degrees N, 6.65 degrees E, 1,310 m above sea level) in order to determine the UV effective snow albedo that was retrieved for both erythemal and UV-A irradiances from measurements and modeling enhancement factors. The results are presented for 15 cloudless days with very variable snow cover and a small snowfall in the middle of the campaign. Erythemal irradiance enhancement due to the surface albedo was found to decrease from approximately +15% to +5% with a jump to +22% after the snowfall, whereas UV-A irradiance enhancement decreased from 7% to 5% and increased to 15% after the snowfall. Thesevalues fit to effective surface albedos of 0.4, 0.1, and 0.5 for erythemal, and to effective albedos of 0.25, 0.1, and 0.4 for UV-A irradiances, respectively. An unexpected difference between the effective albedos retrieved in the two wavelength regions can be explained by the difference of the environment contribution.

  2. Contribution of MODIS Derived Snow Cover Satellite Data into Artificial Neural Network for Streamflow Estimation

    Science.gov (United States)

    Uysal, Gokcen; Arda Sorman, Ali; Sensoy, Aynur

    2014-05-01

    Contribution of snowmelt and correspondingly snow observations are highly important in mountainous basins for modelers who deal with conceptual, physical or soft computing models in terms of effective water resources management. Long term archived continuous data are needed for appropriate training and testing of data driven approaches like artificial neural networks (ANN). Data is scarce at the upper elevations due to the difficulty of installing sufficient automated SNOTEL stations; thus in literatures many attempts are made on the rainfall dominated basins for streamflow estimation studies. On the other hand, optical satellites can easily detect snow because of its high reflectance property. MODIS (Moderate Resolution Imaging Spectroradiometer) satellite that has two platforms (Terra and Aqua) provides daily and 8-daily snow images for different time periods since 2000, therefore snow cover data (SCA) may be useful as an input layer for ANN applications. In this study, a multi-layer perceptron (MLP) model is trained and tested with precipitation, temperature, radiation, previous day discharges as well as MODIS daily SCA data. The weights and biases are optimized with fastest and robust Levenberg-Marquardt backpropagation algorithm. MODIS snow cover images are removed from cloud coverage using certain filtering techniques. The Upper Euphrates River Basin in eastern part of Turkey (10 250 km2) is selected as the application area since it is fed by snowmelt approximately 2/3 of total annual volume during spring and early summer. Several input models and ANN structures are investigated to see the effect of the contributions using 10 years of data (2001-2010) for training and validation. The accuracy of the streamflow estimations is checked with statistical criteria (coefficient of determination, Nash-Sutcliffe model efficiency, root mean square error, mean absolute error) and the results seem to improve when SCA data is introduced. Furthermore, a forecast study is

  3. Influence of winter sea-ice motion on summer ice cover in the Arctic

    Directory of Open Access Journals (Sweden)

    Noriaki Kimura

    2013-11-01

    Full Text Available Summer sea-ice cover in the Arctic varies largely from year to year owing to several factors. This study examines one such factor, the relationship between interannual difference in winter ice motion and ice area in the following summer. A daily-ice velocity product on a 37.5-km resolution grid is prepared using the satellite passive microwave sensor Advanced Microwave Scanning Radiometer—Earth Observing System data for the nine years of 2003–2011. Derived daily-ice motion reveals the dynamic modification of the winter ice cover. The winter ice divergence/convergence is strongly related to the summer ice cover in some regions; the correlation coefficient between the winter ice convergence and summer ice area ranges between 0.5 and 0.9 in areas with high interannual variability. This relation implies that the winter ice redistribution controls the spring ice thickness and the summer ice cover.

  4. Feasibility of winter cover crop production under rainfed conditions

    African Journals Online (AJOL)

    ACSS

    Interaction effects of planting date and cover crop species on cover crop dry weight at termination in Eastern Cape. Province, South Africa. Cover crop dry weight (kg ha. -1. ) 0. 1000. 2000. 3000. 4000. 5000. 6000. 7000. 8000. Barley. Oats. Radish. Rye. Triticale. Vetch. February planted. March planted. April planted. LSD.

  5. CLPX-Satellite: EO-1 Hyperion Surface Reflectance, Snow-Covered Area, and Grain Size, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of apparent surface reflectance, subpixel snow-covered area, and grain size collected from the Hyperion hyperspectral imager. The Hyperion...

  6. A GIS Software Toolkit for Monitoring Areal Snow Cover and Producing Daily Hydrologic Forecasts using NASA Satellite Imagery, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Aniuk Consulting, LLC, proposes to create a GIS software toolkit for monitoring areal snow cover extent and producing streamflow forecasts. This toolkit will be...

  7. The effects of additional black carbon on Arctic sea ice surface albedo: variation with sea ice type and snow cover

    OpenAIRE

    A. A. Marks; M. D. King

    2013-01-01

    Black carbon in sea ice will decrease sea ice surface albedo through increased absorption of incident solar radiation, exacerbating sea ice melting. Previous literature has reported different albedo responses to additions of black carbon in sea ice and has not considered how a snow cover may mitigate the effect of black carbon in sea ice. Sea ice is predominately snow covered. Visible light absorption and light scattering coefficients are calculated for a typical first year and multi-y...

  8. Airborne Ku-Band Polarimetric Radar Remote Sensing of Terrestrial Snow Cover

    Science.gov (United States)

    Yueh, Simon; Cline, Donald; Elder, Kelly

    2008-01-01

    Preliminary analyses of the POLSCAT data acquired from the CLPX-II in winter 2006-2007 are described in this paper. The data showed the response of the Ku-band radarechoes to snowpack changes for various types of background vegetation. We observed about 0.2 to 0.4 dB increases in backscatter for every 1 cm SWE accumulation for sage brush and agricultural fields. The co-polarized VV and HH radar resposnes are similar, while the corss-polarized (VH or HV) echoes showedgreater resposne to the change of SWE. The data also showed the impact of surface hoar growth and freeze/thaw cycles, whichcreated large snow grain sizes and ice lenses, respectively, and consequently increased the radar signals by a few dBs.

  9. Southern Hemisphere origins for interannual variations of Tibetan Plateau snow cover in boreal summer

    Science.gov (United States)

    Wu, Z.

    2017-12-01

    The climate response to the Tibetan Plateau (TP) snow cover (TPSC) has been receiving extensive concern. However, relatively few studies have devoted to revealing the potential factors that can contribute to the TPSC variability on the interannual time scale. Especially during the boreal summer, snow cover can persist over the TP at high elevations, which exerts profound influences on the local and remote climate change. The present study finds that May Southern Hemisphere (SH) annular mode (SAM), the dominating mode of atmospheric circulation variability in the SH extratropics, exhibits a significant positive relationship with the boreal summer TPSC interannual variability. Observational analysis and numerical experiments manifest that the signal of May SAM can be "prolonged" by a meridional Indian Ocean tripole (IOT) sea surface temperature anomaly (SSTA) via atmosphere-ocean interaction. The IOT SSTA pattern persists into the following summer and excites anomalous local-scale zonal vertical circulation. Subsequently, a positive (or negative) tropical dipole rainfall (TDR) mode is induced with deficient (or sufficient) precipitation in tropical western Indian Ocean and sufficient (or deficient) precipitation in eastern Indian Ocean-Maritime continent. Rossby wave source diagnosis reveals that the wave energies, generated by the latent heat release of the TDR mode, propagate northward into western TP. As a response, abnormal cyclonic circulation and upward movement are triggered and prevail over western TP, providing favorable dynamical conditions for more TPSC, and vice versa. Hence, the IOT SSTA plays an "ocean bridge" role and the TDR mode acts as an "atmosphere bridge" role in the process of May SAM impacting the following summer TPSC variability. The results of our work may provide new insight about the cross-equatorial propagation of the SAM influence. Keywords Southern Hemisphere annular mode; Tibetan Plateau snow cover; Rossby wave source

  10. Improvement of Operational Streamflow Prediction with MODIS-derived Fractional Snow Covered Area Observations

    Science.gov (United States)

    Bender, S.; Burgess, A.; Goodale, C. E.; Mattmann, C. A.; Miller, W. P.; Painter, T. H.; Rittger, K. E.; Stokes, M.; Werner, K.

    2013-12-01

    Water managers in the western United States depend heavily on the timing and magnitude of snowmelt-driven runoff for municipal supply, irrigation, maintenance of environmental flows, and power generation. The Colorado Basin River Forecast Center (CBRFC) of the National Weather Service issues operational forecasts of snowmelt-driven streamflow for watersheds within the Colorado River Basin (CRB) and eastern Great Basin (EGB), across a wide variety of scales. Therefore, the CBRFC and its stakeholders consider snowpack observations to be highly valuable. Observations of fractional snow covered area (fSCA) from satellite-borne instrumentation can better inform both forecasters and water users with respect to subsequent snowmelt runoff, particularly when combined with observations from ground-based station networks and/or airborne platforms. As part of a multi-year collaborative effort, CBRFC has partnered with the Jet Propulsion Laboratory (JPL) under funding from NASA to incorporate observations of fSCA from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) into the operational CBRFC hydrologic forecasting and modeling process. In the first year of the collaboration, CBRFC and NASA/JPL integrated snow products into the forecasting and decision making processes of the CBRFC and showed preliminary improvement in operational streamflow forecasts. In late 2012, CBRFC and NASA/JPL began retrospective analysis of relationships between the MODIS Snow Covered Area and Grain size (MODSCAG) fSCA and streamflow patterns for several watersheds within the CRB and the EGB. During the 2013 snowmelt runoff season, CBRFC forecasters used MODIS-derived fSCA semi-quantitatively as a binary indicator of the presence or lack of snow. Indication of the presence or lack of snow by MODIS assisted CBRFC forecasters in determining the cause of divergence between modeled and recently observed streamflow. Several examples of improved forecasts from across the CRB and EGB, informed by

  11. Long-range transported dissolved organic matter, ions and black carbon deposited on Central Asian snow covered glaciers

    Science.gov (United States)

    Schmale, Julia; Kang, Shichang; Peltier, Richard

    2014-05-01

    Ninety percent of the Central Asian population depend on water precipitated in the mountains stored in glaciers and snow cover. Accelerated melting of the snow and ice can be induced by the deposition of airborne impurities such as mineral dust, black carbon and co-emitted species leading to significant reductions of the surface albedo. However, Central Asia is a relatively understudied region and data on the source regions, chemical and microphysical characteristics as well as modelling studies of long-range transported air pollution and dust to the Tien Shan mountains is very scarce. We studied the atmospheric aerosol deposited most likely between summer 2012 and summer 2013on three different glaciers in the Kyrgyz Republic. Samples were taken from four snow pits on the glaciers Abramov (2 pits, 39.59 °N, 71.56 °E, 4390 m elevation, 240 cm deep, and 39.62°N, 71.52 °E, 4275 m elevation, 125 cm deep), Ak-Shiirak (41.80 °N, 78.18 °E, 4325 m elevation, 75 cm deep) and Suek (41.78 °N, 77.75 °E, 4341 m elevation, 200 cm deep). The latter two glaciers are located roughly within 6 and 38 km of an operating gold mine. The snow was analyzed for black carbon, ions, metals and organic carbon. We here focus on the results of inorganic ion measurements and organic carbon speciation based on analysis with an Aerodyne high-resolution time-of-flight aerosol spectrometer (HR-ToF-AMS) and potential pollution sources that can be deduced from the chemical information as well as back trajectories. Average contributions of snow impurities measured by the HR-ToF-AMS were dominated by organic carbon. Relative concentrations of organic carbon, sulfate, nitrate and ammonium in snow were 86 %, 3 %, 9 % and 2 % respectively for Abramov, 92 %, 1 %, 5 % and 1 % for Suek, and 95 %, 1 %, 3 % and 1 % for Ak-Shiirak. Generally, impurities on Suek and Ak-Shiirak were three and five times higher than on Abramov. Mass concentrations of organic carbon were on average 6 times higher in samples

  12. Simulations of a Cold-Air Pool in Utah's Salt Lake Valley: Sensitivity to Land Use and Snow Cover

    Science.gov (United States)

    Foster, Christopher S.; Crosman, Erik T.; Horel, John D.

    2017-02-01

    Obtaining realistic land-surface states for initial and boundary conditions is important for the numerical weather prediction of many atmospheric phenomena. Here we investigate model sensitivity to land use and snow cover for a persistent wintertime cold-air pool in northern Utah during 1-8 January 2011. A Weather Research and Forecast model simulation using the 1993 United States Geological Survey land-use and North American Mesoscale model reanalysis snow-cover datasets is compared to an improved configuration using the modified 2011 National Land Cover Database and a more realistic representation of snow cover. The improved surface specification results in an increase (decrease) in urban land cover (Great Salt Lake surface area), and changes to the snow-cover initialization, depth, extent, and albedo. The results obtained from the model simulations are compared to observations collected during the Persistent Cold-Air Pool Study. The changes in land use and snow cover and the resulting impacts on the surface albedo and surface heat fluxes contributed to near-surface air temperature increases of 1-2°C in urban areas and decreases of 2-4°C in areas surrounding the Great Salt Lake. Although wind speeds in the boundary layer were overestimated in both simulations, shallow thermally-driven and terrain-forced flows were generally lessened in intensity and breadth in response to the decreased areal extent of the Great Salt Lake and increases in the urban footprint.

  13. Quantification of spatial temporal variability of snow cover and hydro-climatic variables based on multi-source remote sensing data in the Swat watershed, Hindukush Mountains, Pakistan

    Science.gov (United States)

    Anjum, Muhammad Naveed; Ding, Yongjian; Shangguan, Donghui; Liu, Junguo; Ahmad, Ijaz; Ijaz, Muhammad Wajid; Khan, Muhammad Imran

    2018-02-01

    The northern part of Hindukush Mountains has a perplexing environment due to the influence of adjacent mountains of Himalaya, Karakoram, and Tibetan Plateau. Although reliable evidences of climate change are available; however, a clear knowledge of snow cover dynamics in the context of climate change is missing for this region. In this study, we used various remotely sensed (TRMM precipitation product, while MODIS temperature and snow cover products) and gauge-based datasets to quantify the spatiotemporal variability of climatic variables and their turn effects over the snow cover area (SCA) and river discharge in the Swat watershed, northern Hindukush Mountains, Pakistan. The Mann-Kendall method and Sen's slope estimator were used to estimate the trends in SCA and hydro-climatic variables, at 5% significant level (P = 0.05). Results show that the winter and springs temperatures have increased (at the rate of 0.079 and 0.059 °C year-1, respectively), while decreasing in the summer and autumn (at the rate of 0.049 and 0.070 °C year-1, respectively). Basin-wide increasing tendency of precipitation was identified with a highest increasing rate of 3.563 mm year-1 in the spring season. A decreasing trend in the winter SCA (at the rate of -0.275% year-1) and increasing trends in other seasons were identified. An increasing tendency of river discharge on annual and seasonal scales was also witnessed. The seasonal variations in discharge showed significant positive and negative relationships with temperature and SCA, respectively. We conclude that the future variations in the temperature and SCA in the higher altitudes of the Swat watershed could substantially affect the seasonality of the river discharge. Moreover, it implies that the effect of ongoing global warming on the SCA in the snowmelt-dominated river basins needs to be considered for sustainable regional planning and management of water resources, hydropower production, and downstream irrigation scheduling.

  14. Monitoring the spatio-temporal evolution of the snow cover in the eastern Alps from MODIS data

    Science.gov (United States)

    Cianfarra, P.; Salvini, F.; Valt, M.

    2009-04-01

    Estimating the snow cover extent in mountain ranges is important for a wide variety purposes including of scientific studies, environmental and meteo-climatic applications, as well as predicting water availability for energy resource and agriculture. Moreover, the monitoring of the spatio-temporal variation of the snow cover thickness, coupled with ground data from weather stations, allows to identify avalanche risk areas after heavy snowfall. The aim of this study is to test an automatic procedure to identify and map the snow coverage for different altitude interval in the eastern part of the Alpine range. There has been much progress since 1966 when the first operational snow mapping was done by NOAA with spaceborne sensors that provide daily, global observations to monitor the variability in space and time in the extent of snow cover. MODIS sensors offer increased improvements relative to the AVHRR that has been operational for many years on the NOAA Polar Operational Environmental Satellite System. In this context the MODIS provides observations at a nominal spatial resolution of 500 m versus the 1.1 km spatial resolution of the AVHRR and continuously available (spatially and temporally), spectral band observation that span the visible and short-wave infrared wavelengths, including those useful for recognize snow cover. The other advantage of using MODIS data is its availability and cost by the NASA's server. In this work we used MOD02 (L1B) data providing calibrated radiance values at the sensor (without atmospheric correction). Snow cover map production included the following steps: selection of the images with clear sky conditions, geometric correction and georeferencing to UTM zone 32 ,WSG 84 ellipsoid, to eliminate the distortion of and the typical bow-tie effect that produces the observed not alignment of the scan lines in the row image; spatial sub setting to produce an image covering an area of about 200 x 120 km; identification of the snow cover was

  15. Enhancement of snow cover change detection with sparse representation and dictionary learning

    Science.gov (United States)

    Varade, D.; Dikshit, O.

    2014-11-01

    Sparse representation and decoding is often used for denoising images and compression of images with respect to inherent features. In this paper, we adopt a methodology incorporating sparse representation of a snow cover change map using the K-SVD trained dictionary and sparse decoding to enhance the change map. The pixels often falsely characterized as "changes" are eliminated using this approach. The preliminary change map was generated using differenced NDSI or S3 maps in case of Resourcesat-2 and Landsat 8 OLI imagery respectively. These maps are extracted into patches for compressed sensing using Discrete Cosine Transform (DCT) to generate an initial dictionary which is trained by the K-SVD approach. The trained dictionary is used for sparse coding of the change map using the Orthogonal Matching Pursuit (OMP) algorithm. The reconstructed change map incorporates a greater degree of smoothing and represents the features (snow cover changes) with better accuracy. The enhanced change map is segmented using kmeans to discriminate between the changed and non-changed pixels. The segmented enhanced change map is compared, firstly with the difference of Support Vector Machine (SVM) classified NDSI maps and secondly with a reference data generated as a mask by visual interpretation of the two input images. The methodology is evaluated using multi-spectral datasets from Resourcesat-2 and Landsat-8. The k-hat statistic is computed to determine the accuracy of the proposed approach.

  16. Modeling of surface dust concentration in snow cover at industrial area using neural networks and kriging

    Science.gov (United States)

    Sergeev, A. P.; Tarasov, D. A.; Buevich, A. G.; Shichkin, A. V.; Tyagunov, A. G.; Medvedev, A. N.

    2017-06-01

    Modeling of spatial distribution of pollutants in the urbanized territories is difficult, especially if there are multiple emission sources. When monitoring such territories, it is often impossible to arrange the necessary detailed sampling. Because of this, the usual methods of analysis and forecasting based on geostatistics are often less effective. Approaches based on artificial neural networks (ANNs) demonstrate the best results under these circumstances. This study compares two models based on ANNs, which are multilayer perceptron (MLP) and generalized regression neural networks (GRNNs) with the base geostatistical method - kriging. Models of the spatial dust distribution in the snow cover around the existing copper quarry and in the area of emissions of a nickel factory were created. To assess the effectiveness of the models three indices were used: the mean absolute error (MAE), the root-mean-square error (RMSE), and the relative root-mean-square error (RRMSE). Taking into account all indices the model of GRNN proved to be the most accurate which included coordinates of the sampling points and the distance to the likely emission source as input parameters for the modeling. Maps of spatial dust distribution in the snow cover were created in the study area. It has been shown that the models based on ANNs were more accurate than the kriging, particularly in the context of a limited data set.

  17. Missing (in-situ) snow cover data hampers climate change and runoff studies in the Greater Himalayas.

    Science.gov (United States)

    Rohrer, Mario; Salzmann, Nadine; Stoffel, Markus; Kulkarni, Anil V

    2013-12-01

    The Himalayas are presently holding the largest ice masses outside the polar regions and thus (temporarily) store important freshwater resources. In contrast to the contemplation of glaciers, the role of runoff from snow cover has received comparably little attention in the past, although (i) its contribution is thought to be at least equally or even more important than that of ice melt in many Himalayan catchments and (ii) climate change is expected to have widespread and significant consequences on snowmelt runoff. Here, we show that change assessment of snowmelt runoff and its timing is not as straightforward as often postulated, mainly as larger partial pressure of H2O, CO2, CH4, and other greenhouse gases might increase net long-wave input for snowmelt quite significantly in a future atmosphere. In addition, changes in the short-wave energy balance - such as the pollution of the snow cover through black carbon - or the sensible or latent heat contribution to snowmelt are likely to alter future snowmelt and runoff characteristics as well. For the assessment of snow cover extent and depletion, but also for its monitoring over the extremely large areas of the Himalayas, remote sensing has been used in the past and is likely to become even more important in the future. However, for the calibration and validation of remotely-sensed data, and even more so in light of possible changes in snow-cover energy balance, we strongly call for more in-situ measurements across the Himalayas, in particular for daily data on new snow and snow cover water equivalent, or the respective energy balance components. Moreover, data should be made accessible to the scientific community, so that the latter can more accurately estimate climate change impacts on Himalayan snow cover and possible consequences thereof on runoff. © 2013 Elsevier B.V. All rights reserved.

  18. Missing (in-situ) snow cover data hampers climate change and runoff studies in the Greater Himalayas

    International Nuclear Information System (INIS)

    Rohrer, Mario; Salzmann, Nadine; Stoffel, Markus; Kulkarni, Anil V.

    2013-01-01

    The Himalayas are presently holding the largest ice masses outside the polar regions and thus (temporarily) store important freshwater resources. In contrast to the contemplation of glaciers, the role of runoff from snow cover has received comparably little attention in the past, although (i) its contribution is thought to be at least equally or even more important than that of ice melt in many Himalayan catchments and (ii) climate change is expected to have widespread and significant consequences on snowmelt runoff. Here, we show that change assessment of snowmelt runoff and its timing is not as straightforward as often postulated, mainly as larger partial pressure of H 2 O, CO 2 , CH 4 , and other greenhouse gases might increase net long-wave input for snowmelt quite significantly in a future atmosphere. In addition, changes in the short-wave energy balance – such as the pollution of the snow cover through black carbon – or the sensible or latent heat contribution to snowmelt are likely to alter future snowmelt and runoff characteristics as well. For the assessment of snow cover extent and depletion, but also for its monitoring over the extremely large areas of the Himalayas, remote sensing has been used in the past and is likely to become even more important in the future. However, for the calibration and validation of remotely-sensed data, and even more so in light of possible changes in snow-cover energy balance, we strongly call for more in-situ measurements across the Himalayas, in particular for daily data on new snow and snow cover water equivalent, or the respective energy balance components. Moreover, data should be made accessible to the scientific community, so that the latter can more accurately estimate climate change impacts on Himalayan snow cover and possible consequences thereof on runoff. - Highlights: • Remotely sensed snow-cover data need to be validated by in-situ measurements. • More in-situ snow measurement programs are needed along

  19. The impact of organochlorines cycling in the cryosphere on global distributions and fate--2. Land ice and temporary snow cover.

    Science.gov (United States)

    Hofmann, Lorenz; Stemmler, Irene; Lammel, Gerhard

    2012-03-01

    Global fate and transport of γ-HCH and DDT was studied using a global multicompartment chemistry-transport model, MPI-MCTM, with and without inclusion of land ice (in Antarctica and Greenland) or snow cover (dynamic). MPI-MCTM is based on coupled ocean and atmosphere general circulation models. After a decade of simulation 4.2% γ-HCH and 2.3% DDT are stored in land ice and snow. Neglection of land ice and snow in modelling would underestimate the total environmental residence time, τ(ov), of γ-HCH and overestimate τ(ov) for DDT, both on the order of 1% and depending on actual compartmental distribution. Volatilisation of DDT from boreal, seasonally snow covered land is enhanced throughout the year, while volatilisation of γ-HCH is only enhanced during the snow-free season. Including land ice and snow cover in modelling matters in particular for the Arctic, where higher burdens are predicted to be stored. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. On a snow cover composition in the vicinity of the Verkhnekamsky Salt Deposit

    Directory of Open Access Journals (Sweden)

    S. M. Blinov

    2015-01-01

    Full Text Available The snow cover chemical composition was investigated on the territory of the Verkhnekamskiy potash-magnesium salt deposit in the zone of influence of atmospheric emissions of Berezniki Potash Mining Complex (Perm Region. The object of researches was the snow in this area. Features of specific pollutants contained in the emissions of these mine groups and their relationship with the air intake and following atmospheric deposition were examined. With regard for specific character of pollutants in the emissions, studies of melt water included determination of the following chemical components – SO42-, Cl-, NO3-, NO2-, НCO3-, Ca2+, Mg2+, Na+, K+, of the pH value as well as suspended solid substances, and total mineralization. An analysis of snow composition was performed on two sites from which one was the surrounding background territory, while another area was the urban territory of city Berezniki, i.e. area of operating mine group. To assess the results the indicator of specific stock macro component was used. Increased specific stock relative to the background snowpack is clearly indicative of components directly related to the extraction and processing of salts Cl-, Na+, K+. The revealed anomalies have a local character and, as a rule, do not extend beyond boundaries of sanitary protection zones of the enterprises. Maps of distribution of values of the specific reserves for the analyzed list of components in the melt water were constructed. Our results obtained for the Verkhnekamskiy Deposit area were compared with similar published data on the territories of cities in the zone influenced by motor roads, reserves, and coastal zones of the Russian Arctic seas.

  1. Short-term winter wheat (Triticum aestivum L.) cover crop grazing influence on calf growth, grain yield, and soil properties

    Science.gov (United States)

    Winter cover cropping has many agronomic benefits and can provide forages base for spring livestock grazing. Winter cover crop grazing has shown immediate economic benefits through increased animal production. Winter wheat pasture grazing is common in beef cow-calf production and stocker operations....

  2. The influence of snow cover on alpine floods reconstructed from the analysis of satellite images. The case of the Hasli-Aare river basin, Berner Oberland (1987-2012)

    Science.gov (United States)

    Cabrera-Medina, Paula; Schulte, Lothar; Carvalho, Filipe; Peña, Juan Carlos; García, Carles

    2016-04-01

    Regarding the hydrological hazards in the Hasli-Aare river over the last century, instrumental and documentary data show that flood frequency and magnitude increased since 1977. One of the main water inputs contributing to peak discharges is given by the thaw of the stored snow. Therefore, the knowledge of the evolution of snow cover is considered essential for the assessment of alpine floods. Snow cover studies can be made by different approaches such as the analysis of data provided by field work or by nivometeorological stations. However, these methods are usually expensive and do not present adequate spatial or temporal coverage data. For this reason, satellite images with different spatial and temporal resolution are an interesting complementary source for the understanding of the snow cover dynamics. The aim of the paper is to study the influence of snow cover variations during years of severe floods that occurred in the upper Aare basin from 1987 to 2012. Three satellite images have been selected for each of the 9 studied events: 1) maximum snow cover during winter, 2) the last image before the event and 3) the first image after the flood. Each image has been processed with the ArcGIS software applying a statistical method of supervised classification. This image processing allows the spatial quantification of the variation of the snow cover in the Aare headwater catchment. Because the melting of snow cover is related to the changes of weather situations before and during the flood episode, it is important to analyse also the nivometeorological data of stations located in the catchment (snow depth, temperature and precipitation). From these data we determined 4 types of flood, which can be classified according to their nivometeorological variables and synoptic situation (500 hPa geopotential and Sea Level Pressure) into two patterns. The first group of events can be associated to an Atlantic pattern recording decreasing temperatures, moderate to high

  3. Effects of over-winter green cover on soil solution nitrate concentrations beneath tillage land.

    Science.gov (United States)

    Premrov, Alina; Coxon, Catherine E; Hackett, Richard; Kirwan, Laura; Richards, Karl G

    2014-02-01

    There is a growing need to reduce nitrogen losses from agricultural systems to increase food production while reducing negative environmental impacts. The efficacy of vegetation cover for reducing nitrate leaching in tillage systems during fallow periods has been widely investigated. Nitrate leaching reductions by natural regeneration (i.e. growth of weeds and crop volunteers) have been investigated to a lesser extent than reductions by planted cover crops. This study compares the efficacy of natural regeneration and a sown cover crop (mustard) relative to no vegetative cover under both a reduced tillage system and conventional plough-based system as potential mitigation measures for reducing over-winter soil solution nitrate concentrations. The study was conducted over three winter fallow seasons on well drained soil, highly susceptible to leaching, under temperate maritime climatic conditions. Mustard cover crop under both reduced tillage and conventional ploughing was observed to be an effective measure for significantly reducing nitrate concentrations. Natural regeneration under reduced tillage was found to significantly reduce the soil solution nitrate concentrations. This was not the case for the natural regeneration under conventional ploughing. The improved efficacy of natural regeneration under reduced tillage could be a consequence of potential stimulation of seedling germination by the autumn reduced tillage practices and improved over-winter plant growth. There was no significant effect of tillage practices on nitrate concentrations. This study shows that over winter covers of mustard and natural regeneration, under reduced tillage, are effective measures for reducing nitrate concentrations in free draining temperate soils. © 2013.

  4. Large-scale Desert Dust Deposition on the Himalayan Snow Cover: A Climatological Perspective from Satellite Observations

    Science.gov (United States)

    Gautam, R.; Hsu, N. C.; Lau, W. K.

    2013-12-01

    The Himalaya-Tibetan Plateau (HTP) has a profound influence on the Asian climate. The HTP are also among the largest snow/ice-covered regions on the Earth and provide major freshwater resource to the downstream densely-populated regions of Asia. Recent studies indicate climate warming over the HTP amplified by atmospheric heating and deposition of absorbing aerosols (e.g. dust and soot) over the HTP snowpack and glaciers. Recently, greater attention has focused on the effects of soot deposition on accelerated snowmelt and glacier retreat in the HTP, associated with increasing anthropogenic emissions in Asia. On the other hand, the role of transported dust affecting snow albedo/melt is not well understood over the HTP, in spite of the large annual cycle of mineral dust loading, particularly over the northern parts of south Asia during pre-monsoon season. This study addresses the large-scale effects of dust deposition on snow albedo in the elevated HTP from a satellite observational perspective. Dust aerosol transport, from southwest Asian arid regions, is observed in satellite imagery as darkening of the Himalayan snowpack. Additionally, multi-year spaceborne lidar observations, from CALIPSO, also show dust advected to elevated altitudes (~5km) over the Himalayan foothills, and episodically reaching the top of the western Himalaya. Spectral surface reflectance analysis of dust-laden snow cover (from MODIS) indicates enhanced absorption in the shorter visible wavelengths, yielding a significant gradient in the visible-nearIR reflectance spectrum. While soot in snow is difficult to distinguish from remote sensing, our spectral reflectance analysis of dust detection in the snowpack is consistent with theoretical simulations of snow darkening due to dust impurity. We find that the western HTP, in general, is influenced by enhanced dust deposition due to its proximity to major dust sources (and prevailing dust transport pathways), compared to the eastern HTP. Coinciding

  5. Technique for radionuclide composition analysis of snow cover in the Chernobyl' NPP 30-km zone using fiber sorbents

    International Nuclear Information System (INIS)

    Kham'yanov, L.P.; Rau, D.F.; Amosov, M.M.; Strel'nikova, A.E.; Tereshchenko, V.I.; Veber, T.S.

    1989-01-01

    The high-sensitivity, simple and fast technique for analysis of large-dispersive and ionic components of snow cover radioactivity is suggested. It is based on separation of a sample by fractions, concentration of the dispersive fraction on mechanical filters and the dissolved one on ion-exchange sorbents and separated fraction spectrometry. The minimum measured contamination level is 3.7 Bq/dm 3 for each radionuclide analyzed. The conclusion is made that the technique suggested is the reliable method for radionuclide content analysis is snow cover samples of the Chernobyl' NPP zone. 1 tab

  6. Nitrate Leaching from Winter Cereal Cover Crops Using Undisturbed Soil-Column Lysimeters.

    Science.gov (United States)

    Meisinger, John J; Ricigliano, Kristin A

    2017-05-01

    Cover crops are important management practices for reducing nitrogen (N) leaching, especially in the Chesapeake Bay watershed, which is under total maximum daily load (TMDL) restraints. Winter cereals are common cool-season crops in the Bay watershed, but studies have not directly compared nitrate-N (NO-N) leaching losses from these species. A 3-yr cover crop lysimeter study was conducted in Beltsville, MD, to directly compare NO-N leaching from a commonly grown cultivar of barley ( L.), rye ( L.), and wheat ( L.), along with a no-cover control, using eight tension-drained undisturbed soil column lysimeters in a completely randomized design with two replicates. The lysimeters were configured to exclude runoff and to estimate NO-N leaching and flow-weighted NO-N concentration (FWNC). The temporal pattern of NO-N leaching showed a consistent highly significant ( < 0.001) effect of lower NO-N leaching with cover crops compared with no cover but showed only small and periodically significant ( < 0.05) effects among the cultivars of barley, rye, and wheat covers. Nitrate-N leaching was more affected by the quantity of establishment-season (mid-October to mid-December) precipitation than by cover crop species. For example, compared with no cover, winter cereal covers reduced NO-N leaching 95% in a dry year and 50% in wet years, with corresponding reductions in FWNC of 92 and 43%, respectively. These results are important for scientists, nutrient managers, and policymakers because they directly compare NO-N leaching from winter cereal covers and expand knowledge for developing management practices for winter cereals that can improve water quality and increase N efficiency in cropping systems. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  7. Winter QPF Sensitivities to Snow Parameterizations and Comparisons to NASA CloudSat Observations

    Science.gov (United States)

    Molthan, Andrew; Haynes, John M.; Jedlovec, Gary J.; Lapenta, William M.

