WorldWideScience

Sample records for ice cores reveal

  1. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  2. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  3. Ice Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, atmospheric trace gases, and other aspects of climate and environment derived from ice cores drilled on glaciers and ice...

  4. Ice Sheets & Ice Cores

    DEFF Research Database (Denmark)

    Mikkelsen, Troels Bøgeholm

    Since the discovery of the Ice Ages it has been evident that Earth’s climate is liable to undergo dramatic changes. The previous climatic period known as the Last Glacial saw large oscillations in the extent of ice sheets covering the Northern hemisphere. Understanding these oscillations known...... as Dansgaard-Oeschger (DO) events would add to our knowledge of the climatic system and – hopefully – enable better forecasts. Likewise, to forecast possible future sea level rise it is crucial to correctly model the large ice sheets on Greenland and Antarctica. This project is divided into two parts...

  5. Ancient biomolecules from deep ice cores reveal a forested southern Greenland.

    Science.gov (United States)

    Willerslev, Eske; Cappellini, Enrico; Boomsma, Wouter; Nielsen, Rasmus; Hebsgaard, Martin B; Brand, Tina B; Hofreiter, Michael; Bunce, Michael; Poinar, Hendrik N; Dahl-Jensen, Dorthe; Johnsen, Sigfus; Steffensen, Jørgen Peder; Bennike, Ole; Schwenninger, Jean-Luc; Nathan, Roger; Armitage, Simon; de Hoog, Cees-Jan; Alfimov, Vasily; Christl, Marcus; Beer, Juerg; Muscheler, Raimund; Barker, Joel; Sharp, Martin; Penkman, Kirsty E H; Haile, James; Taberlet, Pierre; Gilbert, M Thomas P; Casoli, Antonella; Campani, Elisa; Collins, Matthew J

    2007-07-06

    It is difficult to obtain fossil data from the 10% of Earth's terrestrial surface that is covered by thick glaciers and ice sheets, and hence, knowledge of the paleoenvironments of these regions has remained limited. We show that DNA and amino acids from buried organisms can be recovered from the basal sections of deep ice cores, enabling reconstructions of past flora and fauna. We show that high-altitude southern Greenland, currently lying below more than 2 kilometers of ice, was inhabited by a diverse array of conifer trees and insects within the past million years. The results provide direct evidence in support of a forested southern Greenland and suggest that many deep ice cores may contain genetic records of paleoenvironments in their basal sections.

  6. Chernobyl nuclear accident revealed from the 7010 m Muztagata ice core record

    Institute of Scientific and Technical Information of China (English)

    TIAN LiDe; YAO TanDong; WU GuangJian; LI Zhen; XU BaiQing; LI YueFang

    2007-01-01

    The total activity variation with depth from a 41.6 m Muztagata ice core drilled at 7010 m,recorded not only the 1963 radioactive layer due to the thermonuclear test,but also clearly the radioactive peak released by the Chernobyl accident in 1986.This finding indicates that the Chernobyl nuclear accident was clearly recorded in alpine glaciers in the Pamirs of west China,and the layer can be potentially used for ice core dating in other high alpine glaciers in the surrounding regions.

  7. Ice Core Investigations

    Science.gov (United States)

    Krim, Jessica; Brody, Michael

    2008-01-01

    What can glaciers tell us about volcanoes and atmospheric conditions? How does this information relate to our understanding of climate change? Ice Core Investigations is an original and innovative activity that explores these types of questions. It brings together popular science issues such as research, climate change, ice core drilling, and air…

  8. Making an Ice Core.

    Science.gov (United States)

    Kopaska-Merkel, David C.

    1995-01-01

    Explains an activity in which students construct a simulated ice core. Materials required include only a freezer, food coloring, a bottle, and water. This hands-on exercise demonstrates how a glacier is formed, how ice cores are studied, and the nature of precision and accuracy in measurement. Suitable for grades three through eight. (Author/PVD)

  9. Ice Core Investigations

    Science.gov (United States)

    Krim, Jessica; Brody, Michael

    2008-01-01

    What can glaciers tell us about volcanoes and atmospheric conditions? How does this information relate to our understanding of climate change? Ice Core Investigations is an original and innovative activity that explores these types of questions. It brings together popular science issues such as research, climate change, ice core drilling, and air…

  10. Decapitation of high-altitude glaciers on the Tibetan Plateau revealed by ice core tritium and mercury records

    Directory of Open Access Journals (Sweden)

    S. C. Kang

    2015-01-01

    Full Text Available Two ice cores were retrieved from high elevations (~ 5800 m a.s.l. at Mt. Nyainqentanglha and Mt. Geladaindong in the southern to inland Tibetan Plateau. The combined analysis of tritium (3H, 210Pb, mercury tracers, along with other chemical records, revealed that the two coring sites had not received net ice accumulation since at least the 1950s and 1980s, respectively, implying an annual ice loss rate of more than several hundred millimeter water equivalent over these periods. Both mass balance modeling at the sites and in situ data from nearby glaciers confirmed a continuously negative mass balance (or mass loss in the region due to the dramatic warming in the last decades. Along with a recent report on Naimona'nyi Glacier in the Himalaya, the findings suggest that glacier decapitation (i.e., the loss of the accumulation zone is a wide-spread phenomenon from the southern to inland Tibetan Plateau even at the summit regions. This raises concerns over the rapid rate of glacier ice loss and associated changes in surface glacier runoff, water availability, and sea levels.

  11. Consistently dated records from three Greenland ice cores reveal regional millennial-scale isotope gradients with possible Heinrich Event imprint

    Science.gov (United States)

    Seierstad, Inger K.; Rasmussen, Sune O.

    2014-05-01

    We here present records from the NGRIP, GRIP and GISP2 ice cores tied to the same chronology for the past 104 ka at an unprecedented time resolution. The three ice cores have been linked by matching distinct peaks in volcanic proxy records and other impurity records from the three ice cores, assuming that these layers of elevated impurity content represent the same, instantaneous event in the past at all three sites. In total there are more than 900 identified marker horizons between the three cores including previously published match points, of which we introduce a minor revision. Our matching is independently confirmed by new and existing volcanic ash layers (tephra). The depth-depth relationship from the detailed matching is used to transfer the most recent and widely used Greenland ice core chronology, the GICC05modelext timescale, to the two Summit cores, GRIP and GISP2. Furthermore, we provide gas chronologies for the Summit cores that are consistent with the GICC05modelext timescale by utilizing both existing and new unpublished gas data. A comparison of the GICC05modelext and the former GISP2 timescale reveals major discrepancies in short time intervals during the glacial section. We detect a pronounced change in the relative annual layer thickness between the two Summit sites and NGRIP across the Last Glacial termination and early-to-mid Holocene, which can be explained by a relative accumulation increase at NGRIP compared to the Summit region as response to the onset of the Holocene and the climatic optimum. Between stadials and interstadials we infer that the accumulation contrast typically was nearly 10% greater at Summit compared to at NGRIP. The δ18O temperature-proxy records from NGRIP, GRIP and GISP2 are generally very similar and display a synchronous behavior at climate transitions, but the δ18O differences between Summit and NGRIP is slowly changing over the last glacial-interglacial cycle superimposed by abrupt millennial-to centennial scale

  12. Atmospheric Methane in Ice Cores

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The reconstruction of air trapped in ice cores provides us the most direct information about atmospheric CH4 variations in the past history. Ice core records from the "Three Poles (Antarctica, Greenland and Tibetan Plateau)" reveal the detailed fluctuations of atmospheric CH4 concentration with time and are allowed to quantify the CH4 differences among latitudes. These data are indispensably in the farther study of the relationship between greenhouse gases and climatic change, and of the past changes in terrestrial CH4 emissions. Ice cores reconstruction indicates that atmospheric CH4 concentration has increased quickly since industrialization, and the present day's level of atmospheric CH4 (1800 ppbv) is unprecedented during the past Glacial-Interglacial climate cycles.

  13. Ice Cores of the National Ice Core Laboratory

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. National Ice Core Laboratory (NICL) is a facility for storing, curating, and studying ice cores recovered from the polar regions of the world. It provides...

  14. Continuous greenhouse gas measurements from ice cores

    DEFF Research Database (Denmark)

    Stowasser, Christopher

    several applications of the new continuous data sets: (1) Past atmospheric mixing ratios of methane were measured along ca. 800 m of the deep ice core from the North Greenland Eemian Ice Core Drilling project (NEEM) covering almost the complete last glaciation and deglaciation. The record reveals new sub-millennial...

  15. Ancient biomolecules from deep ice cores reveal a forested southern Greenland

    DEFF Research Database (Denmark)

    Willerslev, Eske; Cappellini, Enrico; Boomsma, Wouter Krogh

    2007-01-01

    It is difficult to obtain fossil data from the 10% of Earth's terrestrial surface that is covered by thick glaciers and ice sheets, and hence, knowledge of the paleoenvironments of these regions has remained limited. We show that DNA and amino acids from buried organisms can be recovered from the...

  16. Continuous Chemistry in Ice Cores

    DEFF Research Database (Denmark)

    Kjær, Helle Astrid

    originating from volcanic eruptions, crucial for cross-dating ice cores and relevant for climate interpretations. The method includes a heat bath to minimize the acidifying effect of CO2 both from the laboratory and from the ice itself. While for acidic ice the method finds similar concentrations of H......Ice cores provide high resolution records of past climate and environment. In recent years the use of continuous flow analysis (CFA) systems has increased the measurement throughput, while simultaneously decreasing the risk of contaminating the ice samples. CFA measurements of high temporal...... resolution increase our knowledge on fast climate variations and cover a wide range of proxies informing on a variety of components such as atmospheric transport, volcanic eruptions, forest fires and many more. New CFA methods for the determination of dissolved reactive phosphorus (DRP) and pH are presented...

  17. Evidence of Historical Supernovae in Ice Cores

    Science.gov (United States)

    Young, Donna

    2011-05-01

    Within the framework of the U.S. Greenland Ice Core Science Project (GISP2), an ice core, known as the GISP H-Core, was collected in June, 1992 adjacent to the GISP2 summit drill site. The project scientists, Gisela A.M. Dreschhoff and Edward J. Zeller, were interested in dating solar proton events with volcanic eruptions. The GISP2-H 122-meter firn and ice core is a record of 415 years of liquid electrical conductivity (LEC) and nitrate concentrations, spanning the years 1992 at the surface through 1577 at the bottom. At the National Ice Core Laboratory in Denver, Colorado, the core (beneath the 12-meter firn) was sliced into 1.5 cm sections and analyzed. The resulting data set consisted of 7,776 individual analyses. The ultrahigh resolution sampling technique resulted in a time resolution of one week near the surface and one month at depth. The liquid electrical conductivity (LEC) sequence contains signals from a number of known volcanic eruptions and provides a dating system at specific locations along the core. The terrestrial and solar background nitrate records show seasonal and annual variations, respectively. However, major nitrate anomalies within the record do not correspond to any known terrestrial or solar events. There is evidence that these nitrate anomalies could be a record of supernovae events. Cosmic X-rays ionize atmospheric nitrogen, producing excess nitrate that is then deposited in the Polar Regions. The GISP2-H ice core has revealed nitrate anomalies at the times of the Tycho and Kepler supernovae. The Cassiopeia A supernova event may be documented in the core as well. We have developed a classroom activity for high school and college students, in which they examine several lines of evidence in the Greenland ice core, discriminating among nearby and mid-latitude volcanic activity, solar proton events, and supernovae. Students infer the date of the Cassiopeia A supernova.

  18. Synchronizing ice cores from the Renland and Agassiz ice caps to the Greenland Ice Core Chronology

    DEFF Research Database (Denmark)

    Vinther, Bo Møllesøe; Clausen, Henrik Brink; Fischer, D. A.

    2008-01-01

    Four ice cores from the Agassiz ice cap in the Canadian high arctic and one ice core from the Renland ice cap in eastern Greenland have been synchronized to the Greenland Ice Core Chronology 2005 (GICC05) which is based on annual layer counts in the DYE-3, GRIP and NGRIP ice cores. Volcanic...... reference horizons, seen in electrical conductivity measurements (ECM) have been used to carry out the synchronization throughout the Holocene. The Agassiz ice cores have been matched to the NGRIP ice core ECM signal, while the Renland core has been matched to the GRIP ice core ECM signal, thus tying...... the cores to GICC05. Furthermore, it has been possible to synchronize the Renland ice core to NGRIP-GICC05 in the glacial period back to 60,000 years b2k (years before A.D. 2000), on the basis of a matching of transitions between stadials and interstadials. This work brings the total number of ice core...

  19. Perspectives for DNA studies on polar ice cores

    DEFF Research Database (Denmark)

    Hansen, Anders J.; Willerslev, E.

    2002-01-01

    Recently amplifiable ancient DNA was obtained from a Greenland ice core. The DNA revealed a diversity of fungi, plants, algae and protists and has thereby expanded the range of detectable organic material in fossil glacier ice. The results suggest that ancient DNA can be obtained from other ice...... cores as well. Here, we present some future perspectives for DNA studies on polar ice cores in regard to molecular ecology, DNA damage and degradation, anabiosis and antibiotic resistance genes. Finally, we address some of the methodological problems connected to ancient DNA research....

  20. Variations in air temperature during the last 100 years revealed by δ18 O in the Malan ice core from the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Ninglian; YAO Tandong; PU Jianchen; ZHANG Yongliang; SUN Weizhen; WANG Youqing

    2003-01-01

    By comprehensive analyses, it was found that the variations in δ18O recorded in Malan ice core from the Kekexili Region on the Tibetan Plateau could represent the changes in air temperature during the summer half year (from May to October) over the Kekexili Region and the northern margin of the Tibetan Plateau. The general increase trend in δ18O in this ice core during the past century indicated climate warming, and it was estimated that air temperature during the summer half-year rose about 1.2℃over there then. However, this ice core record documented that the study area has been cooling while most of the world has been dramatically warming since the late 1970s. A teleconnection was found between the variations in δ18O in the Malan ice core and the North Atlantic Oscillation. Moreover,the variations in δ18O in this ice core were similar to that in the summer half-year air temperature over the southern Tibetan Plateau on the centurial time scale, but opposite on the multidecadal time scale.

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

    Science.gov (United States)

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

    2004-12-01

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

  2. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today

    DEFF Research Database (Denmark)

    McConnell, J.R.; Maselli, OJ; Sigl, Michael

    2014-01-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead p...

  3. Continuous greenhouse gas measurements from ice cores

    DEFF Research Database (Denmark)

    Stowasser, Christopher

    -consuming and labor-intensive. This PhD thesis presents the development of a new method for measurements of greenhouse gas mixing ratios from ice cores based on a melting device of a continuous flow analysis (CFA) system. The coupling to a CFA melting device enables time-efficient measurements of high resolution......Ice cores offer the unique possibility to study the history of past atmospheric greenhouse gases over the last 800,000 years, since past atmospheric air is trapped in bubbles in the ice. Since the 1950s, paleo-scientists have developed a variety of techniques to extract the trapped air from...... individual ice core samples, and to measure the mixing ratio of greenhouse gases such as carbon dioxide, methane and nitrous oxide in the extracted air. The discrete measurements have become highly accurate and reproducible, but require relatively large amounts of ice per measured species and are both time...

  4. The Spitzer ice legacy: Ice evolution from cores to protostars

    CERN Document Server

    Oberg, Karin I; Pontoppidan, Klaus M; Broek, Saskia van den; van Dishoeck, Ewine F; Bottinelli, Sandrine; Blake, Geoffrey A; Evans, Neal J

    2011-01-01

    Ices regulate much of the chemistry during star formation and account for up to 80% of the available oxygen and carbon. In this paper, we use the Spitzer c2d ice survey, complimented with data sets on ices in cloud cores and high-mass protostars, to determine standard ice abundances and to present a coherent picture of the evolution of ices during low- and high-mass star formation. The median ice composition H2O:CO:CO2:CH3OH:NH3:CH4:XCN is 100:29:29:3:5:5:0.3 and 100:13:13:4:5:2:0.6 toward low- and high-mass protostars, respectively, and 100:31:38:4:-:-:- in cloud cores. In the low-mass sample, the ice abundances with respect to H2O of CH4, NH3, and the component of CO2 mixed with H2O typically vary by <25%, indicative of co-formation with H2O. In contrast, some CO and CO2 ice components, XCN and CH3OH vary by factors 2-10 between the lower and upper quartile. The XCN band correlates with CO, consistent with its OCN- identification. The origin(s) of the different levels of ice abundance variations are cons...