    2009-01-01

    Steady increases in computing power have allowed for numerical weather prediction models to be initialized and run at high spatial resolution, permitting a transition from larger scale parameterizations of the effects of clouds and precipitation to the simulation of specific microphysical processes and hydrometeor size distributions. Although still relatively coarse in comparison to true cloud resolving models, these high resolution forecasts (on the order of 4 km or less) have demonstrated value in the prediction of severe storm mode and evolution and are being explored for use in winter weather events . Several single-moment bulk water microphysics schemes are available within the latest release of the Weather Research and Forecast (WRF) model suite, including the NASA Goddard Cumulus Ensemble, which incorporate some assumptions in the size distribution of a small number of hydrometeor classes in order to predict their evolution, advection and precipitation within the forecast domain. Although many of these schemes produce similar forecasts of events on the synoptic scale, there are often significant details regarding precipitation and cloud cover, as well as the distribution of water mass among the constituent hydrometeor classes. Unfortunately, validating data for cloud resolving model simulations are sparse. Field campaigns require in-cloud measurements of hydrometeors from aircraft in coordination with extensive and coincident ground based measurements. Radar remote sensing is utilized to detect the spatial coverage and structure of precipitation. Here, two radar systems characterize the structure of winter precipitation for comparison to equivalent features within a forecast model: a 3 GHz, Weather Surveillance Radar-1988 Doppler (WSR-88D) based in Omaha, Nebraska, and the 94 GHz NASA CloudSat Cloud Profiling Radar, a spaceborne instrument and member of the afternoon or "A-Train" of polar orbiting satellites tasked with cataloguing global cloud

  8. Spatiotemporal analysis of snow cover variations at Mt. Kilimanjaro using multi-temporal Landsat images during 27 years

    Science.gov (United States)

    Park, Sung-Hwan; Lee, Moung-Jin; Jung, Hyung-Sup

    2016-06-01

    The Landsat TM and ETM+ images have been acquired for the long period from the 1980s until the present with the temporal resolution of a 16-day repeat cycle from the visible, near infrared (NIR), short wave infrared (SWIR) and thermal infrared (TIR) bands. The Landsat multi-temporal images have been successfully used to monitor variations of the Earth surface during 27 years. In this paper, we observe the variations of (1) the snow cover area, (2) the snowline height and (3) the land surface temperature (LST) lapse rate at Mt. Kilimanjaro using a total number of 15 Landsat-5 TM and Landsat-7 ETM+ images from June 1984-July 2011. Segmentation of normalized difference snow index (NDSI) images with a threshold of 0.6 is used to extract snow cover. Snowline altitude is then determined by combining the snow cover classification maps with a digital elevation model (DEM). And the LST lapse rate is also calculated from the TIR band in the forest area. The results from this study show that (1) the snow cover area largely decreases from 10.1 km2 to 2.3 km2 during about 27 years, which corresponds to a 77.2% reduction, (2) the snowline height rose from 4760 m to 5020 m by about 260 m, and (3) the LST lapse rate shifted from -5.2 °C/km to -2.7 °C/km. This study demonstrates that multi-temporal Landsat images can be successfully used for the spatiotemporal analysis of long-term snow cover changes.

  9. Winter Cover Crop Effects on Nitrate Leaching in Subsurface Drainage as Simulated by RZWQM-DSSAT

    Science.gov (United States)

    Malone, R. W.; Chu, X.; Ma, L.; Li, L.; Kaspar, T.; Jaynes, D.; Saseendran, S. A.; Thorp, K.; Yu, Q.

    2007-12-01

    Planting winter cover crops such as winter rye (Secale cereale L.) after corn and soybean harvest is one of the more promising practices to reduce nitrate loss to streams from tile drainage systems without negatively affecting production. Because availability of replicated tile-drained field data is limited and because use of cover crops to reduce nitrate loss has only been tested over a few years with limited environmental and management conditions, estimating the impacts of cover crops under the range of expected conditions is difficult. If properly tested against observed data, models can objectively estimate the relative effects of different weather conditions and agronomic practices (e.g., various N fertilizer application rates in conjunction with winter cover crops). In this study, an optimized winter wheat cover crop growth component was integrated into the calibrated RZWQM-DSSAT hybrid model and then we compare the observed and simulated effects of a winter cover crop on nitrate leaching losses in subsurface drainage water for a corn-soybean rotation with N fertilizer application rates over 225 kg N ha-1 in corn years. Annual observed and simulated flow-weighted average nitrate concentration (FWANC) in drainage from 2002 to 2005 for the cover crop treatments (CC) were 8.7 and 9.3 mg L-1 compared to 21.3 and 18.2 mg L-1 for no cover crop (CON). The resulting observed and simulated FWANC reductions due to CC were 59% and 49%. Simulations with the optimized model at various N fertilizer rates resulted in average annual drainage N loss differences between CC and CON to increase exponentially from 12 to 34 kg N ha-1 for rates of 11 to 261 kg N ha-1. The results suggest that RZWQM-DSSAT is a promising tool to estimate the relative effects of a winter crop under different conditions on nitrate loss in tile drains and that a winter cover crop can effectively reduce nitrate losses over a range of N fertilizer levels.

  10. The impact of organochlorines cycling in the cryosphere on global distributions and fate – 2. Land ice and temporary snow cover

    International Nuclear Information System (INIS)

    Hofmann, Lorenz; Stemmler, Irene; Lammel, Gerhard

    2012-01-01

    Global fate and transport of γ-HCH and DDT was studied using a global multicompartment chemistry-transport model, MPI-MCTM, with and without inclusion of land ice (in Antarctica and Greenland) or snow cover (dynamic). MPI-MCTM is based on coupled ocean and atmosphere general circulation models. After a decade of simulation 4.2% γ-HCH and 2.3% DDT are stored in land ice and snow. Neglection of land ice and snow in modelling would underestimate the total environmental residence time, τ ov , of γ-HCH and overestimate τ ov for DDT, both on the order of 1% and depending on actual compartmental distribution. Volatilisation of DDT from boreal, seasonally snow covered land is enhanced throughout the year, while volatilisation of γ-HCH is only enhanced during the snow-free season. Including land ice and snow cover in modelling matters in particular for the Arctic, where higher burdens are predicted to be stored. - Highlights: ► Land ice and snow hosts 2–4% of the global environmental burden of γ-HCH and DDT. ► Inclusion of land ice and snow cover matters for global environmental residence time. ► Including of land ice and snow cover matters in particular for the Arctic. - The inclusion of cycling in temporary snow cover and land ice in the model is found relevant for predicted POPs multicompartmental distribution and fate in the Arctic and on the global scale.

  11. Comparison of Mechanical and Chemical Winter Cereal Cover Crop Termination Systems and Cotton Yield in Conservation Agriculture

    Science.gov (United States)

    An integral component of conservation agriculture systems in cotton is the use of a high-residue winter cover crop; however, terminating such cover crops is a cost and planting into high-residue is a challenge. Black oat, rye, and wheat winter cover crops were flattened with a straight-blade mechan...

  12. Deepened winter snow increases stem growth and alters stem δ13C and δ15N in evergreen dwarf shrub Cassiope tetragona in high-arctic Svalbard tundra

    International Nuclear Information System (INIS)

    Blok, Daan; Michelsen, Anders; Elberling, Bo; Weijers, Stef; Löffler, Jörg; Welker, Jeffrey M; Cooper, Elisabeth J

    2015-01-01

    Deeper winter snow is hypothesized to favor shrub growth and may partly explain the shrub expansion observed in many parts of the arctic during the last decades, potentially triggering biophysical feedbacks including regional warming and permafrost thawing. We experimentally tested the effects of winter snow depth on shrub growth and ecophysiology by measuring stem length and stem hydrogen (δ 2 H), carbon (δ 13 C), nitrogen (δ 15 N) and oxygen (δ 18 O) isotopic composition of the circumarctic evergreen dwarf shrub Cassiope tetragona growing in high-arctic Svalbard, Norway. Measurements were carried out on C. tetragona individuals sampled from three tundra sites, each representing a distinct moisture regime (dry heath, meadow, moist meadow). Individuals were sampled along gradients of experimentally manipulated winter snow depths in a six-year old snow fence experiment: in ambient (c. 20 cm), medium (c. 100 cm), and deep snow (c. 150 cm) plots. The deep-snow treatment consistently and significantly increased C. tetragona growth during the 2008–2011 manipulation period compared to growth in ambient-snow plots. Stem δ 15 N and stem N concentration values were significantly higher in deep-snow individuals compared to individuals growing in ambient-snow plots during the course of the experiment, suggesting that soil N-availability was increased in deep-snow plots as a result of increased soil winter N mineralization. Although inter-annual growing season-precipitation δ 2 H and stem δ 2 H records closely matched, snow depth did not change stem δ 2 H or δ 18 O, suggesting that water source usage by C. tetragona was unaltered. Instead, the deep insulating snowpack may have protected C. tetragona shrubs against frost damage, potentially compensating the detrimental effects of a shortened growing season and associated phenological delay on growth. Our findings suggest that an increase in winter precipitation in the High Arctic, as predicted by climate models, has

  13. Evaluating the Impact of Vegetation Cover and Atmospheric Characteristics on the Estimation of Snow Water Equivalent from Spaceborne Microwave Radiometry

    Science.gov (United States)

    Choudhury, Bhaskar J.; Foster, James L.

    2010-01-01

    A radiative transfer model for estimating snow water equivalent (SWE, mm) from satellite-observed brightness temperature (K) at 19 and 37 GHz (respectively, T(sub B(sub, sat,19)) and T(sub B(sub, sat,37)) over partially forested area is presented, as an extension of a previously published model, by considering scattering of radiation within the canopy. For the specific case of dense vegetation covering fractional area f, the model can be written as, SWE = alpha{ A. delta (T(sub B(sub, sat)) + B - C. f}/(l f), where delta T(sub B(sub, sat)), is the difference of T(sub B(sub, sat,19)) and T(sub B(sub, sat,37)), alpha(mm/K) is the slope of SWE vs. brightness temperature difference at 19 and 37 GHz that would be obtained by ignoring the presence of atmosphere, delta(T(sub B)sub g)), for a homogeneous snow cover (which varies with grain size). The parameters A, B, and C, are determined primarily by atmospheric characteristics, and for a likely range of atmospheric conditions appear to be in the range of, respectively, 1.15-1.63, 0.69-2.84 K and 0.59-2.39 K. Ignoring atmospheric correction would introduce bias towards underestimation of SWE (and also, snow cover area and snow depth). Increasing cloud liquid water path (L) has the effect of increasing A, and ignoring this variation of A with L would have the impact of biasing the estimate of SWE (and snow extent). Such biasing is further exacerbated with increasing f, because of the appearance of term (l-f) in the denominator. The impact of ignoring the intercept parameters (B and C) would be noticeable at low values of SWE (appearing as a bias towards underestimation of SWE), which has been determined to be about 6 mm for average environmental conditions. The uncertainty in estimating SWE due to variations in the atmospheric characteristics is likely to be less than 15%, but could be up to 25% for non-vegetated snow-covered areas. Better estimates of SWE (and snow extent) would be obtained by adjusting the parameters of

  14. Flowering cover crops in winter increase pest control but not trophic link diversity

    OpenAIRE

    Damien , Maxime; Le Lann , Cécile; Desneux , Nicolas; Alford , Lucy; Al Hassan , Diab; Georges , Romain; Van Baaren , Joan

    2017-01-01

    International audience; In agrosystems, the increase in non-crop plant diversity by habitat management in or around arable fields contributes to improved Conservation Biological Control. During winter, plant flower are often used as monospecific ground cover and are expected to die before flowering as a result of recurrent frost events. Decreases in minimal temperature due to climate change offers new possibilities for plants used in such sown cover crops to mature and flowers. Changes in pla...

  15. Decrease in hydroclimatic conditions generating floods in the southeast of Belgium over the last 50 years resulting from changes in seasonal snow cover and extreme precipitation events

    Science.gov (United States)

    Wyard, Coraline; Fettweis, Xavier

    2016-04-01

    As a consequence of climate change, several studies concluded that winter flood occurrence could increase in the future in many rivers of northern and western Europe in response to an increase in extreme precipitation events. This study aims to determine if trends in extreme hydroclimatic events generating floods can already be detected over the last century. In particular, we focus on the Ourthe River (southeast of Belgium) which is one of the main tributaries of the Meuse River with a catchment area of 3500 km². In this river, most of the floods occur during winter and about 50% of them are due to rainfall events associated with the melting of the snow which covers the Ardennes during winter. In this study, hydroclimatic conditions favorable to flooding were reconstructed over the 20th century using the regional climate model MAR ("Modèle Atmosphérique Régional") forced by the following reanalyses: the ERA-20C, the ERA-Interim and the NCEP/NCAR-v1. The use of the MAR model allows to compute precipitation, snow depth and run-off resulting from precipitation events and snow melting in any part of the Ourthe river catchment area. Therefore, extreme hydroclimatic events, namely extreme run-off events, which could potentially generate floods, can be reconstructed using the MAR model. As validation, the MAR results were compared to weather station-based data. A trend analysis was then performed in order to study the evolution of conditions favorable to flooding in the Ourthe River catchment. The results show that the MAR model allows the detection of more than 95% of the hydroclimatic conditions which effectively generated observed floods in the Ourthe River over the 1974-2014 period. Conditions favorable to flooding present a negative trend over the last 50 years as a result of a decrease in snow accumulation and in extreme precipitation events. However, significance of these trends depends on the reanalysis used to force the regional climate model as well as the

  16. Decontamination and winter conditions

    International Nuclear Information System (INIS)

    Quenild, C.; Tveten, U.

    1984-12-01

    The report deals with two decontamonation experiments under winter conditions. A snow-covered parking lot was contaminated, and the snow was subsequently removed using standard snow-moving equipment. The snow left behind was collected and the content of contaminant was determined. A non-radioactive contaminant was used. A decontamination factor exceeding 100 was obtained. Although the eksperimental conditions were close to ideal, it is reason to believe that extremely efficient removal of deposited materials on a snow surface is achivable. In another investigation, run-off from agricultural surface, contaminated while covered with snow, was measured A lycimeter was used in this experiment. A stable layer of ice and snow was allowed to form before contamination. The run-off water was collected at each thaw period until all snow and ice was gone. Cs-134 was used as contaminant. Roughly 30% of the Cs-134 with which the area was contaminated ran off with the melt water. Following a reactor accident situation, this would have given a corresponding reduction in the long term doses. Both of these experiments show that consequence calculation assumptions, as they are currently applied to large accident assessment, tend to overestimate the consequences resulting from accidents taking place under winter conditions

  17. Building a Cloud-based Global Snow Observatory

    Science.gov (United States)

    Li, X.; Coll, J. M.

    2016-12-01

    Snow covers some 40 percent of Earth's land masses year in and year out and constitutes a vitally important variable for the planet's climate, hydrology, and biosphere due to its high albedo and insulation. It affects atmospheric circulation patterns, permafrost, glacier mass balance, river discharge, and groundwater recharge (Dietz et al. 2015). Snow is also nature's igloo where species from microscopic fungi to 800-pound moose survive the winter each in its own way (Pauli et al. 2013; Petty et al. 2015). Many studies have found that snow in high elevation regions is particularly sensitive to global climate change and is considered as sentinel of change. For human beings, about one-sixth of the world's population depends on seasonal snow and glaciers for their water supply (Barnett et al. 2005) and more than 50% of mountainous areas have an essential or supportive role for downstream regions (Viviroli et al. 2007). Large snowstorms also have a major impact on society in terms of human life, economic loss, and disruption (Squires et al. 2014). Remote sensing provides a practical approach of monitoring global snow and ice cover change. Based on our comprehensive validation and assessment on MODIS snow products, we build a cloud-based Global Snow Observatory (GSO) using Google Earth Engine (GEE) to serve as a platform for global researchers and the general public to access, visualize, and analyze snow data and to build snowmelt runoff models for mountain watersheds. Specifically, we build the GSO to serve global MODIS daily snow cover data and their analyses through GEE on Google App Engine. The GSO provides users the functions of accessing and extracting cloud-gap-filled snow data and interactive snow cover change exploration. In addition to snow cover frequency (SCF), we also plan to develop several other snow cover parameters, including snow cover duration/days, snow cover onset dates, and snow cover melting dates, and to study the shift and trend of global snow

  18. Assessment of the Performance of Several Roadway Mixes under Rain, Snow, and Winter Maintenance Activities

    OpenAIRE

    Flintsch, Gerardo W.

    2004-01-01

    The purpose of this study was to assess the relative functional performance, including skid resistance and splash and spray, of five hot-mix-asphalt (HMA) surfaces and a tinned portland cement concrete highway surface during controlled wet and wintry weather events. The study compared the way that these surfaces respond to various deicing and anti-icing snow removal and ice control techniques under artificial wintry conditions. In addition, the splash and spray characteristics of the surfaces...

  19. Energy feedbacks of northern high-latitude ecosystems to the climate system due to reduced snow cover during 20th century warming

    Science.gov (United States)

    Euskirchen, E.S.; McGuire, A.D.; Chapin, F.S.

    2007-01-01

    The warming associated with changes in snow cover in northern high-latitude terrestrial regions represents an important energy feedback to the climate system. Here, we simulate snow cover-climate feedbacks (i.e. changes in snow cover on atmospheric heating) across the Pan-arctic over two distinct warming periods during the 20th century, 1910-1940 and 1970-2000. We offer evidence that increases in snow cover-climate feedbacks during 1970-2000 were nearly three times larger than during 1910-1940 because the recent snow-cover change occurred in spring, when radiation load is highest, rather than in autumn. Based on linear regression analysis, we also detected a greater sensitivity of snow cover-climate feedbacks to temperature trends during the more recent time period. Pan-arctic vegetation types differed substantially in snow cover-climate feedbacks. Those with a high seasonal contrast in albedo, such as tundra, showed much larger changes in atmospheric heating than did those with a low seasonal contrast in albedo, such as forests, even if the changes in snow-cover duration were similar across the vegetation types. These changes in energy exchange warrant careful consideration in studies of climate change, particularly with respect to associated shifts in vegetation between forests, grasslands, and tundra. ?? 2007 Blackwell Publishing Ltd.

  20. Water and life from snow: A trillion dollar science question

    Science.gov (United States)

    Sturm, Matthew; Goldstein, Michael A.; Parr, Charles

    2017-05-01

    Snow provides essential resources/services in the form of water for human use, and climate regulation in the form of enhanced cooling of the Earth. In addition, it supports a thriving winter outdoor recreation industry. To date, the financial evaluation of the importance of snow is incomplete and hence the need for accelerated snow research is not as clear as it could be. With snow cover changing worldwide in several worrisome ways, there is pressing need to determine global, regional, and local rates of snow cover change, and to link these to financial analyses that allow for rational decision making, as risks related to those decisions involve trillions of dollars.

  1. Using Air Temperature to Quantitatively Predict the MODIS Fractional Snow Cover Retrieval Errors over the Continental US (CONUS)

    Science.gov (United States)

    Dong, Jiarui; Ek, Mike; Hall, Dorothy K.; Peters-Lidard, Christa; Cosgrove, Brian; Miller, Jeff; Riggs, George A.; Xia, Youlong

    2013-01-01

    In the middle to high latitude and alpine regions, the seasonal snow pack can dominate the surface energy and water budgets due to its high albedo, low thermal conductivity, high emissivity, considerable spatial and temporal variability, and ability to store and then later release a winters cumulative snowfall (Cohen, 1994; Hall, 1998). With this in mind, the snow drought across the U.S. has raised questions about impacts on water supply, ski resorts and agriculture. Knowledge of various snow pack properties is crucial for short-term weather forecasts, climate change prediction, and hydrologic forecasting for producing reliable daily to seasonal forecasts. One potential source of this information is the multi-institution North American Land Data Assimilation System (NLDAS) project (Mitchell et al., 2004). Real-time NLDAS products are used for drought monitoring to support the National Integrated Drought Information System (NIDIS) and as initial conditions for a future NCEP drought forecast system. Additionally, efforts are currently underway to assimilate remotely-sensed estimates of land-surface states such as snowpack information into NLDAS. It is believed that this assimilation will not only produce improved snowpack states that better represent snow evolving conditions, but will directly improve the monitoring of drought.

  2. Tillage effects on N2O emissions as influenced by a winter cover crop

    DEFF Research Database (Denmark)

    Petersen, Søren O; Mutegi, James; Hansen, Elly Møller

    2011-01-01

    emissions may be more important than the effect on soil C. This study monitored emissions of N2O between September 2008 and May 2009 in three tillage treatments, i.e., conventional tillage (CT), reduced tillage (RT) and direct drilling (DD), all with (+CC) or without (−CC) fodder radish as a winter cover...... application by direct injection N2O emissions were stimulated in all tillage treatments, reaching 250–400 μg N m−2 h−1 except in the CT + CC treatment, where emissions peaked at 900 μg N m−2 h−1. Accumulated emissions ranged from 1.6 to 3.9 kg N2O ha−1. A strong positive interaction between cover crop......Conservation tillage practices are widely used to protect against soil erosion and soil C losses, whereas winter cover crops are used mainly to protect against N losses during autumn and winter. For the greenhouse gas balance of a cropping system the effect of reduced tillage and cover crops on N2O...

  3. Arctic Sea Ice, Eurasia Snow, and Extreme Winter Haze in China

    Science.gov (United States)

    Zou, Y.; Wang, Y.; Xie, Z.; Zhang, Y.; Koo, J. H.

    2017-12-01

    Eastern China is experiencing more severe haze pollution in winter during recent years. Though the environmental deterioration in this region is usually attributed to the high intensity of anthropogenic emissions and large contributions from secondary aerosol formation, the impact of climate variability is also indispensable given its significant influence on regional weather systems and pollution ventilation. Here we analyzed the air quality related winter meteorological conditions over Eastern China in the last four decades and showed a worsening trend in poor regional air pollutant ventilation. Such variations increased the probability of extreme air pollution events, which is in good agreement with aerosol observations of recent years. We further identified the key circulation pattern that is conducive to the weakening ventilation and investigated the relationship between synoptic circulation changes and multiple climate forcing variables. Both statistical analysis and numerical sensitivity experiments suggested that the poor ventilation condition is linked to boreal cryosphere changes including Arctic sea ice in preceding autumn and Eurasia snowfall in earlier winter. We conducted comprehensive dynamic diagnosis and proposed a physical mechanism to explain the observed and simulated circulation changes. At last, we examined future projections of winter extreme stagnation events based on the CMIP5 projection data.

  4. Winter annual cover crop has only minor effects on major corn arthropod pests.

    Science.gov (United States)

    Davis, Holly N; Currie, Randall S; Klocke, Norman L; Buschman, Lawrent L

    2010-04-01

    We studied the effects of downy brome, Bromus tectorum L., winter cover crop on several corn, Zea mays L., pests in the summer crop after the cover crop. An experiment was conducted that consisted of two trials with two levels of irrigation, two levels of weed control, and two levels of downy brome. Corn was grown three consecutive years after the downy brome grown during the winter. Banks grass mites, Oligonychus pratensis (Banks), twospotted spider mites, Tetranychus urticae Koch, and predatory mites from the genus Neoseiulus were present in downy brome at the beginning of the growing season. They moved into corn, but their numbers did not differ significantly across the treatments. Larval western corn rootworm, Diabrotica virgifera virgifera LeConte, feeding on corn roots was evaluated the second and third years of corn, production. Irrigation and herbicide treatments had no significant effects on rootworm injury levels. In one trial, rootworm injury ratings were significantly greater in treatments with a history of high versus low brome, but this effect was not significant in the other trial. Rootworm injury seemed to be similar across plots with different surface soil moistures. This suggests that the use of a winter cover crop such as downy brome will not have a major negative impact the arthropods studied.

  5. Numerical modeling of a snow cover on Hooker Island (Franz Josef Land archipelago

    Directory of Open Access Journals (Sweden)

    V. S. Sokratov

    2013-01-01

    Full Text Available Results obtained by simulating snow characteristics with a numerical model of surface heat and moisture exchange SPONSOR are presented. The numerical experiments are carried out for Franz Josef Land with typical Arctic climate conditions. The blizzard evaporation parameter is shown to have great influence on snow depth on territories with high wind speed. This parameter significantly improves the simulation quality of the numerical model. Some discrepancies between evaluated and observed snow depth values can be explained by inaccuracies in precipitation measurements (at least in certain cases and errors in calculations of incoming radiation, mostly due to low accuracy in the cloudiness observations.

  6. Using NASA Earth Observations to Assist the National Park Service in Assessing Snow Cover Distribution and Persistence Changes in the Sky Islands

    Science.gov (United States)

    Bayat, F.; Barrow, C., III; Gonsoroski, E.; Dutta, S.; Lynn, T.; Harville, K.; Spruce, J.

    2017-12-01

    Saguaro National Park in southeastern Arizona occupies one of several unique mountain ranges known collectively as the Sky Islands or the Madrean Archipelago. The Sky Islands are biodiversity hotspots and host different ecosystems, ranging from arid deserts to temperate forests. Snowmelt provides a source of water during the dry season for various flora and fauna inhabiting the region. Climate change and its effect on snow cover is of growing concern by resource managers in this location. Currently, the National Park Service (NPS) monitors water presence via stream gauges, but a synoptic record of snow presence does not exist due to the remote and rugged topography of the region. As a result, it is difficult to study how climate change has affected water resources in the Sky Islands and what effect this has on wildlife and vegetation. This project used NASA Earth observations (e.g., Landsat data) and GIS technology to help the NPS in understanding the role of snow cover in the Sky Islands. Historical snow cover maps were compiled using a combination of snow detection indices to provide spatio-temporal information on snow presence and phenology. With a more complete understanding of snow cover trends in the park, the NPS can further analyze snow cover impacts to improve future land management decisions.

  7. Eddy Covariance flux measurements over an ice/snow covered lake in Finland

    Science.gov (United States)

    Potes, Miguel; Salgado, Rui; Provenzale, Maria; Mammarella, Ivan

    2017-04-01

    The inland water bodies play an important role in the regional heat and mass transfer with the atmosphere. As lakes cover an area of 4.2 million km2, representing an area of more than 3% of Earth continental surface, an increasing concern in estimation of heat and greenhouse gases exchanges between inland water bodies and the atmosphere has been developed in the last years. The eddy covariance (EC) method is the worldwide most common technique used to assess turbulent fluxes over all types of surface. In the framework of two Short Term Scientific Mission of the COST action "A European network for a harmonized monitoring of snow for the benefit of climate change scenarios, hydrology and numerical weather prediction" (ES1404), it was feasible to have parallel EC measurements with two identical equipment over a boreal lake. In this communication the results are related to the period comprised between November 2015 and May 2016, including freezing and ice-free periods. Observed near surface fluxes of momentum, heat and mass (H2O and CO2) were obtained with a new eddy covariance system (EC), Campbell Scientific's IRGASON Integrated Open-Path CO2/H2O Gas Analyzer and 3D Sonic Anemometer, over lake Vanajavesi in Finland. The measurement site is located in a tip of narrow peninsula on the lake (61.133935°N; 24.259119°E), offering very good conditions for eddy covariance flux measurements. The EC system was installed at 2.5m height above the lake surface and was oriented against the prevailing wind direction in the site.

  8. Dominance of grain size impacts on seasonal snow albedo at open sites in New Hampshire

    Science.gov (United States)

    Adolph, Alden C.; Albert, Mary R.; Lazarcik, James; Dibb, Jack E.; Amante, Jacqueline M.; Price, Andrea

    2017-01-01

    Snow cover serves as a major control on the surface energy budget in temperate regions due to its high reflectivity compared to underlying surfaces. Winter in the northeastern United States has changed over the last several decades, resulting in shallower snowpacks, fewer days of snow cover, and increasing precipitation falling as rain in the winter. As these climatic changes occur, it is imperative that we understand current controls on the evolution of seasonal snow albedo in the region. Over three winter seasons between 2013 and 2015, snow characterization measurements were made at three open sites across New Hampshire. These near-daily measurements include spectral albedo, snow optical grain size determined through contact spectroscopy, snow depth, snow density, black carbon content, local meteorological parameters, and analysis of storm trajectories using the Hybrid Single-Particle Lagrangian Integrated Trajectory model. Using analysis of variance, we determine that land-based winter storms result in marginally higher albedo than coastal storms or storms from the Atlantic Ocean. Through multiple regression analysis, we determine that snow grain size is significantly more important in albedo reduction than black carbon content or snow density. And finally, we present a parameterization of albedo based on days since snowfall and temperature that accounts for 52% of variance in albedo over all three sites and years. Our improved understanding of current controls on snow albedo in the region will allow for better assessment of potential response of seasonal snow albedo and snow cover to changing climate.

  9. Performance of complex snow cover descriptions in a distributed hydrological model system: A case study for the high Alpine terrain of the Berchtesgaden Alps.

    Science.gov (United States)

    Warscher, M; Strasser, U; Kraller, G; Marke, T; Franz, H; Kunstmann, H

    2013-05-01

    [1] Runoff generation in Alpine regions is typically affected by snow processes. Snow accumulation, storage, redistribution, and ablation control the availability of water. In this study, several robust parameterizations describing snow processes in Alpine environments were implemented in a fully distributed, physically based hydrological model. Snow cover development is simulated using different methods from a simple temperature index approach, followed by an energy balance scheme, to additionally accounting for gravitational and wind-driven lateral snow redistribution. Test site for the study is the Berchtesgaden National Park (Bavarian Alps, Germany) which is characterized by extreme topography and climate conditions. The performance of the model system in reproducing snow cover dynamics and resulting discharge generation is analyzed and validated via measurements of snow water equivalent and snow depth, satellite-based remote sensing data, and runoff gauge data. Model efficiency (the Nash-Sutcliffe coefficient) for simulated runoff increases from 0.57 to 0.68 in a high Alpine headwater catchment and from 0.62 to 0.64 in total with increasing snow model complexity. In particular, the results show that the introduction of the energy balance scheme reproduces daily fluctuations in the snowmelt rates that trace down to the channel stream. These daily cycles measured in snowmelt and resulting runoff rates could not be reproduced by using the temperature index approach. In addition, accounting for lateral snow transport changes the seasonal distribution of modeled snowmelt amounts, which leads to a higher accuracy in modeling runoff characteristics.

  10. Recharge of an Unconfined Pumice Aquifer: Winter Rainfall Versus Snow Pack, South-central Oregon

    Science.gov (United States)

    Cummings, M. L.; Weatherford, J. M.; Eibert, D.

    2015-12-01

    Walker Rim study area, an uplifted fault block east of the Cascade Range, south-central Oregon, exceeds 1580 m elevation and includes Round Meadow-Sellers Marsh closed basin, and headwaters of Upper Klamath Basin, Deschutes Basin, and Christmas Lake Valley in the Great Basin. The water-bearing unit is 2.8 to 3.0 m thick Plinian pumice fall from the Holocene eruption of Mount Mazama, Cascade Range. The perched pumice aquifer is underlain by low permeability regolith and bedrock. Disruption of the internal continuity of the Plinian pumice fall by fluvial and lacustrine processes resulted in hydrogeologic environments that include fens, wet meadows, and areas of shallow water table. Slopes are low and surface and groundwater pathways follow patterns inherited from the pre-eruption landscape. Discharge for streams and springs and depth to water table measured in open-ended piezometers slotted in the pumice aquifer have been measured between March and October, WY 2011 through WY2015. Yearly occupation on same date has been conducted for middle April, June 1st, and end of October. WY2011 and WY2012 received more precipitation than the 30 year average while WY2014 was the third driest year in 30 years of record. WY2014 and WY2015 provide an interesting contrast. Drought conditions dominated WY2014 while WY2015 was distinct in that the normal cold-season snow pack was replaced by rainfall. Cumulative precipitation exceeded the 30-year average between October and March. The pumice aquifer of wet meadows and areas of shallow water table experienced little recharge in WY2015. Persistence of widespread diffuse discharge from fens declined by middle summer as potentiometric surfaces lowered into confining peat layers or in some settings into the pumice aquifer. Recharge of the perched pumice aquifer in rain-dominated WY2015 was similar to or less than in the snow-dominated drought of WY2014. Rain falling on frozen ground drove runoff rather than aquifer recharge.

  11. Performances of an expanding insect under elevated CO{sub 2} and snow cover in the Alps

    Energy Technology Data Exchange (ETDEWEB)

    Battisti, B.; Petrucco-Toffolo, E. [University of Padova, Legnaro (Italy). Dept. of Environmental Agronomy

    2008-09-30

    Variations of phenology and distribution have been recently highlighted in numerous insect species and attributed to climate change, particularly the increase of temperature and atmospheric carbon dioxide (CO{sub 2}). Both have been shown to have direct and indirect effects on insect species of various ecosystems, though the responses are often species-specific. The pine processionary moth, Thaumetopoea pityocampa (Lepidoptera, Notodontidae) is an important pest of conifers in the Mediterranean region, and has been recently shown to expand its altitudinal range in the Alps, including the mountain pine Pinus mugo as a novel host. We had the opportunity to transplant colonies of the pine processionary moth to a high elevation site well outside of the current range of the insect (Stillberg, Davos, Switzerland, 2180 m), where trees of the mountain pine have been grown for five years under ambient and elevated CO{sub 2} concentrations (ca. 570 ppm). The aim of the study was to evaluate the response of first instar larvae to extreme conditions of temperature and to an altered performance induced by the change of host metabolism under elevated CO{sub 2}. Larval mortality and relative growth rate did not differ between host trees grown in ambient or elevated CO{sub 2}. As extended snow cover may be an important mortality factor of larval colonies on the dwarf trees of mountain pine, we tested the survival of colonies transplanted at two extreme sites of Eastern Alps. The snow cover extended over more than one month proved to be an important mortality factor of larval colonies on mountain pine. We concluded that the first instar larvae of the pine processionary moth are not concerned by unusually low temperature and CO{sub 2} increase whereas they can be later strongly affected by snow accumulation. The decrease of snow cover observed in the last decades, however, may reduce such a risk.

  12. Winter cover crops on processing tomato yield, quality, pest pressure, nitrogen availability, and profit margins.

    Science.gov (United States)

    Belfry, Kimberly D; Trueman, Cheryl; Vyn, Richard J; Loewen, Steven A; Van Eerd, Laura L

    2017-01-01

    Much of cover crop research to date focuses on key indicators of impact without considering the implications over multiple years, in the absence of a systems-based approach. To evaluate the effect of three years of autumn cover crops on subsequent processing tomato (Solanum lycopersicum L.) production in 2010 and 2011, a field split-split-plot factorial design trial with effects of cover crop type, urea ammonium nitrate fertilizer rate (0 or 140 kg N ha-1 preplant broadcast incorporated) and tomato cultivar (early vs. late) was conducted. The main plot factor, cover crop, included a no cover crop control, oat (Avena sativa L.), winter cereal rye (hereafter referred to as rye) (Secale cereale L.), oilseed radish (OSR) (Raphanus sativus L. var. oleiferus Metzg Stokes), and mix of OSR and rye (OSR + rye) treatments. Cover crop biomass of 0.5 to 2.8 and 1.7 to 3.1 Mg ha-1 was attained in early Oct. and the following early May, respectively. In general, OSR increased soil mineral N during cover crop growth and into the succeeding summer tomato growing season, while the remaining cover crops did not differ from the no cover crop control. The lack of a cover crop by N rate interaction in soil and plant N analyses at harvest suggests that growers may not need to modify N fertilizer rates to tomatoes based on cover crop type. Processing tomato fruit quality at harvest (rots, insect or disease damage, Agtron colour, pH, or natural tomato soluble solids (NTSS)) was not affected by cover crop type. In both years, marketable yield in the no cover crop treatment was lower or not statistically different than all planted cover crops. Partial profit margins over both years were 1320 $ ha-1 higher with OSR and $960 higher with oat compared to the no cover crop control. Thus, results from a systems-based approach suggest that the cover crops tested had no observed negative impact on processing tomato production and have the potential to increase marketable yield and profit margins.

  13. Winter cover crops on processing tomato yield, quality, pest pressure, nitrogen availability, and profit margins.

    Directory of Open Access Journals (Sweden)

    Kimberly D Belfry

    Full Text Available Much of cover crop research to date focuses on key indicators of impact without considering the implications over multiple years, in the absence of a systems-based approach. To evaluate the effect of three years of autumn cover crops on subsequent processing tomato (Solanum lycopersicum L. production in 2010 and 2011, a field split-split-plot factorial design trial with effects of cover crop type, urea ammonium nitrate fertilizer rate (0 or 140 kg N ha-1 preplant broadcast incorporated and tomato cultivar (early vs. late was conducted. The main plot factor, cover crop, included a no cover crop control, oat (Avena sativa L., winter cereal rye (hereafter referred to as rye (Secale cereale L., oilseed radish (OSR (Raphanus sativus L. var. oleiferus Metzg Stokes, and mix of OSR and rye (OSR + rye treatments. Cover crop biomass of 0.5 to 2.8 and 1.7 to 3.1 Mg ha-1 was attained in early Oct. and the following early May, respectively. In general, OSR increased soil mineral N during cover crop growth and into the succeeding summer tomato growing season, while the remaining cover crops did not differ from the no cover crop control. The lack of a cover crop by N rate interaction in soil and plant N analyses at harvest suggests that growers may not need to modify N fertilizer rates to tomatoes based on cover crop type. Processing tomato fruit quality at harvest (rots, insect or disease damage, Agtron colour, pH, or natural tomato soluble solids (NTSS was not affected by cover crop type. In both years, marketable yield in the no cover crop treatment was lower or not statistically different than all planted cover crops. Partial profit margins over both years were 1320 $ ha-1 higher with OSR and $960 higher with oat compared to the no cover crop control. Thus, results from a systems-based approach suggest that the cover crops tested had no observed negative impact on processing tomato production and have the potential to increase marketable yield and profit

  14. Performance of Flooded Rice Grown in Succession to Winter Cover Crops

    Directory of Open Access Journals (Sweden)

    Silmara da Correia Luz

    2018-02-01

    Full Text Available ABSTRACT: Mean grain yield of flooded rice in southern Brazil has increased in recent years due to the use of high-yield cultivars and improvement of crop management practices. Nevertheless, stagnation in grain yields has been observed in some rice-producing regions. Adoption of conservation tillage systems based on cover crops may be a strategy to increase rice grain yield potential. The objective of the present study was to evaluate the effect of winter cover crops on initial establishment, development, and grain yield of flooded rice (Oryza sativa L. grown under different fertilization levels and no-tillage. A field experiment was carried out for three consecutive years (2010/11, 2011/12, and 2012/13 in Cachoeirinha, Rio Grande do Sul, South Brazil. Treatments included three winter cover crops [ryegrass (Lolium multiflorum Lam., native serradella (Ornithopus micranthus Benth., and a ryegrass-serradella mixture] and fallow, and three fertilization levels for rice grown in succession. More than 3 Mg ha−1 of serradella aboveground residue or 4 Mg ha−1 of ryegrass residue limited rice emergence in the first year when rainfall in the sowing-emergence period was higher than in the second and third years. In contrast, a large amount of residue (serradella >2 Mg ha−1; ryegrass >3 Mg ha−1 was beneficial to rice emergence when rainfall was low in the sowing-emergence period of the second and third years. The serradella cover crop increased rice aboveground biomass at anthesis by 22 % compared to the ryegrass cover crop. Furthermore, rice grain yield was 15 % higher in succession to serradella than to ryegrass in the third year. Continuous cultivation of flooded rice in succession to ryegrass over three years reduced grain yield by around 1.4 Mg ha−1, regardless of fertilization level. Fertilization for very high production expectations increased rice grain yield in all years, especially in the second year, when solar radiation was higher than

  15. Observed radiative cooling over the Tibetan Plateau for the past three decades driven by snow cover-induced surface albedo anomaly

    Science.gov (United States)

    Chen, Xiaona; Long, Di; Hong, Yang; Liang, Shunlin; Hou, Aizhong

    2017-06-01

    Seasonal snow cover on the Tibetan Plateau (TP) is a sensitive indicator of climate change. Unlike the decreasing snow cover extent and associated weakening of radiative cooling effects for the Northern Hemisphere during recent decades reported by previous studies, snow cover variability over the TP and its impact on the energy budget remain largely unknown. We defined the snow cover-induced radiative forcing (SnRF) as the instantaneous perturbation to Earth's shortwave radiation at the top of the atmosphere (TOA) induced by the presence of snow cover. Here using satellite observations and a radiative kernel approach, we found slightly enhanced SnRF, i.e., a radiative cooling effect on the TP during the past three decades (1982-2014). However, this cooling effect weakened during 2001-2014 because of reduced snow cover at a rate of -0.61% decade-1 and land surface albedo at a rate of -0.72% decade-1. Changes in snow cover fraction are highly correlated with anomalies in land surface albedo (as) over the TP both spatially and temporally. Moreover, the SnRF is closely related to the direct observation of TOA shortwave flux anomalies (R2 = 0.54, p = 0.004) over the TP during 2001-2014. Despite the insignificant interannual variability in SnRF, its intra-annual variability has intensified driven mostly by enhanced SnRF during the snow accumulation season but weakened SnRF during the melt season, indicating greater energy release during the transition between accumulation and melt seasons. This may pose a great challenge to snow meltwater use and flood prediction for transboundary rivers originating from the TP, such as the Brahmaputra River basin.

  16. Use of satellite-derived data for characterization of snow cover and simulation of snowmelt runoff through a distributed physically based model of runoff generation

    Directory of Open Access Journals (Sweden)

    L. S. Kuchment

    2010-02-01

    Full Text Available A technique of using satellite-derived data for constructing continuous snow characteristics fields for distributed snowmelt runoff simulation is presented. The satellite-derived data and the available ground-based meteorological measurements are incorporated in a physically based snowpack model. The snowpack model describes temporal changes of the snow depth, density and water equivalent (SWE, accounting for snow melt, sublimation, refreezing melt water and snow metamorphism processes with a special focus on forest cover effects. The remote sensing data used in the model consist of products include the daily maps of snow covered area (SCA and SWE derived from observations of MODIS and AMSR-E instruments onboard Terra and Aqua satellites as well as available maps of land surface temperature, surface albedo, land cover classes and tree cover fraction. The model was first calibrated against available ground-based snow measurements and then applied to calculate the spatial distribution of snow characteristics using satellite data and interpolated ground-based meteorological data. The satellite-derived SWE data were used for assigning initial conditions and the SCA data were used for control of snow cover simulation. The simulated spatial distributions of snow characteristics were incorporated in a distributed physically based model of runoff generation to calculate snowmelt runoff hydrographs. The presented technique was applied to a study area of approximately 200 000 km2 including the Vyatka River basin with catchment area of 124 000 km2. The correspondence of simulated and observed hydrographs in the Vyatka River are considered as an indicator of the accuracy of constructed fields of snow characteristics and as a measure of effectiveness of utilizing satellite-derived SWE data for runoff simulation.

  17. Some Characteristics of Dust Particles in Atmosphere of Kemerovo City According to Pollution Data of Snow Cover

    Science.gov (United States)

    Golokhvast, K. S.; Manakov, Yu A.; Bykov, A. A.; Chayka, V. V.; Nikiforov, P. A.; Rogulin, R. S.; Romanova, T. Yu; Karabtsov, A. A.; Semenikhin, V. A.

    2017-10-01

    The given paper presents the study results of solid particles contained in snow samples, taken on 10 sites in Kemerovo city in spring 2013. The sites were chosen in such a way as to prevent particles flow into the snow cover in other ways, except with atmospheric precipitation. Kuzbass Botanical Garden was chosen as the check point. In 7 out of 10 sampling sites on the territory of Kemerovo city the presence of particles that are particularly dangerous for human health was found. In one of the areas the particles of 200-400 nm size and with a specific surface area of 14,813.34 cm2/cm3 were detected in ecologically significant quantity (8%).

  18. NOAA JPSS Visible Infrared Imaging Radiometer Suite (VIIRS) Snow Cover/Depth (SCD) Binary Map Environmental Data Record (EDR) from IDPS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a high quality operational Environmental Data Record (EDR) of Binary Snow Cover (BSC) from the Visible Infrared Imaging Radiometer Suite...

  19. Airborne gamma-radiation snow water-equivalent and soil-moisture measurements and satellite areal extent of snow-cover measurements. A user's guide. Version 3.0

    International Nuclear Information System (INIS)

    Carroll, T.; Allen, M.

    1988-01-01

    The National Remote Sensing Hydrology Program is managed by the Office of Hydrology and consists of the Airborne Snow Survey Section and the Satellite Hydrology Section. The Airborne Snow Survey Section makes airborne snow water-equivalent and soil-moisture measurements over large areas of the country subject to a severe and chronic snowmelt flooding threat. The User's Guide is intended primarily to provide field hydrologists with some background on the technical and administrative aspects of the National Remote Sensing Hydrology Program. The guide summarizes the techniques and procedures used to make and distribute real-time, operational airborne snow water-equivalent measurements and satellite areal extent of snow-cover measurements made over large areas of the country. The current airborne and satellite databases are summarized, and procedures to access the real-time observations through both AFOS and through a commercial, electronic bulletin board system are given in the appendices

  20. Statistical adaptation of ALADIN RCM outputs over the French Alps – application to future climate and snow cover

    Directory of Open Access Journals (Sweden)

    M. Rousselot

    2012-07-01

    Full Text Available In this study, snowpack scenarios are modelled across the French Alps using dynamically downscaled variables from the ALADIN Regional Climate Model (RCM for the control period (1961–1990 and three emission scenarios (SRES B1, A1B and A2 for the mid- and late 21st century (2021–2050 and 2071–2100. These variables are statistically adapted to the different elevations, aspects and slopes of the Alpine massifs. For this purpose, we use a simple analogue criterion with ERA40 series as well as an existing detailed climatology of the French Alps (Durand et al., 2009a that provides complete meteorological fields from the SAFRAN analysis model. The resulting scenarios of precipitation, temperature, wind, cloudiness, longwave and shortwave radiation, and humidity are used to run the physical snow model CROCUS and simulate snowpack evolution over the massifs studied. The seasonal and regional characteristics of the simulated climate and snow cover changes are explored, as is the influence of the scenarios on these changes. Preliminary results suggest that the snow water equivalent (SWE of the snowpack will decrease dramatically in the next century, especially in the Southern and Extreme Southern parts of the Alps. This decrease seems to result primarily from a general warming throughout the year, and possibly a deficit of precipitation in the autumn. The magnitude of the snow cover decline follows a marked altitudinal gradient, with the highest altitudes being less exposed to climate change. Scenario A2, with its high concentrations of greenhouse gases, results in a SWE reduction roughly twice as large as in the low-emission scenario B1 by the end of the century. This study needs to be completed using simulations from other RCMs, since a multi-model approach is essential for uncertainty analysis.

  1. Vegetative, productive and qualitative performance of grapevine "Cabernet Sauvignon" according to the use of winter cover crops

    OpenAIRE

    Bettoni, Jean Carlos; Feldberg, Nelson Pires; Nava, Gilberto; Veiga, Milton da; Wildner, Leandro do Prado

    2016-01-01

    ABSTRACT To study the effect of winter cover crops on the vegetative, productive and qualitative behavior of "Cabernet Sauvignon" grapevines, an experiment was conducted in two wine harvests by sowing different species of winter cover crops and additional treatments with manual weeding and mechanical mowing in an experimental vineyard located at the Experimental Station of Epagri in Videira, state of Santa Catarina, Brazil. Plant attributes of the grapevine, such as number of rods and weight ...

  2. Winter sea ice export from the Laptev Sea preconditions the local summer sea ice cover

    Science.gov (United States)

    Krumpen, T.; Haas, C.; Itkin, P.

    2016-12-01

    Interannual variability and trends in sea ice export out of the Laptev Sea were investigated using a combination of observations and satellite data. The Laptev Sea shows a statistically positive trend in ice area export that is likely associated to an increase in ice drift velocity being the consequence of a thinning ice cover further north. Moreover, we could show that there is a high statistical connection of the late winter (Jan-May) sea ice export and ice formation in Laptev Sea polynyas to the summer sea ice concentration. By means of a sensitivity study using a coupled sea ice-ocean model (MITgcm), we could highlight the importance of winter sea ice processes for summer sea ice conditions in the Laptev Sea and likewise in the adjacent Siberian Seas. Years of high ice export have a thinning effect on the ice cover, which in turn preconditions early fast ice break up, pack ice melt and the occurrence of negative sea ice extent anomalies in summer. Our model simulation also indicate that observed increase in the sea ice export from the Laptev Sea is accompanied by an increase in the volume export, which is important for the Arctic sea ice budget.

  3. A triple-moment blowing snow-atmospheric model and its application in computing the seasonal wintertime snow mass budget

    Directory of Open Access Journals (Sweden)

    J. Yang

    2010-06-01

    Full Text Available Many field studies have shown that surface sublimation and blowing snow transport and sublimation have significant influences on the snow mass budget in many high latitude regions. We developed a coupled triple-moment blowing snow-atmospheric modeling system to study the influence of these processes on a seasonal time scale over the Northern Hemisphere. Two simulations were performed. The first is a 5 month simulation for comparison with snow survey measurements over a Saskatchewan site to validate the modeling system. The second simulation covers the 2006/2007 winter period to study the snow mass budget over the Northern Hemisphere. The results show that surface sublimation is significant in Eurasian Continent and the eastern region of North America, reaching a maximum value of 200 mm SWE (Snow Water Equivalent. Over the Arctic Ocean and Northern Canada, surface deposition with an average value of 30 mm SWE was simulated. Blowing snow sublimation was found to return up to 50 mm SWE back to the atmosphere over the Arctic Ocean, while the divergence of blowing snow transport contributes only a few mm SWE to the change in snow mass budget. The results were further stratified in 10 degree latitudinal bands. The results show that surface sublimation decreases with an increase in latitude while blowing snow sublimation increases with latitude. Taken together, the surface sublimation and blowing snow processes was found to distribute 23% to 52% of winter precipitation over the three month winter season.

  4. How Well Are We Measuring Snow? The NOAA/FAA/NCAR Winter Precipitation Test Bed

    Science.gov (United States)

    Baker, B.; Rasmussen, R.; Kochendorfer, J.; Meyers, T.; Nitu, R.; Paul, J.; Smith, C.; Yang, D.

    2012-04-01

    Precipitation is one of the most important atmospheric variables for ecosystems, hydrologic systems, climate, and weather forecasting. Despite its importance, accurate measurement remains challenging, and the lack of recent and complete inter-comparisons leads researchers to discount the importance and severity of measurement errors. These errors are exacerbated for the automated measurement of solid precipitation and underestimates of 20-50% are common. While solid precipitation measurements have been the subject of many studies, there have been only a limited number of coordinated assessments on the accuracy, reliability, and repeatability of automatic precipitation measurements. The most recent comprehensive study, the "WMO Solid Precipitation Measurement Inter-comparison" focused on manual techniques of solid precipitation measurement. Precipitation gauge technology has changed considerably in the last 12 years and the focus has shifted to automated techniques. Given the strong need for automated solid precipitation data from both the climate and weather communities, and the widely varying catch efficiencies of the various instruments, inter-comparison studies are needed. The World Meteorological Organization Committee on Meteorological Instruments and Observations (WMO-CIMO) is organizing a Solid Precipitation Inter-comparison Experiment (WMO-SPICE) focused on automatic precipitation gauges and their configurations, in various climate conditions, building on the significant efforts currently underway in many countries. The inter-comparison will aim at understanding and improving our ability to reliably measure solid precipitation using automatic gauges. The study will take place starting in 2012 at sites around the world including the US, Norway, China, Canada, Japan, Switzerland, Russia, Finland and New Zealand. The NOAA /FAA/NCAR precipitation test bed in Marshall, CO. in partnership with Environment Canada will collect data during the winter of 2011/2012 to

  5. Hydrologic response to and recovery from differing silvicultural systems in a deciduous forest landscape with seasonal snow cover

    Science.gov (United States)

    Buttle, J. M.; Beall, F. D.; Webster, K. L.; Hazlett, P. W.; Creed, I. F.; Semkin, R. G.; Jeffries, D. S.

    2018-02-01

    Hydrological consequences of alternative harvesting strategies in deciduous forest landscapes with seasonal snow cover have received relatively little attention. Most forest harvesting experiments in landscapes with seasonal snow cover have focused on clearcutting in coniferous forests. Few have examined alternative strategies such as selection or shelterwood cutting in deciduous stands whose hydrologic responses to harvesting may differ from those of conifers. This study presents results from a 31-year examination of hydrological response to and recovery from alternative harvesting strategies in a deciduous forest landscape with seasonal snow cover in central Ontario, Canada. A quantitative means of assessing hydrologic recovery to harvesting is also developed. Clearcutting resulted in increased water year (WY) runoff. This was accompanied by increased runoff in all seasons, with greatest relative increases in Summer. Direct runoff and baseflow from treatment catchments generally increased following harvesting, although annual peak streamflow did not. Largest increases in WY runoff and seasonal runoff as well as direct runoff and baseflow generally occurred in the selection harvest catchment, likely as a result of interception of hillslope runoff by a forest access road and redirection to the stream channel. Hydrologic recovery appeared to begin towards the end of the experimental period for several streamflow metrics but was incomplete for all harvesting strategies 15 years after harvesting. Geochemical tracing indicated that harvesting enhanced the relative importance of surface and near-surface water pathways on catchment slopes for all treatments, with the clearcut catchment showing the most pronounced and prolonged response. Such insights into water partitioning between flow pathways may assist assessments of the ecological and biogeochemical consequences of forest disturbance.

  6. A simple model for predicting soil temperature in snow-covered and seasonally frozen soil: model description and testing

    Directory of Open Access Journals (Sweden)

    K. Rankinen

    2004-01-01

    Full Text Available Microbial processes in soil are moisture, nutrient and temperature dependent and, consequently, accurate calculation of soil temperature is important for modelling nitrogen processes. Microbial activity in soil occurs even at sub-zero temperatures so that, in northern latitudes, a method to calculate soil temperature under snow cover and in frozen soils is required. This paper describes a new and simple model to calculate daily values for soil temperature at various depths in both frozen and unfrozen soils. The model requires four parameters: average soil thermal conductivity, specific heat capacity of soil, specific heat capacity due to freezing and thawing and an empirical snow parameter. Precipitation, air temperature and snow depth (measured or calculated are needed as input variables. The proposed model was applied to five sites in different parts of Finland representing different climates and soil types. Observed soil temperatures at depths of 20 and 50 cm (September 1981–August 1990 were used for model calibration. The calibrated model was then tested using observed soil temperatures from September 1990 to August 2001. R2-values of the calibration period varied between 0.87 and 0.96 at a depth of 20 cm and between 0.78 and 0.97 at 50 cm. R2-values of the testing period were between 0.87 and 0.94 at a depth of 20cm, and between 0.80 and 0.98 at 50cm. Thus, despite the simplifications made, the model was able to simulate soil temperature at these study sites. This simple model simulates soil temperature well in the uppermost soil layers where most of the nitrogen processes occur. The small number of parameters required means that the model is suitable for addition to catchment scale models. Keywords: soil temperature, snow model

  7. Use of time series of optical and SAR images in the estimation of snow cover for the optimization of water use in the Andes of Argentina and Chile

    Science.gov (United States)

    Salinas de Salmuni, Graciela; Cabezas Cartes, Ricardo; Menicocci, Felix

    2014-05-01

    This paper describes the progress in the bilateral cooperation project between academic and water resources management institutions from the Andes region of Argentina and Chile. The study zone is located in fragile ecosystems and mountain areas of the Andes (limit zone between the Province of San Juan, Argentina, and the IV Region of Coquimbo, Chile), with arid climate, where snow precipitates in the headwaters of watershed feed the rivers of the region by melting, which are the only source of water for human use, productive and energetic activities, as well as the native flora and fauna. CONAE, the Argentine Space Agency, participates in the Project through the provision of satellite data to the users and by this it contributes to ensuring the continuity of the results of the project. Also, it provides training in digital image processing. The project also includes the participation of water resource management institutions like Secretaria de Recursos Hidricos of Argentina and the Centro de Información de Recursos Naturales de Chile (CIREN), and of academic institution like the University of San Juan (Argentina) and University of La Serena (Chile). These institutions benefit from the incorporation of new methodologies advanced digital image processing and training of staff (researcher, lecturers, PhD Students and technical). Objectives: 1-Improve water distribution incorporating space technology for application in the prediction models of the stream flow. 2- Conduct an inventory of glaciers as well as studies in selected watersheds in the Andean region, aiming to know the water resource, its availability and potential risks to communities in the region. 3. Contribute to vulnerability studies in biodiversity Andean watersheds. Results: For estimation Snow cover Area, the MODIS images are appropriate due their high temporal resolution and allows for monitoring large areas (greater than 10 km) The proposed methodology (Use of snow index, NSDI) is appropriate for

  8. Soil thermal dynamics, snow cover, and frozen depth under five temperature treatments in an ombrotrophic bog: Constrained forecast with data assimilation

    Science.gov (United States)

    Huang, Yuanyuan; Jiang, Jiang; Ma, Shuang; Ricciuto, Daniel; Hanson, Paul J.; Luo, Yiqi

    2017-08-01

    Accurate simulation of soil thermal dynamics is essential for realistic prediction of soil biogeochemical responses to climate change. To facilitate ecological forecasting at the Spruce and Peatland Responses Under Climatic and Environmental change site, we incorporated a soil temperature module into a Terrestrial ECOsystem (TECO) model by accounting for surface energy budget, snow dynamics, and heat transfer among soil layers and during freeze-thaw events. We conditioned TECO with detailed soil temperature and snow depth observations through data assimilation before the model was used for forecasting. The constrained model reproduced variations in observed temperature from different soil layers, the magnitude of snow depth, the timing of snowfall and snowmelt, and the range of frozen depth. The conditioned TECO forecasted probabilistic distributions of soil temperature dynamics in six soil layers, snow, and frozen depths under temperature treatments of +0.0, +2.25, +4.5, +6.75, and +9.0°C. Air warming caused stronger elevation in soil temperature during summer than winter due to winter snow and ice. And soil temperature increased more in shallow soil layers in summer in response to air warming. Whole ecosystem warming (peat + air warmings) generally reduced snow and frozen depths. The accuracy of forecasted snow and frozen depths relied on the precision of weather forcing. Uncertainty is smaller for forecasting soil temperature but large for snow and frozen depths. Timely and effective soil thermal forecast, constrained through data assimilation that combines process-based understanding and detailed observations, provides boundary conditions for better predictions of future biogeochemical cycles.

  9. Soil thermal dynamics, snow cover, and frozen depth under five temperature treatments in an ombrotrophic bog: Constrained forecast with data assimilation: Forecast With Data Assimilation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yuanyuan [Department of Microbiology and Plant Biology, University of Oklahoma, Norman Oklahoma USA; Jiang, Jiang [Department of Microbiology and Plant Biology, University of Oklahoma, Norman Oklahoma USA; Key Laboratory of Soil and Water Conservation and Ecological Restoration in Jiangsu Province, Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing China; Ma, Shuang [Department of Microbiology and Plant Biology, University of Oklahoma, Norman Oklahoma USA; Ricciuto, Daniel [Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge Tennessee USA; Hanson, Paul J. [Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge Tennessee USA; Luo, Yiqi [Department of Microbiology and Plant Biology, University of Oklahoma, Norman Oklahoma USA; Department of Earth System Science, Tsinghua University, Beijing China

    2017-08-01

    Accurate simulation of soil thermal dynamics is essential for realistic prediction of soil biogeochemical responses to climate change. To facilitate ecological forecasting at the Spruce and Peatland Responses Under Climatic and Environmental change site, we incorporated a soil temperature module into a Terrestrial ECOsystem (TECO) model by accounting for surface energy budget, snow dynamics, and heat transfer among soil layers and during freeze-thaw events. We conditioned TECO with detailed soil temperature and snow depth observations through data assimilation before the model was used for forecasting. The constrained model reproduced variations in observed temperature from different soil layers, the magnitude of snow depth, the timing of snowfall and snowmelt, and the range of frozen depth. The conditioned TECO forecasted probabilistic distributions of soil temperature dynamics in six soil layers, snow, and frozen depths under temperature treatments of +0.0, +2.25, +4.5, +6.75, and +9.0°C. Air warming caused stronger elevation in soil temperature during summer than winter due to winter snow and ice. And soil temperature increased more in shallow soil layers in summer in response to air warming. Whole ecosystem warming (peat + air warmings) generally reduced snow and frozen depths. The accuracy of forecasted snow and frozen depths relied on the precision of weather forcing. Uncertainty is smaller for forecasting soil temperature but large for snow and frozen depths. Timely and effective soil thermal forecast, constrained through data assimilation that combines process-based understanding and detailed observations, provides boundary conditions for better predictions of future biogeochemical cycles.

  10. Temporal changes of inorganic ion deposition in the seasonal snow cover for the Austrian Alps (1983-2014)

    Science.gov (United States)

    Greilinger, Marion; Schöner, Wolfgang; Winiwarter, Wilfried; Kasper-Giebl, Anne

    2016-05-01

    A long-term record of inorganic ion concentrations in wet and dry deposition sampled from snow packs at two high altitude glaciers was used to assess impacts of air pollution on remote sites in central Europe. Sampling points were located at Wurtenkees and Goldbergkees near the Sonnblick Observatory (3106 m above sea level), a background site for measuring the status of the atmosphere in Austria's Eastern Alps. Sampling was carried out every spring at the end of the winter accumulation period in the years 1983-2014. Concentrations of major ions (NH4+, SO42-, NO3-, Ca2+, Mg2+, K+, Na+ and Cl-) were determined using ion chromatography (IC) as well as atomic absorption spectroscopy (AAS) in the earlier years. Concentration of H+ was calculated via the measured pH of the samples. Trends in deposition and concentration were analysed for all major ions within the period from 1983 to 2014 using Kendall's tau rank correlation coefficient. From 1983 to 2014, total ion concentration declined ∼25%, i.e. solutions became ∼25% more dilute, indicating reduced acidic atmospheric deposition, even at high altitude in winter snow. SO42- and NO3- concentrations decreased significantly by 70% and 30%, respectively, accompanied by a 54% decrease of H+ concentrations. Ionic concentrations in snowpack were dominated by H+ and SO42- in the earliest decade measured, whereas they were dominated by Ca2+ by the most recent decade. SO42- and H+ depositions, i.e. concentrations multiplied by volume, also showed a significant decrease of more than 50% at both sites. This reflects the successful emission reductions of the precursor gases SO2 and NOx. Seasonal values with significantly elevated spring concentrations of NH4+, SO42- and H+ compared to fall snow reflects the beginning of vertical mixing during spring. All other ions do not show any seasonality. Source identification of the ions was performed using a principal component analysis (PCA). One anthropogenic cluster (SO42-, NO3- and NH

  11. Long-range atmospheric transport of terrestrial biomarkers by the Asian winter monsoon: Evidence from fresh snow from Sapporo, northern Japan

    Science.gov (United States)

    Yamamoto, Shinya; Kawamura, Kimitaka; Seki, Osamu

    2011-07-01

    Molecular distributions of terrestrial biomarkers were investigated in fresh snow samples from Sapporo, northern Japan, to better understand the long-range atmospheric transport of terrestrial organic matter by the Asian winter monsoon. Stable carbon (δ 13C) and hydrogen (δD) isotope ratios of C 22-C 28n-alkanoic acids were also measured to decipher their source regions. The snow samples are found to contain higher plant-derived n-alkanes, n-alkanols and n-alkanoic acids as major components. Relative abundances of these three biomarker classes suggest that they are likely derived from higher plants in the Asian continent. The C 27/C 31 ratios of terrestrial n-alkanes in the snow samples range from 1.3 to 5.5, being similar to those of the plants growing in the latitudes >40°N of East Asia. The δ 13C values of the n-alkanoic acids in the snow samples (-33.4 to -27.6‰) are similar to those of typical C 3 gymnosperm from Sapporo (-34.9 to -29.3‰). However, the δD values of the n-alkanoic acids (-208 to -148‰) are found to be significantly depleted with deuterium (by ˜72‰) than those of plant leaves from Sapporo. Such depletion can be most likely interpreted by the long-range atmospheric transport of the n-alkanoic acids from vegetation in the latitudes further north of Sapporo because the δD values of terrestrial higher plants tend to decrease northward in East Asia reflecting the δD of precipitation. Together with the results of backward trajectory analyses, this study suggests that the terrestrial biomarkers in the Sapporo snow samples are likely transported from Siberia, Russian Far East and northeast China to northern Japan by the Asian winter monsoon.

  12. Regional variation in the chemical composition of winter snow pack and terricolous lichens in relation to sources of acid emissions in the Usa river basin, northeast European Russia

    International Nuclear Information System (INIS)

    Walker, T.R.; Crittenden, P.D.; Young, S.D.

    2003-01-01

    The chemistry of winter snow pack and terricolous lichens indicate pollution distribution in Arctic Russia. - The chemical composition of snow and terricolous lichens was determined along transects through the Subarctic towns of Vorkuta (130 km west-east), Inta (240 km south-north) and Usinsk (140 km, southwest-northeast) in the Usa river basin, northeast European Russia. Evidence of pollution gradients was found on two spatial scales. First, on the Inta transect, northward decreases in concentrations of N in the lichen Cladonia stellaris (from 0.57 mmol N g -1 at 90 km south to 0.43 mmol N g -1 at 130 km north of Inta) and winter deposition of non-sea salt sulphate (from 29.3 to 12.8 mol ha -1 at 90 km south and 110 km north of Inta, respectively) were attributed to long range transport of N and S from lower latitudes. Second, increased ionic content (SO 4 2- , Ca 2+ , K + ) and pH of snow, and modified N concentration and the concentration ratios K + :Mg 2+ and K + : (Mg 2+ +Ca 2+ ) in lichens (Cladonia arbuscula and Flavocetraria cucullata) within ca. 25-40 km of Vorkuta and Inta were largely attributed to local deposition of alkaline coal ash. Total sulphate concentrations in snow varied from ca. 5 μmol l -1 at remote sites to ca. 19 μmol l -1 near Vorkuta. Nitrate concentration in snow (typically ca. 9 μmol l -1 ) did not vary with proximity to perceived pollution sources

  13. Study on Assessment Model of Classification for Snow Disasters in Tibet Plateau

    Science.gov (United States)

    Jia, L., Sr.; Xiao, T.; Wang, C.; Du, J.; Chen, D.; Zhou, Z.