  5. Characteristics of a crater glacier at Ushkovsky volcano, Kamchatka, Russia, as revealed by the physical properties of ice cores and borehole thermometry

    OpenAIRE

    Shiraiwa, Takayuki; Murav'yev, Yaroslav D.; Kameda,Takao; Nishio,Fumihiko; Toyama, Yoko; Takahashi, Akiyoshi; Ovsyannikov, Alexander A.; Salamatin, Andrey N.; YAMAGATA, Kotaro

    2001-01-01

    A glacier at the summit of Ushkovskyvolcano, Kamchatka peninsula, Russia, was studied in order to obtain information about the physical characteristics of a glacier that fills a volcanic crater. The glacier has a gentle surface and a concave basal profile with a maximum measured depth of 240 m at site K2. The annual accumulation rate was 0.54 m a-1 w.e., and the 10 m depth temperature was -15.8°C. A 211.70 m long ice core drilled at K2 indicates that (1) the site is categorized as a percolati...

  6. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today

    OpenAIRE

    J. R. McConnell; O. J. Maselli; Sigl, M.; P. Vallelonga; Neumann, T; H. Anschütz; R. C. Bales; Curran, M.A.J.; S. B. Das; Edwards, R.; Kipfstuhl, S.; Layman, L; E. R. Thomas

    2014-01-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was a...

  7. Siple Dome ice reveals two modes of millennial CO2 change during the last ice age.

    Science.gov (United States)

    Ahn, Jinho; Brook, Edward J

    2014-04-29

    Reconstruction of atmospheric CO2 during times of past abrupt climate change may help us better understand climate-carbon cycle feedbacks. Previous ice core studies reveal simultaneous increases in atmospheric CO2 and Antarctic temperature during times when Greenland and the northern hemisphere experienced very long, cold stadial conditions during the last ice age. Whether this relationship extends to all of the numerous stadial events in the Greenland ice core record has not been clear. Here we present a high-resolution record of atmospheric CO2 from the Siple Dome ice core, Antarctica for part of the last ice age. We find that CO2 does not significantly change during the short Greenlandic stadial events, implying that the climate system perturbation that produced the short stadials was not strong enough to substantially alter the carbon cycle.

  8. Continuous Chemistry in Ice Cores

    DEFF Research Database (Denmark)

    Kjær, Helle Astrid

    on parameters involved in the study of photolysis as a source of in situ CO2. The concentration of organic substances in Greenland ice is poorly known due to their low levels and the fact that only a few studies evaluate the concentrations of specific organic compounds. Light does not penetrate deep...... depth was found as a function of wavelength. Further, by computational chemistry hybrid density functional methods (DFT), the four most common conformers of pyruvic acid were investigated in both gas, water and ice using the DFT model CAM-B3LYP with dielectric medium methods. A de rease of the energy...

  9. Ice chemistry in starless molecular cores

    CERN Document Server

    Kalvans, Juris

    2015-01-01

    Starless molecular cores are natural laboratories for interstellar molecular chemistry research. The chemistry of ices in such objects was investigated with a three-phase (gas, surface, and mantle) model. We considered the center part of five starless cores, with their physical conditions derived from observations. The ice chemistry of oxygen, nitrogen, sulfur, and complex organic molecules (COMs) was analyzed. We found that an ice-depth dimension, measured, e.g., in monolayers, is essential for modeling of chemistry in interstellar ices. Particularly, the H2O:CO:CO2:N2:NH3 ice abundance ratio regulates the production and destruction of minor species. It is suggested that photodesorption during core collapse period is responsible for high abundance of interstellar H2O2 and O2H, and other species synthesized on the surface. The calculated abundances of COMs in ice were compared to observed gas-phase values. Smaller activation barriers for CO and H2CO hydrogenation may help explain the production of a number of...

  10. Sedimentary record of ice divide migration and ice streams in the Keewatin core region of the Laurentide Ice Sheet

    Science.gov (United States)

    Hodder, Tyler J.; Ross, Martin; Menzies, John

    2016-06-01

    The Aberdeen Lake region of central mainland Nunavut is a former core region of the Laurentide Ice Sheet that is characterized by streamlined glacial landforms classified into multiple crosscutting flow sets and near continuous till blanket. The presence of widespread till near the centre of the Keewatin Ice Dome raises questions about its origin. Detailed drillcore logging revealed a complex stratigraphy consisting of at least 6 till units, variably preserved across the study area. Till provenance analysis indicates deposition by near opposite-trending ice flow phases, interpreted as evidence of reconfiguration of the Keewatin Ice Divide. At the surface, large north-northwesterly aligned landforms are present across the study area. The till stratigraphy within these landforms indicates the same NNW ice flow phase is responsible for considerable till production. This ice flow phase is also correlated to a long regional dispersal train of erratics toward the Gulf of Boothia. The production of an extensive, thick (~ 12 m), till sheet during the NNW-trending ice flow phase occurred far from the ice margin at a time of extensive ice cover of mainland Nunavut, likely from an east-west oriented ice divide. A deglacial westerly trending ice flow phase formed small drumlins atop the larger NNW streamlined till ridges and deposited a surficial till unit that is too thin to mask the NNW flow set across the study area. It is proposed that the Boothia paleo-ice stream catchment area propagated deep into the Laurentide Ice Sheet and contributed to significant till production in this core region of the Keewatin Sector prior to the westerly ice flow shift. The apparent relationship between till thickness and the size of the associated or correlated drumlins, flow sets, and dispersal trains indicates complex erosion/deposition interplay is involved in the formation of streamlined subglacial landforms.

  11. Ices in starless and starforming cores

    CERN Document Server

    Oberg, Karin I; Pontoppidan, Klaus M; Broek, Saskia van den; van Dishoeck, Ewine F; Bottinelli, Sandrine; Blake, Geoffrey A; Evans, Neal J

    2011-01-01

    Icy grain mantles are commonly observed through infrared spectroscopy toward dense clouds, cloud cores, protostellar envelopes and protoplanetary disks. Up to 80% of the available oxygen, carbon and nitrogen are found in such ices; the most common ice constituents - H2O, CO2 and CO - are second in abundance only to H2 in many star forming regions. In addition to being a molecular reservoir, ice chemistry is responsible for much of the chemical evolution from H2O to complex, prebiotic molecules. Combining the existing ISO, Spitzer, VLT and Keck ice data results in a large sample of ice sources (\\sime80) that span all stages of star formation and a large range of protostellar luminosities (<0.1-105 L\\odot). Here we summarize the different techniques that have been applied to mine this ice data set on information on typical ice compositions in different environments and what this implies about how ices form and evolve during star and planet formation. The focus is on how to maximize the use of empirical const...

  12. Atmospheric Pb variations in Central Asia since 1955 from Muztagata ice core record, eastern Pamirs

    Institute of Scientific and Technical Information of China (English)

    LI Zhen; YAO Tandong; TIAN Lide; XU Baiqing; LI Yuefang

    2006-01-01

    A Muztagata ice core recovered at 7010 m altitude in East Pamirs provides a Pb concentration record from 1955 to 2000. The result reveals increasing Pb concentrations from 1955 to 1993, with two Pb concentration peaks in 1980 and 1993. After 1993, Pb concentrations in ice core show an obviously declining trend. Analysis shows that the lead in the Muztagata ice core mainly came from anthropogenic emissions from countries in Central Asia, while the local emission had little contribution.

  13. Annual Accumulation Data from 1997 and 1998 PARCA Ice Cores

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains annual accumulation data in water equivalent from 14 ice cores collected in 1997 and 16 ice cores collected in 1998. Data are provided in...

  14. Records of volcanic events since AD 1800 in the East Rongbuk ice core from Mt. Qomolangma

    Institute of Scientific and Technical Information of China (English)

    XU JianZhong; KASPARI S.; HOU ShuGui; KANG ShiChang; QIN DaHe; REN JiaWen; MAYEWSKI p

    2009-01-01

    Continuous Bi profile of the East Rongbuk (ER) ice core near Mr.Qomolangma reveals nine major volcanic events since AD 1800.Compared with Volcanic Explosivity Index (VEI),it shows that the con-centrations of Bi in the ER ice core can reflect the major volcanic events within the key areas.This provides a good horizon layer for ice core dating,as well as a basis for reconstructing a long sequence of volcanic records from the Qinghai-Xizang (Tibet) Plateau ice cores.

  15. Direct chemical analysis of frozen ice cores by UV-laser ablation ICPMS

    DEFF Research Database (Denmark)

    Müller, Wolfgang; Shelley, J. Michael G.; Rasmussen, Sune Olander

    2011-01-01

    Cryo-cell UV-LA-ICPMS is a new technique for direct chemical analysis of frozen ice cores at high spatial resolution (micrometer). It was tested in a pilot study on NGRIP ice and reveals sea ice/dust records and annual layer signatures at unprecedented spatial/time resolution. Uniquely...

  16. Antarctic-Wide Array of High-Resolution Ice Core Records Reveals Pervasive Lead Pollution Began in 1889 and Persists Today

    Science.gov (United States)

    McConnell, J. R.; Maselli, O. J.; Sigl, M.; Vallelonga, P.; Neumann, Thomas Allen; Anschutz, H.; Bales, R. C.; Curran, M. A. J.; Das, S. B.; Edwards, R.; Kipfstuhl, S.; Layman, L.; Thomas, E. R.

    2014-01-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.

  17. Fabric along the NEEM ice core, Greenland, and its comparison with GRIP and NGRIP ice cores

    Science.gov (United States)

    Montagnat, M.; Azuma, N.; Dahl-Jensen, D.; Eichler, J.; Fujita, S.; Gillet-Chaulet, F.; Kipfstuhl, S.; Samyn, D.; Svensson, A.; Weikusat, I.

    2014-07-01

    Fabric (distribution of crystallographic orientations) along the full NEEM ice core, Greenland was measured in the field by an automatic ice texture analyzer every 10 m, from 33 m down to 2461 m depth. The fabric evolves from a slightly anisotropic fabric at the top, toward a strong single maximum at about 2300 m, which is typical of a deformation pattern mostly driven by uniaxial compression and simple shearing. A sharp increase in the fabric strengthening rate is observed at the Holocene to Wisconsin (HW) climatic transition. From a simple model we estimate that this depth is located at a transition from a state dominated by vertical compression to a state dominated by vertical shear. Comparisons are made to two others ice cores drilled along the same ridge; the GRIP ice core, drilled at the summit of the ice sheet, and the NGRIP ice core, drilled 325 km to the NNW of the summit along the ridge, and 365 km upstream from NEEM. This comparison tends to demonstrate that the ice viscosity change with the HW climatic transition must be associated with the shear-dominated state to induce the abrupt fabric strengthening observed at NEEM. This comparison therefore reflects the increasing role of shear deformation on the coring site when moving NW along the ridge from GRIP to NGRIP and NEEM. The difference in fabric profiles between NEEM and NGRIP also evidences a stronger lateral extension associated with a sharper ridge at NGRIP. Further along the core, centimeter scale abrupt texture (fabric and microstructure) variations are observed in the bottom part of the core. Their positions are in good agreement with the observed folding layers in Dahl-Jensen et al. (2013).

  18. An Antarctic ice core recording both supernovae and solar cycles

    CERN Document Server

    Motizuki, Yuko; Makishima, Kazuo; Bamba, Aya; Nakai, Yoichi; Yano, Yasushige; Igarashi, Makoto; Motoyama, Hideaki; Kamiyama, Kokichi; Suzuki, Keisuke; Imamura, Takashi

    2009-01-01

    Ice cores are known to be rich in information regarding past climates, and the possibility that they record astronomical phenomena has also been discussed. Rood et al. were the first to suggest, in 1979, that nitrate ion (NO3-) concentration spikes observed in the depth profile of a South Pole ice core might correlate with the known historical supernovae (SNe), Tycho (AD 1572), Kepler (AD 1604), and SN 1181 (AD 1181). Their findings, however, were not supported by subsequent examinations by different groups using different ice cores, and the results have remained controversial and confusing. Here we present a precision analysis of an ice core drilled in 2001 at Dome Fuji station in Antarctica. It revealed highly significant three NO3- spikes dating from the 10th to the 11th century. Two of them are coincident with SN 1006 (AD 1006) and the Crab Nebula SN (AD 1054), within the uncertainty of our absolute dating based on known volcanic signals. Moreover, by applying time-series analyses to the measured NO3- con...

  19. The History of Early Polar Ice Cores

    Science.gov (United States)

    2008-01-01

    measurements in the Jamesway field laboratory used to study changing stress relaxation in ice core samples...remaining five individuals unknown. (Photo from H. Bader, ca 1990.) Figure 6. Field camp at Site 2, 1956–1957. The insulated canvas “ Jamesway ...view of the Site 2 drill tower and support structures, 1957. The Jamesway shelter in the background served as a heated office and warm laboratory at

  20. Post-coring entrapment of modern air in some shallow ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and ice cores

    Directory of Open Access Journals (Sweden)

    M. Aydin

    2010-06-01

    Full Text Available In this study, we report measurements of CFC-12 (CCl2F2 in firn air and in air extracted from shallow ice cores from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, some of the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for the presence of modern air entrapped in the shallow ice core samples that likely contained open pores at the time of collection. We propose that this is due to closure of the open pores after drilling, entrapping modern air and resulting in elevated CFC-12 mixing ratios. Our results reveal that open porosity can exist below the maximum depth at which firn air samples can be collected, particularly at sites with lower accumulation rates. CFC-12 measurements demonstrate that post-drilling closure of open pores can lead to a change in the composition of bubble air in shallow ice cores through purely physical processes. The results have implications for investigations involving trace gas composition of bubbles in shallow ice cores collected near the firn-ice transition.

  1. Comparison between Greenland Ice-Margin an Ice-Core Oxygen-18 Records

    DEFF Research Database (Denmark)

    Reeh, Niels; Oerter, H.; Thomsen, H. Højmark

    2002-01-01

    or more records were obtained along closely spaced parallel sampling profiles, showing good reproducibility of the records. We present ice-margin delta(18)O records reaching back to the Pleistocene. Many of the characteristic delta(18)O variations known from Greenland deep ice cores can be recognized......Old ice for palaeoenvironmental studies retrieved by deep core drilling in the central regions of the large ice sheets can also be retrieved from the ice-sheet margins. The delta(18)O content of the surface ice was studied at 15 different Greenland ice-margin locations. At some locations, two...... at locations near the central ice divide. This is in accordance with deep ice-core results. We conclude that delta(18)O records measured on ice from the Greenland ice-sheet margin provide useful information about past climate and dynamics of the ice sheet, and thus are important (and cheap) supplements to deep...

  2. Ground-penetrating radar reveals ice thickness and undisturbed englacial layers at Kilimanjaro's Northern Ice Field

    Science.gov (United States)

    Bohleber, Pascal; Sold, Leo; Hardy, Douglas R.; Schwikowski, Margit; Klenk, Patrick; Fischer, Andrea; Sirguey, Pascal; Cullen, Nicolas J.; Potocki, Mariusz; Hoffmann, Helene; Mayewski, Paul

    2017-02-01

    Although its Holocene glacier history is still subject to debate, the ongoing iconic decline of Kilimanjaro's largest remaining ice body, the Northern Ice Field (NIF), has been documented extensively based on surface and photogrammetric measurements. The study presented here adds, for the first time, ground-penetrating radar (GPR) data at centre frequencies of 100 and 200 MHz to investigate bed topography, ice thickness and internal stratigraphy at NIF. The direct comparison of the GPR signal to the visible glacier stratigraphy at NIF's vertical walls is used to validate ice thickness and reveals that the major internal reflections seen by GPR can be associated with dust layers. Internal reflections can be traced consistently within our 200 MHz profiles, indicating an uninterrupted, spatially coherent internal layering within NIF's central flat area. We show that, at least for the upper 30 m, it is possible to follow isochrone layers between two former NIF ice core drilling sites and a sampling site on NIF's vertical wall. As a result, these isochrone layers provide constraints for future attempts at linking age-depth information obtained from multiple locations at NIF. The GPR profiles reveal an ice thickness ranging between (6.1 ± 0.5) and (53.5 ± 1.0) m. Combining these data with a very high resolution digital elevation model we spatially extrapolate ice thickness and give an estimate of the total ice volume remaining at NIF's southern portion as (12.0 ± 0.3) × 106 m3.

  3. Characterization of rapid climate changes through isotope analyses of ice and entrapped air in the NEEM ice core

    DEFF Research Database (Denmark)

    Guillevic, Myriam

    Greenland ice core have revealed the occurrence of rapid climatic instabilities during the last glacial period, known as Dansgaard-Oeschger (DO) events, while marine cores from the North Atlantic have evidenced layers of ice rafted debris deposited by icebergs melt, caused by the collapse...... four Greenland deep ice cores (GRIP, GISP2, NGRIP and NEEM) are investigated over a series of Dansgaard– Oeschger events (DO 8, 9 and 10). Combined with firn modeling, δ15N data allow us to quantify abrupt temperature increases for each drill site (1σ = 0.6°C for NEEM, GRIP and GISP2, 1.5°C for NGRIP...

  4. Climatic variations since the Little Ice Age recorded in the Guliya Ice Core

    Institute of Scientific and Technical Information of China (English)

    姚檀栋; 焦克勤; 田立德; 杨志红; 施维林; Lonnie G. Thompson

    1996-01-01

    The climatic variations since the Little Ice Age recorded in the Guliya Ice Core are discussed based on glacial δ18O and accumulation records in the Guliya Ice Core. Several obvious climate fluctuation events since 1570 can be observed according to the records. In the past 400 years, the 17th and 19th centuries are relatively cool periods with less precipitation, and the 18th and 20th centuries are relatively warm periods with high precipitation. The study has also revealed the close relationship between temperature and precipitation on the plateau. Warming corresponds to high precipitation and cooling corresponds to less precipitation, which is related with the influence of monsoon on this region.

  5. Holocene accumulation and ice flow near the West Antarctic Ice Sheet Divide ice core site

    Science.gov (United States)

    Koutnik, Michelle R.; Fudge, T. J.; Conway, Howard; Waddington, Edwin D.; Neumann, Thomas A.; Cuffey, Kurt M.; Buizert, Christo; Taylor, Kendrick C.

    2016-05-01

    The West Antarctic Ice Sheet Divide Core (WDC) provided a high-resolution climate record from near the Ross-Amundsen Divide in Central West Antarctica. In addition, radar-detected internal layers in the vicinity of the WDC site have been dated directly from the ice core to provide spatial variations in the age structure of the region. Using these two data sets together, we first infer a high-resolution Holocene accumulation-rate history from 9.2 kyr of the ice-core timescale and then confirm that this climate history is consistent with internal layers upstream of the core site. Even though the WDC was drilled only 24 km from the modern ice divide, advection of ice from upstream must be taken into account. We evaluate histories of accumulation rate by using a flowband model to generate internal layers that we compare to observed layers. Results show that the centennially averaged accumulation rate was over 20% lower than modern at 9.2 kyr before present (B.P.), increased by 40% from 9.2 to 2.3 kyr B.P., and decreased by at least 10% over the past 2 kyr B.P. to the modern values; these Holocene accumulation-rate changes in Central West Antarctica are larger than changes inferred from East Antarctic ice-core records. Despite significant changes in accumulation rate, throughout the Holocene the regional accumulation pattern has likely remained similar to today, and the ice-divide position has likely remained on average within 5 km of its modern position. Continent-scale ice-sheet models used for reconstructions of West Antarctic ice volume should incorporate this accumulation history.

  6. Ice core melt features in relation to Antarctic coastal climate

    NARCIS (Netherlands)

    Kaczmarska, M.; Isaksson, E.; Karlöf, L.; Brandt, O.; Winther, J.G.; van de Wal, R.S.W.; van den Broeke, M.R.; Johnsen, S.J.

    2006-01-01

    Measurement of light intensity transmission was carried out on an ice core S100 from coastal Dronning Maud Land (DML). Ice lenses were observed in digital pictures of the core and recorded as peaks in the light transmittance record. The frequency of ice layer occurrence was compared with climate pro

  7. Post-coring entrapment of modern air in polar ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and shallow ice cores

    Directory of Open Access Journals (Sweden)

    M. Aydin

    2010-01-01

    Full Text Available In this study, we report the first measurements of CFC-12 (CCl2F2 in air extracted from shallow ice cores along with firn air CFC-12 measurements from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for presence of modern air entrapped in shallow ice core samples. We propose that this is due to closure of open pores after drilling, entrapping modern air and resulting in elevated CFC-12 mixing ratios. Our measurements reveal the presence of open porosity below the depth at which firn air samples can be collected and demonstrate how the composition of bubble air in shallow ice cores can be altered during the post-drilling period through purely physical processes. These results have implications for investigations involving trace gas composition of bubbles in shallow ice cores.

  8. Identification of deformation mechanisms in ice core samples

    OpenAIRE

    Kuiper, E.N.; Weikusat, I.; Drury, M.R.; Pennock, G.M.; de Winter, Matthijs

    2014-01-01

    To determine active deformation mechanisms in polar ice. We use LM and Electron BackScattered Diffraction to identify possible slip systems of subgrain boundaries in EDML (Antarctica) and NEEM (Greenland) ice cores.

  9. Ice-sheet flow conditions deduced from mechanical tests of ice core

    DEFF Research Database (Denmark)

    Miyamoto, Atsushi; Narita, Hideki; Hondoh, Takeo;

    1999-01-01

    Uniaxial compression tests were performed on samples of the Greenland Ice Core Project (GRIP) deep ice core, both in the field and later in a cold-room laboratory, in order to understand the ice-flow behavior of large ice sheets. Experiments were conducted under conditions of constant strain rate......-core samples with basal planes parallel to the horizontal plane of the ice sheet. The ice-flow enhancement factors show a gradual increase with depth down to approximately 2000 m. These results can be interpreted in terms of an increase in the fourth-order Schmid factor. Below 2000 m depth, the flow...

  10. Eemian interglacial reconstructed from a Greenland folded ice core

    DEFF Research Database (Denmark)

    Dahl-Jensen, D.; Albert, M.R.; Aldahan, A.

    2013-01-01

    , the thickness of the northwest Greenland ice sheet decreased by 400 ± 250 metres, reaching surface elevations 122,000 years ago of 130 ± 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during......Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new...... North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis...

  11. Microorganisms in the Malan ice core and their relation to climatic and environmental changes

    Science.gov (United States)

    Yao, Tandong; Xiang, Shurong; Zhang, Xiaojun; Wang, Ninglian; Wang, Youqing

    2006-03-01

    A 102-m-long ice core retrieved from the Malan Ice Cap on the Tibetan Plateau provides us with a historical record of the microorganisms trapped in the ice. The microorganisms in the Malan ice core are identified as α, β, and γ-Proteobacteia, and the LGC, HGC, and CFB group by means of the results of 16S rRNA sequence analysis and physiological characteristics, while the eukaryotes in the ice core are mainly composed of Chlamydomonas sp. and Pseudochlorella sp. based on the phylogenetic examination of the 18S rRNA gene. The microbial populations show observable differences at different depths in the ice core, reflecting the effects of climatic and environmental changes on the distribution of the microorganisms in the glacier. Examination of the Malan ice core shows four general periods of microbial concentration, which correspond to four phases of temperature revealed by δ18O values in the core. Observations also indicate that microorganism concentrations tend to be negatively correlated with the temperature at a relatively long timescale and, to some extent, positively correlated with mineral concentrations. The present study demonstrates that more microorganisms are associated with colder periods while fewer microorganisms are associated with warm periods, which provides us with a new proxy for the reconstruction of past climatic and environmental changes by means of ice core analysis.

  12. Continuous measurements of methane mixing ratios from ice cores

    Directory of Open Access Journals (Sweden)

    C. Stowasser

    2012-05-01

    Full Text Available This work presents a new, field-deployable technique for continuous, high-resolution measurements of methane mixing ratios from ice cores. The technique is based on a continuous flow analysis system, where ice core samples cut along the long axis of an ice core are melted continuously. The past atmospheric air contained in the ice is separated from the melt water stream via a system for continuous gas extraction. The extracted gas is dehumidified and then analyzed by a Wavelength Scanned-Cavity Ring Down Spectrometer for methane mixing ratios. We assess the performance of the new measurement technique in terms of precision (±0.8 ppbv, 1σ, accuracy (±8 ppbv, temporal (ca. 100 s, and spatial resolution (ca. 5 cm. Using a firn air transport model, we compare the resolution of the measurement technique to the resolution of the atmospheric methane signal as preserved in ice cores in Greenland. We conclude that our measurement technique can resolve all climatically relevant variations as preserved in the ice down to an ice depth of at least 1980 m (66 000 yr before present in the North Greenland Eemian Ice Drilling ice core. Furthermore, we describe the modifications, which are necessary to make a commercially available spectrometer suitable for continuous methane mixing ratio measurements from ice cores.

  13. Continuous measurements of methane mixing ratios from ice cores

    Directory of Open Access Journals (Sweden)

    C. Stowasser

    2012-01-01

    Full Text Available This work presents a new, field-deployable technique for continuous, high-resolution measurements of methane mixing ratios from ice cores. The technique is based on a continuous flow analysis system, where ice core samples cut along the long axis of an ice core are melted continuously. The past atmospheric air contained in the ice is separated from the melt water stream via a system for continuous gas extraction. The extracted gas is dehumidified and then analyzed by a Wavelength Scanned-Cavity Ring Down Spectrometer for methane mixing ratios. We assess the performance of the new measurement technique in terms of precision (±0.8 ppbv, 1 σ, accuracy (±8 ppbv, temporal (ca. 100 s and spatial resolution (ca. 6 cm. Using a firn air transport model, we compare the resolution of the measurement technique to the resolution of the atmospheric methane signal as preserved in ice cores in Greenland. We conclude that our measurement technique can resolve all climatically relevant variations as preserved in the ice down to an ice depth of at least 1980 m (66 000 yr before present in the North Greenland Eemian Ice Drilling ice core. Furthermore, we describe the modifications which are necessary to make a commercially available spectrometer suitable for continuous methane mixing ratio measurements from ice cores.

  14. Influence of sea ice on ocean water vapor isotopes and Greenland ice core records

    Science.gov (United States)

    Klein, Eric S.; Welker, Jeffrey M.

    2016-12-01

    A warming climate results in sea ice loss and impacts to the Arctic water cycle. The water isotope parameter deuterium excess, a moisture source proxy, can serve as a tracer to help understand hydrological changes due to sea ice loss. However, unlocking the sea ice change signal of isotopes from ice cores requires understanding how sea ice changes impact deuterium excess, which is unknown. Here we present the first isotope data linking a gradient of sea ice extents to oceanic water vapor deuterium excess values. Initial loss of sea ice extent leads to lower deuterium excess moisture sources, and then values progressively increase with further ice loss. Our new process-based interpretation suggests that past rapid (1-3 years) Greenland ice core changes in deuterium excess during warming might not be the result of abrupt atmospheric circulation shifts, but rather gradual loss of sea ice extent at northern latitude moisture sources.

  15. Sea ice and pollution-modulated changes in Greenland ice core methanesulfonate and bromine

    Science.gov (United States)

    Maselli, Olivia J.; Chellman, Nathan J.; Grieman, Mackenzie; Layman, Lawrence; McConnell, Joseph R.; Pasteris, Daniel; Rhodes, Rachael H.; Saltzman, Eric; Sigl, Michael

    2017-01-01

    Reconstruction of past changes in Arctic sea ice extent may be critical for understanding its future evolution. Methanesulfonate (MSA) and bromine concentrations preserved in ice cores have both been proposed as indicators of past sea ice conditions. In this study, two ice cores from central and north-eastern Greenland were analysed at sub-annual resolution for MSA (CH3SO3H) and bromine, covering the time period 1750-2010. We examine correlations between ice core MSA and the HadISST1 ICE sea ice dataset and consult back trajectories to infer the likely source regions. A strong correlation between the low-frequency MSA and bromine records during pre-industrial times indicates that both chemical species are likely linked to processes occurring on or near sea ice in the same source regions. The positive correlation between ice core MSA and bromine persists until the mid-20th century, when the acidity of Greenland ice begins to increase markedly due to increased fossil fuel emissions. After that time, MSA levels decrease as a result of declining sea ice extent but bromine levels increase. We consider several possible explanations and ultimately suggest that increased acidity, specifically nitric acid, of snow on sea ice stimulates the release of reactive Br from sea ice, resulting in increased transport and deposition on the Greenland ice sheet.

  16. Characterization of rapid climate changes through isotope analyses of ice and entrapped air in the NEEM ice core

    DEFF Research Database (Denmark)

    Guillevic, Myriam

    Greenland ice core have revealed the occurrence of rapid climatic instabilities during the last glacial period, known as Dansgaard-Oeschger (DO) events, while marine cores from the North Atlantic have evidenced layers of ice rafted debris deposited by icebergs melt, caused by the collapse...... of Northern hemisphere ice sheets, known as Heinrich events. The imprint of DO and Heinrich events is also recorded at mid to low latitudes in different archives of the northern hemisphere. A detailed multi-proxy study of the sequence of these rapid instabilities is essential for understanding the climate...... mechanisms at play. Recent analytical developments have made possible to measure new paleoclimate proxies in Greenland ice cores. In this thesis we first contribute to these analytical developments by measuring the new innovative parameter 17O-excess at LSCE (Laboratoire des Sciences du Climatet de l...

  17. The Second Deep Ice Coring Project at Dome Fuji, Antarctica

    Directory of Open Access Journals (Sweden)

    Hideaki Motoyama

    2007-09-01

    Full Text Available Throughout the history of the polar icecaps, dust and aerosols have been transported through the atmosphere to the poles, to be preserved within the annually freezing ice of the growing ice shields. Therefore, the Antarctic ice sheet is a “time capsule" for environmental data, containing information of ancient periods of Earth’s history. To unravel this history and decode cycles in glaciations and global change is among the major goals of the Dome Fuji Ice Coring Project.

  18. First continuous phosphate record from Greenland ice cores

    Directory of Open Access Journals (Sweden)

    H. A. Kjær

    2011-11-01

    Full Text Available A continuous and highly sensitive absorption method for detection of soluble phosphate in ice cores has been developed using a molybdate reagent and a 2 m liquid waveguide (LWCC. The method is optimized to meet the low concentrations of phosphate in Greenland ice, it has a detection limit of around 0.1 ppb and a depth resolution of approximately 2 cm. The new method has been applied to obtain phosphate concentrations from segments of two Northern Greenland ice cores: from a shallow firn core covering the most recent 120 yr and from the recently obtained deep NEEM ice core in which sections from the late glacial period have been analysed. Phosphate concentrations in 20th century ice are around 0.32 ppb with no indication of anthropogenic influence in the most recent ice. In the glacial part of the NEEM ice core concentrations in the cold stadial periods are significantly higher, in the range of 6–24 ppb, while interstadial ice concentrations are around 2 ppb. In the shallow firn core, a strong correlation between concentrations of phosphate and insoluble dust suggests a similar deposition pattern for phosphate and dust. In the glacial ice, phosphate and dust also correlate quite strongly, however it is most likely that this correlation originates from the phosphate binding to dust during transport, with only a fraction coming directly from dust. Additionally a constant ratio between phosphate and potassium concentrations shows evidence of a possible biogenic land source.

  19. On the nature of the dirty ice at the bottom of the GISP2 ice core

    Science.gov (United States)

    Bender, Michael L.; Burgess, Edward; Alley, Richard B.; Barnett, Bruce; Clow, Gary D.