    2017-12-01

    Based on Tibetan Plateau snow observation data from 39 meteorological stations during 1979-2013, we found 4 indexes for assessment model, as snow depth, the max snow depth, snow cover areas and snow duration respectively. The recurrence period of snow disasters and event distance function were calculated by normal probability density function. And the assessment model classification for snow disasters was also studied. The main contents of this research are summarized as follows: (1) The assessment model of classification for Snow Disasters was build. The snow depth, the max snow depth, snow cover areas and snow duration were selected as indexes for model, and the standard of Classification was found. The four indexes form the evaluation vector, thus euclidean distance was calculated to classify the snow disasters form the first to fifth class snow disaster. (2) The assessment of snow disasters was studied. In 370 cases of heavy snowfall in four seasons, the first class snow disaster occurred 257 times, and 69.46% of the whole cases. The second to fourth class snow disaster occurred 22.44%, 4.05% respectively. The probability of snow disaster is highest in spring, and the probability is similar in autumn and winter. (3) The average of snow depth in the fourth class snow disaster was 2.56cm, the max of snow depth is 7.45cm, the snow cover areas is 0.17 and snow duration is 57.2d. There are 4, 7, 4 times of the fourth class snow disaster in 1980s, 1990s, 2000s respectively, and 9 times occurred in winter. In December 1981, there was the fourth class snow disaster lasted for three months. During 2006-2013, up to the third class snow disaster were occurred every year, and the fourth class snow disaster occurred 4 times. In 21st century, although the times of the class snow disaster was descend, but it still has hugely damages at plateau areas. Key words: Snow Disasters; Tibet plateau; Classification; Assessment Model Acknowledgements: This study was supported by

  14. Evaluation of MODIS Albedo Product (MCD43A) over Grassland, Agriculture and Forest Surface Types During Dormant and Snow-Covered Periods

    Science.gov (United States)

    Wang, Zhousen; Schaaf, Crystal B.; Strahler, Alan H.; Chopping, Mark J.; Roman, Miguel O.; Shuai, Yanmin; Woodcock, Curtis E.; Hollinger, David Y.; Fitzjarrald, David R.

    2013-01-01

    This study assesses the Moderate-resolution Imaging Spectroradiometer (MODIS) BRDF/albedo 8 day standard product and products from the daily Direct Broadcast BRDF/albedo algorithm, and shows that these products agree well with ground-based albedo measurements during the more difficult periods of vegetation dormancy and snow cover. Cropland, grassland, deciduous and coniferous forests are considered. Using an integrated validation strategy, analyses of the representativeness of the surface heterogeneity under both dormant and snow-covered situations are performed to decide whether direct comparisons between ground measurements and 500-m satellite observations can be made or whether finer spatial resolution airborne or spaceborne data are required to scale the results at each location. Landsat Enhanced Thematic Mapper Plus (ETM +) data are used to generate finer scale representations of albedo at each location to fully link ground data with satellite data. In general, results indicate the root mean square errors (RMSEs) are less than 0.030 over spatially representative sites of agriculture/grassland during the dormant periods and less than 0.050 during the snow-covered periods for MCD43A albedo products. For forest, the RMSEs are less than 0.020 during the dormant period and 0.025 during the snow-covered periods. However, a daily retrieval strategy is necessary to capture ephemeral snow events or rapidly changing situations such as the spring snow melt.

  15. [Effects of ground cover and water-retaining agent on winter wheat growth and precipitation utilization].

    Science.gov (United States)

    Wu, Ji-Cheng; Guan, Xiu-Juan; Yang, Yong-Hui

    2011-01-01

    An investigation was made at a hilly upland in western Henan Province to understand the effects of water-retaining agent (0, 45, and 60 kg x hm(-2)), straw mulching (3000 and 6000 kg x hm(-2)), and plastic mulching (thickness straw- or plastic mulching was combined with the use of water-retaining agent. Comparing with the control, all the measures increased the soil moisture content at different growth stages by 0.1%-6.5%. Plastic film mulching had the best water-retention effect before jointing stage, whereas water-retaining agent showed its best effect after jointing stage. Soil moisture content was the lowest at flowering and grain-filling stages. Land cover increased the grain yield by 2.6%-20.1%. The yield increment was the greatest (14.2%-20.1%) by the combined use of straw mulching and water-retaining agent, followed by plastic mulching combined with water-retaining agent (11.9% on average). Land cover also improved the precipitation use efficiency (0.4-3.2 kg x mm(-1) x hm(-2)) in a similar trend as the grain yield. This study showed that land cover and water-retaining agent improved soil moisture and nutrition conditions and precipitation utilization, which in turn, promoted the tillering of winter wheat, and increased the grain number per ear and the 1000-grain mass.

  16. The strengthening relationship between Eurasian snow cover and December haze days in central North China after the mid-1990s

    Science.gov (United States)

    Yin, Zhicong; Wang, Huijun

    2018-04-01

    The haze pollution in December has become increasingly serious over recent decades and imposes damage on society, ecosystems, and human health. In addition to anthropogenic emissions, climate change and variability were conducive to haze in China. In this study, the relationship between the snow cover over eastern Europe and western Siberia (SCES) and the number of haze days in December in central North China was analyzed. This relationship significantly strengthened after the mid-1990s, which is attributed to the effective connections between the SCES and the Eurasian atmospheric circulations. During 1998-2016, the SCES significantly influenced the soil moisture and land surface radiation, and then the combined underlying drivers of enhanced soil moisture and radiative cooling moved the the East Asia jet stream northward and induced anomalous, anti-cyclonic circulation over central North China. Modulated by such atmospheric circulations, the local lower boundary layer, the decreased surface wind, and the more humid air were conducive to the worsening dispersion conditions and frequent haze occurrences. In contrast, from 1979 to 1997, the linkage between the SCES and soil moisture was negligible. Furthermore, the correlated radiative cooling was distributed narrowly and far from the key area of snow cover. The associated atmospheric circulations with the SCES were not significantly linked with the ventilation conditions over central North China. Consequently, the relationship between the SCES and the number of hazy days in central North China was insignificant before the mid-1990s but has strengthened and has become significant since then.

  17. The strengthening relationship between Eurasian snow cover and December haze days in central North China after the mid-1990s

    Directory of Open Access Journals (Sweden)

    Z. Yin

    2018-04-01

    Full Text Available The haze pollution in December has become increasingly serious over recent decades and imposes damage on society, ecosystems, and human health. In addition to anthropogenic emissions, climate change and variability were conducive to haze in China. In this study, the relationship between the snow cover over eastern Europe and western Siberia (SCES and the number of haze days in December in central North China was analyzed. This relationship significantly strengthened after the mid-1990s, which is attributed to the effective connections between the SCES and the Eurasian atmospheric circulations. During 1998–2016, the SCES significantly influenced the soil moisture and land surface radiation, and then the combined underlying drivers of enhanced soil moisture and radiative cooling moved the the East Asia jet stream northward and induced anomalous, anti-cyclonic circulation over central North China. Modulated by such atmospheric circulations, the local lower boundary layer, the decreased surface wind, and the more humid air were conducive to the worsening dispersion conditions and frequent haze occurrences. In contrast, from 1979 to 1997, the linkage between the SCES and soil moisture was negligible. Furthermore, the correlated radiative cooling was distributed narrowly and far from the key area of snow cover. The associated atmospheric circulations with the SCES were not significantly linked with the ventilation conditions over central North China. Consequently, the relationship between the SCES and the number of hazy days in central North China was insignificant before the mid-1990s but has strengthened and has become significant since then.

  18. Influence of beech and spruce sub-montane forests on snow cover in Poľana Biosphere Reserve

    Czech Academy of Sciences Publication Activity Database

    Šatala, T.; Tesař, Miroslav; Hanzelová, M.; Bartík, M.; Šípek, Václav; Škvarenina, J.; Minďáš, J.; Waldhauserová, P.D.

    2017-01-01

    Roč. 72, č. 8 (2017), s. 854-861 ISSN 0006-3088 R&D Projects: GA ČR GA16-05665S Institutional support: RVO:67985874 Keywords : snow water equivalent * snow depth * snow accumulation * snow melting Subject RIV: DA - Hydrology ; Limnology Impact factor: 0.759, year: 2016

  19. Influence of beech and spruce sub-montane forests on snow cover in Poľana Biosphere Reserve

    Czech Academy of Sciences Publication Activity Database

    Šatala, T.; Tesař, Miroslav; Hanzelová, M.; Bartík, M.; Šípek, Václav; Škvarenina, J.; Minďáš, J.; Waldhauserová, P.D.

    2017-01-01

    Roč. 72, č. 8 (2017), s. 854-861 ISSN 0006-3088 R&D Projects: GA ČR GA16-05665S Institutional support: RVO:67985874 Keywords : snow water equivalent * snow depth * snow accumulation * snow melting Subject RIV: DA - Hydrology ; Limnology OBOR OECD: Hydrology Impact factor: 0.759, year: 2016

  20. Airborn Ku-band polarimetric radar remote sensing of terrestrial snow cover

    Science.gov (United States)

    Simon H. Yueh; Steve J. Dinardo; Ahmed Akgiray; Richard West; Donald W. Cline; Kelly Elder

    2009-01-01

    Characteristics of the Ku-band polarimetric scatterometer (POLSCAT) data acquired from five sets of aircraft flights in the winter months of 2006-2008 for the second Cold Land Processes Experiment (CLPX-II) in Colorado are described in this paper. The data showed the response of the Ku-band radar echoes to snowpack changes for various types of background vegetation in...

  1. Toxic elements (As, Se, Cd, Hg, Pb) and their mineral and technogenic formations in the snow cover in the vicinity of the industrial enterprises of Tomsk

    International Nuclear Information System (INIS)

    Talovskaya, A V; Filimonenko, E A; Osipova, N A; Lyapina, E E; Azikov, E G Y

    2014-01-01

    Snow samples were collected in four industrial areas of Tomsk where brickworks, factories for the production of reinforced concrete structures, machine repair industries and local boilers, petrochemical plant and thermal power station are located. Study of insoluble fraction of aerosols in snow and melted snow water was performed to determine the contents of the emissions from these facilities. The insoluble fraction of aerosols in snow is aerosol particles deposited on snow cover. As, Se, Cd, Hg, Pb concentration was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Mineral modes of the elements were determined by scanning electron microscope. It was found the snow cover is mainly polluted by As, Se, Cd, Hg, Pb in the thermal power station impact area, by As – in the brickworks impact area, by Se – in the impact area of densely located factories for the production of reinforced concrete structures, machine repair industries and local boilers. The research results show that the mineral modes of As are associated with arsenopyrite, of Pb – with galena in the insoluble fraction of aerosols in snow

  2. Snow-atmosphere coupling and its impact on temperature variability and extremes over North America

    Science.gov (United States)

    Diro, G. T.; Sushama, L.; Huziy, O.

    2017-07-01

    The impact of snow-atmosphere coupling on climate variability and extremes over North America is investigated using modeling experiments with the fifth generation Canadian Regional Climate Model (CRCM5). To this end, two CRCM5 simulations driven by ERA-Interim reanalysis for the 1981-2010 period are performed, where snow cover and depth are prescribed (uncoupled) in one simulation while they evolve interactively (coupled) during model integration in the second one. Results indicate systematic influence of snow cover and snow depth variability on the inter-annual variability of soil and air temperatures during winter and spring seasons. Inter-annual variability of air temperature is larger in the coupled simulation, with snow cover and depth variability accounting for 40-60% of winter temperature variability over the Mid-west, Northern Great Plains and over the Canadian Prairies. The contribution of snow variability reaches even more than 70% during spring and the regions of high snow-temperature coupling extend north of the boreal forests. The dominant process contributing to the snow-atmosphere coupling is the albedo effect in winter, while the hydrological effect controls the coupling in spring. Snow cover/depth variability at different locations is also found to affect extremes. For instance, variability of cold-spell characteristics is sensitive to snow cover/depth variation over the Mid-west and Northern Great Plains, whereas, warm-spell variability is sensitive to snow variation primarily in regions with climatologically extensive snow cover such as northeast Canada and the Rockies. Furthermore, snow-atmosphere interactions appear to have contributed to enhancing the number of cold spell days during the 2002 spring, which is the coldest recorded during the study period, by over 50%, over western North America. Additional results also provide useful information on the importance of the interactions of snow with large-scale mode of variability in modulating

  3. Snow-atmosphere coupling and its impact on temperature variability and extremes over North America

    Science.gov (United States)

    Diro, G. T.; Sushama, L.; Huziy, O.

    2018-04-01

    The impact of snow-atmosphere coupling on climate variability and extremes over North America is investigated using modeling experiments with the fifth generation Canadian Regional Climate Model (CRCM5). To this end, two CRCM5 simulations driven by ERA-Interim reanalysis for the 1981-2010 period are performed, where snow cover and depth are prescribed (uncoupled) in one simulation while they evolve interactively (coupled) during model integration in the second one. Results indicate systematic influence of snow cover and snow depth variability on the inter-annual variability of soil and air temperatures during winter and spring seasons. Inter-annual variability of air temperature is larger in the coupled simulation, with snow cover and depth variability accounting for 40-60% of winter temperature variability over the Mid-west, Northern Great Plains and over the Canadian Prairies. The contribution of snow variability reaches even more than 70% during spring and the regions of high snow-temperature coupling extend north of the boreal forests. The dominant process contributing to the snow-atmosphere coupling is the albedo effect in winter, while the hydrological effect controls the coupling in spring. Snow cover/depth variability at different locations is also found to affect extremes. For instance, variability of cold-spell characteristics is sensitive to snow cover/depth variation over the Mid-west and Northern Great Plains, whereas, warm-spell variability is sensitive to snow variation primarily in regions with climatologically extensive snow cover such as northeast Canada and the Rockies. Furthermore, snow-atmosphere interactions appear to have contributed to enhancing the number of cold spell days during the 2002 spring, which is the coldest recorded during the study period, by over 50%, over western North America. Additional results also provide useful information on the importance of the interactions of snow with large-scale mode of variability in modulating

  4. Researches on snow distribution Correlation Based on Arctic Oscillation and over Qinghai-Tibet Plateau

    Science.gov (United States)

    Xiao, T.; Wang, C.; Jia, L.; Du, J.; Chen, Q.

    2017-12-01

    Based on Qinghai-Tibetan Plateau observation data and reanalysis data, the characteristics of snow cover days and depth were analyzed. The relationship between Arctic Oscillation and Qinghai-Tibet Plateau snow cover and its reasons were analyzed. The relationship between Arctic Oscillation and warm and cold climate's temperature and snow cover were also analyzed. And last, the influence of Arctic Oscillation and El Nino Southern Oscillation on the distribution of snow cover days in the Tibetan Plateau was also analyzed. The main contents of this paper are summarized as follows: (1) The interdecadal change of annual snow depth and cover days had a "less-more-less" trend, and both the abrupt change year was 1998. The significant cycle of snow depth is 2 3 years, and snow cover days is 1 3 years. The distribution of large value both snow depths and cover day were same. (2) The Arctic oscillation is significantly related to the number of snow cover days and temperatures in the Tibetan Plateau, but the relationship between AO and the snow cover depth is not significant. The Arctic Oscillation can affect the temperature in Tibetan Plateau by the atmospheric circulation field, thus affecting the Tibetan Plateau snow days in winter. (3). In the past 35 years, warm winter events increased, and cold winter events decreased, and the warming effect of the Qinghai-Tibet Plateau is significant. When the Arctic oscillation index is positive, the plateau is prone to regional cold winter events, and the temperature is less, then the snow cover days increase. The snow cover day also has the relationship with ENSO. When Nino3 index is positive, the Qinghai-Tibet Plateau snow days seem to increase, when the Nino3 index is negative, most of the snow days reduced. Key words: Arctic Oscillation Qinghai-Tibetan Plateau; Snow distribution; Cold and Warm Winter. ENSO Acknowledgements. This study was supported by National Natural Science Foundation of China Fund Project (91337215

  5. Increasing winter conductive heat transfer in the Arctic sea-ice-covered areas: 1979–2014

    Science.gov (United States)

    Fan, Xieyu; Bi, Haibo; Wang, Yunhe; Fu, Min; Zhou, Xuan; Xu, Xiuli; Huang, Haijun

    2017-12-01

    Sea ice is a quite sensitive indicator in response to regional and global climate changes. Based on monthly mean Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) sea ice thickness fields, we computed the conductive heat flux (CHF) in the Arctic Ocean in the four winter months (November-February) for a long period of 36 years (1979-2014). The calculated results for each month manifest the increasing extension of the domain with high CHF values since 1979 till 2014. In 2014, regions of roughly 90% of the central Arctic Ocean have been dominated by the CHF values larger than 18 W m-2 (November-December) and 12 W m-2 (January-February), especially significant in the shelf seas around the Arctic Ocean. Moreover, the population distribution frequency (PDF) patterns of the CHF with time show gradually peak shifting toward increased CHF values. The spatiotemporal patterns in terms of the trends in sea ice thickness and other three geophysical parameters, surface air temperature (SAT), sea ice thickness (SIT), and CHF, are well coupled. This suggests that the thinner sea ice cover preconditions for the more oceanic heat loss into atmosphere (as suggested by increased CHF values), which probably contributes to warmer atmosphere which in turn in the long run will cause thinner ice cover. This represents a positive feedback mechanism of which the overall effects would amplify the Arctic climate changes.

  6. Hydrocarbons (aliphatic and aromatic) in the snow-ice cover in the Arctic

    International Nuclear Information System (INIS)

    Nemirovskaya, I.A.; Novigatsky, A.N.; Kluvitkin, A.A.

    2002-01-01

    This paper presented the concentration and composition of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) in snow and ice-infested waters in the France-Victoria trough in the northern Barents Sea and in the Mendeleev ridge in the Amerasian basin of the Arctic Ocean. Extreme conditions such as low temperatures, ice sheets and the polar nights render the arctic environment susceptible to oil spills. Hydrocarbons found in these northern seas experience significant transformations. In order to determine the sources, pathways and transformations of the pollutants, it is necessary to know their origin. Hydrocarbon distributions is determined mostly by natural hydrobiological and geochemical conditions. The regularity of migration is determined by natural factors such as formation and circulation of air and ice drift. There is evidence suggesting that the hydrocarbons come from pyrogenic sources. It was noted that hydrocarbons could be degraded even at low temperatures. 17 refs., 1 tab

  7. Winter cover crop seeding rate and variety effects during eight years of organic vegetables: III. Cover crop residue quality and nitrogen mineralization

    Science.gov (United States)

    Winter cover crops (CC) can improve nutrient-use efficiency in tillage-intensive systems. Shoot residue quality and soil mineral N following incorporation of rye (Secale cereale L.), legume-rye, and mustard CC was determined in December to February or March during the first 8 yr of the Salinas Orga...

  8. Effect of land cover change on snow free surface albedo across the continental United States

    Science.gov (United States)

    Land cover changes (e.g., forest to grassland) affect albedo, and changes in albedo can influence radiative forcing (warming, cooling). We empirically tested albedo response to land cover change for 130 locations across the continental United States using high resolution (30 m-&t...

  9. Effect of Winter Cover Crops on Soil Nitrogen Availability, Corn Yield, and Nitrate Leaching

    Directory of Open Access Journals (Sweden)

    S. Kuo

    2001-01-01

    Full Text Available Biculture of nonlegumes and legumes could serve as cover crops for increasing main crop yield, while reducing NO3 leaching. This study, conducted from 1994 to 1999, determined the effect of monocultured cereal rye (Secale cereale L., annual ryegrass (Lolium multiflorum, and hairy vetch (Vicia villosa, and bicultured rye/vetch and ryegrass/vetch on N availability in soil, corn (Zea mays L. yield, and NO3-N leaching in a silt loam soil. The field had been in corn and cover crop rotation since 1987. In addition to the cover crop treatments, there were four N fertilizer rates (0, 67, 134, and 201 kg N ha-1, referred to as N0, N1, N2, and N3, respectively applied to corn. The experiment was a randomized split-block design with three replications for each treatment. Lysimeters were installed in 1987 at 0.75 m below the soil surface for leachate collection for the N0, N2, and N3 treatments. The result showed that vetch monoculture had the most influence on soil N availability and corn yield, followed by the bicultures. Rye or ryegrass monoculture had either no effect or an adverse effect on corn yield and soil N availability. Leachate NO3-N concentration was highest where vetch cover crop was planted regardless of N rates, which suggests that N mineralization of vetch N continued well into the fall and winter. Leachate NO3-N concentration increased with increasing N fertilizer rates and exceeded the U.S. Environmental Protection Agency’s drinking water standard of 10 mg N l�1 even at recommended N rate for corn in this region (coastal Pacific Northwest. In comparisons of the average NO3-N concentration during the period of high N leaching, monocultured rye and ryegrass or bicultured rye/vetch and ryegrass/vetch very effectively decreased N leaching in 1998 with dry fall weather. The amount of N available for leaching (determined based on the presidedress nitrate test, the amount of N fertilizer applied, and N uptake correlated well with average NO3

  10. Effect of winter cover crops on soil nitrogen availability, corn yield, and nitrate leaching.

    Science.gov (United States)

    Kuo, S; Huang, B; Bembenek, R

    2001-10-25

    Biculture of nonlegumes and legumes could serve as cover crops for increasing main crop yield, while reducing NO3 leaching. This study, conducted from 1994 to 1999, determined the effect of monocultured cereal rye (Secale cereale L.), annual ryegrass (Lolium multiflorum), and hairy vetch (Vicia villosa), and bicultured rye/vetch and ryegrass/vetch on N availability in soil, corn (Zea mays L.) yield, and NO3-N leaching in a silt loam soil. The field had been in corn and cover crop rotation since 1987. In addition to the cover crop treatments, there were four N fertilizer rates (0, 67, 134, and 201 kg N ha(-1), referred to as N0, N1, N2, and N3, respectively) applied to corn. The experiment was a randomized split-block design with three replications for each treatment. Lysimeters were installed in 1987 at 0.75 m below the soil surface for leachate collection for the N 0, N 2, and N 3 treatments. The result showed that vetch monoculture had the most influence on soil N availability and corn yield, followed by the bicultures. Rye or ryegrass monoculture had either no effect or an adverse effect on corn yield and soil N availability. Leachate NO3-N concentration was highest where vetch cover crop was planted regardless of N rates, which suggests that N mineralization of vetch N continued well into the fall and winter. Leachate NO3-N concentration increased with increasing N fertilizer rates and exceeded the U.S. Environmental Protection Agency's drinking water standard of 10 mg N l(-1) even at recommended N rate for corn in this region (coastal Pacific Northwest). In comparisons of the average NO3-N concentration during the period of high N leaching, monocultured rye and ryegrass or bicultured rye/vetch and ryegrass/vetch very effectively decreased N leaching in 1998 with dry fall weather. The amount of N available for leaching (determined based on the presidedress nitrate test, the amount of N fertilizer applied, and N uptake) correlated well with average NO3-N during

  11. Ligninolytic Activity at 0 °C of Fungi on Oak Leaves Under Snow Cover in a Mixed Forest in Japan.

    Science.gov (United States)

    Miyamoto, Toshizumi; Koda, Keiichi; Kawaguchi, Arata; Uraki, Yasumitsu

    2017-08-01

    Despite the importance of litter decomposition under snow cover in boreal forests and tundra, very little is known regarding the characteristics and functions of litter-decomposing fungi adapted to the cold climate. We investigated the decomposition of oak leaves in a heavy snowfall forest region of Japan. The rate of litter weight loss reached 26.5% during the snow cover period for 7 months and accounted for 64.6% of the annual loss (41.1%). Although no statistically significant lignin loss was detected, decolourization portions of oak leaf litter, which was attributable to the activities of ligninolytic fungi, were observed during snow cover period. This suggests that fungi involved in litter decomposition can produce extracellular enzymes to degrade lignin that remain active at 0 °C. Fungi were isolated from oak leaves collected from the forest floor under the snow layer. One hundred and sixty-six strains were isolated and classified into 33 operational taxonomic units (OTUs) based on culture characteristics and nuclear rDNA internal transcribed spacer (ITS) region sequences. To test the ability to degrade lignin, the production of extracellular phenoloxidases by isolates was quantified at 0 °C. Ten OTUs (9 Ascomycota and 1 Basidiomycota) of fungi exhibited mycelial growth and ligninolytic activity. These results suggested that some litter-decomposing fungi that had the potential to degrade lignin at 0 °C significantly contribute to litter decomposition under snow cover.

  12. Radiative forcing over the conterminous United States due to contemporary land cover land use change and sensitivity to snow and interannual albedo variability

    Science.gov (United States)

    Barnes, Christopher A.; Roy, David P.

    2010-01-01

    Satellite-derived land cover land use (LCLU), snow and albedo data, and incoming surface solar radiation reanalysis data were used to study the impact of LCLU change from 1973 to 2000 on surface albedo and radiative forcing for 58 ecoregions covering 69% of the conterminous United States. A net positive surface radiative forcing (i.e., warming) of 0.029 Wm−2 due to LCLU albedo change from 1973 to 2000 was estimated. The forcings for individual ecoregions were similar in magnitude to current global forcing estimates, with the most negative forcing (as low as −0.367 Wm−2) due to the transition to forest and the most positive forcing (up to 0.337 Wm−2) due to the conversion to grass/shrub. Snow exacerbated both negative and positive forcing for LCLU transitions between snow-hiding and snow-revealing LCLU classes. The surface radiative forcing estimates were highly sensitive to snow-free interannual albedo variability that had a percent average monthly variation from 1.6% to 4.3% across the ecoregions. The results described in this paper enhance our understanding of contemporary LCLU change on surface radiative forcing and suggest that future forcing estimates should model snow and interannual albedo variation.

  13. Particle size distribution, chemical composition and meteorological factor analysis: A case study during wintertime snow cover in Zhengzhou, China

    Science.gov (United States)

    Yu, Fei; Wang, Qun; Yan, Qishe; Jiang, Nan; Wei, Junhua; Wei, Zhiyuan; Yin, Shasha

    2018-04-01

    There was a significant snowfall event in North China from November 23 to 25 in 2015. Considering that most of the bare surface and road dust were covered by snow, the effect of dust and soil could be ignored. Atmospheric particle samples were collected in Zhengzhou, China during a haze event from November 28 to December 4, 2015. To better understand the formation and evolution of this hazy event, the size distribution, particle number, composition of particles and meteorological parameters were measured and analyzed. Results show that the meteorological conditions played an important role in the occurrence and elimination of this event. The hourly fine particle matter (PM2.5) concentration was positively correlated with relative humidity (r = 0.84, p pollutant control measures for primary emission (dust) and secondary aerosol gaseous precursor (NH3, NO2 and SO2).

  14. The Impact Of Snow Melt On Surface Runoff Of Sava River In Slovenia

    Science.gov (United States)

    Horvat, A.; Brilly, M.; Vidmar, A.; Kobold, M.

    2009-04-01

    Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Snow remains on the ground until it melts or sublimates. Spring snow melt is a major source of water supply to areas in temperate zones near mountains that catch and hold winter snow, especially those with a prolonged dry summer. In such places, water equivalent is of great interest to water managers wishing to predict spring runoff and the water supply of cities downstream. In temperate zone like in Slovenia the snow melts in the spring and contributes certain amount of water to surface flow. This amount of water can be great and can cause serious floods in case of fast snow melt. For this reason we tried to determine the influence of snow melt on the largest river basin in Slovenia - Sava River basin, on surface runoff. We would like to find out if snow melt in Slovenian Alps can cause spring floods and how serious it can be. First of all we studied the caracteristics of Sava River basin - geology, hydrology, clima, relief and snow conditions in details for each subbasin. Furtermore we focused on snow and described the snow phenomenom in Slovenia, detailed on Sava River basin. We collected all available data on snow - snow water equivalent and snow depth. Snow water equivalent is a much more useful measurement to hydrologists than snow depth, as the density of cool freshly fallen snow widely varies. New snow commonly has a density of between 5% and 15% of water. But unfortunately there is not a lot of available data of SWE available for Slovenia. Later on we compared the data of snow depth and river runoff for some of the 40 winter seasons. Finally we analyzed the use of satellite images for Slovenia to determine the snow cover for hydrology reason. We concluded that snow melt in Slovenia does not have a greater influence on Sava River flow. The snow cover in Alps can melt fast due to higher temperatures but the water distributes

  15. Vertical distribution and diel vertical migration of krill beneath snow-covered ice and in ice-free waters

    KAUST Repository

    Vestheim, Hege

    2013-11-11

    A bottom mounted upward looking Simrad EK60 120-kHz echo sounder was used to study scattering layers (SLs) and individuals of the krill Meganyctiphanes norvegica. The mooring was situated at 150-m depth in the Oslofjord, connected with an onshore cable for power and transmission of digitized data. Records spanned 5 months from late autumn to spring. A current meter and CTD was associated with the acoustic mooring and a shore-based webcam monitored ice conditions in the fjord. The continuous measurements were supplemented with intermittent krill sampling campaigns and their physical and biological environment.The krill carried out diel vertical migration (DVM) throughout the winter, regardless of the distribution of potential prey. The fjord froze over in mid-winter and the daytime distribution of a mid-water SL of krill immediately became shallower associated with snow fall after freezing, likely related to reduction of light intensities. Still, a fraction of the population always descended all the way to the bottom, so that the krill population by day seemed to inhabit waters with light levels spanning up to six orders of magnitude. Deep-living krill ascended in synchrony with the rest of the population in the afternoon, but individuals consistently reappeared in near-bottom waters already? 1 h after the ascent. Thereafter, the krill appeared to undertake asynchronous migrations, with some krill always being present in near-bottom waters even though the entire population appeared to undertake DVM. The Author 2013. Published by Oxford University Press. All rights reserved.

  16. Origin of elemental carbon in snow from western Siberia and northwestern European Russia during winter-spring 2014, 2015 and 2016

    Science.gov (United States)

    Evangeliou, Nikolaos; Shevchenko, Vladimir P.; Espen Yttri, Karl; Eckhardt, Sabine; Sollum, Espen; Pokrovsky, Oleg S.; Kobelev, Vasily O.; Korobov, Vladimir B.; Lobanov, Andrey A.; Starodymova, Dina P.; Vorobiev, Sergey N.; Thompson, Rona L.; Stohl, Andreas

    2018-01-01

    Short-lived climate forcers have been proven important both for the climate and human health. In particular, black carbon (BC) is an important climate forcer both as an aerosol and when deposited on snow and ice surface because of its strong light absorption. This paper presents measurements of elemental carbon (EC; a measurement-based definition of BC) in snow collected from western Siberia and northwestern European Russia during 2014, 2015 and 2016. The Russian Arctic is of great interest to the scientific community due to the large uncertainty of emission sources there. We have determined the major contributing sources of BC in snow in western Siberia and northwestern European Russia using a Lagrangian atmospheric transport model. For the first time, we use a recently developed feature that calculates deposition in backward (so-called retroplume) simulations allowing estimation of the specific locations of sources that contribute to the deposited mass. EC concentrations in snow from western Siberia and northwestern European Russia were highly variable depending on the sampling location. Modelled BC and measured EC were moderately correlated (R = 0.53-0.83) and a systematic region-specific model underestimation was found. The model underestimated observations by 42 % (RMSE = 49 ng g-1) in 2014, 48 % (RMSE = 37 ng g-1) in 2015 and 27 % (RMSE = 43 ng g-1) in 2016. For EC sampled in northwestern European Russia the underestimation by the model was smaller (fractional bias, FB > -100 %). In this region, the major sources were transportation activities and domestic combustion in Finland. When sampling shifted to western Siberia, the model underestimation was more significant (FB model calculations was also evaluated using two independent datasets of BC measurements in snow covering the entire Arctic. The model underestimated BC concentrations in snow especially for samples collected in springtime.

  17. Rolled-crimped winter rye cover effects on hand-weeding times and fruit yield and quality of cucurbits

    Science.gov (United States)

    Fruit and vegetables produced without pesticides are in demand by some segments of society. However, weeds often are deleterious in such crops, and managing them without herbicides is difficult. Stale seedbeds and rolled-crimped winter rye cover crops are non-chemical methods that may help manage we...

  18. [MONITORING OF THE CONTENT OF HEAVY METALS AND ELEMENTS IN THE SNOW COVER IN AGRICULTURAL SOILS AT THE TERRITORY OF THE MOSCOW REGION].

    Science.gov (United States)

    Ermakov, A A; Karpova, E A; Malysheva, A G; Mikhaylova, R I; Ryzhova, I N

    2015-01-01

    The monitoring of snow cover pollution by heavy metals and elements (zinc, copper, lead, cadmium, arsenic, nickel, chromium, strontium, manganese, fluorine, lithium) was performed in 20 districts of the Moscow region in 2009, 2012 and 2013. The assessment of the levels of contamination by heavy metals and elements was given by means of comparison of them with the average values in the snow cover near Moscow in the end of the last century and in some areas of the world, that no exposed to technological environmental impact. 7 districts of Moscow region were characterized by a high content of lead and cadmium in the snow water. It requires the control of water, soil and agricultural products pollution.