    2010-01-01

    We present data on the triple Ar isotope composition in trapped gas from clean, stratigraphically disturbed ice between 2800 and 3040m depth in the GISP2 ice core, and from basal dirty ice from 3040 to 3053m depth. We also present data for the abundance and isotopic composition of O2 and N2, and abundance of Ar, in the basal dirty ice. The Ar/N2 ratio of dirty basal ice, the heavy isotope enrichment (reflecting gravitational fractionation), and the total gas content all indicate that the gases in basal dirty ice originate from the assimilation of clean ice of the overlying glacier, which comprises most of the ice in the dirty bottom layer. O2 is partly to completely depleted in basal ice, reflecting active metabolism. The gravitationally corrected ratio of 40Ar/38Ar, which decreases with age in the global atmosphere, is compatible with an age of 100-250ka for clean disturbed ice. In basal ice, 40Ar is present in excess due to injection of radiogenic 40Ar produced in the underlying continental crust. The weak depth gradient of 40Ar in the dirty basal ice, and the distribution of dirt, indicate mixing within the basal ice, while various published lines of evidence indicate mixing within the overlying clean, disturbed ice. Excess CH4, which reaches thousands of ppm in basal dirty ice at GRIP, is virtually absent in overlying clean disturbed ice, demonstrating that mixing of dirty basal ice into the overlying clean ice, if it occurs at all, is very slow. Order-of-magnitude estimates indicate that the mixing rate of clean ice into dirty ice is sufficient to maintain a steady thickness of dirty ice against thinning from the mean ice flow. The dirty ice appears to consist of two or more basal components in addition to clean glacial ice. A small amount of soil or permafrost, plus preglacial snow, lake or ground ice could explain the observations.

  20. On the nature of the dirty ice at the bottom of the GISP2 ice core

    Science.gov (United States)

    Bender, Michael L.; Burgess, Edward; Alley, Richard B.; Barnett, Bruce; Clow, Gary D.

    2010-11-01

    We present data on the triple Ar isotope composition in trapped gas from clean, stratigraphically disturbed ice between 2800 and 3040 m depth in the GISP2 ice core, and from basal dirty ice from 3040 to 3053 m depth. We also present data for the abundance and isotopic composition of O 2 and N 2, and abundance of Ar, in the basal dirty ice. The Ar/N 2 ratio of dirty basal ice, the heavy isotope enrichment (reflecting gravitational fractionation), and the total gas content all indicate that the gases in basal dirty ice originate from the assimilation of clean ice of the overlying glacier, which comprises most of the ice in the dirty bottom layer. O 2 is partly to completely depleted in basal ice, reflecting active metabolism. The gravitationally corrected ratio of 40Ar/ 38Ar, which decreases with age in the global atmosphere, is compatible with an age of 100-250 ka for clean disturbed ice. In basal ice, 40Ar is present in excess due to injection of radiogenic 40Ar produced in the underlying continental crust. The weak depth gradient of 40Ar in the dirty basal ice, and the distribution of dirt, indicate mixing within the basal ice, while various published lines of evidence indicate mixing within the overlying clean, disturbed ice. Excess CH 4, which reaches thousands of ppm in basal dirty ice at GRIP, is virtually absent in overlying clean disturbed ice, demonstrating that mixing of dirty basal ice into the overlying clean ice, if it occurs at all, is very slow. Order-of-magnitude estimates indicate that the mixing rate of clean ice into dirty ice is sufficient to maintain a steady thickness of dirty ice against thinning from the mean ice flow. The dirty ice appears to consist of two or more basal components in addition to clean glacial ice. A small amount of soil or permafrost, plus preglacial snow, lake or ground ice could explain the observations.

  1. Bellingshausen Sea ice extent recorded in an Antarctic Peninsula ice core

    Science.gov (United States)

    Porter, Stacy E.; Parkinson, Claire L.; Mosley-Thompson, Ellen

    2016-12-01

    Annual net accumulation (An) from the Bruce Plateau (BP) ice core retrieved from the Antarctic Peninsula exhibits a notable relationship with sea ice extent (SIE) in the Bellingshausen Sea. Over the satellite era, both BP An and Bellingshausen SIE are influenced by large-scale climatic factors such as the Amundsen Sea Low, Southern Annular Mode, and Southern Oscillation. In addition to the direct response of BP An to Bellingshausen SIE (e.g., more open water as a moisture source), these large-scale climate phenomena also link the BP and the Bellingshausen Sea indirectly such that they exhibit similar responses (e.g., northerly wind anomalies advect warm, moist air to the Antarctic Peninsula and neighboring Bellingshausen Sea, which reduces SIE and increases An). Comparison with a time series of fast ice at South Orkney Islands reveals a relationship between BP An and sea ice in the northern Weddell Sea that is relatively consistent over the twentieth century, except when it is modulated by atmospheric wave patterns described by the Trans-Polar Index. The trend of increasing accumulation on the Bruce Plateau since 1970 agrees with other climate records and reconstructions in the region and suggests that the current rate of sea ice loss in the Bellingshausen Sea is unrivaled in the twentieth century.

  2. Ice core evidence for extensive melting of the greenland ice sheet in the last interglacial.

    Science.gov (United States)

    Koerner, R M

    1989-05-26

    Evidence from ice at the bottom of ice cores from the Canadian Arctic Islands and Camp Century and Dye-3 in Greenland suggests that the Greenland ice sheet melted extensively or completely during the last interglacial period more than 100 ka (thousand years ago), in contrast to earlier interpretations. The presence of dirt particles in the basal ice has previously been thought to indicate that the base of the ice sheets had melted and that the evidence for the time of original growth of these ice masses had been destroyed. However, the particles most likely blew onto the ice when the dimensions of the ice caps and ice sheets were much smaller. Ice texture, gas content, and other evidence also suggest that the basal ice at each drill site is superimposed ice, a type of ice typical of the early growth stages of an ice cap or ice sheet. If the present-day ice masses began their growth during the last interglacial, the ice sheet from the earlier (Illinoian) glacial period must have competely or largely melted during the early part of the same interglacial period. If such melting did occur, the 6-meter higher-than-present sea level during the Sangamon cannot be attributed to disintegration of the West Antarctic ice sheet, as has been suggested.

  3. Abrupt climatic changes on the Tibetan Plateau during the Last Ice Age——Comparative study of the Guliya ice core with the Greenland GRIP ice core

    Institute of Scientific and Technical Information of China (English)

    姚檀栋

    1999-01-01

    Based on a comparative study of the Gtdiya ice core with the Greenland GRIP ice core, the abrupt climatic changes on the Tibetan Plateau during the Last Ice Age have been examined. The major stadial-interstadial events and 7 warm events (BrΦrump, Odderade, Oerel, Glinde, Hengelo, Denekamp, BΦlling) are consistent in the two ice cores. However, there are some unique features in the Guliya ice core records. The transition from warm to cold periods in the Guliya ice core is faster than that in the Greenland GRIP ice core. The magnitude of the climatic changes in the Guliya ice core is also larger than that in the Greenland GRIP ice core. Another significant feature of the Guliya ice core records is that there is a series of cycles of about 200 a from 18 to 35 kaBP. 22 warm events and 20 cold events with a fluctuation magnitude of 7℃ have been distinguished. The warm and cold events with a fluctuation magnitude within 3℃ are as high as 100. It is speculated that the abrupt climatic changes in different

  4. Annual layering in the NGRIP ice core during the Eemian

    DEFF Research Database (Denmark)

    Svensson, Anders; Bigler, Matthias; Kettner, Ernesto

    2011-01-01

    records and visual stratigraphy, and stratigraphic layer counting has been performed back to 60 ka. In the deepest part of the core, however, the ice is close to the pressure melting point, the visual stratigraphy is dominated by crystal boundaries, and annual layering is not visible to the naked eye....... In this study, we apply a newly developed setup for high-resolution ice core impurity analysis to produce continuous records of dust, sodium and ammonium concentrations as well as conductivity of melt water. We analyzed three 2.2m sections of ice from the Eemian and the glacial inception. In all of the analyzed......The Greenland NGRIP ice core continuously covers the period from present day back to 123 ka before present, which includes several thousand years of ice from the previous interglacial period, MIS 5e or the Eemian. In the glacial part of the core, annual layers can be identified from impurity...

  5. Estimation of ice sheet attenuation by using radar sounder and ice core data

    Science.gov (United States)

    Ilisei, Ana-Maria; Li, Jilu; Gogineni, Sivaprasad; Bruzzone, Lorenzo

    2016-10-01

    Due to their great impact on the environment and society, the study of the ice sheets has become a major concern of the scientific community. In particular, the estimation of the ice attenuation is crucial since it enables a more precise characterization of the ice and basal conditions. Although such problem has been often addressed in the literature, the assessment of the ice attenuation is subject to several hypotheses and uncertainties, resulting in a wide range of possible interpretations of the properties of the ice. In this paper, we propose a method for constraining the ice attenuation profiles in the vicinity of an ice core by jointly using coincident radar sounder (RS) data (radargrams) and dielectric profile (DEP) data. Radargrams contain measurements of radar reflected power from ice subsurface dielectric discontinuities (layers) on wide areas. DEP data contain ice dielectric permittivity measurements collected at an ice core. The method relies on the detection of ice layers in the radargrams, the estimation of their depth and reflectivity from the DEP data, and the use of the radar equation for the estimation of ice attenuation through the whole ice column and locally at each layer position. The method has been applied to RS and DEP data acquired at the NEEM core site in Greenland. Experimental results confirm the effectiveness of the proposed method.

  6. Continuous flow analysis of labile iron in ice-cores.

    Science.gov (United States)

    Hiscock, William T; Fischer, Hubertus; Bigler, Matthias; Gfeller, Gideon; Leuenberger, Daiana; Mini, Olivia

    2013-05-07

    The important active and passive role of mineral dust aerosol in the climate and the global carbon cycle over the last glacial/interglacial cycles has been recognized. However, little data on the most important aeolian dust-derived biological micronutrient, iron (Fe), has so far been available from ice-cores from Greenland or Antarctica. Furthermore, Fe deposition reconstructions derived from the palaeoproxies particulate dust and calcium differ significantly from the Fe flux data available. The ability to measure high temporal resolution Fe data in polar ice-cores is crucial for the study of the timing and magnitude of relationships between geochemical events and biological responses in the open ocean. This work adapts an existing flow injection analysis (FIA) methodology for low-level trace Fe determinations with an existing glaciochemical analysis system, continuous flow analysis (CFA) of ice-cores. Fe-induced oxidation of N,N'-dimethyl-p-pheylenediamine (DPD) is used to quantify the biologically more important and easily leachable Fe fraction released in a controlled digestion step at pH ~1.0. The developed method was successfully applied to the determination of labile Fe in ice-core samples collected from the Antarctic Byrd ice-core and the Greenland Ice-Core Project (GRIP) ice-core.

  7. The microstructure of polar ice. Part I: Highlights from ice core research

    Science.gov (United States)

    Faria, Sérgio H.; Weikusat, Ilka; Azuma, Nobuhiko

    2014-04-01

    Polar ice sheets play a fundamental role in Earth's climate system, by interacting actively and passively with the environment. Active interactions include the creeping flow of ice and its effects on polar geomorphology, global sea level, ocean and atmospheric circulation, and so on. Passive interactions are mainly established by the formation of climate records within the ice, in form of air bubbles, dust particles, salt microinclusions and other derivatives of airborne impurities buried by recurrent snowfalls. For a half-century scientists have been drilling deep ice cores in Antarctica and Greenland for studying such records, which can go back to around a million years. Experience shows, however, that the ice-sheet flow generally disrupts the stratigraphy of the bottom part of deep ice cores, destroying the integrity of the oldest records. For all these reasons glaciologists have been studying the microstructure of polar ice cores for decades, in order to understand the genesis and fate of ice-core climate records, as well as to learn more about the physical properties of polar ice, aiming at better climate-record interpretations and ever more precise models of ice-sheet dynamics. In this Part I we review the main difficulties and advances in deep ice core drilling in Antarctica and Greenland, together with the major contributions of deep ice coring to the research on natural ice microstructures. In particular, we discuss in detail the microstructural findings from Camp Century, Byrd, Dye 3, GRIP, GISP2, NorthGRIP, Vostok, Dome C, EDML, and Dome Fuji, besides commenting also on the earlier results of some pioneering ventures, like the Jungfraujoch Expedition and the Norwegian-British-Swedish Antarctic Expedition, among others. In the companion Part II of this work (Faria et al., 2014), the review proceeds with a survey of the state-of-the-art understanding of natural ice microstructures and some exciting prospects in this field of research.

  8. Ice Core Records of Recent Northwest Greenland Climate

    Science.gov (United States)

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

    2014-12-01

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

  9. WD2014: A new reference chronology for ice cores from Antarctica?

    Science.gov (United States)

    Sigl, Michael; McConnell, Joseph R.; Winstrup, Mai; Fudge, Taylor J.; Cole-Dai, Jihong; Ferris, David; Taylor, Kendrick; Buizert, Christo; Rhodes, Rachael; McGwire, Ken; Welten, Kees C.; Woodruff, Thomas E.; Dunbar, Nelia; Iverson, Nels; Maselli, Olivia J.; Pasteris, Daniel R.; Muscheler, Raimund

    2015-04-01

    Here we present a chronology (WD2014) for the upper part (0-2850 m, 31.2 ka BP) of the West Antarctic Ice Sheet (WAIS)-Divide ice core which is based on layer counting of distinctive annual cycles preserved in the elemental, chemical and electrical conductivity records. These cycles are caused by the seasonally varying impurity concentrations in snowfall reflecting source strength of emissions, transport and deposition efficiency. A new ice core chronology has been developed using manual interpretation as well as by using a layer detection algorithm based on Hidden Markov Models taking advantage of the large suite of sub-annually resolved and co-registered aerosol records from high-resolution continuous measurements. The age model is validated against the absolute dated radiocarbon calibration curve IntCal13 using ice-core Be-10 measurements for proxy synchronization. These records reveal an unprecedented accuracy of the new ice core chronology since the Last Glacial Maximum. The new chronology can become a reference chronology for ice cores with synchronization to other ice cores achievable through the unique high-resolution sulfur record indicating hundreds of volcanic signals common to many other deep ice cores in Antarctica. A developing tephra framework for ice cores from West Antarctica will allow to better integrating Antarctic ice cores and the marine and terrestrial records from the southern hemisphere in the future, thus gaining a detailed chronologic picture of climatic changes and environmental consequences for the region over the past 31,000 years. This southern hemisphere perspective is a fundamental step in developing a detailed global understanding of the effects of past climate changes, and its implications for the future. Due to a small ice-age gas-age difference (delta-age) at WAIS Divide - because of high annual snowfall rates at this site - and a new high-resolution WAIS CH4 record, this new ice core chronology provides also independent

  10. An Ice Core Melter System for Continuous Major and Trace Chemical Analyses of a New Mt. Logan Summit Ice Core

    Science.gov (United States)

    Osterberg, E. C.; Handley, M. J.; Sneed, S. D.; Mayewski, P. A.; Kreutz, K. J.; Fisher, D. A.

    2004-12-01

    fractions of the same sample by IC and ICP-MS validates sample coregistration. Preliminary analyses of data from the 2001 Mt. Logan summit ice core confirm subannual resolution sampling and annual scale variability of major and trace elements. Accumulation rate models and isotope data suggest that annual resolution will be possible to 1000-2000 y.b.p., with multi-annual to centennial resolution for the remainder of the Holocene and possibly including the last deglaciation. Dust proxy elements, including REEs, strongly co-vary in time-series and reveal concentration ratio fluctuations interpreted as source region changes. Volcanic eruptions are characterized by elevated concentrations of S, SO42-, Cu, Sb, Zn and other trace elements. Concentrations of potential anthropogenic contaminants are also discussed.