  19. Snow cover and vegetation-induced decrease in global albedo from 2002 to 2016

    OpenAIRE

    Li, Qiuping; Ma, Mingguo; Wu, Xiaodan; Yang, Hong

    2018-01-01

    Land surface albedo is an essential parameter in regional and global climate models, and it is markedly influenced by land cover change. Variations in the albedo can affect the surface radiation budget and further impact the global climate. In this study, the interannual variation of albedo from 2002 to 2016 was estimated on the global scale using Moderate Resolution Imaging Spectroradiometer (MODIS) datasets. The presence and causes of the albedo changes for each specific region were also ex...

  20. Temporal monitoring of the soil freeze-thaw cycles over snow-cover land by using off-ground GPR

    KAUST Repository

    Jadoon, Khan

    2013-07-01

    We performed off-ground ground-penetrating radar (GPR) measurements over a bare agricultural field to monitor the freeze-thaw cycles over snow-cover. The GPR system consisted of a vector network analyzer combined with an off-ground monostatic horn antenna, thereby setting up an ultra-wideband stepped-frequency continuous-wave radar. Measurements were performed during nine days and the surface of the bare soil was exposed to snow fall, evaporation and precipitation as the GPR antenna was mounted 110 cm above the ground. Soil surface dielectric permittivity was retrieved using an inversion of time-domain GPR data focused on the surface reflection. The GPR forward model used combines a full-waveform solution of Maxwell\\'s equations for three-dimensional wave propagation in planar layered media together with global reflection and transmission functions to account for the antenna and its interactions with the medium. Temperature and permittivity sensors were installed at six depths to monitor the soil dynamics in the top 8 cm depth. Significant effects of soil dynamics were observed in the time-lapse GPR, temperature and permittivity data and in particular freeze and thaw events were clearly visible. A good agreement of the trend was observed between the temperature, permittivity and GPR time-lapse data with respect to five freeze-thaw cycles. The GPR-derived permittivity was in good agreement with sensor observations. The proposed method appears to be promising for the real-time mapping and monitoring of the frozen layer at the field scale. © 2013 IEEE.

  1. Hg in snow cover and snowmelt waters in high-sulfide tailing regions (Ursk tailing dump site, Kemerovo region, Russia).

    Science.gov (United States)

    Gustaytis, M A; Myagkaya, I N; Chumbaev, A S

    2018-07-01

    Gold-bearing polymetallic Cu-Zn deposits of sulphur-pyrite ores were discovered in the Novo-Ursk region in the 1930s. The average content of mercury (Hg) was approximately 120 μg/g at the time. A comprehensive study of Hg distribution in waste of metal ore enrichment industry was carried out in the cold season on the tailing dump site and in adjacent areas. Mercury concentration in among snow particulate, dissolved and colloid fractions was determined. The maximal Hg content in particulate fraction from the waste tailing site ranged 230-573 μg/g. Such indices as the frequency of aerosol dust deposition events per units of time and area, enrichment factor and the total load allowed to establish that the territory of the tailing waste dump site had a snow cover highly contaminated with dust deposited at a rate of 247-480 mg/(m 2 ∙day). Adjacent areas could be considered as area with low Hg contamination rate with average deposition rate of 30 mg/(m 2 ∙day). The elemental composition of the aerosol dust depositions was determined as well, which allowed to reveal the extent of enrichment waste dispersion throughout adjacent areas. The amount of Hg entering environment with snowmelt water discharge was estimated. As a result of snowmelting, in 2014 the nearest to the dump site hydrographic network got Hg as 7.1 g with colloids and as 5880 g as particles. The results obtained allowed to assess the degree of Hg contamination of areas under the impact of metal enrichment industry. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Evaluation of MODIS albedo product (MCD43A) over grassland, agriculture and forest surface types during dormant and snow-covered periods

    Science.gov (United States)

    Zhuosen Wang; Crystal B. Schaaf; Alan H. Strahler; Mark J. Chopping; Miguel O. Román; Yanmin Shuai; Curtis E. Woodcock; David Y. Hollinger; David R. Fitzjarrald

    2014-01-01

    This study assesses the Moderate-resolution Imaging Spectroradiometer (MODIS) BRDF/albedo 8 day standard product and products from the daily Direct Broadcast BRDF/albedo algorithm, and shows that these products agree well with ground-based albedo measurements during the more difficult periods of vegetation dormancy and snow cover. Cropland, grassland, deciduous and...

  3. Features of Duration and Borders of the Bedding of Snow Cover in the Conditions of Climatic Changes in the Territory of Northern Kazakhstan According to Land and Space Monitoring

    Science.gov (United States)

    Salnikov, Vitaliy; Turulina, Galina; Polyakova, Svetlana; Muratova, Nadiya; Kauazov, Azamat; Abugalieva, Aigul; Tazhibayeva, Tamara

    2014-05-01

    Precipitation and air temperature datasets from 34 meteorological stations were analyzed to reveal the regional climate changes at the territory in North Kazakhstan over the last 58 years (i.e., 1950-2008). Peculiarities and conditions of snow cover formation and melting have been analyzed at territory of Northern Kazakhstan using surface and space monitoring data. Methods of both the geo-informational processing of remote probing data and statistical processing of databases on snow cover, air temperature and precipitations have been used. Analysis of snow cover observations data for territory of Northern Kazakhstan has shown that the stable snow cover might be observed since the middle of November till the beginning of April. In a few last decades the tendency is observed for longevity decrease of snow cover bedding that appears to be on the background air temperature increase and insignificant increase of cold period precipitations due to the later bedding of the snow cover and its earlier destruction. Peculiarities of atmospheric circulation in Atlantic-Eurasian sector of Northern Semi sphere and their influence of formation of snow cover at territory of Northern Kazakhstan. The higher longevity of the snow cover bedding is defined by the predominance of E form circulation and lower longevity - by the predominance of W+C circulation form. Analysis conducted of the highest height of snow cover bedding has shown that for period of 1936-2012 in the most cases the statistically reliable decreasing trends are observed with the linear trend coefficients of 0,50 - 0,60 cm/year. The method is offered for determination of probable characteristics of the snow cover decade height. Using data of space monitoring are allocated the frontiers of snow cover bedding for the period of snow melting 1982-2008 and the snow cover melting maps are developed. The results further confirm the proposition that snow cover availability is an important and limiting factor in the generation

  4. Impact of climate change in Switzerland on socioeconomic snow indices

    Science.gov (United States)

    Schmucki, Edgar; Marty, Christoph; Fierz, Charles; Weingartner, Rolf; Lehning, Michael

    2017-02-01

    Snow is a key element for many socioeconomic activities in mountainous regions. Due to the sensitivity of the snow cover to variations of temperature and precipitation, major changes caused by climate change are expected to happen. We analyze the evolution of some key snow indices under future climatic conditions. Ten downscaled and postprocessed climate scenarios from the ENSEMBLES database have been used to feed the physics-based snow model SNOWPACK. The projected snow cover has been calculated for 11 stations representing the diverse climates found in Switzerland. For the first time, such a setup is used to reveal changes in frequently applied snow indices and their implications on various socioeconomic sectors. Toward the end of the twenty-first century, a continuous snow cover is likely only guaranteed at high elevations above 2000 m a.s.l., whereas at mid elevations (1000-1700 m a.s.l.), roughly 50 % of all winters might be characterized by an ephemeral snow cover. Low elevations (below 500 m a.s.l.) are projected to experience only 2 days with snowfall per year and show the strongest relative reductions in mean winter snow depth of around 90 %. The range of the mean relative reductions of the snow indices is dominated by uncertainties from different GCM-RCM projections and amounts to approximately 30 %. Despite these uncertainties, all snow indices show a clear decrease in all scenario periods and the relative reductions increase toward lower elevations. These strong reductions can serve as a basis for policy makers in the fields of tourism, ecology, and hydropower.

  5. AHP 28: Longing for Snow-covered Peaks: Deity Possession in the Philippines

    Directory of Open Access Journals (Sweden)

    Lhundrom ལྷུན་འགྲུབ། (Lhun 'grub, Tunzhi

    2013-12-01

    Full Text Available "Roach!" Adriano screamed. I turned and saw him running naked out of the bathroom, desperately trying to cover himself with a towel. He ran into the room where Madi, the landlord, and I were watching a local show on TV. "It won't bite you!" said Madi, standing up, looking annoyed. "I'll take care of this just this once. Next time, do it yourself." He then grabbed a broom from behind the door and went inside the bathroom. "Why are you always angry?! We pay you 3,000 pesos a month," Adriano responded unhappily, which is how he usually talked to Madi. Quarreling was constant in the boarding house and small issues sometimes grew into fierce conflicts. ...

  6. Effects of soil temperature and snow cover on the mortality of overwintering pupae of the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae).

    Science.gov (United States)

    Huang, Jian

    2016-07-01

    Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is one of the most damaging insect pests in the world. However, little is known about the effects of snow cover and soil temperature on the overwintering pupae of H. armigera. A field experiment was conducted from November 2, 2012 to April 24, 2013 at the agrometeorological experimental station in Wulanwusu, China. Overwintering pupae were embedded into the soil at depths of 5, 10, and 15 cm in the following four treatments: without snow cover, snow cover, and increased temperatures from 600 and 1200 W infrared lights. The results showed that snow cover and rising temperatures could all markedly increase soil temperatures, which was helpful in improving the survival of the overwintering pupae of H. armigera. The mortality of overwintering pupae (MOP) at a depth of 15 cm was the highest, and the MOP at a depth of 5 cm followed. The lower accumulated temperature (≤0 °C) (AT ≤ °C) led to the higher MOP, and the lower diurnal soil temperature range (DSTR) likely led to the lower MOP. After snowmelt, the MOPs at the depths of 5 and 10 cm increased as the soil temperature increased, especially in April. The AT of the soil (≤0 °C) was the factor with the strongest effect on MOP. The soil moisture content was not a major factor affecting the MOP in this semiarid region because precipitation was 45 mm over the entire experimental period. With climate warming, the MOP will likely decrease, and the overwintering boundary air temperatures of H. armigera should be expanded due to higher soil temperatures and increased snow cover.

  7. Effects of soil temperature and snow cover on the mortality of overwintering pupae of the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

    Science.gov (United States)

    Huang, Jian

    2016-07-01

    Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is one of the most damaging insect pests in the world. However, little is known about the effects of snow cover and soil temperature on the overwintering pupae of H. armigera. A field experiment was conducted from November 2, 2012 to April 24, 2013 at the agrometeorological experimental station in Wulanwusu, China. Overwintering pupae were embedded into the soil at depths of 5, 10, and 15 cm in the following four treatments: without snow cover, snow cover, and increased temperatures from 600 and 1200 W infrared lights. The results showed that snow cover and rising temperatures could all markedly increase soil temperatures, which was helpful in improving the survival of the overwintering pupae of H. armigera. The mortality of overwintering pupae (MOP) at a depth of 15 cm was the highest, and the MOP at a depth of 5 cm followed. The lower accumulated temperature (≤0 °C) (AT ≤ °C) led to the higher MOP, and the lower diurnal soil temperature range (DSTR) likely led to the lower MOP. After snowmelt, the MOPs at the depths of 5 and 10 cm increased as the soil temperature increased, especially in April. The AT of the soil (≤0 °C) was the factor with the strongest effect on MOP. The soil moisture content was not a major factor affecting the MOP in this semiarid region because precipitation was 45 mm over the entire experimental period. With climate warming, the MOP will likely decrease, and the overwintering boundary air temperatures of H. armigera should be expanded due to higher soil temperatures and increased snow cover.

  8. Vegetative, productive and qualitative performance of grapevine "Cabernet Sauvignon" according to the use of winter cover crops

    Directory of Open Access Journals (Sweden)

    Jean Carlos Bettoni

    Full Text Available ABSTRACT To study the effect of winter cover crops on the vegetative, productive and qualitative behavior of "Cabernet Sauvignon" grapevines, an experiment was conducted in two wine harvests by sowing different species of winter cover crops and additional treatments with manual weeding and mechanical mowing in an experimental vineyard located at the Experimental Station of Epagri in Videira, state of Santa Catarina, Brazil. Plant attributes of the grapevine, such as number of rods and weight of pruned material and number of branches per plant. At the time of skin color change, petioles of recently matured leaves were collected for analysis of the levels of N, P, K, Ca, Mg, Fe, Mn, Zn and B. Moments before harvest, 100 grape berries were collected randomly to determine the total soluble solids, titratable acidity and pH. At harvest, the number of bunches per branch, the number and mass of clusters per plant and the average mass of clusters per plot were determined. Fresh and dry matter yields of the cover crop and weed plants were also determined when coverage reached full bloom. The winter cover crops did not alter the yield and quality of "Cabernet Sauvignon" grapes and showed no differences from each other for the management of spontaneous vegetation by hand weeding or mechanical mowing. Rye and ryegrass are effective alternatives for weed control alternatives. The species of white and red clover present difficulty in initial establishment, producing a small amount of biomass.

  9. Effects of an Ice Plate Formed by Inundation before the Continuous Snow Cover on Surface Soil Water after Disappearance of the Snow Cover at a Rotational Paddy in a Snowy Cold Region in the Period from Autumn of 2007 to Spring of 2008

    Science.gov (United States)

    Matsuda, Shuh; Mukai, Hiroyuki; Sato, Yoshikazu

    When melt water remains on the soil surface for a long time in rotational paddies in Hokkaido, a snowy cold region of Japan, machine work in the early spring is delayed, resulting in growth delay of crops and decrease in income. Ice plates can be made in paddies in Hokkaido by filling the paddies with water before the continuous snow cover, and melt water flows from the edges of the ice plate. It is expected that the surface soil water after disappearance of the snow cover can be reduced if melt water can flow to an underdrain through open channels along the levees in the paddy. In this study, the effects of an ice plate formed by inundation before the continuous snow cover on surface soil water after disappearance of the snow cover at a rotational paddy in the period from autumn of 2007 to spring of 2008 were examined. It was found that the volumetric water content in the ice plate area was lower than that in the conventional area after disappearance of the snow cover.

  10. Nutritional composition and in vitro digestibility of grass and legume winter (cover) crops.

    Science.gov (United States)

    Brown, A N; Ferreira, G; Teets, C L; Thomason, W E; Teutsch, C D

    2018-03-01

    In dairy farming systems, growing winter crops for forage is frequently limited to annual grasses grown in monoculture. The objectives of this study were to determine how cropping grasses alone or in mixtures with legumes affects the yield, nutritional composition, and in vitro digestibility of fresh and ensiled winter crops and the yield, nutritional composition, and in vitro digestibility of the subsequent summer crops. Experimental plots were planted with 15 different winter crops at 3 locations in Virginia. At each site, 4 plots of each treatment were planted in a randomized complete block design. The 15 treatments included 5 winter annual grasses [barley (BA), ryegrass (RG), rye (RY), triticale (TR), and wheat (WT)] in monoculture [i.e., no legumes (NO)] or with 1 of 2 winter annual legumes [crimson clover (CC) and hairy vetch (HV)]. After harvesting the winter crops, corn and forage sorghum were planted within the same plots perpendicular to the winter crop plantings. The nutritional composition and the in vitro digestibility of winter and summer crops were determined for fresh and ensiled samples. Growing grasses in mixtures with CC increased forage dry matter (DM) yield (2.84 Mg/ha), but the yield of mixtures with HV (2.47 Mg/ha) was similar to that of grasses grown in monoculture (2.40 Mg/ha). Growing grasses in mixtures with legumes increased the crude protein concentration of the fresh forage from 13.0% to 15.5% for CC and to 17.3% for HV. For neutral detergent fiber (NDF) concentrations, the interaction between grasses and legumes was significant for both fresh and ensiled forages. Growing BA, RY, and TR in mixtures with legumes decreased NDF concentrations, whereas growing RG and WT with legumes did not affect the NDF concentrations of either the fresh or the ensiled forages. Growing grasses in mixtures with legumes decreased the concentration of sugars of fresh forages relative to grasses grown in monoculture. Primarily, this decrease can be

  11. Possible association of the western Tibetan Plateau snow cover with the decadal to interdecadal variations of northern China heatwave frequency

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhiwei [Nanjing University of Information Science and Technology, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing (China); Chinese Academy of Sciences, State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Beijing (China); Jiang, Zhihong; Zhong, Shanshan; Wang, Lijuan [Nanjing University of Information Science and Technology, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing (China); Li, Jianping [Chinese Academy of Sciences, State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Beijing (China)

    2012-11-15

    Northern China has been subject to increased heatwave frequency (HWF) in recent decades, which deteriorates the local droughts and desertification. More than half a billion people face drinking water shortages and worsening ecological environment. In this study, the variability in the western Tibetan Plateau snow cover (TPSC) is observed to have an intimate linkage with the first empirical orthogonal function mode of the summer HWF across China. This distinct leading mode is dominated by the decadal to inter-decadal variability and features a mono-sign pattern with the extreme value center prevailing over northern China and high pressure anomalies at mid- and upper troposphere over Mongolia and the adjacent regions. A simplified general circulation model is utilized to examine the possible physical mechanism. A reduced TPSC anomaly can induce a positive geopotential height anomaly at the mid- and upper troposphere and subsequently enhance the climatological high pressure ridge over Mongolia and the adjacent regions. The subsidence associated with the high pressure anomalies tends to suppress the local cloud formation, which increases the net radiation budget, heats the surface, and favors more heatwaves. On the other hand, the surface heating can excite high pressure anomalies at mid- and upper troposphere. The latter further strengthens the upper troposphere high pressure anomalies over Mongolia and the adjacent regions. Through such positive feedback effect, the TPSC is tied to the interdecadal variations of the northern China HWF. (orig.)

  12. Ground measurements of the hemispherical-directional reflectance of Arctic snow covered tundra for the validation of satellite remote sensing products

    Science.gov (United States)

    Ball, C. P.; Marks, A. A.; Green, P.; Mac Arthur, A.; Fox, N.; King, M. D.

    2013-12-01

    Surface albedo is the hemispherical and wavelength integrated reflectance over the visible, near infrared and shortwave infrared regions of the solar spectrum. The albedo of Arctic snow can be in excess of 0.8 and it is a critical component in the global radiation budget because it determines the proportion of solar radiation absorbed, and reflected, over a large part of the Earth's surface. We present here our first results of the angularly resolved surface reflectance of Arctic snow at high solar zenith angles (~80°) suitable for the validation of satellite remote sensing products. The hemispherical directional reflectance factor (HDRF) of Arctic snow covered tundra was measured using the GonioRAdiometric Spectrometer System (GRASS) during a three-week field campaign in Ny-Ålesund, Svalbard, in March/April 2013. The measurements provide one of few existing HDRF datasets at high solar zenith angles for wind-blown Arctic snow covered tundra (conditions typical of the Arctic region), and the first ground-based measure of HDRF at Ny-Ålesund. The HDRF was recorded under clear sky conditions with 10° intervals in view zenith, and 30° intervals in view azimuth, for several typical sites over a wavelength range of 400-1500 nm at 1 nm resolution. Satellite sensors such as MODIS, AVHRR and VIIRS offer a method to monitor the surface albedo with high spatial and temporal resolution. However, snow reflectance is anisotropic and is dependent on view and illumination angle and the wavelength of the incident light. Spaceborne sensors subtend a discrete angle to the target surface and measure radiance over a limited number of narrow spectral bands. Therefore, the derivation of the surface albedo requires accurate knowledge of the surfaces bidirectional reflectance as a function of wavelength. The ultimate accuracy to which satellite sensors are able to measure snow surface properties such as albedo is dependant on the accuracy of the BRDF model, which can only be assessed

  13. Distribution of VOCs between air and snow at the Jungfraujoch high alpine research station, Switzerland, during CLACE 5 (winter 2006

    Directory of Open Access Journals (Sweden)

    E. Starokozhev

    2009-05-01

    Full Text Available Volatile organic compounds (VOCs were analyzed in air and snow samples at the Jungfraujoch high alpine research station in Switzerland as part of CLACE 5 (CLoud and Aerosol Characterization Experiment during February/March 2006. The fluxes of individual compounds in ambient air were calculated from gas phase concentrations and wind speed. The highest concentrations and flux values were observed for the aromatic hydrocarbons benzene (14.3 μg.m−2 s−1, 1,3,5-trimethylbenzene (5.27 μg.m−2 s−1, toluene (4.40 μg.m−2 −1, and the aliphatic hydrocarbons i-butane (7.87 μg.m−2 s−1, i-pentane (3.61 μg.m−2 s−1 and n-butane (3.23 μg.m−2 s−1. The measured concentrations and fluxes were used to calculate the efficiency of removal of VOCs by snow, which is defined as difference between the initial and final concentration/flux values of compounds before and after wet deposition. The removal efficiency was calculated at −24°C (−13.7°C and ranged from 37% (35% for o-xylene to 93% (63% for i-pentane. The distribution coefficients of VOCs between the air and snow phases were derived from published poly-parameter linear free energy relationship (pp-LFER data, and compared with distribution coefficients obtained from the simultaneous measurements of VOC concentrations in air and snow at Jungfraujoch. The coefficients calculated from pp-LFER exceeded those values measured in the present study, which indicates more efficient snow scavenging of the VOCs investigated than suggested by theoretical predictions.

  14. Sustainability of winter tourism in a changing climate over Kashmir Himalaya.

    Science.gov (United States)

    Dar, Reyaz Ahmad; Rashid, Irfan; Romshoo, Shakil Ahmad; Marazi, Asif

    2014-04-01

    Mountain areas are sensitive to climate change. Implications of climate change can be seen in less snow, receding glaciers, increasing temperatures, and decreasing precipitation. Climate change is also a severe threat to snow-related winter sports such as skiing, snowboarding, and cross-country skiing. The change in climate will put further pressure on the sensitive environment of high mountains. Therefore, in this study, an attempt has been made to know the impact of climate change on the snow precipitation, water resources, and winter tourism in the two famous tourist resorts of the Kashmir Valley. Our findings show that winters are getting prolonged with little snow falls on account of climate change. The average minimum and maximum temperatures are showing statistically significant increasing trends for winter months. The precipitation is showing decreasing trends in both the regions. A considerable area in these regions remains under the snow and glacier cover throughout the year especially during the winter and spring seasons. However, time series analysis of LandSat MODIS images using Normalized Difference Snow Index shows a decreasing trend in snow cover in both the regions from past few years. Similarly, the stream discharge, comprising predominantly of snow- and glacier-melt, is showing a statistically significant declining trend despite the melting of these glaciers. The predicted futuristic trends of temperature from Predicting Regional Climates for Impact Studies regional climate model are showing an increase which may enhance snow-melting in the near future posing a serious threat to the sustainability of winter tourism in the region. Hence, it becomes essential to monitor the changes in temperature and snow cover depletion in these basins in order to evaluate their effect on the winter tourism and water resources in the region.

  15. The effects of additional black carbon on the albedo of Arctic sea ice: variation with sea ice type and snow cover

    Directory of Open Access Journals (Sweden)

    A. A. Marks

    2013-07-01

    Full Text Available The response of the albedo of bare sea ice and snow-covered sea ice to the addition of black carbon is calculated. Visible light absorption and light-scattering cross-sections are derived for a typical first-year and multi-year sea ice with both "dry" and "wet" snow types. The cross-sections are derived using data from a 1970s field study that recorded both reflectivity and light penetration in Arctic sea ice and snow overlying sea ice. The variation of absorption cross-section over the visible wavelengths suggests black carbon is the dominating light-absorbing impurity. The response of first-year and multi-year sea ice albedo to increasing black carbon, from 1 to 1024 ng g−1, in a top 5 cm layer of a 155 cm-thick sea ice was calculated using a radiative-transfer model. The albedo of the first-year sea ice is more sensitive to additional loadings of black carbon than the multi-year sea ice. An addition of 8 ng g−1 of black carbon causes a decrease to 98.7% of the original albedo for first-year sea ice compared to a decrease to 99.7% for the albedo of multi-year sea ice, at a wavelength of 500 nm. The albedo of sea ice is surprisingly unresponsive to additional black carbon up to 100 ng g−1 . Snow layers on sea ice may mitigate the effects of black carbon in sea ice. Wet and dry snow layers of 0.5, 1, 2, 5 and 10 cm depth were added onto the sea ice surface. The albedo of the snow surface was calculated whilst the black carbon in the underlying sea ice was increased. A layer of snow 0.5 cm thick greatly diminishes the effect of black carbon in sea ice on the surface albedo. The albedo of a 2–5 cm snow layer (less than the e-folding depth of snow is still influenced by the underlying sea ice, but the effect of additional black carbon in the sea ice is masked.

  16. Returning Winter Cover Crop Residue Influences Soil Aggregation and Humic Substances under Double-cropped Rice Fields

    Directory of Open Access Journals (Sweden)

    Haiming Tang

    2017-11-01

    Full Text Available ABSTRACT Residue management in cropping systems may improve soil quality. However, there are few studies on the effects of residue management on soil aggregation and carbon content in the humin (C-HUM, humic acid (C-HAF and fulvic acid (C-FAF fractions in South China. Therefore, the effects on soil aggregation and on the C-HUM, C-HAF, C-FAF from incorporating winter cover crop residues in a double-cropped rice (Oryza sativa L. system in South China fields were studied. The experiment has been conducted since winter 2004. Five winter cropping systems were used: rice-rice-ryegrass (Ry-R-R, rice-rice-Chinese milk vetch (Mv-R-R, rice-rice-potato (Po-R-R, rice-rice-rape (Ra-R-R and rice-rice with winter fallow (Fa-R-R. The results indicated that the organic C content in the paddy soil under the Ry-R-R, Mv-R-R, Po-R-R, and Ra-R-R systems was significantly higher than the content in the Fa-R-R system at the early rice and late rice maturity stages. The different sizes of aggregates under the five treatments showed similar trends. The Po-R-R systems had the highest percentage of soil aggregates in each size class and the Fa-R-R systems had the lowest percentage of soil aggregates in each size class in the 0.00-0.05, 0.05-0.10, and 0.10-0.20 m soil depth at the early rice and late rice maturity stages. The C-HUM, C-HAF, and C-FAF increased through long-term application of winter cover crop residues. Statistical analysis showed that the C-HAF under the Ra-R-R systems was significantly higher than that in the Fa-R-R systems at the early rice and late rice maturity stages. The C-FAF and C-HUM under the Mv-R-R systems was significantly higher than the C-FAF and C-HUM in the Fa-R-R systems at the early rice and late rice maturity stages. As a result, the soil organic C content, the soil aggregates in each size class, and the C-HUM, C-HAF, and C-FAF increased from application of winter cover crop residues in double-cropped rice systems.

  17. Green manuring effect of pure and mixed barley - hairy vetch winter cover crops on maize and processing tomato N nutrition

    DEFF Research Database (Denmark)

    Tosti, Giacomo; Benincasa, Paolo; Farneselli, Michela

    2012-01-01

    with the appropriate critical N dilution curves. The results highlight the effectiveness of mixtures for the management of the winter cover crop practice. In the two considered years, the species proportion influences the aboveground biomass (ranging from 2.90 to 5.94 Mg ha-1) and N accumulation (ranging from 73......Adopting mixtures between legumes and non legumes can be an efficient tool to merge the advantages of the single species in the fall-sown cover crop practice. Nevertheless there is a lack of information on how the species proportion may affect N accumulation and C/N of the cover crops and how...... this can influence the N uptake and N status of different subsequent summer cash crops. In this study the N effect of barley (Hordeum vulgare L.) and hairy vetch (Vicia villosa Roth.) grown in pure stands or in mixtures with different sowing proportion was tested on maize (Zea Mays L.) and processing...

  18. Assessment of Northern Hemisphere Snow Water Equivalent Datasets in ESA SnowPEx project

    Science.gov (United States)

    Luojus, Kari; Pulliainen, Jouni; Cohen, Juval; Ikonen, Jaakko; Derksen, Chris; Mudryk, Lawrence; Nagler, Thomas; Bojkov, Bojan

    2016-04-01

    Reliable information on snow cover across the Northern Hemisphere and Arctic and sub-Arctic regions is needed for climate monitoring, for understanding the Arctic climate system, and for the evaluation of the role of snow cover and its feedback in climate models. In addition to being of significant interest for climatological investigations, reliable information on snow cover is of high value for the purpose of hydrological forecasting and numerical weather prediction. Terrestrial snow covers up to 50 million km² of the Northern Hemisphere in winter and is characterized by high spatial and temporal variability. Therefore satellite observations provide the best means for timely and complete observations of the global snow cover. There are a number of independent SWE products available that describe the snow conditions on multi-decadal and global scales. Some products are derived using satellite-based information while others rely on meteorological observations and modelling. What is common to practically all the existing hemispheric SWE products, is that their retrieval performance on hemispherical and multi-decadal scales are not accurately known. The purpose of the ESA funded SnowPEx project is to obtain a quantitative understanding of the uncertainty in satellite- as well as model-based SWE products through an internationally coordinated and consistent evaluation exercise. The currently available Northern Hemisphere wide satellite-based SWE datasets which were assessed include 1) the GlobSnow SWE, 2) the NASA Standard SWE, 3) NASA prototype and 4) NSIDC-SSM/I SWE products. The model-based datasets include: 5) the Global Land Data Assimilation System Version 2 (GLDAS-2) product 6) the European Centre for Medium-Range Forecasts Interim Land Reanalysis (ERA-I-Land) which uses a simple snow scheme 7) the Modern Era Retrospective Analysis for Research and Applications (MERRA) which uses an intermediate complexity snow scheme; and 8) SWE from the Crocus snow scheme, a

  19. Persistent reduction of segment growth and photosynthesis in a widespread and important sub-Arctic moss species after cessation of three years of experimental winter warming

    NARCIS (Netherlands)

    Bjerke, J.W.; Bokhorst, S.F.; Callaghan, T.V.; Phoenix, G.K.

    2017-01-01

    Winter is a period of dormancy for plants of cold environments. However, winter climate is changing, leading to an increasing frequency of stochastic warm periods (winter warming events) and concomitant reductions in snow cover. These conditions can break dormancy for some plants and expose them to

  20. Observations of atmospheric chemical deposition to high Arctic snow

    Science.gov (United States)

    Macdonald, Katrina M.; Sharma, Sangeeta; Toom, Desiree; Chivulescu, Alina; Hanna, Sarah; Bertram, Allan K.; Platt, Andrew; Elsasser, Mike; Huang, Lin; Tarasick, David; Chellman, Nathan; McConnell, Joseph R.; Bozem, Heiko; Kunkel, Daniel; Duan Lei, Ying; Evans, Greg J.; Abbatt, Jonathan P. D.

    2017-05-01

    Rapidly rising temperatures and loss of snow and ice cover have demonstrated the unique vulnerability of the high Arctic to climate change. There are major uncertainties in modelling the chemical depositional and scavenging processes of Arctic snow. To that end, fresh snow samples collected on average every 4 days at Alert, Nunavut, from September 2014 to June 2015 were analyzed for black carbon, major ions, and metals, and their concentrations and fluxes were reported. Comparison with simultaneous measurements of atmospheric aerosol mass loadings yields effective deposition velocities that encompass all processes by which the atmospheric species are transferred to the snow. It is inferred from these values that dry deposition is the dominant removal mechanism for several compounds over the winter while wet deposition increased in importance in the fall and spring, possibly due to enhanced scavenging by mixed-phase clouds. Black carbon aerosol was the least efficiently deposited species to the snow.

  1. Impact of sea ice cover changes on the Northern Hemisphere atmospheric winter circulation

    Directory of Open Access Journals (Sweden)

    D. Handorf

    2012-01-01

    Full Text Available The response of the Arctic atmosphere to low and high sea ice concentration phases based on European Center for Medium-Range Weather Forecast (ECMWF Re-Analysis Interim (ERA-Interim atmospheric data and Hadley Centre's sea ice dataset (HadISST1 from 1989 until 2010 has been studied. Time slices of winter atmospheric circulation with high (1990–2000 and low (2001–2010 sea ice concentration in the preceding August/September have been analysed with respect to tropospheric interactions between planetary and baroclinic waves. It is shown that a changed sea ice concentration over the Arctic Ocean impacts differently the development of synoptic and planetary atmospheric circulation systems. During the low ice phase, stronger heat release to the atmosphere over the Arctic Ocean reduces the atmospheric vertical static stability. This leads to an earlier onset of baroclinic instability that further modulates the non-linear interactions between baroclinic wave energy fluxes on time scales of 2.5–6 d and planetary scales of 10–90 d. Our analysis suggests that Arctic sea ice concentration changes exert a remote impact on the large-scale atmospheric circulation during winter, exhibiting a barotropic structure with similar patterns of pressure anomalies at the surface and in the mid-troposphere. These are connected to pronounced planetary wave train changes notably over the North Pacific.

  2. Seedling establishment at the alpine tree line - Can there be too much winter protection?

    Science.gov (United States)

    Lett, S.; Wardle, D.; Nilsson, M. C.; Dorrepaal, E.