  11. Synchronization of ice core records via atmospheric gases

    Directory of Open Access Journals (Sweden)

    T. Blunier

    2007-06-01

    Full Text Available To interpret new high resolution climate records it becomes more and more important to know about the succession of climate events. Such knowledge is hard to get especially when dealing with different types of climate archives. Even for ice cores a direct synchronization between ice cores from Greenland and Antarctica has not been possible so far due to the lack of time markers occurring in both hemispheres. Fortunately, variations in the time series of global gas records can be used as indirect time markers. Here we discuss in detail the steps that are necessary to synchronize ice cores via global gas records exemplified on the synchronization of the EPICA ice core from Dronning Maud Land to a Greenland record from North GRIP.

  12. Forward modeling of δ18O in Andean ice cores

    Science.gov (United States)

    Hurley, J. V.; Vuille, M.; Hardy, D. R.

    2016-08-01

    Tropical ice core archives are among the best dated and highest resolution from the tropics, but a thorough understanding of processes that shape their isotope signature as well as the simulation of observed variability remain incomplete. To address this, we develop a tropical Andean ice core isotope forward model from in situ hydrologic observations and satellite water vapor isotope measurements. A control simulation of snow δ18O captures the mean and seasonal trend but underestimates the observed intraseasonal variability. The simulation of observed variability is improved by including amount effects associated with South American cold air incursions, linking synoptic-scale disturbances and monsoon dynamics to tropical ice core δ18O. The forward model was calibrated with and run under present-day conditions but can also be driven with past climate forcings to reconstruct paleomonsoon variability. The model is transferable and may be used to render a (paleo)climatic context at other ice core locations.

  13. North Atlantic Deep Water Formation: Information from Ice Cores

    Science.gov (United States)

    Oeschger, H.

    1984-01-01

    The main results of measurements of the CO2 concentration of air occluded in natural ice during periods of climatic change are presented, as well as other measured ice core parameters. Elements of an interpretation of the data in terms of mechanisms of changing environmental systems are briefly discussed.

  14. Eemian interglacial reconstructed from a Greenland folded ice core

    NARCIS (Netherlands)

    Dahl-Jensen, D.; Albert, M.; Roeckmann, T.; Zheng, J.

    2013-01-01

    Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North

  15. The Eemian ice from the new Greenland ice core at NEEM

    Science.gov (United States)

    Dahl-Jensen, D.

    2010-12-01

    Bedrock has been reached Tuesday July 27 2010 at the deep ice core drilling site, NEEM, on the Greenland Ice Sheet at the depth 2537.36 m. The NEEM scientists from the 14 nations participating in NEEM project are very excited and happy. The goals of 5 years work are reached and we have got what we came for. Ice from the warm interglacial Eemian period 130.000 to 115.000 years before present and even older ice found under the Eemian ice. The last 2 m of ice before the bedrock is full of material from the bedrock under the ice. We find stones from bedrock, conglomerates and mud and expect the ice to be rich in traces of DNA and pollen that can tell us how about the vegetation before the site was covered with ice and hopefully we will be able to determine how old these traces are. A flow model will be presented based on ice core data and internal radio echo sounding data discussing the origin of the ice from the Eemian climate period and the path of flow it has followed. A very important question to answer is how far back in time and at what depth we expect to have an undisturbed climate record and how what the record can tell us about the evolution of the Greenland ice sheet.

  16. Raman spectroscopy on ice cores from Greenland and Antarctica

    Science.gov (United States)

    Weikusat, C.; Kipfstuhl, S.

    2012-04-01

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

  17. Continuous melting and ion chromatographic analyses of ice cores.

    Science.gov (United States)

    Huber, T M; Schwikowski, M; Gäggele, H W

    2001-06-22

    A new method for determining concentrations of organic and inorganic ions in ice cores by continuous melting and contemporaneous ion chromatographic analyses was developed. A subcore is melted on a melting device and the meltwater produced is collected in two parallel sample loops and then analyzed simultaneously by two ion chromatographs, one for anions and one for cations. For most of the analyzed species, lower or equal blank values were achieved with the continuous melting and analysis technique compared to the conventional analysis. Comparison of the continuous melting and ion chromatographic analysis with the conventional analysis of a real ice core segment showed good agreement in concentration profiles and total amounts of ionic species. Thus, the newly developed method is well suited for ice core analysis and has the advantages of lower ice consumption, less time-consuming sample preparation and lower risk of contamination.

  18. Annual layering in the NGRIP ice core during the Eemian

    DEFF Research Database (Denmark)

    Svensson, Anders; Bigler, Matthias; Kettner, Ernesto

    2011-01-01

    The Greenland NGRIP ice core continuously covers the period from present day back to 123 ka before present, which includes several thousand years of ice from the previous interglacial period, MIS 5e or the Eemian. In the glacial part of the core, annual layers can be identified from impurity...... records and visual stratigraphy, and stratigraphic layer counting has been performed back to 60 ka. In the deepest part of the core, however, the ice is close to the pressure melting point, the visual stratigraphy is dominated by crystal boundaries, and annual layering is not visible to the naked eye...... migration in the deep and warm NGRIP ice. Based on annual layer counting of the new records, we determine a mean annual layer thickness close to 11mm for all three sections, which, to first order, confirms the modeled NGRIP time scale (ss09sea). The counting does, however, suggest a longer duration...

  19. Measurements of sea ice proxies from Antarctic coastal shallow cores

    Science.gov (United States)

    Maffezzoli, Niccolò; Vallelonga, Paul; Spolaor, Andrea; Barbante, Carlo; Frezzotti, Massimo

    2015-04-01

    Despite its close relationship with climate, the climatic impact of sea ice remains only partially understood: an indication of this is the Arctic sea ice which is declining at a faster rate than models predict. Thus, the need for reliable sea ice proxies is of crucial importance. Among the sea ice proxies that can be extracted from ice cores, interest has recently been shown in the halogens Iodine (I) and Bromine (Br) (Spolaor, A., et al., 2013a, 2013b). The production of sea ice is a source of Sodium and Bromine aerosols through frost flower crystal formation and sublimation of salty blowing snow, while Iodine is emitted by the algae living underneath sea ice. We present here the results of Na, Br and I measurements in Antarctic shallow cores, drilled during a traverse made in late 2013 - early 2014 from Talos Dome (72° 00'S, 159°12'E) to GV7 (70° 41'S, 158° 51'E) seeking for sea ice signature. The samples were kept frozen until the analyses, that were carried out by Sector Field Mass Spectroscopy Inductive Coupled Plasma (SFMS-ICP): special precautions and experimental steps were adopted for the detection of such elements. The coastal location of the cores allows a clear signal from the nearby sea ice masses. The multiple cores are located about 50 km from each other and can help us to infer the provenance of the sea ice that contributed to the proxy signature. Moreover, by simultaneously determining other chemical elements and compounds in the snow, it is possible to determine the relative timing of their deposition, thus helping us to understand their processes of emission and deposition.

  20. First investigations of an ice core from Eisriesenwelt cave (Austria

    Directory of Open Access Journals (Sweden)

    B. May

    2011-02-01

    Full Text Available Investigations into the genesis and dynamical properties of cave ice are essential for assessing the climate significance of these underground glaciers. We drilled an ice core through a 7.1 m-thick ice body filling a large cavern of the dynamic ice cave Eisenriesenwelt (Austria. In addition to visual core inspections, quasi-continuous measurements at 2 cm resolution comprised particulate matter, stable water isotope (δ18O, δD and electrolytic conductivity profiles supplemented by specifically selected samples analyzed for tritium and radiocarbon. We found that recent ablation led to an almost complete loss of bomb-derived tritium removing any ice accumulated since, at least, the early fifties leaving the actual ice surface even below the natural tritium level. The small particulate organic masses rendered radiocarbon dating inconclusive, though a crude estimate gave a basal ice age in the order of several thousand years. The visual stratigraphy and all investigated parameters showed a clear dichotomy between the upper 2 m and the bottom 3 m of the core, which points to a substantial change in the ice formation process. Main features of the core comprise the changing appearance and composition of distinct cryocalcite layers, extremely low total ion content and a surprisingly high variability of the isotope signature. Co-isotope evaluation (δD versus δ18O of the core in comparison with data from precipitation and karst spring water clearly indicate that ice formation is governed by (slow freezing of dripping water.

  1. Changes of the Bacterial Abundance and Communities in Shallow Ice Cores from Dunde and Muztagata Glaciers, Western China.

    Science.gov (United States)

    Chen, Yong; Li, Xiang-Kai; Si, Jing; Wu, Guang-Jian; Tian, Li-De; Xiang, Shu-Rong

    2016-01-01

    In this study, six bacterial community structures were analyzed from the Dunde ice core (9.5-m-long) using 16S rRNA gene cloning library technology. Compared to the Muztagata mountain ice core (37-m-long), the Dunde ice core has different dominant community structures, with five genus-related groups Blastococcus sp./Propionibacterium, Cryobacterium-related., Flavobacterium sp., Pedobacter sp., and Polaromas sp. that are frequently found in the six tested ice layers from 1990 to 2000. Live and total microbial density patterns were examined and related to the dynamics of physical-chemical parameters, mineral particle concentrations, and stable isotopic ratios in the precipitations collected from both Muztagata and Dunde ice cores. The Muztagata ice core revealed seasonal response patterns for both live and total cell density, with high cell density occurring in the warming spring and summer months indicated by the proxy value of the stable isotopic ratios. Seasonal analysis of live cell density for the Dunde ice core was not successful due to the limitations of sampling resolution. Both ice cores showed that the cell density peaks were frequently associated with high concentrations of particles. A comparison of microbial communities in the Dunde and Muztagata glaciers showed that similar taxonomic members exist in the related ice cores, but the composition of the prevalent genus-related groups is largely different between the two geographically different glaciers. This indicates that the micro-biogeography associated with geographic differences was mainly influenced by a few dominant taxonomic groups.

  2. Chemical signals of past climate and environment from polar ice cores and firn air.

    Science.gov (United States)

    Wolff, Eric W

    2012-10-07

    Chemical and isotopic records obtained from polar ice cores have provided some of the most iconic datasets in Earth system science. Here, I discuss how the different records are formed in the ice sheets, emphasising in particular the contrast between chemistry held in the snow/ice phase, and that which is trapped in air bubbles. Air diffusing slowly through the upper firn layers of the ice sheet can also be sampled in large volumes to give more recent historical information on atmospheric composition. The chemical and geophysical issues that have to be solved to interpret ice core data in terms of atmospheric composition and emission changes are also highlighted. Ice cores and firn air have provided particularly strong evidence about recent changes (last few decades to centuries), including otherwise inaccessible data on increases in compounds that are active as greenhouse gases or as agents of stratospheric depletion. On longer timescales (up to 800,000 years in Antarctica), ice cores reveal major changes in biogeochemical cycling, which acted as feedbacks on the very major changes in climate between glacial and interglacial periods.

  3. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core

    Science.gov (United States)

    Spolaor, Andrea; Vallelonga, Paul; Turetta, Clara; Maffezzoli, Niccolò; Cozzi, Giulio; Gabrieli, Jacopo; Barbante, Carlo; Goto-Azuma, Kumiko; Saiz-Lopez, Alfonso; Cuevas, Carlos A.; Dahl-Jensen, Dorthe

    2016-09-01

    Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called “bromine explosions” and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice. We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values. First-year sea ice extent was lowest during the glacial stadials suggesting complete coverage of the Arctic Ocean by multi-year sea ice. These findings demonstrate a clear relationship between temperature and first-year sea ice extent in the Arctic and suggest multi-year sea ice will continue to decline as polar amplification drives Arctic temperatures beyond the 2 °C global average warming target of the recent COP21 Paris climate agreement.

  4. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core.

    Science.gov (United States)

    Spolaor, Andrea; Vallelonga, Paul; Turetta, Clara; Maffezzoli, Niccolò; Cozzi, Giulio; Gabrieli, Jacopo; Barbante, Carlo; Goto-Azuma, Kumiko; Saiz-Lopez, Alfonso; Cuevas, Carlos A; Dahl-Jensen, Dorthe

    2016-09-21

    Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called "bromine explosions" and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice. We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values. First-year sea ice extent was lowest during the glacial stadials suggesting complete coverage of the Arctic Ocean by multi-year sea ice. These findings demonstrate a clear relationship between temperature and first-year sea ice extent in the Arctic and suggest multi-year sea ice will continue to decline as polar amplification drives Arctic temperatures beyond the 2 °C global average warming target of the recent COP21 Paris climate agreement.

  5. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core

    Science.gov (United States)

    Spolaor, Andrea; Vallelonga, Paul; Turetta, Clara; Maffezzoli, Niccolò; Cozzi, Giulio; Gabrieli, Jacopo; Barbante, Carlo; Goto-Azuma, Kumiko; Saiz-Lopez, Alfonso; Cuevas, Carlos A.; Dahl-Jensen, Dorthe

    2016-01-01

    Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called “bromine explosions” and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice. We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values. First-year sea ice extent was lowest during the glacial stadials suggesting complete coverage of the Arctic Ocean by multi-year sea ice. These findings demonstrate a clear relationship between temperature and first-year sea ice extent in the Arctic and suggest multi-year sea ice will continue to decline as polar amplification drives Arctic temperatures beyond the 2 °C global average warming target of the recent COP21 Paris climate agreement. PMID:27650478

  6. The isotopic composition of methane in polar ice cores

    Science.gov (United States)

    Craig, H.; Chou, C. C.; Welhan, J. A.; Stevens, C. M.; Engelkemeir, A.

    1988-01-01

    Air bubbles in polar ice cores indicate that about 300 years ago the atmospheric mixing ratio of methane began to increase rapidly. Today the mixing ratio is about 1.7 parts per million by volume, and, having doubled once in the past several hundred years, it will double again in the next 60 years if current rates continue. Carbon isotope ratios in methane up to 350 years in age have been measured with as little as 25 kilograms of polar ice recovered in 4-meter-long ice-core segments. The data show that: (1) in situ microbiology or chemistry has not altered the ice-core methane concentrations, and (2) that the carbon-13 to carbon-12 ratio of atmospheric CH4 in ice from 100 years and 300 years ago was about 2 per mil lower than at present. Atmospheric methane has a rich spectrum of isotopic sources: the ice-core data indicate that anthropogenic burning of the earth's biomass is the principal cause of the recent C-13H4 enrichment, although other factors may also contribute.

  7. Annual layering in the NGRIP ice core during the Eemian

    Directory of Open Access Journals (Sweden)

    A. Svensson

    2011-02-01

    Full Text Available The Greenland NGRIP ice core continuously covers the period from present day back to 123 ka before present, which includes several thousand years of ice from the previous interglacial period, MIS 5e or the Eemian. In the glacial part of the core annual layers can be identified from impurity records and visual stratigraphy, and stratigraphic layer counting has been performed back to 60 ka. In the deepest part of the core, however, the ice is close to the pressure melting point, the visual stratigraphy is dominated by crystal boundaries, and annual layering is not visible to the naked eye. In this study, we apply a newly developed setup for high-resolution ice core impurity analysis to produce continuous records of dust, sodium and ammonium concentrations as well as conductivity of melt water. We analyzed three 2.2 m sections of ice from the Eemian and the glacial inception. In all of the analyzed ice, annual layers can clearly be recognized, most prominently in the dust and conductivity profiles. Part of the samples is, however, contaminated in dust, most likely from drill liquid. It is interesting that the annual layering is preserved despite a very active crystal growth and grain boundary migration in the deep and warm NGRIP ice. Based on annual layer counting of the new records, we determine a mean annual layer thickness close to 11 mm for all three sections, which, to first order, confirms the modeled NGRIP time scale (ss09sea. The counting does, however, suggest a longer duration of the climatically warmest part of the NGRIP record (MIS5e of up to 1 ka as compared to the model estimate. Our results suggest that stratigraphic layer counting is possible basically throughout the entire NGRIP ice core provided sufficiently highly-resolved profiles become available.