    2014-12-01

    snow cover is the dominant, positive control on winter survival of tree seedlings above the current tree line, irrespective of the bryophyte cover. In a milder climate, however, the role of snow cover depends on the bryophyte cover, with negative effects of extra snow on seedling survival in the presence of bryophytes and vice versa.

  3. Sunn hemp as a cover crop to reduce nitrogen inputs for winter wheat

    Science.gov (United States)

    The tropical legume sunn hemp (Crotalaria juncea L.) has the potential to perform as a beneficial cover crop in the southeastern United States due to its ability to accumulate large amounts of biomass and symbiotic nitrogen (N) in a short period of time during the summer months. Planting sunn hemp,...

  4. Financial evaluation of the integration of satellite technology for snow cover measurements at a hydroelectric plant. (Utilization of Radarsat I in the La Grande river basin, Quebec)

    International Nuclear Information System (INIS)

    Martin, D.; Bernier, M.; Sasseville, J.L.; Charbonneau, R.

    1999-01-01

    The emergence, on the markets, of new technologies evokes, for the potential users, a lot of questions concerning the implementation and operation costs associated with these technologies. Nevertheless, for a lot of users, costs should be considered with the benefits these technologies are able to generate. The benefit-cost analysis is a useful tool for a financial evaluation of the transferability of the technology. This method has been selected to evaluate the eventual implementation of remote sensing technologies for snow cover measurements in the La Grande river basin (Quebec, Canada). Indeed, a better assessment of the snow water equivalent leads to a better forecasting of the water inputs due to the snowmelt. Thus, the improvement of the snow cover monitoring has direct impact on hydroelectric reservoir management. The benefit-cost analysis was used to compare three acquisition modes of the satellite Radarsat 1 (ScanSAR, Wide and Standard). The costs considered for this project are: R and D costs and operations costs (the purchase of images and costs of ground truth measurements). We evaluated the raw benefits on the basis of reducing the standard deviation of predicted inflows. The results show that the ScanSAR mode is the primary remote sensing tool for the monitoring of the snow cover, on an operational basis. With this acquisition mode, the benefit-cost ratios range between 2.3:1 and 3.9:1, using a conservative 4% reduction of the standard deviation. Even if the reduction is only 3%, ScanSAR remains profitable. Due to the large number of images needed to cover all the territory, the Standard and Wide modes are penalized by the purchase and the processing costs of the data and with delays associated to the processing. Nevertheless, with these two modes, it could be possible to work with a partial coverage of the watershed, 75% being covered in 4 days in Wide mod. The estimated B/C ratios (1.5:1 and 2:1) confirm the advantages of this alternative

  5. Snow sublimation in mountain environments and its sensitivity to forest disturbance and climate warming

    Science.gov (United States)

    Sexstone, Graham A.; Clow, David W.; Fassnacht, Steven R.; Liston, Glen E.; Hiemstra, Christopher A.; Knowles, John F.; Penn, Colin A.

    2018-01-01

    Snow sublimation is an important component of the snow mass balance, but the spatial and temporal variability of this process is not well understood in mountain environments. This study combines a process‐based snow model (SnowModel) with eddy covariance (EC) measurements to investigate (1) the spatio‐temporal variability of simulated snow sublimation with respect to station observations, (2) the contribution of snow sublimation to the ablation of the snowpack, and (3) the sensitivity and response of snow sublimation to bark beetle‐induced forest mortality and climate warming across the north‐central Colorado Rocky Mountains. EC‐based observations of snow sublimation compared well with simulated snow sublimation at stations dominated by surface and canopy sublimation, but blowing snow sublimation in alpine areas was not well captured by the EC instrumentation. Water balance calculations provided an important validation of simulated sublimation at the watershed scale. Simulated snow sublimation across the study area was equivalent to 28% of winter precipitation on average, and the highest relative snow sublimation fluxes occurred during the lowest snow years. Snow sublimation from forested areas accounted for the majority of sublimation fluxes, highlighting the importance of canopy and sub‐canopy surface sublimation in this region. Simulations incorporating the effects of tree mortality due to bark‐beetle disturbance resulted in a 4% reduction in snow sublimation from forested areas. Snow sublimation rates corresponding to climate warming simulations remained unchanged or slightly increased, but total sublimation losses decreased by up to 6% because of a reduction in snow covered area and duration.

  6. Unexpected Patterns in Snow and Dirt

    Science.gov (United States)

    Ackerson, Bruce J.

    2018-01-01

    For more than 30 years, Albert A. Bartlett published "Thermal patterns in the snow" in this journal. These are patterns produced by heat sources underneath the snow. Bartlett's articles encouraged me to pay attention to patterns in snow and to understanding them. At winter's end the last snow becomes dirty and is heaped into piles. This…

  7. Analyses of newly digitised and reconstructed snow series over the last 100+ years in Switzerland

    Science.gov (United States)

    Scherrer, S. C.; Wüthrich, C.; Croci-Maspoli, M.; Appenzeller, C.

    2010-09-01

    Snow is an important socio-economic factor in the Swiss Alpine region (tourism, hydro-electricity, drinking water) and responsible for considerable natural hazards such as avalanches. In addition, high-quality long-term snow series can be used as an excellent indicator of climate change. The objectives of this study are threefold. First, suitable long-term snow series from different altitudes and regions in Switzerland have been selected, missing data digitized and the entire series quality checked. Second, the long-term snow series have been used for trend analyses over a time period >100 years. Third, snow depth series have been reconstructed using daily new snow, temperature and precipitation as input variables. This made it possible to analyse snow depth related variables such as days with snow pack. Results show that the snow cover is varying substantially on seasonal and decadal time scales. The analyses of the decadal new snow trends during the last 100 years shows unprecedented low new snow sums in the winter seasons (DJF) of the 1990s. The 100 year trend of days with snow pack reveals a significant decrease for stations below 800 m asl in the winter season (DJF) and for stations around 1800 m asl in spring (MAM). Similar results were found for seasonal new snow sums. The results of the trend analyses are also discussed with respect to temperature and precipitation trends. Finally we will also shortly discuss how especially "precious" snow measurements have been identified and incorporated in a National Basic Climatological Network (NBCN) as well as in the Global Climate Observing System (GCOS).

  8. Snow Fun.

    Science.gov (United States)

    Finlay, Joy

    1988-01-01

    Describes several learning activities that can be done with children in the snow. Includes shake paintings, snow sculpture, snow "snakes," snow-ball contests, an igloo experience, and how to make snowshoes. (TW)

  9. Identification and evaluation of slip and fall risk on ice and snow

    OpenAIRE

    Gao, Chuansi

    2001-01-01

    Roads and pavements covered with ice and snow during winter in the Nordic and other cold regions are slippery, which result in the prevalence of slip and fall accidents among not only the public, but also outdoor workers. Literature and injury statistics revealed that the most frequently specified contributory factor for occupational slip, trip and fall accidents in Sweden is snow and ice. Road accident research showed that the largest numbers of traffic casualties occurred during walking, fo...

  10. Travel in adverse winter weather conditions by blind pedestrians.

    Science.gov (United States)

    2015-08-31

    Winter weather creates many orientation and mobility (O&M) challenges for people who are visually impaired. Getting the cane tip stuck is one of the noticeable challenges when traveling in snow, particularly when the walking surface is covered in dee...

  11. Temporal Monitoring of the Soil Freeze-Thaw Cycles over a Snow-Covered Surface by Using Air-Launched Ground-Penetrating Radar

    Directory of Open Access Journals (Sweden)

    Khan Zaib Jadoon

    2015-09-01

    Full Text Available We tested an off-ground ground-penetrating radar (GPR system at a fixed location over a bare agricultural field to monitor the soil freeze-thaw cycles over a snow-covered surface. The GPR system consisted of a monostatic horn antenna combined with a vector network analyzer, providing an ultra-wideband stepped-frequency continuous-wave radar. An antenna calibration experiment was performed to filter antenna and back scattered effects from the raw GPR data. Near the GPR setup, sensors were installed in the soil to monitor the dynamics of soil temperature and dielectric permittivity at different depths. The soil permittivity was retrieved via inversion of time domain GPR data focused on the surface reflection. Significant effects of soil dynamics were observed in the time-lapse GPR, temperature and dielectric permittivity measurements. In particular, five freeze and thaw events were clearly detectable, indicating that the GPR signals respond to the contrast between the dielectric permittivity of frozen and thawed soil. The GPR-derived permittivity was in good agreement with sensor observations. Overall, the off-ground nature of the GPR system permits non-invasive time-lapse observation of the soil freeze-thaw dynamics without disturbing the structure of the snow cover. The proposed method shows promise for the real-time mapping and monitoring of the shallow frozen layer at the field scale.

  12. Webcam network and image database for studies of phenological changes of vegetation and snow cover in Finland, image time series from 2014 to 2016

    Science.gov (United States)

    Peltoniemi, Mikko; Aurela, Mika; Böttcher, Kristin; Kolari, Pasi; Loehr, John; Karhu, Jouni; Linkosalmi, Maiju; Melih Tanis, Cemal; Tuovinen, Juha-Pekka; Nadir Arslan, Ali

    2018-01-01

    In recent years, monitoring of the status of ecosystems using low-cost web (IP) or time lapse cameras has received wide interest. With broad spatial coverage and high temporal resolution, networked cameras can provide information about snow cover and vegetation status, serve as ground truths to Earth observations and be useful for gap-filling of cloudy areas in Earth observation time series. Networked cameras can also play an important role in supplementing laborious phenological field surveys and citizen science projects, which also suffer from observer-dependent observation bias. We established a network of digital surveillance cameras for automated monitoring of phenological activity of vegetation and snow cover in the boreal ecosystems of Finland. Cameras were mounted at 14 sites, each site having 1-3 cameras. Here, we document the network, basic camera information and access to images in the permanent data repository (http://www.zenodo.org/communities/phenology_camera/). Individual DOI-referenced image time series consist of half-hourly images collected between 2014 and 2016 (https://doi.org/10.5281/zenodo.1066862). Additionally, we present an example of a colour index time series derived from images from two contrasting sites.

  13. Temporal Monitoring of the Soil Freeze-Thaw Cycles over a Snow-Covered Surface by Using Air-Launched Ground-Penetrating Radar

    KAUST Repository

    Jadoon, Khan

    2015-09-18

    We tested an off-ground ground-penetrating radar (GPR) system at a fixed location over a bare agricultural field to monitor the soil freeze-thaw cycles over a snow-covered surface. The GPR system consisted of a monostatic horn antenna combined with a vector network analyzer, providing an ultra-wideband stepped-frequency continuous-wave radar. An antenna calibration experiment was performed to filter antenna and back scattered effects from the raw GPR data. Near the GPR setup, sensors were installed in the soil to monitor the dynamics of soil temperature and dielectric permittivity at different depths. The soil permittivity was retrieved via inversion of time domain GPR data focused on the surface reflection. Significant effects of soil dynamics were observed in the time-lapse GPR, temperature and dielectric permittivity measurements. In particular, five freeze and thaw events were clearly detectable, indicating that the GPR signals respond to the contrast between the dielectric permittivity of frozen and thawed soil. The GPR-derived permittivity was in good agreement with sensor observations. Overall, the off-ground nature of the GPR system permits non-invasive time-lapse observation of the soil freeze-thaw dynamics without disturbing the structure of the snow cover. The proposed method shows promise for the real-time mapping and monitoring of the shallow frozen layer at the field scale.

  14. Relationship Between Satellite-Derived Snow Cover and Snowmelt-Runoff Timing and Stream Power in the Wind River Range, Wyoming

    Science.gov (United States)

    Hall, Dorothy K.; Foster, James L.; DiGirolamo, Nicolo E.; Riggs, George A.

    2010-01-01

    Earlier onset of springtime weather including earlier snowmelt has been documented in the western United States over at least the last 50 years. Because the majority (>70%) of the water supply in the western U.S. comes from snowmelt, analysis of the declining spring snowpack (and shrinking glaciers) has important implications for streamflow management. The amount of water in a snowpack influences stream discharge which can also influence erosion and sediment transport by changing stream power, or the rate at which a stream can do work such as move sediment and erode the stream bed. The focus of this work is the Wind River Range (WRR) in west-central Wyoming. Ten years of Moderate-Resolution Imaging Spectroradiometer (MODIS) snow-cover, cloud- gap-filled (CGF) map products and 30 years of discharge and meteorological station data are studied. Streamflow data from six streams in the WRR drainage basins show lower annual discharge and earlier snowmelt in the decade of the 2000s than in the previous three decades, though no trend of either lower streamflow or earlier snowmelt was observed using MODIS snow-cover maps within the decade of the 2000s. Results show a statistically-significant trend at the 95% confidence level (or higher) of increasing weekly maximum air temperature (for three out of the five meteorological stations studied) in the decade of the 1970s, and also for the 40-year study period. MODIS-derived snow cover (percent of basin covered) measured on 30 April explains over 89% of the variance in discharge for maximum monthly streamflow in the decade of the 2000s using Spearman rank correlation analysis. We also investigated stream power for Bull Lake Creek Above Bull Lake from 1970 to 2009; a statistically-significant end toward reduced stream power was found (significant at the 90% confidence level). Observed changes in streamflow and stream power may be related to increasing weekly maximum air temperature measured during the 40-year study period. The

  15. The engineering approach to winter sports

    CERN Document Server

    Cheli, Federico; Maldifassi, Stefano; Melzi, Stefano; Sabbioni, Edoardo

    2016-01-01

    The Engineering Approach to Winter Sports presents the state-of-the-art research in the field of winter sports in a harmonized and comprehensive way for a diverse audience of engineers, equipment and facilities designers, and materials scientists. The book examines the physics and chemistry of snow and ice with particular focus on the interaction (friction) between sports equipment and snow/ice, how it is influenced by environmental factors, such as temperature and pressure, as well as by contaminants and how it can be modified through the use of ski waxes or the microtextures of blades or ski soles. The authors also cover, in turn, the different disciplines in winter sports:  skiing (both alpine and cross country), skating and jumping, bob sledding and skeleton, hockey and curling, with attention given to both equipment design and on the simulation of gesture and  track optimization.

  16. Modeling winter ozone episodes near oil and natural gas fields in Wyoming

    Science.gov (United States)

    Wu, Yuling; Rappenglück, Bernhard; Pour-Biazar, Arastoo; Field, Robert A.; Soltis, Jeff

    2017-04-01

    Wintertime ozone episodes have been reported in the oil and natural gas (O&NG) producing fields in Uintah Basin, Utah and the Upper Green River Basin (UGRB) in Wyoming in recent years. High concentrations of ozone precursors facilitated by favorable meteorological conditions, including low wind and shallow boundary layer (BL), were found in these episodes, although the exact roles of these precursor species in different O&NG fields are to be determined. Meanwhile, snow cover is also found to play an important role in these winter ozone episodes as the cold snow covered surface enhances the inversion, further limits the BL and the high snow albedo greatly boosts photolysis reactions that are closely related to ozone chemistry. In this study, we utilize model simulation to explore the role of chemical compositions, in terms of different VOC groups and NOx, and that of the enhanced photolysis due to snow cover in the UGRB ozone episodes in the late winter of 2011.

  17. ANALYSIS OF SPATIAL-TEMPORAL VARIATION OF LAND SURFACE TEMPERATURE, VEGETATION AND SNOW COVER IN LAR NATIONAL PARK OF IRAN

    Directory of Open Access Journals (Sweden)

    M. Arekhi

    2016-10-01

    Full Text Available Changes in land surface reflectance measured by remote sensing data can be useful in climate change studies. This study attempts to analyze the spatial-temporal extent change of vegetation greenness, Land Surface Temperature (LST, and Normalized Difference Snow Index (NDSI in late spring at the Lar National Park of Iran using Landsat data. Vegetation indices (VIs, LST, and NDSI maps were calculated for each date (1985, 1994, 2010, and 2015. All VIs have shown an increasing trend from 1985 to 2015 which depicted increase of vegetation. Spectral reflectance of all bands is declining from 1985 to 2015 except in near-infrared (NIR bands. High reflectance in NIR bands is due to increased vegetation greenness. The reduction was seen in the visible bands that show increased vegetation photosynthetic activity. In the short-wave infrared bands (SWIR were observed reduced trend from 1985 to 2015 which is indicate increased vegetation. Also, in the mid-wave infrared (MWIR bands were observed a declining trend which is the result of decreasing soil fraction from 1985 to 2015. LST has increased from 23.27 °C in 1985 to 27.45 °C in 2015. Snow patches were decreased over the study period. In conclusion, VIs and surface reflectance bands are considered the main tool to display vegetation change. Also, high VIs values showed healthy and dense vegetation. The results of our study will provide valuable information in preliminary climate change studies.

  18. Wind drifted snow influence on the water and mass balance in the mountainous catchment "Modry potok", the Giant Mountains, Czech Republic.

    Science.gov (United States)

    Dvorak, I. J.; Fottova, D.; Tesar, M.; Kocianova, M.; Harcarik, J.

    2009-04-01

    There are very specific components of the water balance in the mountain headwater regions. Beside the point of cloud- and fog-water deposition it is mainly accumulation of water in the snow cover drifted into the watershed by the wind. Uneven distribution of the snow cover over the mountainous terrain is a well known phenomenon in all alpine and arctic areas. The result of this uneveness is a mosaic of microhabitats with various snow depths, different melting dates and snow free periods. Wire probes can be reliably used up to snow depths of 3 m only. To get more realistic data, two digital models using kinematic carrier phase-based GPS measurements were developed: (1) a model for snow surface data, applied at the end of winter seasons from 2000 to 2008, and (2) a model for the underlying snow free ground surface, applied after the snow melting in August 2000. These two models, overlaid in the GIS environment, have identified snow depths. For the creation of digital elevation models (DEMs), the TOPOGRID command in ArcInfo was used, which generated a grid of elevations from 3-D point, line, and polygon data. The snow depths were obtained and snow maps constructed accordingly. These "snow" results can be used for more realistic estimation of water content of snow in the watershed, distribution of snow depth during the winter seasons and define the water and mass balance more precisely. The objectives of this study were to highlight water storage in the snow-beds and show the GPS kinematic measurements as a contribution to understand more the snow accumulating and melting processes in the Modry potok catchment (2,62 km2, 1010 - 1554 m a.s.l.) in the Giant Mts. The research is supported by the Ministry of the Environment of the Czech Republic (SP/1a6/151/07) and by the Krkonose National Park Administration in Vrchlabi.

  19. Spatial and temporal variation in snow accumulation in the Central Spanish Pyrenees

    Science.gov (United States)

    López-Moreno, I.; Beguería, S.; García-Ruiz, J. M.

    2003-04-01

    Water stored in winter snowpack represents a valuable resource in mountainous regions. The distribution of the snow determines the availability of water resources during snowmelt period, as well as the development of the economy based on winter sports. This work analyses the main factors that explain the variation in snow accumulation in the Central Spanish Pyrenees. Data about evolution of snowpack is provided by the measurement of 106 sticks installed in the study area from 1985. The snow depth is measured in two moments of the year, at the beginning of March and at the end of April or beginning of May. Snow depth, of both measurements moments, has been mapped using linear regression between snow depth and different topographic and geographic variables derived from the digital terrain model. In order to improve the estimation interpolated residuals values have been subtracted. The variability of the interannual snow distribution has been analysed with a factorial analysis in order to obtain different annual patterns of snowpack distribution. Relation between the dominant winter weather-type and the different patterns, provided by the factorial analysis, has been studied. The weather-type classification has been obtained using the Jenkinson and Collison system based on daily series of sea level atmospheric pressure measured around the Iberian Peninsula with a 5º x 10º scale. Thus, it is possible to know the influence of the prevailing winter synoptic situations in the snowpack distribution. The results show that topographic and geographic variables have a high capacity to explain the spatial distribution of the average snow cover during the study period. Nevertheless, the annual snow accumulation is the result of the arrival of frontal disturbances that come from different directions. By that, it is complex to relate the different snow distribution patterns to the main winter synoptic conditions of each year.

  20. SWANN: The Snow Water Artificial Neural Network Modelling System

    Science.gov (United States)

    Broxton, P. D.; van Leeuwen, W.; Biederman, J. A.

    2017-12-01

    Snowmelt from mountain forests is important for water supply and ecosystem health. Along Arizona's Mogollon Rim, snowmelt contributes to rivers and streams that provide a significant water supply for hydro-electric power generation, agriculture, and human consumption in central Arizona. In this project, we are building a snow monitoring system for the Salt River Project (SRP), which supplies water and power to millions of customers in the Phoenix metropolitan area. We are using process-based hydrological models and artificial neural networks (ANNs) to generate information about both snow water equivalent (SWE) and snow cover. The snow-cover data is generated with ANNs that are applied to Landsat and MODIS satellite reflectance data. The SWE data is generated using a combination of gridded SWE estimates generated by process-based snow models and ANNs that account for variations in topography, forest cover, and solar radiation. The models are trained and evaluated with snow data from SNOTEL stations as well as from aerial LiDAR and field data that we collected this past winter in northern Arizona, as well as with similar data from other sites in the Southwest US. These snow data are produced in near-real time, and we have built a prototype decision support tool to deliver them to SRP. This tool is designed to provide daily-to annual operational monitoring of spatial and temporal changes in SWE and snow cover conditions over the entire Salt River Watershed (covering 17,000 km2), and features advanced web mapping capabilities and watershed analytics displayed as graphical data.

  1. Technical snow production in skiing areas: conditions, practice, monitoring and modelling. A case study in Mayrhofen/Austria

    Science.gov (United States)

    Strasser, Ulrich; Hanzer, Florian; Marke, Thomas; Rothleitner, Michael

    2017-04-01

    The production of technical snow today is a self-evident feature of modern alpine skiing resort management. Millions of Euros are invested every year for the technical infrastructure and its operation to produce a homogeneous and continuing snow cover on the skiing slopes for the winter season in almost every larger destination in the Alps. In Austria, skiing tourism is a significant factor of the national economic structure. We present the framing conditions of technical snow production in the mid-size skiing resort of Mayrhofen (Zillertal Alps/Austria, 136 km slopes, elevation range 630 - 2.500 m a.s.l.). Production conditions are defined by the availability of water, the planned date for the season opening, and the climatic conditions in the weeks before. By means of an adapted snow production strategy an attempt is made to ecologically and economically optimize the use of water and energy resources. Monitoring of the snow cover is supported by a network of low-cost sensors and mobile snow depth recordings. Finally, technical snow production is simulated with the spatially distributed, physically based hydroclimatological model AMUNDSEN. The model explicitly considers individual snow guns and distributes the produced snow along the slopes. The amount of simulated snow produced by each device is a function of its type, of actual wet-bulb temperature at the location, of ski area infrastructure (in terms of water supply and pumping capacity), and of snow demand.

  2. Performance modeling and valuation of snow-covered PV systems: examination of a simplified approach to decrease forecasting error.

    Science.gov (United States)

    Bosman, Lisa B; Darling, Seth B

    2018-03-22

    The advent of modern solar energy technologies can improve the costs of energy consumption on a global, national, and regional level, ultimately spanning stakeholders from governmental entities to utility companies, corporations, and residential homeowners. For those stakeholders experiencing the four seasons, accurately accounting for snow-related energy losses is important for effectively predicting photovoltaic performance energy generation and valuation. This paper provides an examination of a new, simplified approach to decrease snow-related forecasting error, in comparison to current solar energy performance models. A new method is proposed to allow model designers, and ultimately users, the opportunity to better understand the return on investment for solar energy systems located in snowy environments. The new method is validated using two different sets of solar energy systems located near Green Bay, WI, USA: a 3.0-kW micro inverter system and a 13.2-kW central inverter system. Both systems were unobstructed, facing south, and set at a tilt of 26.56°. Data were collected beginning in May 2014 (micro inverter system) and October 2014 (central inverter system), through January 2018. In comparison to reference industry standard solar energy prediction applications (PVWatts and PVsyst), the new method results in lower mean absolute percent errors per kilowatt hour of 0.039 and 0.055%, respectively, for the micro inverter system and central inverter system. The statistical analysis provides support for incorporating this new method into freely available, online, up-to-date prediction applications, such as PVWatts and PVsyst.

  3. Simulation of wind-induced snow transport and sublimation in alpine terrain using a fully coupled snowpack/atmosphere model

    Science.gov (United States)

    Vionnet, V.; Martin, E.; Masson, V.; Guyomarc'h, G.; Naaim-Bouvet, F.; Prokop, A.; Durand, Y.; Lac, C.

    2014-03-01

    In alpine regions, wind-induced snow transport strongly influences the spatio-temporal evolution of the snow cover throughout the winter season. To gain understanding on the complex processes that drive the redistribution of snow, a new numerical model is developed. It directly couples the detailed snowpack model Crocus with the atmospheric model Meso-NH. Meso-NH/Crocus simulates snow transport in saltation and in turbulent suspension and includes the sublimation of suspended snow particles. The coupled model is evaluated against data collected around the experimental site of Col du Lac Blanc (2720 m a.s.l., French Alps). First, 1-D simulations show that a detailed representation of the first metres of the atmosphere is required to reproduce strong gradients of blowing snow concentration and compute mass exchange between the snowpack and the atmosphere. Secondly, 3-D simulations of a blowing snow event without concurrent snowfall have been carried out. Results show that the model captures the main structures of atmospheric flow in alpine terrain. However, at 50 m grid spacing, the model reproduces only the patterns of snow erosion and deposition at the ridge scale and misses smaller scale patterns observed by terrestrial laser scanning. When activated, the sublimation of suspended snow particles causes a reduction of deposited snow mass of 5.3% over the calculation domain. Total sublimation (surface + blowing snow) is three times higher than surface sublimation in a simulation neglecting blowing snow sublimation.

  4. Combining snow depth and innovative skier flow measurements in order to improve snow grooming techniques

    Science.gov (United States)

    Carmagnola, Carlo Maria; Albrecht, Stéphane; Hargoaa, Olivier

    2017-04-01

    In the last decades, ski resort managers have massively improved their snow management practices, in order to adapt their strategies to the inter-annual variability in snow conditions and to the effects of climate change. New real-time informations, such as snow depth measurements carried out on the ski slopes by grooming machines during their daily operations, have become available, allowing high saving, efficiency and optimization gains (reducing for instance the groomer fuel consumption and operation time and the need for machine-made snow production). In order to take a step forward in improving the grooming techniques, it would be necessary to keep into account also the snow erosion by skiers, which depends mostly on the snow surface properties and on the skier attendance. Today, however, most ski resort managers have only a vague idea of the evolution of the skier flows on each slope during the winter season. In this context, we have developed a new sensor (named Skiflux) able to measure the skier attendance using an infrared beam crossing the slopes. Ten Skiflux sensors have been deployed during the 2016/17 winter season at Val Thorens ski area (French Alps), covering a whole sector of the resort. A dedicated software showing the number of skier passages in real time as been developed as well. Combining this new Skiflux dataset with the snow depth measurements from grooming machines (Snowsat System) and the snow and meteorological conditions measured in-situ (Liberty System from Technoalpin), we were able to create a "real-time skiability index" accounting for the quality of the surface snow and its evolution during the day. Moreover, this new framework allowed us to improve the preparation of ski slopes, suggesting new strategies for adapting the grooming working schedule to the snow quality and the skier attendance. In the near future, this work will benefit from the advances made within the H2020 PROSNOW project ("Provision of a prediction system allowing

  5. Evaluating the relationship between biomass, percent groundcover and remote sensing indices across six winter cover crop fields in Maryland, United States

    Science.gov (United States)

    Prabhakara, Kusuma; Hively, W. Dean; McCarty, Gregory W.

    2015-07-01

    Winter cover crops are an essential part of managing nutrient and sediment losses from agricultural lands. Cover crops lessen sedimentation by reducing erosion, and the accumulation of nitrogen in aboveground biomass results in reduced nutrient runoff. Winter cover crops are planted in the fall and are usually terminated in early spring, making them susceptible to senescence, frost burn, and leaf yellowing due to wintertime conditions. This study sought to determine to what extent remote sensing indices are capable of accurately estimating the percent groundcover and biomass of winter cover crops, and to analyze under what critical ranges these relationships are strong and under which conditions they break down. Cover crop growth on six fields planted to barley, rye, ryegrass, triticale or wheat was measured over the 2012-2013 winter growing season. Data collection included spectral reflectance measurements, aboveground biomass, and percent groundcover. Ten vegetation indices were evaluated using surface reflectance data from a 16-band CROPSCAN sensor. Restricting analysis to sampling dates before the onset of prolonged freezing temperatures and leaf yellowing resulted in increased estimation accuracy. There was a strong relationship between the normalized difference vegetation index (NDVI) and percent groundcover (r2 = 0.93) suggesting that date restrictions effectively eliminate yellowing vegetation from analysis. The triangular vegetation index (TVI) was most accurate in estimating high ranges of biomass (r2 = 0.86), while NDVI did not experience a clustering of values in the low and medium biomass ranges but saturated in the higher range (>1500 kg/ha). The results of this study show that accounting for index saturation, senescence, and frost burn on leaves can greatly increase the accuracy of estimates of percent groundcover and biomass for winter cover crops.

  6. Towards Year-round Estimation of Terrestrial Water Storage over Snow-Covered Terrain via Multi-sensor Assimilation of GRACE/GRACE-FO and AMSR-E/AMSR-2.

    Science.gov (United States)

    Wang, J.; Xue, Y.; Forman, B. A.; Girotto, M.; Reichle, R. H.

    2017-12-01

    The Gravity and Recovery Climate Experiment (GRACE) has revolutionized large-scale remote sensing of the Earth's terrestrial hydrologic cycle and has provided an unprecedented observational constraint for global land surface models. However, the coarse-scale (in space and time), vertically-integrated measure of terrestrial water storage (TWS) limits GRACE's applicability to smaller scale hydrologic applications. In order to enhance model-based estimates of TWS while effectively adding resolution (in space and time) to the coarse-scale TWS retrievals, a multi-variate, multi-sensor data assimilation framework is presented here that simultaneously assimilates gravimetric retrievals of TWS in conjunction with passive microwave (PMW) brightness temperature (Tb) observations over snow-covered terrain. The framework uses the NASA Catchment Land Surface Model (Catchment) and an ensemble Kalman filter (EnKF). A synthetic assimilation experiment is presented for the Volga river basin in Russia. The skill of the output from the assimilation of synthetic observations is compared with that of model estimates generated without the benefit of assimilating the synthetic observations. It is shown that the EnKF framework improves modeled estimates of TWS, snow depth, and snow mass (a.k.a. snow water equivalent). The data assimilation routine produces a conditioned (updated) estimate that is more accurate and contains less uncertainty during both the snow accumulation phase of the snow season as well as during the snow ablation season.

  7. Assessing the impacts of future climate conditions on the effectiveness of winter cover crops in reducing nitrate loads into the Chesapeake Bay Watersheds using SWAT model

    Science.gov (United States)

    Winter cover crops (WCCs) have been widely implemented in the Coastal Plain of the Chesapeake Bay watershed (CBW) due to their high effectiveness at reducing nitrate loads. However, future climate conditions (FCCs) are expected to exacerbate water quality degradation in the CBW by increasing nitrat...

  8. Assessing climate change impacts on winter cover crop nitrate uptake efficiency on the coastal plain of the Chesapeake Bay watershed using the SWAT model

    Science.gov (United States)

    Climate change is expected to exacerbate water quality degradation in the Chesapeake Bay watershed (CBW). Winter cover crops (WCCs) have been widely implemented in this region owing to their high effectiveness at reducing nitrate loads. However, little is known about climate change impacts on the ef...

  9. Canadian snow and sea ice: historical trends and projections

    Science.gov (United States)

    Mudryk, Lawrence R.; Derksen, Chris; Howell, Stephen; Laliberté, Fred; Thackeray, Chad; Sospedra-Alfonso, Reinel; Vionnet, Vincent; Kushner, Paul J.; Brown, Ross

    2018-04-01

    The Canadian Sea Ice and Snow Evolution (CanSISE) Network is a climate research network focused on developing and applying state of the art observational data to advance dynamical prediction, projections, and understanding of seasonal snow cover and sea ice in Canada and the circumpolar Arctic. Here, we present an assessment from the CanSISE Network on trends in the historical record of snow cover (fraction, water equivalent) and sea ice (area, concentration, type, and thickness) across Canada. We also assess projected changes in snow cover and sea ice likely to occur by mid-century, as simulated by the Coupled Model Intercomparison Project Phase 5 (CMIP5) suite of Earth system models. The historical datasets show that the fraction of Canadian land and marine areas covered by snow and ice is decreasing over time, with seasonal and regional variability in the trends consistent with regional differences in surface temperature trends. In particular, summer sea ice cover has decreased significantly across nearly all Canadian marine regions, and the rate of multi-year ice loss in the Beaufort Sea and Canadian Arctic Archipelago has nearly doubled over the last 8 years. The multi-model consensus over the 2020-2050 period shows reductions in fall and spring snow cover fraction and sea ice concentration of 5-10 % per decade (or 15-30 % in total), with similar reductions in winter sea ice concentration in both Hudson Bay and eastern Canadian waters. Peak pre-melt terrestrial snow water equivalent reductions of up to 10 % per decade (30 % in total) are projected across southern Canada.