  8. Annual layering in the NGRIP ice core during the Eemian

    Directory of Open Access Journals (Sweden)

    A. Svensson

    2011-12-01

    Full Text Available The Greenland NGRIP ice core continuously covers the period from present day back to 123 ka before present, which includes several thousand years of ice from the previous interglacial period, MIS 5e or the Eemian. In the glacial part of the core, annual layers can be identified from impurity records and visual stratigraphy, and stratigraphic layer counting has been performed back to 60 ka. In the deepest part of the core, however, the ice is close to the pressure melting point, the visual stratigraphy is dominated by crystal boundaries, and annual layering is not visible to the naked eye. In this study, we apply a newly developed setup for high-resolution ice core impurity analysis to produce continuous records of dust, sodium and ammonium concentrations as well as conductivity of melt water. We analyzed three 2.2 m sections of ice from the Eemian and the glacial inception. In all of the analyzed ice, annual layers can clearly be recognized, most prominently in the dust and conductivity profiles. Part of the samples is, however, contaminated in dust, most likely from drill liquid. It is interesting that the annual layering is preserved despite a very active crystal growth and grain boundary migration in the deep and warm NGRIP ice. Based on annual layer counting of the new records, we determine a mean annual layer thickness close to 11 mm for all three sections, which, to first order, confirms the modeled NGRIP time scale (ss09sea. The counting does, however, suggest a longer duration of the climatically warmest part of the NGRIP record (MIS5e of up to 1 ka as compared to the model estimate. Our results suggest that stratigraphic layer counting is possible basically throughout the entire NGRIP ice core, provided sufficiently highly-resolved profiles become available.

  9. Calibrated cryo-cell UV-LA-ICPMS elemental concentrations from the NGRIP ice core reveal abrupt, sub-annual variability in dust across the GI-21.2 interstadial period

    Science.gov (United States)

    Della Lunga, Damiano; Müller, Wolfgang; Olander Rasmussen, Sune; Svensson, Anders; Vallelonga, Paul

    2017-05-01

    Several abrupt shifts from periods of extreme cold (Greenland stadials, GS) to relatively warmer conditions (Greenland interstadials, GI) called Dansgaard-Oeschger events are recorded in the Greenland ice cores. Using cryo-cell UV-laser-ablation inductively coupled-plasma mass spectrometry (UV-LA-ICPMS), we analysed a 2.85 m NGRIP ice core section (2691.50-2688.65 m depth, age interval 84.86-85.09 ka b2k, thus covering ˜ 230 years) across the transitions of GI-21.2, a short-lived interstadial prior to interstadial GI-21.1. GI-21.2 is a ˜ 100-year long period with δ18O values 3-4 ‰ higher than the following ˜ 200 years of stadial conditions (GS-21.2), which precede the major GI-21.1 warming. We report concentrations of major elements indicative of dust and/or sea salt (Na, Fe, Al, Ca, Mg) at a spatial resolution of ˜ 200 µm, while maintaining detection limits in the low-ppb range, thereby achieving sub-annual time resolution even in deep NGRIP ice. We present an improved external calibration and quantification procedure using a set of five ice standards made from aqueous (international) standard solutions. Our results show that element concentrations decrease drastically (more than 10-fold) at the warming onset of GI-21.2 at the scale of a single year, followed by relatively low concentrations characterizing the interstadial part before gradually reaching again typical stadial values.

  10. A first chronology for the NEEM ice core

    Directory of Open Access Journals (Sweden)

    S. O. Rasmussen

    2013-05-01

    Full Text Available A stratigraphy-based chronology for the North Greenland Eemian Ice Drilling (NEEM ice core has been derived by transferring the annual layer counted Greenland Ice Core Chronology 2005 (GICC05 from the NGRIP core to the NEEM core using 787 match points of mainly volcanic origin identified in the Electrical Conductivity Measurement (ECM and Dielectrical Profiling (DEP records. Tephra horizons found in both the NEEM and NGRIP ice cores are used to test the matching based on ECM and DEP and provide additional horizons used for the time scale transfer. A thinning function reflecting the accumulated strain along the core has been determined using a Dansgaard–Johnsen flow model and an isotope-dependent accumulation rate parameterization. Flow parameters are determined from Monte Carlo analysis constrained by the observed depth-age horizons. In order to construct a chronology for the gas phase, the ice age–gas age difference (Δage has been reconstructed using a coupled firn densification–heat diffusion model. Temperature and accumulation inputs to the Δage model, initially derived from the water isotope proxies, have been adjusted to optimize the fit to timing constraints from δ15N of nitrogen and high-resolution methane data during the abrupt onsets of interstadials. The ice and gas chronologies and the corresponding thinning function represent the first chronology for the NEEM core, and based on both the flow and firn modelling results, the accumulation history for the NEEM site has been reconstructed, providing the necessary basis for further analysis of the records from NEEM.

  11. Pre-cometary ice composition from hot core chemistry.

    Science.gov (United States)

    Tornow, Carmen; Kührt, Ekkehard; Motschmann, Uwe

    2005-10-01

    Pre-cometary ice located around star-forming regions contains molecules that are pre-biotic compounds or pre-biotic precursors. Molecular line surveys of hot cores provide information on the composition of the ice since it sublimates near these sites. We have combined a hydrostatic hot core model with a complex network of chemical reactions to calculate the time-dependent abundances of molecules, ions, and radicals. The model considers the interaction between the ice and gas phase. It is applied to the Orion hot core where high-mass star formation occurs, and to the solar-mass binary protostar system IRAS 16293-2422. Our calculations show that at the end of the hot core phase both star-forming sites produce the same prebiotic CN-bearing molecules. However, in the Orion hot core these molecules are formed in larger abundances. A comparison of the calculated values with the abundances derived from the observed line data requires a chemically unprocessed molecular cloud as the initial state of hot core evolution. Thus, it appears that these objects are formed at a much younger cloud stage than previously thought. This implies that the ice phase of the young clouds does not contain CN-bearing molecules in large abundances before the hot core has been formed. The pre-biotic molecules synthesized in hot cores cause a chemical enrichment in the gas phase and in the pre-cometary ice. This enrichment is thought to be an important extraterrestrial aspect of the formation of life on Earth and elsewhere.

  12. Evidence for warmer interglacials in East Antarctic ice cores.

    Science.gov (United States)

    Sime, L C; Wolff, E W; Oliver, K I C; Tindall, J C

    2009-11-19

    Stable isotope ratios of oxygen and hydrogen in the Antarctic ice core record have revolutionized our understanding of Pleistocene climate variations and have allowed reconstructions of Antarctic temperature over the past 800,000 years (800 kyr; refs 1, 2). The relationship between the D/H ratio of mean annual precipitation and mean annual surface air temperature is said to be uniform +/-10% over East Antarctica and constant with time +/-20% (refs 3-5). In the absence of strong independent temperature proxy evidence allowing us to calibrate individual ice cores, prior general circulation model (GCM) studies have supported the assumption of constant uniform conversion for climates cooler than that of the present day. Here we analyse the three available 340 kyr East Antarctic ice core records alongside input from GCM modelling. We show that for warmer interglacial periods the relationship between temperature and the isotopic signature varies among ice core sites, and that therefore the conversions must be nonlinear for at least some sites. Model results indicate that the isotopic composition of East Antarctic ice is less sensitive to temperature changes during warmer climates. We conclude that previous temperature estimates from interglacial climates are likely to be too low. The available evidence is consistent with a peak Antarctic interglacial temperature that was at least 6 K higher than that of the present day -approximately double the widely quoted 3 +/- 1.5 K (refs 5, 6).

  13. An automated approach for annual layer counting in ice cores

    DEFF Research Database (Denmark)

    Winstrup, Mai; Svensson, A. M.; Rasmussen, S. O.;

    2012-01-01

    detection algorithm lies in the way it is able to imitate the manual procedures for annual layer counting, while being based on statistical criteria for annual layer identification. The most likely positions of multiple layer boundaries in a section of ice core data are determined simultaneously......, and a probabilistic uncertainty estimate of the resulting layer count is provided, ensuring an objective treatment of ambiguous layers in the data. Furthermore, multiple data series can be incorporated and used simultaneously. In this study, the automated layer counting algorithm has been applied to two ice core...

  14. An automated approach for annual layer counting in ice cores

    DEFF Research Database (Denmark)

    Winstrup, Mai; Svensson, A. M.; Rasmussen, S. O.;

    2012-01-01

    detection algorithm lies in the way it is able to imitate the manual procedures for annual layer counting, while being based on statistical criteria for annual layer identification. The most likely positions of multiple layer boundaries in a section of ice core data are determined simultaneously......, and a probabilistic uncertainty estimate of the resulting layer count is provided, ensuring an objective treatment of ambiguous layers in the data. Furthermore, multiple data series can be incorporated and used simultaneously. In this study, the automated layer counting algorithm has been applied to an ice core...

  15. Ice core extraction at Naimona'nyi Glacier

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Headed by YAO Tandong,director of the CAS Institute of Tibetan Plateau Research, and Prof. Lonnie Thompson from Ohio State University, a group of Sino-US scientists have recently wound up their work on ice core extraction at a glacier 6,100meters above the sea level on the Mt. Naimona'nyi in southwest Himalayas. After more than twomonth hard work, they recovered four ice cores, three to the bedrock with a length of 113.65, 137.77 and 158.04 meters, respectively and a shallow one, providing fresh data for reconstructing climate variation since the last Glacial Epoch in the region.

  16. Evidence for general instability of past climate from a 250-KYR ice-core record

    DEFF Research Database (Denmark)

    Johnsen, Sigfus Johann; Clausen, Henrik Brink; Dahl-Jensen, Dorthe

    1993-01-01

     results1,2 from two ice cores drilled in central Greenland have revealed large, abrupt climate changes of at least regional extent during the late stages of the last glaciation, suggesting that climate in the North Atlantic region is able to reorganize itself rapidly, perhaps even within a few...... decades. Here we present a detailed stable-isotope record for the full length of the Greenland Ice-core Project Summit ice core, extending over the past 250 kyr according to a calculated timescale. We find that climate instability was not confined to the last glaciation, but appears also to have been...... marked during the last interglacial (as explored more fully in a companion paper3) and during the previous Saale-Holstein glacial cycle. This is in contrast with the extreme stability of the Holocene, suggesting that recent climate stability may be the exception rather than the rule. The last...

  17. Influence of the Tungurahua eruption on the ice core records of Chimborazo, Ecuador

    Directory of Open Access Journals (Sweden)

    P. Ginot

    2010-08-01

    Full Text Available The comparison of two shallow ice cores recovered in 1999 and 2000 from the same place on Chimborazo summit glacier revealed the influence of the coincident Tungurahua volcanic eruption on their stable isotope and chemical records. The surface snow melting and water percolation induced from the ash deposition caused a preferential elution and re-localization of certain ionic species, while the stable isotope records were not very affected. Additionally, the comparison of the ionic amount and some selected ratios preserved along the ice core column reports under which processes the chemical species are introduced in the snow pack, as snow flake condensation nuclei, by atmospheric scavenging or by dry deposition. This preliminary study is essential for the interpretation of the deep Chimborazo ice core, or for other sites where surrounding volcanic activity may disturb the glaciochemical records.

  18. Influence of the Tungurahua eruption on the ice core records of Chimborazo, Ecuador

    Directory of Open Access Journals (Sweden)

    P. Ginot

    2010-12-01

    Full Text Available The comparison of two shallow ice cores recovered in 1999 and 2000 from the same place on the Chimborazo summit glacier revealed the influence of the coincident Tungurahua volcanic eruption on their stable isotope and chemical records. The surface snow melting and water percolation induced from the ash deposition caused a preferential elution and re-localization of certain ionic species, while the stable isotope records were not affected. Additionally, the comparison of the ionic amount and some selected ion ratios preserved along the ice core column reports under which processes the chemical species are introduced in the snow pack, as snow flake condensation nuclei, by atmospheric scavenging or by dry deposition. This preliminary study is essential for the interpretation of the deep Chimborazo ice core, or for other sites where surrounding volcanic activity influences the glaciochemical records.

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

    DEFF Research Database (Denmark)

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

    2001-01-01

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

  20. High Resolution Continuous Flow Analysis System for Polar Ice Cores

    Science.gov (United States)

    Dallmayr, Remi; Azuma, Kumiko; Yamada, Hironobu; Kjær, Helle Astrid; Vallelonga, Paul; Azuma, Nobuhiko; Takata, Morimasa

    2014-05-01

    In the last decades, Continuous Flow Analysis (CFA) technology for ice core analyses has been developed to reconstruct the past changes of the climate system 1), 2). Compared with traditional analyses of discrete samples, a CFA system offers much faster and higher depth resolution analyses. It also generates a decontaminated sample stream without time-consuming sample processing procedure by using the inner area of an ice-core sample.. The CFA system that we have been developing is currently able to continuously measure stable water isotopes 3) and electrolytic conductivity, as well as to collect discrete samples for the both inner and outer areas with variable depth resolutions. Chemistry analyses4) and methane-gas analysis 5) are planned to be added using the continuous water stream system 5). In order to optimize the resolution of the current system with minimal sample volumes necessary for different analyses, our CFA system typically melts an ice core at 1.6 cm/min. Instead of using a wire position encoder with typical 1mm positioning resolution 6), we decided to use a high-accuracy CCD Laser displacement sensor (LKG-G505, Keyence). At the 1.6 cm/min melt rate, the positioning resolution was increased to 0.27mm. Also, the mixing volume that occurs in our open split debubbler is regulated using its weight. The overflow pumping rate is smoothly PID controlled to maintain the weight as low as possible, while keeping a safety buffer of water to avoid air bubbles downstream. To evaluate the system's depth-resolution, we will present the preliminary data of electrolytic conductivity obtained by melting 12 bags of the North Greenland Eemian Ice Drilling (NEEM) ice core. The samples correspond to different climate intervals (Greenland Stadial 21, 22, Greenland Stadial 5, Greenland Interstadial 5, Greenland Interstadial 7, Greenland Stadial 8). We will present results for the Greenland Stadial -8, whose depths and ages are between 1723.7 and 1724.8 meters, and 35.520 to

  1. A first chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core

    Science.gov (United States)

    Rasmussen, S. O.; Abbott, P. M.; Blunier, T.; Bourne, A. J.; Brook, E.; Buchardt, S. L.; Buizert, C.; Chappellaz, J.; Clausen, H. B.; Cook, E.; Dahl-Jensen, D.; Davies, S. M.; Guillevic, M.; Kipfstuhl, S.; Laepple, T.; Seierstad, I. K.; Severinghaus, J. P.; Steffensen, J. P.; Stowasser, C.; Svensson, A.; Vallelonga, P.; Vinther, B. M.; Wilhelms, F.; Winstrup, M.

    2013-12-01

    A stratigraphy-based chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core has been derived by transferring the annual layer counted Greenland Ice Core Chronology 2005 (GICC05) and its model extension (GICC05modelext) from the NGRIP core to the NEEM core using 787 match points of mainly volcanic origin identified in the electrical conductivity measurement (ECM) and dielectrical profiling (DEP) records. Tephra horizons found in both the NEEM and NGRIP ice cores are used to test the matching based on ECM and DEP and provide five additional horizons used for the timescale transfer. A thinning function reflecting the accumulated strain along the core has been determined using a Dansgaard-Johnsen flow model and an isotope-dependent accumulation rate parameterization. Flow parameters are determined from Monte Carlo analysis constrained by the observed depth-age horizons. In order to construct a chronology for the gas phase, the ice age-gas age difference (Δage) has been reconstructed using a coupled firn densification-heat diffusion model. Temperature and accumulation inputs to the Δage model, initially derived from the water isotope proxies, have been adjusted to optimize the fit to timing constraints from δ15N of nitrogen and high-resolution methane data during the abrupt onset of Greenland interstadials. The ice and gas chronologies and the corresponding thinning function represent the first chronology for the NEEM core, named GICC05modelext-NEEM-1. Based on both the flow and firn modelling results, the accumulation history for the NEEM site has been reconstructed. Together, the timescale and accumulation reconstruction provide the necessary basis for further analysis of the records from NEEM.

  2. Grain size record of microparticles in the Muztagata ice core

    Institute of Scientific and Technical Information of China (English)

    WU; Guangjian; YAO; Tandong; XU; Baiqin; LI; Zheng; TIAN; Lide; DUAN; Keqin; WEN; Linke

    2006-01-01

    The dust transport and sediment characteristics are discussed based on analysis of microparticle size and size distribution in the Muztagata ice core at 6350 m a.s.l. The finer particles with diameter of 1―5μm are the dominant fraction in number, while middle and coarse particles mainly contribute to the total volume. The lognormal distribution characteristics can be seen for some high concentration samples, showing that model size and standard variation are greater than that in the Greenland ice cores. However, size-volume distribution of some low concentration samples is abnormal. Those distributions reflect the dust deposit process in high mountain glaciers at mid-low latitudes and show differences from those in polar ice sheet.

  3. Neutrino oscillation studies with IceCube-DeepCore

    Science.gov (United States)

    Aartsen, M. G.; Abraham, K.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Altmann, D.; Anderson, T.; Ansseau, I.; Archinger, M.; Arguelles, C.; Arlen, T. C.; Auffenberg, J.; Bai, X.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Becker, K.-H.; Beiser, E.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brayeur, L.; Bretz, H.-P.; Buzinsky, N.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Collin, G. H.; Conrad, J. M.; Cowen, D. F.; Cruz Silva, A. H.; Daughhetee, J.; Davis, J. C.; Day, M.; de André, J. P. A. M.; De Clercq, C.; del Pino Rosendo, E.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dumm, J. P.; Dunkman, M.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Euler, S.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Feintzeig, J.; Felde, J.; Filimonov, K.; Finley, C.; Flis, S.; Fösig, C.-C.; Fuchs, T.; Gaisser, T. K.; Gaior, R.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Gier, D.; Gladstone, L.; Glagla, M.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Góra, D.; Grant, D.; Griffith, Z.; Groß, A.; Ha, C.; Haack, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Hansen, E.; Hansmann, B.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Holzapfel, K.; Homeier, A.; Hoshina, K.; Huang, F.; Huber, M.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jones, B. J. P.; Jurkovic, M.; Kappes, A.; Karg, T.; Karle, A.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kemp, J.; Kheirandish, A.; Kiryluk, J.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Konietz, R.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, G.; Kroll, M.; Krückl, G.; Kunnen, J.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lesiak-Bzdak, M.; Leuermann, M.; Leuner, J.; Lu, L.; Lünemann, J.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mandelartz, M.; Maruyama, R.; Mase, K.; Matis, H. S.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meli, A.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Middell, E.; Mohrmann, L.; Montaruli, T.; Morse, R.; Nahnhauer, R.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; Omairat, A.; O'Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Paul, L.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Quinnan, M.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Reimann, R.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Richter, S.; Riedel, B.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Sabbatini, L.; Sander, H.-G.; Sandrock, A.; Sandroos, J.; Sarkar, S.; Schatto, K.; Schimp, M.; Schmidt, T.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schulte, L.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stahlberg, M.; Stamatikos, M.; Stanev, T.; Stasik, A.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Ström, R.; Strotjohann, N. L.; Sullivan, G. W.; Sutherland, M.; Taavola, H.; Taboada, I.; Tatar, J.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Turcati, A.; Unger, E.; Usner, M.; Vallecorsa, S.; Vandenbroucke, J.; van Eijndhoven, N.; Vanheule, S.; van Santen, J.; Veenkamp, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandkowsky, N.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wills, L.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zoll, M.

    2016-07-01

    IceCube, a gigaton-scale neutrino detector located at the South Pole, was primarily designed to search for astrophysical neutrinos with energies of PeV and higher. This goal has been achieved with the detection of the highest energy neutrinos to date. At the other end of the energy spectrum, the DeepCore extension lowers the energy threshold of the detector to approximately 10 GeV and opens the door for oscillation studies using atmospheric neutrinos. An analysis of the disappearance of these neutrinos has been completed, with the results produced being complementary with dedicated oscillation experiments. Following a review of the detector principle and performance, the method used to make these calculations, as well as the results, is detailed. Finally, the future prospects of IceCube-DeepCore and the next generation of neutrino experiments at the South Pole (IceCube-Gen2, specifically the PINGU sub-detector) are briefly discussed.

  4. Neutrino oscillation studies with IceCube-DeepCore

    Energy Technology Data Exchange (ETDEWEB)

    Aartsen, M.G. [Department of Physics, University of Adelaide, Adelaide, 5005 (Australia); Abraham, K. [Technische Universität München, D-85748 Garching (Germany); Ackermann, M. [DESY, D-15735 Zeuthen (Germany); Adams, J. [Dept. of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Aguilar, J.A. [Université Libre de Bruxelles, Science Faculty CP230, B-1050 Brussels (Belgium); Ahlers, M. [Dept. of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin, Madison, WI 53706 (United States); Ahrens, M. [Oskar Klein Centre and Dept. of Physics, Stockholm University, SE-10691 Stockholm (Sweden); Altmann, D. [Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen (Germany); Anderson, T. [Dept. of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Ansseau, I. [Université Libre de Bruxelles, Science Faculty CP230, B-1050 Brussels (Belgium); Archinger, M. [Institute of Physics, University of Mainz, Staudinger Weg 7, D-55099 Mainz (Germany); Arguelles, C. [Dept. of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin, Madison, WI 53706 (United States); Arlen, T.C. [Dept. of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Auffenberg, J. [III. Physikalisches Institut, RWTH Aachen University, D-52056 Aachen (Germany); Bai, X. [Physics Department, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States); Barwick, S.W. [Dept. of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Baum, V. [Institute of Physics, University of Mainz, Staudinger Weg 7, D-55099 Mainz (Germany); and others

    2016-07-15

    IceCube, a gigaton-scale neutrino detector located at the South Pole, was primarily designed to search for astrophysical neutrinos with energies of PeV and higher. This goal has been achieved with the detection of the highest energy neutrinos to date. At the other end of the energy spectrum, the DeepCore extension lowers the energy threshold of the detector to approximately 10 GeV and opens the door for oscillation studies using atmospheric neutrinos. An analysis of the disappearance of these neutrinos has been completed, with the results produced being complementary with dedicated oscillation experiments. Following a review of the detector principle and performance, the method used to make these calculations, as well as the results, is detailed. Finally, the future prospects of IceCube-DeepCore and the next generation of neutrino experiments at the South Pole (IceCube-Gen2, specifically the PINGU sub-detector) are briefly discussed.

  5. Ice core reconstruction of Antarctic climate change and implications

    OpenAIRE

    Mayewski,Paul Andrew

    2012-01-01

    Antarctica is the Earth’s largest environmental library for ice cores. Examples of the scientific fin-dings of the 21-nation consortium called the International Trans Antarctic Scientific Expedition (ITASE) under the auspices of the Scientific Committee for Antarctic Research (SCAR) are presented with special emphasis on the value of these records in reconstructing atmospheric circulation over Antarctica and the Southern Ocean.

  6. China's first successful recovery of ice core in Mongolia

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ In collaboration with their colleagues from the ROK and Mongolia,CAS scientists achieved their first success in obtaining a 40.18m ice core in a drilling operation from 5 to 20 June in an expedition to the (Hovd) Tsambagarav glacier in Altay Mountains of Mongolia.

  7. Recent increase in Antarctic Peninsula ice core uranium concentrations

    Science.gov (United States)

    Potocki, Mariusz; Mayewski, Paul A.; Kurbatov, Andrei V.; Simões, Jefferson C.; Dixon, Daniel A.; Goodwin, Ian; Carleton, Andrew M.; Handley, Michael J.; Jaña, Ricardo; Korotkikh, Elena V.

    2016-09-01

    Understanding the distribution of airborne uranium is important because it can result in both chemical and radiological toxicity. Ice cores offer the most robust reconstruction of past atmospheric levels of toxic substances. Here we present the first sub-annually dated, continuously sampled ice core documenting change in U levels in the Southern Hemisphere. The ice core was recovered from the Detroit Plateau, northern Antarctic Peninsula, in 2007 by a joint Brazilian-Chilean-US team. It displays a significant increase in U concentration that coincides with reported mining activities in the Southern Hemisphere, notably Australia. Raw U concentrations in the Detroit Plateau ice core increased by as much as 102 between the 1980s and 2000s accompanied by increased variability in recent years. Decadal mean U concentrations increased by a factor of ∼3 from 1980 to 2007, reaching a mean of 205 pg/L from 2000 to 2007. The fact that other terrestrial source dust elements such as Ce, La, Pr, and Ti do not show a similar increase and that the increased U concentrations are enriched above natural crustal levels, supports an anthropogenic source for the U as opposed to a change in atmospheric circulation.

  8. Continuous flow analysis of total organic carbon in polar ice cores.

    Science.gov (United States)

    Federer, Urs; Kaufmann, Patrik R; Hutterli, Manuel A; Schüpbach, Simon; Stocker, Thomas F

    2008-11-01

    Ice cores are a widely used archive to reconstruct past changes of the climate system. This is done by measuring the concentration of substances in the ice and in the air of bubbles enclosed in ice. Some species pertaining to the carbon cycle (e.g., CO2, CH4) are routinely measured. However, information about the organic fraction of the impurities in polar ice is still very limited. Therefore, we developed a new method to determine the content of total organic carbon (TOC) in ice cores using a continuous flow analysis (CFA) system. The method is based on photochemical oxidation of TOC and the electrolytic quantification of the CO2 produced during oxidation. The TOC instrument features a limit of detection of 2 ppbC and a response time of 60 s at a sample flow rate of 0.7 mL/min and a linear measurement range of 2-4000 ppbC. First measurements on the ice core from Talos Dome, Antarctica, reveal TOC concentrations varying between 80 and 360 ppbC in the 20 m section presented.

  9. Earth's Climate History from Glaciers and Ice Cores

    Science.gov (United States)

    Thompson, Lonnie

    2013-03-01

    Glaciers serve both as recorders and early indicators of climate change. Over the past 35 years our research team has recovered climatic and environmental histories from ice cores drilled in both Polar Regions and from low to mid-latitude, high-elevation ice fields. Those ice core -derived proxy records extending back 25,000 years have made it possible to compare glacial stage conditions in the Tropics with those in the Polar Regions. High-resolution records of δ18O (in part a temperature proxy) demonstrate that the current warming at high elevations in the mid- to lower latitudes is unprecedented for the last two millennia, although at many sites the early Holocene was warmer than today. Remarkable similarities between changes in the highland and coastal cultures of Peru and regional climate variability, especially precipitation, imply a strong connection between prehistoric human activities and regional climate. Ice cores retrieved from shrinking glaciers around the world confirm their continuous existence for periods ranging from hundreds to thousands of years, suggesting that current climatological conditions in those regions today are different from those under which these ice fields originated and have been sustained. The ongoing widespread melting of high-elevation glaciers and ice caps, particularly in low to middle latitudes, provides strong evidence that a large-scale, pervasive and, in some cases, rapid change in Earth's climate system is underway. Observations of glacier shrinkage during the 20th and 21st century girdle the globe from the South American Andes, the Himalayas, Kilimanjaro (Tanzania, Africa) and glaciers near Puncak Jaya, Indonesia (New Guinea). The history and fate of these ice caps, told through the adventure, beauty and the scientific evidence from some of world's most remote mountain tops, provide a global perspective for contemporary climate. NSF Paleoclimate Program

  10. Biological proxies recorded in a Belukha ice core, Russian Altai

    Science.gov (United States)

    Papina, T.; Blyakharchuk, T.; Eichler, A.; Malygina, N.; Mitrofanova, E.; Schwikowski, M.

    2013-10-01

    Different biological proxies such as pollen, cysts, and diatoms were identified and quantified in the upper part of a Belukha ice core from the Russian Altai. The ice core from the Belukha glacier collected in 2001 (4062 m a.s.l., 49°48' N, 86°34' E) was analyzed with annual resolution in the period 1964-2000. Daily data of the frequency of synoptic patterns observed in the Northern Hemisphere along with daily data of precipitation have been used to identify the predominant atmospheric circulations (elementary circulating mechanisms, or ECMs) generating the entry of biological proxies on the glacier surface. It was shown that the high-resolution records of diatoms, cysts, spores, and plant pollen in the Belukha ice core are the biological proxies for the changes in the structure of precipitation in the Altai region since these records can reflect changes in the contribution of different atmospheric circulation to annual or seasonal precipitation. The joint consideration of the transport ability of the biological species and the data of precipitation allowed us to determine the main modern sources of biological proxies deposited at the Belukha glacier. The main sources of diatoms in the Belukha ice core are water bodies of the Aral, Caspian, and northern Kazakhstan basins; coniferous tree pollen originated from the taiga forest of the boreal zone of western Siberia; pollen of deciduous trees and herbs from steppe and forest-steppe vegetation in the northern Altai and eastern Kazakhstan; and cysts and spores of plants were transported from local water bodies and forests. The identified source regions of the biological species are supported by back trajectory analyses and are in good agreement with emission source regions of the trace elements in the ice core.

  11. Alpine ice core records from Pacific North America

    Science.gov (United States)

    Steig, E. J.; Clark, D. H.; Pettit, E.

    2006-12-01

    Climate in the northeast Pacific shows significant multi-decadal and longer timescale variability, yet the instrumental record in western North America is relatively short. Paleoclimate proxy data, therefore, are essential to understanding climate variability in this region. A number of promising proxy-based reconstructions have been published recently, but additional constraints are needed. Ice core records are particularly useful for these reconstructions because they provide both high-resolution proxy data (such as δ18O and ion concentrations, which reflect large scale circulation changes) and direct measures of snow accumulation. Furthermore, at high altitude sites where ablation rates are small, snow accumulation is a highly reliable measure of total precipitation. At Mt. Logan, St. Elias Range, Yukon Territory, annual accumulation is significantly correlated with large scale climate indices such as the Aleutian Low pressure index. Perhaps more importantly, annual layer thickness in the Mt. Logan core is demonstrably reliable as an indicator of wintertime accumulation extremes not just at the site, but over a fairly large geographic area. Similar records have also been obtained at Mt. Churchill-Bona (AK) and Eclipse Dome (YT), also in the Wrangell/St. Elias range. A sufficiently complete spatial network of cores could in principle be used to develop a robust estimate of past winter precipitation variability across western Canada and Alaska. Mt. Waddington, British Columbia Coast Range, is one of the most promising sites for an ice core at temperate latitudes in North America. Mt. Waddington's location is highly complementary to the Wrangell/St. Elias sites: precipitation, temperature and geopotential height anomalies all tend to be opposite in sign in the two geographic regions. An accumulation record from Waddington, therefore, has considerable potential for refining reconstructions of precipitation and large scale circulation across the region. In July 2006

  12. Self-consistent ice-sheet properties: ice dynamics, temperature, accumulation, delta-age and chronologies for ice cores and radar isochrones

    Science.gov (United States)

    Lundin, J.; Waddington, E. D.; Conway, H.

    2011-12-01

    Ice sheet behavior has not previously been modeled to force self-consistency, to determine histories of accumulation, temperature, and ice dynamics that incorporate the ice-age/gas-age offset (delta-age) and sparse depth-age measurements from ice cores. An iterative scheme is used to combine several modular components into one self-consistent model. The goal is to determine a suite of histories constrained by the depth-age data from ice cores and ice radar that are part of a physically self-consistent ice sheet. The model is tested using a synthetic data set resembling WAIS divide. Using synthetic data provides proof of concept that histories of accumulation, temperature and ice dynamics can be recovered by the self-consistent model, and that the depth-age from ice cores and ice radar can be matched. Results from synthetic data show we can recover the ice-sheet properties used to generate the data and we can improve the depth-age chronologies by interpolating with an ice-flow model where data are sparse. When this self-consistent model can be applied to field data, results will (1) improve chronologies for ice cores and radar layers, (2) determine histories of accumulation for GCM modelling, and (3) improve estimates of past ice sheet configurations, incorporating data from ice cores and ice radar.