  10. Frozen soil and snow cover with respect to the hydrological land-surface behaviour; Gefrorener Boden und Schneebedeckung unter besonderer Beruecksichtigung des hydrologischen Verhaltens der Landoberflaeche

    Energy Technology Data Exchange (ETDEWEB)

    Warrach, K. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Atmosphaerenphysik

    2000-07-01

    Investigations of the water and energy cycle in the climate system using atmospheric circulation models require a proper representation of the land surface. The land-surface model SEWAB calculates the vertical exchange of water and energy between the atmosphere and the land-surface. This includes the calculation of runoff from the land-surface into the rivers and of the vertical heat and water fluxes within the soil. The inclusion of soil freezing and thawing and the accumulation and ablation of a snow cover in SEWAB is introduced. Additionally changes in the runoff calculation such as the inclusion of the TOPMODEL-approach to consider orographic effects are made. Applications carried out for various regions of North America show good agreement between model results and measurements. (orig.)

  11. Evaluation of forest snow processes models (SnowMKIP2)

    Science.gov (United States)

    Nick Rutter; Richard Essery; John Pomeroy; Nuria Altimir; Kostas Andreadis; Ian Baker; Alan Barr; Paul Bartlett; Aaron Boone; Huiping Deng; Herve Douville; Emanuel Dutra; Kelly Elder; others

    2009-01-01

    Thirty-three snowpack models of varying complexity and purpose were evaluated across a wide range of hydrometeorological and forest canopy conditions at five Northern Hemisphere locations, for up to two winter snow seasons. Modeled estimates of snow water equivalent (SWE) or depth were compared to observations at forest and open sites at each location. Precipitation...

  12. Development of a land surface model with coupled snow and frozen soil physics

    Science.gov (United States)

    Wang, Lei; Zhou, Jing; Qi, Jia; Sun, Litao; Yang, Kun; Tian, Lide; Lin, Yanluan; Liu, Wenbin; Shrestha, Maheswor; Xue, Yongkang; Koike, Toshio; Ma, Yaoming; Li, Xiuping; Chen, Yingying; Chen, Deliang; Piao, Shilong; Lu, Hui

    2017-06-01

    Snow and frozen soil are important factors that influence terrestrial water and energy balances through snowpack accumulation and melt and soil freeze-thaw. In this study, a new land surface model (LSM) with coupled snow and frozen soil physics was developed based on a hydrologically improved LSM (HydroSiB2). First, an energy-balance-based three-layer snow model was incorporated into HydroSiB2 (hereafter HydroSiB2-S) to provide an improved description of the internal processes of the snow pack. Second, a universal and simplified soil model was coupled with HydroSiB2-S to depict soil water freezing and thawing (hereafter HydroSiB2-SF). In order to avoid the instability caused by the uncertainty in estimating water phase changes, enthalpy was adopted as a prognostic variable instead of snow/soil temperature in the energy balance equation of the snow/frozen soil module. The newly developed models were then carefully evaluated at two typical sites of the Tibetan Plateau (TP) (one snow covered and the other snow free, both with underlying frozen soil). At the snow-covered site in northeastern TP (DY), HydroSiB2-SF demonstrated significant improvements over HydroSiB2-F (same as HydroSiB2-SF but using the original single-layer snow module of HydroSiB2), showing the importance of snow internal processes in three-layer snow parameterization. At the snow-free site in southwestern TP (Ngari), HydroSiB2-SF reasonably simulated soil water phase changes while HydroSiB2-S did not, indicating the crucial role of frozen soil parameterization in depicting the soil thermal and water dynamics. Finally, HydroSiB2-SF proved to be capable of simulating upward moisture fluxes toward the freezing front from the underlying soil layers in winter.

  13. A Comparison of the SNICAR Radiative Transfer Model to In Situ Snow Characterization Measurements at Sites in New England, USA

    Science.gov (United States)

    Adolph, A. C.; Albert, M. R.; Dibb, J. E.; Lazarcik, J.; Amante, J.

    2016-12-01

    As a highly reflective material, snow serves as an important control on surface energy balance. Given the current changes in climate and the sensitivity of snow cover to rising temperatures, it is critical that we understand the role of snow and its associated feedbacks in the climate system. Much of snow albedo research has focused on polar or high altitude snow packs, but rapid changes are also occurring in temperate regions; in the northeastern United States of America, changing climate has resulted in shallower snow packs and fewer days of snow cover. As these changes occur and we seek to understand the associated implications for snow albedo within climate dynamics, it is imperative that we are able to accurately represent snow in models. The SNow, ICe, and Aerosol Radiation model (SNICAR), developed by Flanner and Zender (2005) and used in the IPCC assessments, provides upward and downward radiative fluxes of one or many snow layers based on the following inputs: snow depth, density, grain size, and impurity content; solar zenith angle; lighting conditions; and albedo of the surface beneath the snowpack. To our knowledge, the SNICAR model has not been validated with data from a mid-latitude temperate region. Through a measurement campaign that occurred from winter 2013-2016, we have collected over 400 independent observations of a suite of snow characterization measurements and spectral snow albedo from three different sites in New Hampshire, USA. Comparison of our spectral albedo measurements to the SNICAR albedo derived from measured snow properties and illumination conditions will allow for validation of the model or recommendations for improvement based on the sensitivities found in the data.

  14. Snow, ice and solar radiation

    NARCIS (Netherlands)

    Kuipers Munneke, P.

    2009-01-01

    The snow-covered ice sheets of Antarctica and Greenland reflect most of the incoming solar radiation. The reflectivity, commonly called the albedo, of snow on these ice sheets has been observed to vary in space and time. In this thesis, temporal and spatial changes in snow albedo is found to depend

  15. Species-specific detection of Lobaria pulmonaria (lichenized ascomycete) diaspores in litter samples trapped in snow cover.

    Science.gov (United States)

    Walser, J C; Zoller, S; Büchler, U; Scheidegger, C

    2001-09-01

    The foliose lichen Lobaria pulmonaria has suffered a substantial decline in central and northern Europe during the twentieth century and is now considered to be critically endangered in many European lowland regions. Based on demographic studies, it has been proposed that under the present environmental conditions and forest management regimes, dispersal of diaspores and subsequent establishment of new thalli are insufficient to maintain the remnant small lowland populations. Chances of long-term survival may therefore be reduced. The data and analytical power of these demographic studies are limited. Since lichen diaspores show very few species-specific morphological characteristics, and are therefore almost indistinguishable, the accurate assessment of diaspore flux would be a fundamental first step in better understanding the life cycle of L. pulmonaria. Here we present a new molecular approach to investigate the dispersal of L. pulmonaria diaspores in its natural environment by specifically identifying small amounts of DNA in snow litter samples at varying distances from known sources. We used a species-specific polymerase chain reaction (PCR) primer pair to amplify the ribosomal internal transcribed spacer region (ITS rDNA) and a sensitive automated PCR product detection system using fluorescent labelled primers. We detected considerable amounts of naturally dispersed diaspores, deposited as far as 50 m away from the closest potential source. Diaspores were only found in the direction of the prevailing wind. Diaspore deposition varied from 1.2 diaspores per m(2) per day at 50 m distance from the source to 15 diaspores per m(2) per day at 1 m distance. The method described in this paper opens up perspectives for studies of population dynamics and dispersal ecology mainly in lichenized ascomycetes but also in other organisms with small, wind-dispersed diaspores.

  16. Snow multivariable data assimilation for hydrological predictions in Alpine sites

    Science.gov (United States)

    Piazzi, Gaia; Thirel, Guillaume; Campo, Lorenzo; Gabellani, Simone; Stevenin, Hervè

    2017-04-01

    Snowpack dynamics (snow accumulation and ablation) strongly impacts on hydrological processes in Alpine areas. During the winter season the presence of snow cover (snow accumulation) reduces the drainage in the basin with a resulting lower watershed time of concentration in case of possible rainfall events. Moreover, the release of the significant water volume stored in winter (snowmelt) considerably contributes to the total discharge during the melting period. Therefore when modeling hydrological processes in snow-dominated catchments the quality of predictions deeply depends on how the model succeeds in catching snowpack dynamics. The integration of a hydrological model with a snow module allows improving predictions of river discharges. Besides the well-known modeling limitations (uncertainty in parameterizations; possible errors affecting both meteorological forcing data and initial conditions; approximations in boundary conditions), there are physical factors that make an exhaustive reconstruction of snow dynamics complicated: snow intermittence in space and time, stratification and slow phenomena like metamorphism processes, uncertainty in snowfall evaluation, wind transportation, etc. Data Assimilation (DA) techniques provide an objective methodology to combine several independent snow-related data sources (model simulations, ground-based measurements and remote sensed observations) in order to obtain the most likely estimate of snowpack state. This study presents SMASH (Snow Multidata Assimilation System for Hydrology), a multi-layer snow dynamic model strengthened by a multivariable DA framework for hydrological purposes. The model is physically based on mass and energy balances and can be used to reproduce the main physical processes occurring within the snowpack: accumulation, density dynamics, melting, sublimation, radiative balance, heat and mass exchanges. The model is driven by observed forcing meteorological data (air temperature, wind velocity

  17. Analysis of the snow-atmosphere energy balance during wet-snow instabilities and implications for avalanche prediction

    Directory of Open Access Journals (Sweden)

    C. Mitterer

    2013-02-01

    Full Text Available Wet-snow avalanches are notoriously difficult to predict; their formation mechanism is poorly understood since in situ measurements representing the thermal and mechanical evolution are difficult to perform. Instead, air temperature is commonly used as a predictor variable for days with high wet-snow avalanche danger – often with limited success. As melt water is a major driver of wet-snow instability and snow melt depends on the energy input into the snow cover, we computed the energy balance for predicting periods with high wet-snow avalanche activity. The energy balance was partly measured and partly modelled for virtual slopes at different elevations for the aspects south and north using the 1-D snow cover model SNOWPACK. We used measured meteorological variables and computed energy balance and its components to compare wet-snow avalanche days to non-avalanche days for four consecutive winter seasons in the surroundings of Davos, Switzerland. Air temperature, the net shortwave radiation and the energy input integrated over 3 or 5 days showed best results in discriminating event from non-event days. Multivariate statistics, however, revealed that for better predicting avalanche days, information on the cold content of the snowpack is necessary. Wet-snow avalanche activity was closely related to periods when large parts of the snowpack reached an isothermal state (0 °C and energy input exceeded a maximum value of 200 kJ m−2 in one day, or the 3-day sum of positive energy input was larger than 1.2 MJ m−2. Prediction accuracy with measured meteorological variables was as good as with computed energy balance parameters, but simulated energy balance variables accounted better for different aspects, slopes and elevations than meteorological data.

  18. Simulation of wind-induced snow transport in alpine terrain using a fully coupled snowpack/atmosphere model

    Science.gov (United States)

    Vionnet, V.; Martin, E.; Masson, V.; Guyomarc'h, G.; Naaim-Bouvet, F.; Prokop, A.; Durand, Y.; Lac, C.

    2013-06-01

    In alpine regions, wind-induced snow transport strongly influences the spatio-temporal evolution of the snow cover throughout the winter season. To gain understanding on the complex processes that drive the redistribution of snow, a new numerical model is developed. It couples directly the detailed snowpack model Crocus with the atmospheric model Meso-NH. Meso-NH/Crocus simulates snow transport in saltation and in turbulent suspension and includes the sublimation of suspended snow particles. A detailed representation of the first meters of the atmosphere allows a fine reproduction of the erosion and deposition process. The coupled model is evaluated against data collected around the experimental site of Col du Lac Blanc (2720 m a.s.l., French Alps). For this purpose, a blowing snow event without concurrent snowfall has been selected and simulated. Results show that the model captures the main structures of atmospheric flow in alpine terrain, the vertical profile of wind speed and the snow particles fluxes near the surface. However, the horizontal resolution of 50 m is found to be insufficient to simulate the location of areas of snow erosion and deposition observed by terrestrial laser scanning. When activated, the sublimation of suspended snow particles causes a reduction in deposition of 5.3%. Total sublimation (surface + blowing snow) is three times higher than surface sublimation in a simulation neglecting blowing snow sublimation.

  19. Debris-covered glacier anomaly? Morphological factors controlling changes in the mass balance, surface area, terminus position, and snow line altitude of Himalayan glaciers

    Science.gov (United States)

    Salerno, Franco; Thakuri, Sudeep; Tartari, Gianni; Nuimura, Takayuki; Sunako, Sojiro; Sakai, Akiko; Fujita, Koji

    2017-08-01

    What are the main morphological factors that control the heterogeneous responses of debris-covered glaciers to climate change in the southern central Himalaya? A debate is open whether thinning rates on debris-covered glaciers are comparable to those of debris-free ones. Previous studies have adopted a deterministic approach, which is indispensable, but is also limiting in that only a few glaciers can be monitored. In this context, we propose a statistical analysis based on a wider glacier population as a complement to these deterministic studies. We analysed 28 glaciers situated on the southern slopes of Mt. Everest in the central southern Himalaya during the period 1992-2008. This study combined data compiled by three distinct studies for a common period and population of glaciers for use in a robust statistical analysis. Generally, surface gradient was the main morphological factor controlling the features and responses of the glaciers to climate change. In particular, the key points that emerged are as follows. 1) Reduced downstream surface gradient is responsible for increased glacier thinning. 2) The development of supraglacial ponds is a further controlling factor of glacier thinning: where supraglacial ponds develop, the glaciers register further surface lowering. 3) Debris coverage and thickness index were not found to be significantly responsible for the development of supraglacial ponds, changes in elevation, or shifts in snow line altitude.

  20. Assessment of the AquaCrop model for use in simulation of irrigated winter wheat canopy cover, biomass, and grain yield in the North China Plain.

    Directory of Open Access Journals (Sweden)

    Xiu-liang Jin

    Full Text Available Improving winter wheat water use efficiency in the North China Plain (NCP, China is essential in light of current irrigation water shortages. In this study, the AquaCrop model was used to calibrate, and validate winter wheat crop performance under various planting dates and irrigation application rates. All experiments were conducted at the Xiaotangshan experimental site in Beijing, China, during seasons of 2008/2009, 2009/2010, 2010/2011 and 2011/2012. This model was first calibrated using data from 2008/2009 and 2009/2010, and subsequently validated using data from 2010/2011 and 2011/2012. The results showed that the simulated canopy cover (CC, biomass yield (BY and grain yield (GY were consistent with the measured CC, BY and GY, with corresponding coefficients of determination (R(2 of 0.93, 0.91 and 0.93, respectively. In addition, relationships between BY, GY and transpiration (T, (R(2 = 0.57 and 0.71, respectively was observed. These results suggest that frequent irrigation with a small amount of water significantly improved BY and GY. Collectively, these results indicate that the AquaCrop model can be used in the evaluation of various winter wheat irrigation strategies. The AquaCrop model predicted winter wheat CC, BY and GY with acceptable accuracy. Therefore, we concluded that AquaCrop is a useful decision-making tool for use in efforts to optimize wheat winter planting dates, and irrigation strategies.

  1. Assessment of the AquaCrop model for use in simulation of irrigated winter wheat canopy cover, biomass, and grain yield in the North China Plain.

    Science.gov (United States)

    Jin, Xiu-liang; Feng, Hai-kuan; Zhu, Xin-kai; Li, Zhen-hai; Song, Sen-nan; Song, Xiao-yu; Yang, Gui-Jun; Xu, Xin-gang; Guo, Wen-shan

    2014-01-01

    Improving winter wheat water use efficiency in the North China Plain (NCP), China is essential in light of current irrigation water shortages. In this study, the AquaCrop model was used to calibrate, and validate winter wheat crop performance under various planting dates and irrigation application rates. All experiments were conducted at the Xiaotangshan experimental site in Beijing, China, during seasons of 2008/2009, 2009/2010, 2010/2011 and 2011/2012. This model was first calibrated using data from 2008/2009 and 2009/2010, and subsequently validated using data from 2010/2011 and 2011/2012. The results showed that the simulated canopy cover (CC), biomass yield (BY) and grain yield (GY) were consistent with the measured CC, BY and GY, with corresponding coefficients of determination (R(2)) of 0.93, 0.91 and 0.93, respectively. In addition, relationships between BY, GY and transpiration (T), (R(2) = 0.57 and 0.71, respectively) was observed. These results suggest that frequent irrigation with a small amount of water significantly improved BY and GY. Collectively, these results indicate that the AquaCrop model can be used in the evaluation of various winter wheat irrigation strategies. The AquaCrop model predicted winter wheat CC, BY and GY with acceptable accuracy. Therefore, we concluded that AquaCrop is a useful decision-making tool for use in efforts to optimize wheat winter planting dates, and irrigation strategies.

  2. Run-off of strontium with melting snow in spring

    International Nuclear Information System (INIS)

    Quenild, C.; Tveten, U.

    1986-09-01

    When assessing the consequences of atmospheric releases caused by a large reactor accident, one usually finds that the major contributions to the dose are via nutrition and from exposure to radiation from radioactive materials deposited on ground. The experiment described is concerned with run-off from agricultural surface which has been contaminated with strontiom while covered with snow. Migration experiments show a significant difference between summer and winter conditions. Roughly 54% of the strontium with which the experimental area was contaminated, ran off with the melt-water. Under winter conditions, portions of the contaminant will flow with the melt-water without coming in contact with the soil

  3. Validation of NOAA-Interactive Multisensor Snow and Ice Mapping System (IMS by Comparison with Ground-Based Measurements over Continental United States

    Directory of Open Access Journals (Sweden)

    Reza Khanbilvardi

    2012-04-01

    Full Text Available In this study, daily maps of snow cover distribution and sea ice extent produced by NOAA’s interactive multisensor snow and ice mapping system (IMS were validated using in situ snow depth data from observing stations obtained from NOAA’s National Climatic Data Center (NCDC for calendar years 2006 to 2010. IMS provides daily maps of snow and sea ice extent within the Northern Hemisphere using data from combination of geostationary and polar orbiting satellites in visible, infrared and microwave spectrums. Statistical correspondence between the IMS and in situ point measurements has been evaluated assuming that ground measurements are discrete and continuously distributed over a 4 km IMS snow cover maps. Advanced Very High Resolution Radiometer (AVHRR land and snow classification data are supplemental datasets used in the further analysis of correspondence between the IMS product and in situ measurements. The comparison of IMS maps with in situ snow observations conducted over a period of four years has demonstrated a good correspondence of the data sets. The daily rate of agreement between the products mostly ranges between 80% and 90% during the Northern Hemisphere through the winter seasons when about a quarter to one third of the territory of continental US is covered with snow. Further, better agreement was observed for stations recording higher snow depth. The uncertainties in validation of IMS snow product with stationed NCDC data were discussed.

  4. Influence of Dust and Black Carbon on the Snow Albedo in the NASA Goddard Earth Observing System Version 5 Land Surface Model

    Science.gov (United States)

    Yasunari, Teppei J.; Koster, Randal D.; Lau, K. M.; Aoki, Teruo; Sud, Yogesh C.; Yamazaki, Takeshi; Motoyoshi, Hiroki; Kodama, Yuji

    2011-01-01

    Present-day land surface models rarely account for the influence of both black carbon and dust in the snow on the snow albedo. Snow impurities increase the absorption of incoming shortwave radiation (particularly in the visible bands), whereby they have major consequences for the evolution of snowmelt and life cycles of snowpack. A new parameterization of these snow impurities was included in the catchment-based land surface model used in the National Aeronautics and Space Administration Goddard Earth Observing System version 5. Validation tests against in situ observed data were performed for the winter of 2003.2004 in Sapporo, Japan, for both the new snow albedo parameterization (which explicitly accounts for snow impurities) and the preexisting baseline albedo parameterization (which does not). Validation tests reveal that daily variations of snow depth and snow surface albedo are more realistically simulated with the new parameterization. Reasonable perturbations in the assigned snow impurity concentrations, as inferred from the observational data, produce significant changes in snowpack depth and radiative flux interactions. These findings illustrate the importance of parameterizing the influence of snow impurities on the snow surface albedo for proper simulation of the life cycle of snow cover.

  5. Drones application on snow and ice surveys in alpine areas

    Science.gov (United States)

    La Rocca, Leonardo; Bonetti, Luigi; Fioletti, Matteo; Peretti, Giovanni

    2015-04-01

    scientific point of view. All flight was performed by remote controlled aero models with high resolution camera. Aero models were able to take off and to ground on snow covered or icy surfaces since the specific aerodynamic configuration and specific engine used to. All winter surveys were executed flying low to obtain a tridimensional reconstruction of an High resolution Digital Elevation Model (DEM) of snow cover and ice cover and on summer as been developed the DEM were snow amass in the maximum avalanche risk period. The difference between winter and summer DEM (difference between two point clouds) let to individuate the snow depth, and it was used as input data for the snow avalanche model for the Aprica site (Bergamo - Italy).

  6. Simulation of snow accumulation and melt in needleleaf forest environments

    Directory of Open Access Journals (Sweden)

    C. R. Ellis

    2010-06-01

    Full Text Available Drawing upon numerous field studies and modelling exercises of snow processes, the Cold Regions Hydrological Model (CRHM was developed to simulate the four season hydrological cycle in cold regions. CRHM includes modules describing radiative, turbulent and conductive energy exchanges to snow in open and forest environments, as well as account for losses from canopy snow sublimation and rain evaporation. Due to the physical-basis and rigorous testing of each module, there is a minimal need for model calibration. To evaluate CRHM, simulations of snow accumulation and melt were compared to observations collected at paired forest and clearing sites of varying latitude, elevation, forest cover density, and climate. Overall, results show that CRHM is capable of characterising the variation in snow accumulation between forest and clearing sites, achieving a model efficiency of 0.51 for simulations at individual sites. Simulations of canopy sublimation losses slightly overestimated observed losses from a weighed cut tree, having a model efficiency of 0.41 for daily losses. Good model performance was demonstrated in simulating energy fluxes to snow at the clearings, but results were degraded from this under forest cover due to errors in simulating sub-canopy net longwave radiation. However, expressed as cumulative energy to snow over the winter, simulated values were 96% and 98% of that observed at the forest and clearing sites, respectively. Overall, the good representation of the substantial variations in mass and energy between forest and clearing sites suggests that CRHM may be useful as an analytical or predictive tool for snow processes in needleleaf forest environments.

  7. On the Linkage between Springtime Eurasian Snow Cover Retreat due to the Global Warming and Changes in Summertime Atmospheric Circulation over Japan and East Asia

    Science.gov (United States)

    Nozawa, T.; Fujiwara, S.

    2017-12-01

    According to the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5), snow cover extent (SCE) over the northern hemisphere is greatly decreasing in spring. This change is expected to affect atmospheric circulation change via land-atmosphere interactions. In this study, we investigated relationships between spring SCE anomaly over the Eurasia and changes in atmospheric circulations, mainly analyzing the Japanese 55-year Reanalysis (JRA-55). Differences in composites of zonal winds at upper and middle levels between large and small SCE years over Western Siberia in spring show that, around Japan and East Asia, jet stream in small SCE years is shifted southward in April and June. We also analyzed surface temperature and soil moisture and find that, in small SCE years, surface temperature in Western Siberia and Central Asia is increased and soil moisture reduced significantly in June. The air temperature in the middle and low level atmosphere also significantly increased and have wave-like pattern in May. These results suggest that there are some linkages between the springtime Eurasian SCE reduction and changes in summertime jet stream over Japan and East Asia through land-atmosphere interactions.

  8. Quantifying forest mortality with the remote sensing of snow

    Science.gov (United States)

    Baker, Emily Hewitt

    Greenhouse gas emissions have altered global climate significantly, increasing the frequency of drought, fire, and pest-related mortality in forests across the western United States, with increasing area affected each year. Associated changes in forests are of great concern for the public, land managers, and the broader scientific community. These increased stresses have resulted in a widespread, spatially heterogeneous decline of forest canopies, which in turn exerts strong controls on the accumulation and melt of the snowpack, and changes forest-atmosphere exchanges of carbon, water, and energy. Most satellite-based retrievals of summer-season forest data are insufficient to quantify canopy, as opposed to the combination of canopy and undergrowth, since the signals of the two types of vegetation greenness have proven persistently difficult to distinguish. To overcome this issue, this research develops a method to quantify forest canopy cover using winter-season fractional snow covered area (FSCA) data from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) snow covered area and grain size (MODSCAG) algorithm. In areas where the ground surface and undergrowth are completely snow-covered, a pixel comprises only forest canopy and snow. Following a snowfall event, FSCA initially rises, as snow is intercepted in the canopy, and then falls, as snow unloads. A select set of local minima in a winter F SCA timeseries form a threshold where canopy is snow-free, but forest understory is snow-covered. This serves as a spatially-explicit measurement of forest canopy, and viewable gap fraction (VGF) on a yearly basis. Using this method, we determine that MODIS-observed VGF is significantly correlated with an independent product of yearly crown mortality derived from spectral analysis of Landsat imagery at 25 high-mortality sites in northern Colorado. (r =0.96 +/-0.03, p =0.03). Additionally, we determine the lag timing between green-stage tree mortality and

  9. Influence of snowpack internal structure on snow metamorphism and melting intensity on Hansbreen, Svalbard

    Directory of Open Access Journals (Sweden)

    Laska Michał

    2016-06-01

    Full Text Available This paper presents a detailed study of melting processes conducted on Hansbreen – a tidewater glacier terminating in the Hornsund fjord, Spitsbergen. The fieldwork was carried out from April to July 2010. The study included observations of meltwater distribution within snow profiles in different locations and determination of its penetration time to the glacier ice surface. In addition, the variability of the snow temperature and heat transfer within the snow cover were measured. The main objective concerns the impact of meltwater on the diversity of physical characteristics of the snow cover and its melting dynamics. The obtained results indicate a time delay between the beginning of the melting processes and meltwater reaching the ice surface. The time necessary for meltwater to percolate through the entire snowpack in both, the ablation zone and the equilibrium line zone amounted to c. 12 days, despite a much greater snow depth at the upper site. An elongated retention of meltwater in the lower part of the glacier was caused by a higher amount of icy layers (ice formations and melt-freeze crusts, resulting from winter thaws, which delayed water penetration. For this reason, a reconstruction of rain-on-snow events was carried out. Such results give new insight into the processes of the reactivation of the glacier drainage system and the release of freshwater into the sea after the winter period.

  10. Wet meadow ecosystems contribute the majority of overwinter soil respiration from snow-scoured alpine tundra

    Science.gov (United States)

    Knowles, John F.; Blanken, Peter D.; Williams, Mark W.

    2016-04-01

    We measured soil respiration across a soil moisture gradient ranging from dry to wet snow-scoured alpine tundra soils throughout three winters and two summers. In the absence of snow accumulation, soil moisture variability was principally determined by the combination of mesotopographical hydrological focusing and shallow subsurface permeability, which resulted in a patchwork of comingled ecosystem types along a single alpine ridge. To constrain the subsequent carbon cycling variability, we compared three measures of effective diffusivity and three methods to calculate gradient method soil respiration from four typical vegetation communities. Overwinter soil respiration was primarily restricted to wet meadow locations, and a conservative estimate of the rate of overwinter soil respiration from snow-scoured wet meadow tundra was 69-90% of the maximum carbon dioxide (CO2) respired by seasonally snow-covered soils within this same catchment. This was attributed to higher overwinter soil temperatures at wet meadow locations relative to fellfield, dry meadow, and moist meadow communities, which supported liquid water and heterotrophic respiration throughout the winter. These results were corroborated by eddy covariance-based measurements that demonstrated an average of 272 g C m-2 overwinter carbon loss during the study period. As a result, we updated a conceptual model of soil respiration versus snow cover to express the potential for soil respiration variability from snow-scoured alpine tundra.

  11. Evaluation of snow and frozen soil parameterization in a cryosphere land surface modeling framework in the Tibetan Plateau

    Science.gov (United States)

    Zhou, J.

    2017-12-01

    Snow and frozen soil are important components in the Tibetan Plateau, and influence the water cycle and energy balances through snowpack accumulation and melt and soil freeze-thaw. In this study, a new cryosphere land surface model (LSM) with coupled snow and frozen soil parameterization was developed based on a hydrologically improved LSM (HydroSiB2). First, an energy-balance-based three-layer snow model was incorporated into HydroSiB2 (hereafter HydroSiB2-S) to provide an improved description of the internal processes of the snow pack. Second, a universal and simplified soil model was coupled with HydroSiB2-S to depict soil water freezing and thawing (hereafter HydroSiB2-SF). In order to avoid the instability caused by the uncertainty in estimating water phase changes, enthalpy was adopted as a prognostic variable instead of snow/soil temperature in the energy balance equation of the snow/frozen soil module. The newly developed models were then carefully evaluated at two typical sites of the Tibetan Plateau (TP) (one snow covered and the other snow free, both with underlying frozen soil). At the snow-covered site in northeastern TP (DY), HydroSiB2-SF demonstrated significant improvements over HydroSiB2-F (same as HydroSiB2-SF but using the original single-layer snow module of HydroSiB2), showing the importance of snow internal processes in three-layer snow parameterization. At the snow-free site in southwestern TP (Ngari), HydroSiB2-SF reasonably simulated soil water phase changes while HydroSiB2-S did not, indicating the crucial role of frozen soil parameterization in depicting the soil thermal and water dynamics. Finally, HydroSiB2-SF proved to be capable of simulating upward moisture fluxes toward the freezing front from the underlying soil layers in winter.

  12. Energy balance of a sparse coniferous high-latitude forest under winter conditions

    NARCIS (Netherlands)

    Gryning, S.E.; Batchvarova, E.; DeBruin, H.A.R.

    2001-01-01

    Measurements carried out in Northern Finland on radiation and turbulent fluxes over a sparse, sub-arctic boreal forest with snow covered ground were analysed. The measurements represent late winter conditions characterised by low solar elevation angles. During the experiment (12-24 March 1997) day

  13. Effect of winter cover crop grazing on animal performance and antibiotic resistance during pre-weaning period in beef cattle

    Science.gov (United States)

    We investigated the effect of winter wheat grazing on body weight gain and the level of antibiotic resistant bacteria in beef cattle. Calves and cows (16 each) were equally randomized into tall fescue or wheat pastures. Body weights and fecal samples were taken on d 0, d 7, d 14 and d 21. Samples we...

  14. Studies of diffuse and direct solar radiation over snow

    International Nuclear Information System (INIS)

    Wesely, M.L.; Everett, R.G.

    1976-01-01

    Two interesting questions can be addressed by examination of solar radiation records obtained while the surface is covered with snow. One concerns the extent to which airborne particulate matter affects solar radiation received at the surface during winter conditions that are typical of those in the northeastern quarter of the United States. The other relates to the importance of complicated light scatterng in the earth-atmosphere system when the surface albedo is large. With the snow surface reflecting 50% or more of the incident radiation, it is likely that a significant addition to diffuse radiation would result from light that is reflected from the surface and then scattered back to the earth by the atmosphere. Preliminary data from measurements made during the winter of 1975 to 1976 are reported

  15. Antarctic snow and global climate

    International Nuclear Information System (INIS)

    Granberg, H.B.

    2001-01-01

    Global circulation models (GCM) indicate that global warming will be most pronounced at polar regions and high latitudes, causing concern about the stability of the Antarctic ice cap. A project entitled the Seasonal Snow in Antarctica examined the properties of the near surface snow to determine the current conditions that influence snow cover development. The goal was to assess the response of the snow cover in Queen Maud Land (QML) to an increased atmospheric carbon dioxide content. The Antarctic snow cover in QML was examined as part of the FINNARP expeditions in 1999 and 2000 which examined the processes that influence the snow cover. Its energy and mass balance were also assessed by examining the near surface snow strata in shallow (1-2 m) pits and by taking measurements of environmental variables. This made it possible to determine if the glacier is in danger of melting at this northerly location in the Antarctic. The study also made it possible to determine which variables need to change and by how much, for significant melting to occur. It was shown that the Antarctic anticyclone creates particular conditions that protect the snow cover from melting. The anticyclone brings dry air from the stratosphere during most of the year and is exempt from the water vapour feedback. It was concluded that even a doubling of atmospheric carbon dioxide will not produce major snow melt runoff. 8 refs

  16. Winter radiation extinction and reflection in a boreal pine canopy: measurements and modelling

    International Nuclear Information System (INIS)

    Pomeroy, J.W.; Dion, K.

    1996-01-01

    Predicting the rate of snow melt and intercepted snow sublimation in boreal forests requires an understanding of the effects of snow-covered conifers on the exchange of radiant energy. This study examined the amount of intercepted snow on a jack pine canopy in the boreal forest of central Saskatchewan and the shortwave and net radiation exchange with this canopy, to determine the effect of intercepted snow and canopy structure on shortwave radiation reflection and extinction and net radiation attenuation in a boreal forest. The study focused on clear sky conditions, which are common during winter in the continental boreal forest. Intercepted snow was found to have no influence on the clear-sky albedo of the canopy, the extinction of short wave radiation by the canopy or ratio of net radiation at the canopy top to that at the surface snow cover. Because of the low albedo of the snow-covered canopy, net radiation at the canopy top remains positive and a large potential source of energy for sublimation. The canopy albedo declines somewhat as the extinction efficiency of the underlying canopy increases. The extinction efficiency of short wave radiation in the canopy depends on solar angle because of the approximately horizontal orientation of pine branches. For low solar angles above the horizon, the extinction efficiency is quite low and short wave transmissivity through the canopy is relatively high. As the solar angle increases, extinction increases up to angles of about 50°, and then declines. Extinction of short wave radiation in the canopy strongly influences the attenuation of net radiation by the canopy. Short wave radiation that is extinguished by branches is radiated as long wave, partly downwards to the snow cover. The ratio of net radiation at the canopy top to that at the snow cover surface increases with the extinction of short wave radiation and is negative for low extinction efficiencies. For the pine canopy examined, the daily mean net radiation at

  17. Transport of marine fish larvae to Saroma-ko Lagoon (Hokkaido, Japan) in relation to the availability of zooplankton prey under the winter ice cover

    Science.gov (United States)

    Fortier, Martin; Fortier, Louis

    1997-02-01

    To assess the importance of ice-covered Saroma-ko Lagoon as a winter nursery area for young fish spawned offshore, we monitored the recruitment of marine fish larvae from the Sea of Okhotsk to the lagoon as well as the availability of larval fish prey under the ice cover from 24 February to 23 March 1992. Sand lance ( Ammodytes sp.) and walleye pollock ( Theragra chalcogramma) larvae recruited to the lagoon on flood tide whereas snake prickleback ( Lumpenus sagitta) larvae were exported to the Sea of Okhotsk on ebb. Before the ice breakup, ice microalgae made up the bulk of the microalgal biomass in the lagoon. The production and release of ice algae did not trigger the maturation of the late copepodite stages of copepods, and the proportion of adult females in the copepod assemblage remained low. The production of copepod nauplii (the main prey of fish larvae) under the ice was probably insufficient to insure suitable feeding and growth of fish larvae entering the lagoon in winter. Sand lance larvae, the most abundant species to colonize the lagoon in February-March, had to survive for nearly two months at low food abundance. Based on our results, the importance of Saroma-ko Lagoon as a winter nursery area for fish larvae appears negligible.

  18. Scaling precipitation input to spatially distributed hydrological models by measured snow distribution

    Directory of Open Access Journals (Sweden)

    Christian Vögeli

    2016-12-01

    Full Text Available Accurate knowledge on snow distribution in alpine terrain is crucial for various applicationssuch as flood risk assessment, avalanche warning or managing water supply and hydro-power.To simulate the seasonal snow cover development in alpine terrain, the spatially distributed,physics-based model Alpine3D is suitable. The model is typically driven by spatial interpolationsof observations from automatic weather stations (AWS, leading to errors in the spatial distributionof atmospheric forcing. With recent advances in remote sensing techniques, maps of snowdepth can be acquired with high spatial resolution and accuracy. In this work, maps of the snowdepth distribution, calculated from summer and winter digital surface models based on AirborneDigital Sensors (ADS, are used to scale precipitation input data, with the aim to improve theaccuracy of simulation of the spatial distribution of snow with Alpine3D. A simple method toscale and redistribute precipitation is presented and the performance is analysed. The scalingmethod is only applied if it is snowing. For rainfall the precipitation is distributed by interpolation,with a simple air temperature threshold used for the determination of the precipitation phase.It was found that the accuracy of spatial snow distribution could be improved significantly forthe simulated domain. The standard deviation of absolute snow depth error is reduced up toa factor 3.4 to less than 20 cm. The mean absolute error in snow distribution was reducedwhen using representative input sources for the simulation domain. For inter-annual scaling, themodel performance could also be improved, even when using a remote sensing dataset from adifferent winter. In conclusion, using remote sensing data to process precipitation input, complexprocesses such as preferential snow deposition and snow relocation due to wind or avalanches,can be substituted and modelling performance of spatial snow distribution is improved.

  19. Regime shift of snow days in Switzerland

    Science.gov (United States)

    Marty, Christoph

    2008-06-01

    The number of days with a snow depth above a certain threshold is the key factor for winter tourism in an Alpine country like Switzerland. An investigation of 34 long-term stations between 200 and 1800 m asl (above sea level) going back for at least the last 60 years (1948-2007) shows an unprecedented series of low snow winters in the last 20 years. The signal is uniform despite high regional differences. A shift detection analysis revealed a significant step-like decrease in snow days at the end of the 1980's with no clear trend since then. This abrupt change resulted in a loss of 20% to 60% of the total snow days. The stepwise increase of the mean winter temperature at the end of the 1980's and its close correlation with the snow day anomalies corroborate the sensitivity of the mid-latitude winter to the climate change induced temperature increase.

  20. Snow Leopard

    Indian Academy of Sciences (India)

    the Central Asian mountains and the Indian Himalayan re- gion. Owing to their ... ographical range and associated ecological, social, and cultural ... Central Asia. Snow Leopard: Morphology. The ability of snow leopards to camouflage with the surrounding landscape of rocks, sparse low vegetation, and snow is crucial for.

  1. Sensitivity Analysis of Snow Patterns in Swiss Ski Resorts to Shifts in Temperature, Precipitation and Humidity Under Condition of Climate Change

    Science.gov (United States)

    Uhlmann, B.; Goyette, S.; Beniston, M.

    2008-12-01

    The value of snow as a resource has considerably increased in Swiss mountain regions, in particular in the context of winter tourism. In the perspective of a warming climate, it is thus important to quantify the potential changes in snow amount and duration that could have large repercussions on the economy of ski resorts. Because of the fine spatial variability of snow, the use of a Surface Energy Balance Model (SEBM) is adequate to simulate local snow cover evolution. A perturbation method has been developed to generate plausible future meteorological input data required for SEBM simulations in order to assess the changes in snow cover patterns. Current and future snow depths have also been simulated within the ski areas themselves. The results show a large decrease of the snow depths and duration, even at high elevation in a warmer climate and emphasize the sensitivity of snow to topographical characteristics of the resorts. The study highlights the fact that not only the altitude of a domain but also its exposure, localization inland and slope gradients need to be taken into account when evaluating current and future snow depths. This method enables a precise assessment of the snow pattern over a small area.

  2. Spatiotemporal variability of snow depth across the Eurasian continent from 1966 to 2012

    Science.gov (United States)

    Zhong, Xinyue; Zhang, Tingjun; Kang, Shichang; Wang, Kang; Zheng, Lei; Hu, Yuantao; Wang, Huijuan

    2018-01-01

    Snow depth is one of the key physical parameters for understanding land surface energy balance, soil thermal regime, water cycle, and assessing water resources from local community to regional industrial water supply. Previous studies by using in situ data are mostly site specific; data from satellite remote sensing may cover a large area or global scale, but uncertainties remain large. The primary objective of this study is to investigate spatial variability and temporal change in snow depth across the Eurasian continent. Data used include long-term (1966-2012) ground-based measurements from 1814 stations. Spatially, long-term (1971-2000) mean annual snow depths of >20 cm were recorded in northeastern European Russia, the Yenisei River basin, Kamchatka Peninsula, and Sakhalin. Annual mean and maximum snow depth increased by 0.2 and 0.6 cm decade-1 from 1966 through 2012. Seasonally, monthly mean snow depth decreased in autumn and increased in winter and spring over the study period. Regionally, snow depth significantly increased in areas north of 50° N. Compared with air temperature, snowfall had greater influence on snow depth during November through March across the former Soviet Union. This study provides a baseline for snow depth climatology and changes across the Eurasian continent, which would significantly help to better understanding climate system and climate changes on regional, hemispheric, or even global scales.

  3. Impacts of extreme winter warming events on plant physiology in a sub-Arctic heath community.

    Science.gov (United States)

    Bokhorst, Stef; Bjerke, Jarle W; Davey, Matthew P; Taulavuori, Kari; Taulavuori, Erja; Laine, Kari; Callaghan, Terry V; Phoenix, Gareth K

    2010-10-01

    Insulation provided by snow cover and tolerance of freezing by physiological acclimation allows Arctic plants to survive cold winter temperatures. However, both the protection mechanisms may be lost with winter climate change, especially during extreme winter warming events where loss of snow cover from snow melt results in exposure of plants to warm temperatures and then returning extreme cold in the absence of insulating snow. These events cause considerable damage to Arctic plants, but physiological responses behind such damage remain unknown. Here, we report simulations of extreme winter warming events using infrared heating lamps and soil warming cables in a sub-Arctic heathland. During these events, we measured maximum quantum yield of photosystem II (PSII), photosynthesis, respiration, bud swelling and associated bud carbohydrate changes and lipid peroxidation to identify physiological responses during and after the winter warming events in three dwarf shrub species: Empetrum hermaphroditum, Vaccinium vitis-idaea and Vaccinium myrtillus. Winter warming increased maximum quantum yield of PSII, and photosynthesis was initiated for E. hermaphroditum and V. vitis-idaea. Bud swelling, bud carbohydrate decreases and lipid peroxidation were largest for E. hermaphroditum, whereas V. myrtillus and V. vitis-idaea showed no or less strong responses. Increased physiological activity and bud swelling suggest that sub-Arctic plants can initiate spring-like development in response to a short winter warming event. Lipid peroxidation suggests that plants experience increased winter stress. The observed differences between species in physiological responses are broadly consistent with interspecific differences in damage seen in previous studies, with E. hermaphroditum and V. myrtillus tending to be most sensitive. This suggests that initiation of spring-like development may be a major driver in the damage caused by winter warming events that are predicted to become more

  4. Cloud-based Computing and Applications of New Snow Metrics for Societal Benefit

    Science.gov (United States)

    Nolin, A. W.; Sproles, E. A.; Crumley, R. L.; Wilson, A.; Mar, E.; van de Kerk, M.; Prugh, L.

    2017-12-01

    Seasonal and interannual variability in snow cover affects socio-environmental systems including water resources, forest ecology, freshwater and terrestrial habitat, and winter recreation. We have developed two new seasonal snow metrics: snow cover frequency (SCF) and snow disappearance date (SDD). These metrics are calculated at 500-m resolution using NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover data (MOD10A1). SCF is the number of times snow is observed in a pixel over the user-defined observation period. SDD is the last date of observed snow in a water year. These pixel-level metrics are calculated rapidly and globally in the Google Earth Engine cloud-based environment. SCF and SDD can be interactively visualized in a map-based interface, allowing users to explore spatial and temporal snowcover patterns from 2000-present. These metrics are especially valuable in regions where snow data are sparse or non-existent. We have used these metrics in several ongoing projects. When SCF was linked with a simple hydrologic model in the La Laguna watershed in northern Chile, it successfully predicted summer low flows with a Nash-Sutcliffe value of 0.86. SCF has also been used to help explain changes in Dall sheep populations in Alaska where sheep populations are negatively impacted by late snow cover and low snowline elevation during the spring lambing season. In forest management, SCF and SDD appear to be valuable predictors of post-wildfire vegetation growth. We see a positive relationship between winter SCF and subsequent summer greening for several years post-fire. For western US winter recreation, we are exploring trends in SDD and SCF for regions where snow sports are economically important. In a world with declining snowpacks and increasing uncertainty, these metrics extend across elevations and fill data gaps to provide valuable information for decision-making. SCF and SDD are being produced so that anyone with Internet access and a Google

  5. A Framework for Thinking about the Spatial Variability of Snow across Multiple Scales and Climate Zones (Invited)

    Science.gov (United States)

    Sturm, M.

    2010-12-01

    It is well known that snow on the ground (or on lake and sea ice) varies at a myriad of scales ranging from millimeters to hundreds of kilometers. Many studies have focused directly, or in part, on snow heterogeneity at one or more of these scales, but a consistent broad framework within which these studies can be placed has yet to be developed. Consequently, the overall approach to scaling issues and snow variability is disjoint and inefficient. Nevertheless, strong common threads unite these issues. At the finest scale within-layer variations always arise from vapor transport and snow metamorphism. Layer properties vary based on weather during deposition and following snowfall (winter history). At plot to landscape scales, micro and macro topography and vegetation interact with wind, solar irradience, melt water percolation, and gravity to produce lateral variations in depth and snow water equivalent. At the coarsest scales, synoptic and climate gradients produce facies changes in both layers and bulk snow cover characteristics that vary in predictable ways. Here a preliminary multi-scale framework for snow variations is suggested and its utility discussed. At the largest scale, the framework uses the snow climate classification as a first discriminator. These classes are divided into wind-affected vs. non-wind-affected snow. Landscape and local variations in topography are then superimposed on these coarser-scale variations. Because vegetation varies with both climate and topography, it correlates with, as well as drives variations snow property variations; it becomes the third discriminator. Using these discriminators, similarities in snow variations and critical inherent length scales of several types of snow covers are explored.

  6. Climate change in winter versus the growing-season leads to different effects on soil microbial activity in northern hardwood forests

    Science.gov (United States)

    Sorensen, P. O.; Templer, P. H.; Finzi, A.

    2014-12-01

    Mean winter air temperatures have risen by approximately 2.5˚ C per decade over the last fifty years in the northeastern U.S., reducing the maximum depth of winter snowpack by approximately 26 cm over this period and the duration of winter snow cover by 3.6 to 4.2 days per decade. Forest soils in this region are projected to experience a greater number of freeze-thaw cycles and lower minimum winter soil temperatures as the depth and duration of winter snow cover declines in the next century. Climate change is likely to result not only in lower soil temperatures during winter, but also higher soil temperatures during the growing-season. We conducted two complementary experiments to determine how colder soils in winter and warmer soils in the growing-season affect microbial activity in hardwood forests at Harvard Forest, MA and Hubbard Brook Experimental Forest, NH. A combination of removing snow via shoveling and buried heating cables were used to induce freeze-thaw events during winter and to warm soils 5˚C above ambient temperatures during the growing-season. Increasing the depth and duration of soil frost via snow-removal resulted in short-term reductions in soil nitrogen (N) production via microbial proteolytic enzyme activity and net N mineralization following snowmelt, prior to tree leaf-out. Declining mass specific rates of carbon (C) and N mineralization associated with five years of snow removal at Hubbard Brook Experimental Forest may be an indication of microbial physiological adaptation to winter climate change. Freeze-thaw cycles during winter reduced microbial extracellular enzyme activity and the temperature sensitivity of microbial C and N mineralization during the growing-season, potentially offsetting nutrient and soil C losses due to soil warming in the growing-season. Our multiple experimental approaches show that winter climate change is likely to contribute to reduced microbial activity in northern hardwood forests.

  7. Work of Breathing into Snow in the Presence versus Absence of an Artificial Air Pocket Affects Hypoxia and Hypercapnia of a Victim Covered with Avalanche Snow: A Randomized Double Blind Crossover Study.

    Directory of Open Access Journals (Sweden)

    Karel Roubík

    Full Text Available Presence of an air pocket and its size play an important role in survival of victims buried in the avalanche snow. Even small air pockets facilitate breathing. We hypothesize that the size of the air pocket significantly affects the airflow resistance and work of breathing. The aims of the study are (1 to investigate the effect of the presence of an air pocket on gas exchange and work of breathing in subjects breathing into the simulated avalanche snow and (2 to test whether it is possible to breathe with no air pocket. The prospective interventional double-blinded study involved 12 male volunteers, from which 10 completed the whole protocol. Each volunteer underwent two phases of the experiment in a random order: phase "AP"--breathing into the snow with a one-liter air pocket, and phase "NP"--breathing into the snow with no air pocket. Physiological parameters, fractions of oxygen and carbon dioxide in the airways and work of breathing expressed as pressure-time product were recorded continuously. The main finding of the study is that it is possible to breath in the avalanche snow even with no air pocket (0 L volume, but breathing under this condition is associated with significantly increased work of breathing. The significant differences were initially observed for end-tidal values of the respiratory gases (EtO2 and EtCO2 and peripheral oxygen saturation (SpO2 between AP and NP phases, whereas significant differences in inspiratory fractions occurred much later (for FIO2 or never (for FICO2. The limiting factor in no air pocket conditions is excessive increase in work of breathing that induces increase in metabolism accompanied by higher oxygen consumption and carbon dioxide production. The presence of even a small air pocket reduces significantly the work of breathing.

  8. Work of Breathing into Snow in the Presence versus Absence of an Artificial Air Pocket Affects Hypoxia and Hypercapnia of a Victim Covered with Avalanche Snow: A Randomized Double Blind Crossover Study

    Science.gov (United States)

    2015-01-01

    Presence of an air pocket and its size play an important role in survival of victims buried in the avalanche snow. Even small air pockets facilitate breathing. We hypothesize that the size of the air pocket significantly affects the airflow resistance and work of breathing. The aims of the study are (1) to investigate the effect of the presence of an air pocket on gas exchange and work of breathing in subjects breathing into the simulated avalanche snow and (2) to test whether it is possible to breathe with no air pocket. The prospective interventional double-blinded study involved 12 male volunteers, from which 10 completed the whole protocol. Each volunteer underwent two phases of the experiment in a random order: phase “AP”—breathing into the snow with a one-liter air pocket, and phase “NP”—breathing into the snow with no air pocket. Physiological parameters, fractions of oxygen and carbon dioxide in the airways and work of breathing expressed as pressure-time product were recorded continuously. The main finding of the study is that it is possible to breath in the avalanche snow even with no air pocket (0 L volume), but breathing under this condition is associated with significantly increased work of breathing. The significant differences were initially observed for end-tidal values of the respiratory gases (EtO2 and EtCO2) and peripheral oxygen saturation (SpO2) between AP and NP phases, whereas significant differences in inspiratory fractions occurred much later (for FIO2) or never (for FICO2). The limiting factor in no air pocket conditions is excessive increase in work of breathing that induces increase in metabolism accompanied by higher oxygen consumption and carbon dioxide production. The presence of even a small air pocket reduces significantly the work of breathing. PMID:26666523

  9. The magnitude of the snow-sourced reactive nitrogen flux to the boundary layer in the Uintah Basin, Utah, USA

    Directory of Open Access Journals (Sweden)

    M. Zatko

    2016-11-01

    Full Text Available Reactive nitrogen (Nr  =  NO, NO2, HONO and volatile organic carbon emissions from oil and gas extraction activities play a major role in wintertime ground-level ozone exceedance events of up to 140 ppb in the Uintah Basin in eastern Utah. Such events occur only when the ground is snow covered, due to the impacts of snow on the stability and depth of the boundary layer and ultraviolet actinic flux at the surface. Recycling of reactive nitrogen from the photolysis of snow nitrate has been observed in polar and mid-latitude snow, but snow-sourced reactive nitrogen fluxes in mid-latitude regions have not yet been quantified in the field. Here we present vertical profiles of snow nitrate concentration and nitrogen isotopes (δ15N collected during the Uintah Basin Winter Ozone Study 2014 (UBWOS 2014, along with observations of insoluble light-absorbing impurities, radiation equivalent mean ice grain radii, and snow density that determine snow optical properties. We use the snow optical properties and nitrate concentrations to calculate ultraviolet actinic flux in snow and the production of Nr from the photolysis of snow nitrate. The observed δ15N(NO3− is used to constrain modeled fractional loss of snow nitrate in a snow chemistry column model, and thus the source of Nr to the overlying boundary layer. Snow-surface δ15N(NO3− measurements range from −5 to 10 ‰ and suggest that the local nitrate burden in the Uintah Basin is dominated by primary emissions from anthropogenic sources, except during fresh snowfall events, where remote NOx sources from beyond the basin are dominant. Modeled daily averaged snow-sourced Nr fluxes range from 5.6 to 71  ×  107 molec cm−2 s−1 over the course of the field campaign, with a maximum noontime value of 3.1  ×  109 molec cm−2 s−1. The top-down emission estimate of primary, anthropogenic NOx in Uintah and Duchesne counties is at least 300 times higher than

  10. Unexpected Patterns in Snow and Dirt

    Science.gov (United States)

    Ackerson, Bruce J.

    2018-01-01

    For more than 30 years, Albert A. Bartlett published "Thermal patterns in the snow" in this journal. These are patterns produced by heat sources underneath the snow. Bartlett's articles encouraged me to pay attention to patterns in snow and to understanding them. At winter's end the last snow becomes dirty and is heaped into piles. This snow comes from the final clearing of sidewalks and driveways. The patterns observed in these piles defied my intuition. This melting snow develops edges where dirt accumulates, in contrast to ice cubes, which lose sharp edges and become more spherical upon melting. Furthermore, dirt absorbs more radiation than snow and yet doesn't melt and round the sharp edges of snow, where dirt accumulates.

  11. Multiproxy summer and winter surface air temperature field reconstructions for southern South America covering the past centuries

    Energy Technology Data Exchange (ETDEWEB)

    Neukom, R.; Grosjean, M.; Wanner, H. [University of Bern, Oeschger Centre for Climate Change Research (OCCR), Bern (Switzerland); University of Bern, Institute of Geography, Climatology and Meteorology, Bern (Switzerland); Luterbacher, J. [Justus Liebig University of Giessen, Department of Geography, Climatology, Climate Dynamics and Climate Change, Giessen (Germany); Villalba, R.; Morales, M.; Srur, A. [CONICET, Instituto Argentino de Nivologia, Glaciologia y Ciencias Ambientales (IANIGLA), Mendoza (Argentina); Kuettel, M. [University of Bern, Oeschger Centre for Climate Change Research (OCCR), Bern (Switzerland); University of Bern, Institute of Geography, Climatology and Meteorology, Bern (Switzerland); University of Washington, Department of Earth and Space Sciences, Seattle (United States); Frank, D. [Swiss Federal Research Institute WSL, Birmensdorf (Switzerland); Jones, P.D. [University of East Anglia, Climatic Research Unit, School of Environmental Sciences, Norwich (United Kingdom); Aravena, J.-C. [Centro de Estudios Cuaternarios de Fuego Patagonia y Antartica (CEQUA), Punta Arenas (Chile); Black, D.E. [Stony Brook University, School of Marine and Atmospheric Sciences, Stony Brook (United States); Christie, D.A.; Urrutia, R. [Universidad Austral de Chile Valdivia, Laboratorio de Dendrocronologia, Facultad de Ciencias Forestales y Recursos Naturales, Valdivia (Chile); D' Arrigo, R. [Earth Institute at Columbia University, Tree-Ring Laboratory, Lamont-Doherty Earth Observatory, Palisades, NY (United States); Lara, A. [Universidad Austral de Chile Valdivia, Laboratorio de Dendrocronologia, Facultad de Ciencias Forestales y Recursos Naturales, Valdivia (Chile); Nucleo Cientifico Milenio FORECOS, Fundacion FORECOS, Valdivia (Chile); Soliz-Gamboa, C. [Utrecht Univ., Inst. of Environmental Biology, Utrecht (Netherlands); Gunten, L. von [Univ. of Bern (Switzerland); Univ. of Massachusetts, Climate System Research Center, Amherst (United States)

    2011-07-15

    We statistically reconstruct austral summer (winter) surface air temperature fields back to ad 900 (1706) using 22 (20) annually resolved predictors from natural and human archives from southern South America (SSA). This represents the first regional-scale climate field reconstruction for parts of the Southern Hemisphere at this high temporal resolution. We apply three different reconstruction techniques: multivariate principal component regression, composite plus scaling, and regularized expectation maximization. There is generally good agreement between the results of the three methods on interannual and decadal timescales. The field reconstructions allow us to describe differences and similarities in the temperature evolution of different sub-regions of SSA. The reconstructed SSA mean summer temperatures between 900 and 1350 are mostly above the 1901-1995 climatology. After 1350, we reconstruct a sharp transition to colder conditions, which last until approximately 1700. The summers in the eighteenth century are relatively warm with a subsequent cold relapse peaking around 1850. In the twentieth century, summer temperatures reach conditions similar to earlier warm periods. The winter temperatures in the eighteenth and nineteenth centuries were mostly below the twentieth century average. The uncertainties of our reconstructions are generally largest in the eastern lowlands of SSA, where the coverage with proxy data is poorest. Verifications with independent summer temperature proxies and instrumental measurements suggest that the interannual and multi-decadal variations of SSA temperatures are well captured by our reconstructions. This new dataset can be used for data/model comparison and data assimilation as well as for detection and attribution studies at sub-continental scales. (orig.)

  12. Snow Matters

    DEFF Research Database (Denmark)

    Gyimóthy, Szilvia; Jensen, Martin Trandberg

    2018-01-01

    attribute of high altitude mountain destinations. Hitherto, researchers mostly engaged with snowclad landscapes as a backstage; trying to deconstruct the complex symbolism and representational qualities of this elusive substance. Despite snow being a strategically crucial condition for tourism in the Alps......This chapter explores the performative potential of snow for Alpine tourism, by drawing attention to its material and nonrepresentational significance for tourism practices. European imagination has been preoccupied with snow since medieval times and even today, snow features as the sine que non...

  13. One-dimensional simulation of lake and ice dynamics during winter

    Directory of Open Access Journals (Sweden)

    Ali Oveisy

    2014-04-01

    Full Text Available An ice formation model, based on the solution of the heat conduction equation across blue ice, white ice and snow cover, is integrated into the Dynamic Reservoir Simulation Model (DYRESM to allow for one-dimensional (vertical winter simulation of lake dynamics during periods of ice cover. This is an extension of a previous three-layer snow and ice model to include two-way coupling between the ice and the water column. The process-based ice formation is suitable for application to mid-latitude regions and includes: snowmelt due to rain; formation of white ice; and variability in snow density, snow conductivity, and ice and snow albedo. The model was validated against published observations from Harmon lake, British Columbia, and new observations from Eagle lake, Ontario. The ice thickness and water column temperature profile beneath the ice were predicted with Root Mean Square Deviations (RMSD of 1 cm and 0.38°C, respectively, during the winter of 1990-91in Harmon lake. In Eagle lake the 2011-12 year-round water column temperature profile was predicted with an RMSD of 1.8°C. Improved prediction of under-ice lake temperature, relative to published results from simpler models, demonstrates the need for models that accurately capture ice-formation processes, including ice to water column coupling, formation of both blue and white ice layers, and process-based ice and snow parameters (density, conductivity and albedo.

  14. Davos-Laret Remote Sensing Field Laboratory: 2016/2017 Winter Season L-Band Measurements Data-Processing and Analysis

    Directory of Open Access Journals (Sweden)

    Reza Naderpour

    2017-11-01

    Full Text Available The L-band radiometry data and in-situ ground and snow measurements performed during the 2016/2017 winter campaign at the Davos-Laret remote sensing field laboratory are presented and discussed. An improved version of the procedure for the computation of L-band brightness temperatures from ELBARA radiometer raw data is introduced. This procedure includes a thorough explanation of the calibration and filtering including a refined radio frequency interference (RFI mitigation approach. This new mitigation approach not only performs better than conventional “normality” tests (kurtosis and skewness but also allows for the quantification of measurement uncertainty introduced by non-thermal noise contributions. The brightness temperatures of natural snow covered areas and areas with a reflector beneath the snow are simulated for varying amounts of snow liquid water content distributed across the snow profile. Both measured and simulated brightness temperatures emanating from natural snow covered areas and areas with a reflector beneath the snow reveal noticeable sensitivity with respect to snow liquid water. This indicates the possibility of estimating snow liquid water using L-band radiometry. It is also shown that distinct daily increases in brightness temperatures measured over the areas with the reflector placed on the ground indicate the onset of the snow melting season, also known as “early-spring snow”.

  15. Cold truths: how winter drives responses of terrestrial organisms to climate change.

    Science.gov (United States)

    Williams, Caroline M; Henry, Hugh A L; Sinclair, Brent J

    2015-02-01

    Winter is a key driver of individual performance, community composition, and ecological interactions in terrestrial habitats. Although climate change research tends to focus on performance in the growing season, climate change is also modifying winter conditions rapidly. Changes to winter temperatures, the variability of winter conditions, and winter snow cover can interact to induce cold injury, alter energy and water balance, advance or retard phenology, and modify community interactions. Species vary in their susceptibility to these winter drivers, hampering efforts to predict biological responses to climate change. Existing frameworks for predicting the impacts of climate change do not incorporate the complexity of organismal responses to winter. Here, we synthesise organismal responses to winter climate change, and use this synthesis to build a framework to predict exposure and sensitivity to negative impacts. This framework can be used to estimate the vulnerability of species to winter climate change. We describe the importance of relationships between winter conditions and performance during the growing season in determining fitness, and demonstrate how summer and winter processes are linked. Incorporating winter into current models will require concerted effort from theoreticians and empiricists, and the expansion of current growing-season studies to incorporate winter. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

  16. Winter climate change effects on soil C and N cycles in urban grasslands.

    Science.gov (United States)

    Durán, Jorge; Rodríguez, Alexandra; Morse, Jennifer L; Groffman, Peter M

    2013-09-01

    Despite growing recognition of the role that cities have in global biogeochemical cycles, urban systems are among the least understood of all ecosystems. Urban grasslands are expanding rapidly along with urbanization, which is expected to increase at unprecedented rates in upcoming decades. The large and increasing area of urban grasslands and their impact on water and air quality justify the need for a better understanding of their biogeochemical cycles. There is also great uncertainty about the effect that climate change, especially changes in winter snow cover, will have on nutrient cycles in urban grasslands. We aimed to evaluate how reduced snow accumulation directly affects winter soil frost dynamics, and indirectly greenhouse gas fluxes and the processing of carbon (C) and nitrogen (N) during the subsequent growing season in northern urban grasslands. Both artificial and natural snow reduction increased winter soil frost, affecting winter microbial C and N processing, accelerating C and N cycles and increasing soil : atmosphere greenhouse gas exchange during the subsequent growing season. With lower snow accumulations that are predicted with climate change, we found decreases in N retention in these ecosystems, and increases in N2 O and CO2 flux to the atmosphere, significantly increasing the global warming potential of urban grasslands. Our results suggest that the environmental impacts of these rapidly expanding ecosystems are likely to increase as climate change brings milder winters and more extensive soil frost. © 2013 John Wiley & Sons Ltd.

  17. Seasonal and inter-annual variability of aerosol optical properties during 2005-2010 over Red Mountain Pass and Impact on the Snow Cover of the San Juan Mountains

    Science.gov (United States)

    Singh, R. P.; Gautam, R.; Painter, T. H.

    2011-12-01

    Growing body of evidence suggests the significant role of aerosol solar absorption in accelerated seasonal snowmelt in the cryosphere and elevated mountain regions via snow contamination and radiative warming processes. Characterization of aerosol optical properties over seasonal snow cover and snowpacks is therefore important towards the better understanding of aerosol radiative effects and associated impact on snow albedo. In this study, we present seasonal variations in column-integrated aerosol optical properties retrieved from AERONET sunphotometer measurements (2005-2010) at Red Mountain Pass (37.90° N, 107.72° W, 3368 msl) in the San Juan Mountains, in the vicinity of the North American Great Basin and Colorado Plateau deserts. The aerosol optical depth (AOD) measured at 500nm is generally low (pollutant transport. In addition, the possibility of the observed increased coarse-mode influence associated with mineral dust influx cannot be ruled out, due to westerly-airmass driven transport from arid/desert regions as suggested by backward trajectory simulations. A meteorological coupling is also found in the summer season between AOD and column water vapor retrieved from AERONET with co-occurring enhanced water vapor and AOD. Based on column measurements, it is difficult to ascertain the aerosol composition, however, the summer-time enhanced aerosol loading as presented here is consistent with the increased dust deposition in the San Juan mountain snow cover as reported in recent studies. In summary, this study is expected to better understand the seasonal and inter-annual aerosol column variations and is an attempt to provide an insight into the effects of aerosol solar absorption on accelerated seasonal snowmelt in the San Juan mountains.

  18. Snow density climatology across the former USSR

    Science.gov (United States)

    Zhong, X.; Zhang, T.; Wang, K.

    2014-04-01

    Snow density is one of the basic properties used to describe snow cover characteristics, and it is a key factor for linking snow depth and snow water equivalent, which are critical for water resources assessment and modeling inputs. In this study, we used long-term data from ground-based measurements to investigate snow density (bulk density) climatology and its spatiotemporal variations across the former Soviet Union (USSR) from 1966 to 2008. The results showed that the long-term monthly mean snow density was approximately 0.22 ± 0.05 g cm-3 over the study area. The maximum and minimum monthly mean snow density was about 0.33 g cm-3 in June, and 0.14 g cm-3 in October, respectively. Maritime and ephemeral snow had the highest monthly mean snow density, while taiga snow had the lowest. The higher values of monthly snow density were mainly located in the European regions of the former USSR, on the coast of Arctic Russia, and the Kamchatka Peninsula, while the lower snow density occurred in central Siberia. Significant increasing trends of snow density from September through June of the next year were observed, however, the rate of the increase varied with different snow classes. The long-term (1966-2008) monthly and annual mean snow densities had significant decreasing trends, especially during the autumn months. Spatially, significant positive trends in monthly mean snow density lay in the southwestern areas of the former USSR in November and December and gradually expanded in Russia from February through April. Significant negative trends mainly lay in the European Russia and the southern Russia. There was a high correlation of snow density with elevation for tundra snow and snow density was highly correlated with latitude for prairie snow.

  19. Snow Leopard

    Indian Academy of Sciences (India)

    Owing to their secretive nature and inaccessible habitat,little is known about its ecology and distribution. Due toits endangered status and high aesthetic value, the snow leopardis considered as an 'umbrella species' for wildlife conservationin the Indian Himalayas. This article summarizes thecurrent knowledge on snow ...

  20. Snow Leopard

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 22; Issue 7. Snow Leopard: Ecology and Conservation Issues in India. Abhishek Ghoshal. General Article Volume 22 Issue 7 July 2017 pp 677- ... Keywords. Ecology, carnivore, conservation, Himalayas, mammal, snow leopard, Panthera uncia, wildlife.