  13. IceChrono v1: a probabilistic model to compute a common and optimal chronology for several ice cores

    Directory of Open Access Journals (Sweden)

    F. Parrenin

    2014-10-01

    Full Text Available Polar ice cores provides exceptional archives of past environmental conditions. Dating ice and air bubbles/hydrates in ice cores is complicated since it involves different dating methods: modeling of the sedimentation process (accumulation of snow at surface, densification of snow into ice with air trapping and ice flow, use of dated horizons by comparison to other well dated targets (other dated paleo-archives or calculated variations of Earth's orbital parameters, use of dated depth intervals, use of Δdepth information (depth shift between synchronous events in the ice matrix and its air/hydrate content, use of stratigraphic links in between ice cores (ice-ice, air-air or mix ice-air links. Here I propose IceChrono v1, a new probabilistic model to combine these different kinds of chronological information to obtain a common and optimized chronology for several ice cores, as well as its confidence interval. It is based on the inversion of three quantities: the surface accumulation rate, the Lock-In Depth (LID of air bubbles and the vertical thinning function. IceChrono is similar in scope to the Datice model, but has differences on the mathematical, numerical and programming point of views. I apply IceChrono on two dating experiments. The first one is similar to the AICC2012 experiment and I find similar results than Datice within a few centuries, which is a confirmation of both IceChrono and Datice codes. The second experiment involves only the Berkner ice core in Antarctica and I produce the first dating of this ice core. IceChrono v1 is freely available under the GPL v3 open source license.

  14. Quantifying signal dispersion in a hybrid ice core melting system.

    Science.gov (United States)

    Breton, Daniel J; Koffman, Bess G; Kurbatov, Andrei V; Kreutz, Karl J; Hamilton, Gordon S

    2012-11-06

    We describe a microcontroller-based ice core melting and data logging system allowing simultaneous depth coregistration of a continuous flow analysis (CFA) system (for microparticle and conductivity measurement) and a discrete sample analysis system (for geochemistry and microparticles), both supplied from the same melted ice core section. This hybrid melting system employs an ice parcel tracking algorithm which calculates real-time sample transport through all portions of the meltwater handling system, enabling accurate (1 mm) depth coregistration of all measurements. Signal dispersion is analyzed using residence time theory, experimental results of tracer injection tests and antiparallel melting of replicate cores to rigorously quantify the signal dispersion in our system. Our dispersion-limited resolution is 1.0 cm in ice and ~2 cm in firn. We experimentally observe the peak lead phenomenon, where signal dispersion causes the measured CFA peak associated with a given event to be depth assigned ~1 cm shallower than the true event depth. Dispersion effects on resolution and signal depth assignment are discussed in detail. Our results have implications for comparisons of chemistry and physical properties data recorded using multiple instruments and for deconvolution methods of enhancing CFA depth resolution.

  15. Coring to the West Antarctic ice sheet bed with a new Deep Ice Sheet Coring (DISC) drill

    Science.gov (United States)

    Bentley, C. R.; Taylor, K. C.; Shturmakov, A. J.; Mason, W. P.; Emmel, G. R.; Lebar, D. A.

    2005-05-01

    As a contribution to IPY 2007-2008, the U.S. ice core research community, supported by the National Science Foundation, plans to core through the West Antarctic ice sheet (WAIS) at the ice-flow divide between the Ross Sea and Amundsen Sea drainage systems. The aim is to develop a unique series of interrelated climatic, ice-dynamic, and biologic records focused on understanding interactions among global earth systems. There will be approximately 15 separate but synergistic projects to analyze the ice and interpret the records. The most significant expected outcome of the WAIS Divide program will be climate records for the last ~40,000 years with an annually resolved chronology (through layer counting), comparable to the records from central Greenland. The data will also extend, at lower temporal resolution, to approximately 100,000 BP. These records will permit comparison of environmental conditions between the northern and southern hemispheres, and study of greenhouse gas concentrations in the paleoatmosphere, with unprecedented detail. To accomplish the coring, an innovative new Deep Ice Sheet Coring (DISC) drill is being built at the University of Wisconsin. The modular design of the bore-hole assembly (sonde) provides high flexibility for producing a 122 mm diameter ice core to depths of 4,000 m with maximum core lengths of 4 m. The DISC drill has a rotating outer barrel that can be used with or without an inner barrel designed to improve core recovery in brittle ice. Separate and independent motors for the drill and pump allow cutter speeds from 0 to 150 rpm and pump rates from 0 to 140 gpm. The high pumping rate should alleviate problems drilling in warm ice near the bed; it also helps make tripping speeds several times faster than with the old US drill. Other innovations include vibration and acoustic sensors for monitoring the drilling process, a segmented core barrel to avoid the formerly persistent problem of bent core barrels, and a high-speed data

  16. Early Holocene climate oscillations recorded in three Greenland ice cores

    DEFF Research Database (Denmark)

    Rasmussen, Sune Olander; Vinther, Bo Møllesøe; Clausen, Henrik Brink;

    2007-01-01

    A new ice core chronology for the Greenland DYE-3, GRIP, and NGRIP ice cores has been constructed, making it possible to compare the d18O and accumulation signals recorded in the three cores on an almost annual scale throughout the Holocene. We here introduce the new time scale and investigate d18O...... and accumulation anomalies that are common to the three cores in the Early Holocene (7.9–11.7 ka before present). Three time periods with significant and synchronous anomalies in the d18O and accumulation signals stand out: the well-known 8.2 ka event, an event of shorter duration but of almost similar amplitude...... around 9.3 ka before present, and the Preboreal Oscillation during the first centuries of the Holocene. For each of these sections, we present a d18O anomaly curve and a common accumulation signal that represents regional changes in the accumulation rate over the Greenland ice cap....

  17. Revised estimates of Greenland ice sheet thinning histories based on ice-core records

    DEFF Research Database (Denmark)

    Lecavalier, B.S.; Milne, G.A.; Fisher, D.A.;

    2013-01-01

    -based reconstructions and, to some extent, the estimated elevation histories. A key component of the ice core analysis involved removing the influence of vertical surface motion on the dO signal measured from the Agassiz and Renland ice caps. We re-visit the original analysis with the intent to determine if the use...... height changes on the dO signal from the two ice cores. This procedure is complicated by the fact that dO contained in Agassiz ice is influenced by land height changes distant from the ice cap and so selecting a single location at which to compute the land height signal is not possible. Uncertainty...... in this selection is further complicated by the possible influence of Innuitian ice during the early Holocene (12-8 ka BP). Our results indicate that a more accurate treatment of the uplift correction leads to elevation histories that are, in general, shifted down relative to the original curves at GRIP, NGRIP, DYE...

  18. POLLiCE (POLLen in the iCE): climate history from Adamello ice cores

    Science.gov (United States)

    Cristofori, Antonella; Festi, Daniela; Maggi, Valter; Casarotto, Christian; Bertoni, Elena; Vernesi, Cristiano

    2017-04-01

    Glaciers can be viewed as the most complete and effective past climate and environment archives severely threatened by climate change. These threats are particularly dramatic across European Alps. The Adamello glacier is the largest, 16.4 km2, and deepest, 270 m, Italian glacier. We aim at estimating biodiversity changes over the last centuries in relation to climate and human activities in the Adamello catchment area. We, therefore, recently launched the POLLiCE project (pollice.fmach.it) for specifically targeting the biological component (e.g. pollen, leaves, plant remains) trapped in ice cores. Classical morphological pollen analysis will be accompanied by DNA metabarcoding. This approach has the potential to provide a detailed taxonomical identification - at least genus level- thus circumventing the limitations of microscopic analysis such as time-consuming procedures and shared features of pollen grains among different taxa. Moreover, ice cores are subjected to chemical and physical analyses - stable isotopes, ions, hyperspectral imaging, etc.- for stratigraphic and climatic determination of seasonality. A pilot drilling was conducted on March 2015 and the resulting 5 m core has been analysed in terms of pollen spectrum, stable isotopes and ions in order to demonstrate the feasibility of the study. The first encouraging results showed that even in this superficial core a stratigraphy is evident with indication of seasonality as highlighted by both by pollen taxa and stable isotopes. Finally, DNA has been successfully extracted and amplified with specific DNA barcodes. A medium drilling was performed on April 2016 with the extraction of a 45 m ice core. The analysis of this core constitutes the subject of a specific research project, CALICE*, just funded by Euregio Science Fund (IPN57). The entire depth, 270 m, of the Adamello glacier is scheduled to be drilled in 2018 winter to secure the unique memory archived by the ice. * See EGU2017 poster by Festi et al

  19. New constraints on the gas age-ice age difference along the EPICA ice cores, 0–50 kyr

    Directory of Open Access Journals (Sweden)

    J. Chappellaz

    2007-08-01

    Full Text Available Gas is trapped in polar ice sheets at ~50–120 m below the surface and is therefore younger than the surrounding ice. Firn densification models are used to evaluate this ice age-gas age difference (Δage in the past. However, such models need to be validated by data, in particular for periods colder than present day on the East Antarctic plateau. Here we bring new constraints to test a firn densification model applied to the EPICA Dome C (EDC site for the last 50 kyr, by linking the EDC ice core to the EPICA Dronning Maud Land (EDML ice core, both in the ice phase (using volcanic horizons and in the gas phase (using rapid methane variations. We also use the structured 10Be peak, occurring 41 kyr before present (BP and due to the low geomagnetic field associated with the Laschamp event, to experimentally estimate the Δage during this event. Our results seem to reveal an overestimate of the Δage by the firn densification model during the last glacial period at EDC. Tests with different accumulation rates and temperature scenarios do not entirely resolve this discrepancy. Although the exact reasons for the Δage overestimate at the two EPICA sites remain unknown at this stage, we conclude that current densification model simulations have deficits under glacial climatic conditions. Whatever the cause of the Δage overestimate, our finding suggests that the phase relationship between CO2 and EDC temperature previously inferred for the start of the last deglaciation (lag of CO2 by 800±600 yr seems to be overestimated.

  20. New constraints on the gas age-ice age difference along the EPICA ice cores, 0–50 kyr

    Directory of Open Access Journals (Sweden)

    J. Chappellaz

    2007-03-01

    Full Text Available Gas is trapped in polar ice sheets at ~50–120 m below the surface and is therefore younger than the surrounding ice. Firn densification models are used to evaluate this ice age-gas age difference (Δage in the past. However, such models are not well tested on low accumulation and cold sites of the East Antarctic plateau, especially for periods with different climatic conditions. Here we bring new constraints to test a firn densification model applied to the EPICA Dome C (EDC site for the last 50 kyr, by linking the EDC ice core to the EPICA Dronning Maud Land (EDML ice core, both in the ice phase (using volcanic horizons and in the gas phase (using rapid methane variations. We use the structured 10Be peak, occurring 41 kyr before present (BP and due to the low geomagnetic field associated with the Laschamp event, to experimentally estimate the Δage and Δdepth during this event. It allows us to evaluate the model and to link together climatic archives from EDC and EDML to NorthGRIP (Greenland. Our results reveal an overestimate of the Δage by the firn densification model during the last glacial period at EDC. Tests with different accumulation rates and temperature scenarios do not entirely resolve this discrepancy. Our finding suggests that the phase relationship between CO2 and EDC temperature inferred at the start of the last deglaciation (lag of CO2 by 800±600 yr is overestimated and that the CO2 increase could well have been in phase or slightly leading the temperature increase at EDC.

  1. Quantification of viable endospores from a Greenland ice core.

    Science.gov (United States)

    Yung, Pun To; Shafaat, Hannah S; Connon, Stephanie A; Ponce, Adrian

    2007-02-01

    Endospores (i.e., bacterial spores) embedded in polar ices present an opportunity to investigate the most durable form of life in an ideal medium for maintaining long-term viability. However, little is known about the endospore distribution and viability in polar ices. We have determined germinable endospore concentrations of bacterial spores capable of germination in a Greenland ice core (GISP2 94 m, ID# G2-271) using two complementary endospore viability assays (EVA), recently developed in our laboratory. These assays are based on bulk spectroscopic analysis (i.e., spectroEVA), and direct microscopic enumeration (i.e., microEVA) of ice core concentrates. Both assays detect dipicolinic acid (DPA) release during l-alanine induced germination via terbium ion (Tb3+)-DPA luminescence. Using spectroEVA, the germinable and total bacterial spore concentrations were found to be 295+/-19 spores mL(-1) and 369+/-36 spores mL(-1), respectively, (i.e., 80% of the endospores were capable of germination). Using microEVA, the germinating endospore concentration was found to be 27+/-2 spores mL(-1). The total cell concentration, as determined by DAPI stain fluorescence microscopy, was 7.0 x 10(3)+/-6.7 x 10(2) cells mL(-1). Culturing attempts yielded 2 CFU mL(-1) (4 degrees C). We conclude that endospores capable of germination in the GISP2 ice cores are readily determined using novel endospore viability assays.

  2. Low-latitude ice cores and freshwater availability

    Science.gov (United States)

    Kehrwald, Natalie Marie

    2009-12-01

    Recent retreat of Tibetan Plateau glaciers affects at least half a billion people. Himalayan glaciers seasonally release meltwater into tributaries of the Indus, Ganges, and Brahmaputra Rivers and supply freshwater necessary to support agricultural and economic practices. Tibetan Plateau glaciers are retreating more rapidly than mountain glaciers elsewhere in the world, and this retreat is accelerating. The Naimona'nyi (30°27'N; 81°91'E, 6050 m a.s.l), Guliya (35°17'N; 81°29'E, 6710 m a.s.l.) and Dasuopu (28°23'N; 85°43'E, 7200 m a.s.l.) ice cores place this recent retreat into a longer time perspective through quantifying climate parameters such as past temperature, aridity, and atmospheric chemistry. Naimona'nyi has not accumulated mass since at least 1950, as evidenced by the virtual lack of radiogenic isotopes (36Cl, 3 H, and beta radioactivity) present in the ice core. These isotopes were produced by U.S. and Soviet atmospheric thermonuclear bomb tests conducted in the 1950s and 1960s and provide independent dating horizons for the ice cores. Lead-210 dates imply that the uppermost preserved glacial ice on Naimona'nyi formed during the 1940s. While this is the highest documented glacial thinning in the world other glaciers at elevations similar to that of Naimona'nyi, such as Kilimanjaro (3°4'S; 37°21'E, 5893 m a.s.l.), are also losing mass at their summits. The global scope of high-elevation glacial thinning suggests that ablation on the Earth's highest ice fields may be more prevalent as global mean temperatures continue to increase. Glacial thinning has not been taken into account in future projections of regional freshwater availability, and the net mass loss indicates that Himalayan glaciers currently store less freshwater than assumed in models. The acceleration of Tibetan Plateau glacial retreat has been hypothesized to be due in part to deposition of black carbon (BC) from biomass burning on to ice fields, thereby lowering the reflectivity of

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

    Energy Technology Data Exchange (ETDEWEB)

    Steig, E.J.

    1996-12-31

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

  4. Comparison of northern and central Greenland ice cores records of methanesulfonate covering the last glacial period

    DEFF Research Database (Denmark)

    Jonsell, U.; Hansson, M. E.; Siggaard-Andersen, M-L-

    2007-01-01

    Methanesulfonate (MS-) is measured in ice cores with the objective to obtain a proxy record of marine phytoplankton production of dimethylsulfide (DMS). We present a continuous MS- record covering the last glacial period from the North Greenland Ice Core Project (NGRIP) ice core and compare...... this record with the corresponding records previously presented from Greenland and, in particular, with the GISP2 ice core located 320 km south of NGRIP. Despite that the records have similar mean concentrations, their responses to climatic changes during the last glacial period are slightly different. NGRIP...... ice cores. Udgivelsesdato: 31 July...

  5. Instrumentation for the PICO deep ice coring drill

    OpenAIRE

    1994-01-01

    An electronic data collection and control system has been developed for the PICO 13.2cm deep ice coring drill. It monitors a variety of drilling parameters including inclination, depth, temperature, pressure, RPM, weight and others. It also displays this data for the drill operator and allows the operator to control speed and direction of the drill motor. The display program allows setting limits on all parameters so an alarm sounds if anything goes wrong. This instrumentation package will be...

  6. Ice core precipitation record in central Tibetan plateau since AD 1600

    Directory of Open Access Journals (Sweden)

    T. Yao

    2008-02-01

    Full Text Available Lack of reliable long-term precipitation record from northern Tibetan Plateau has constrained the understanding of precipitation variation in this region. An ice core drilled from the Puruogangri Ice Field on central Tibetan Plateau in the year 2000 helped reveal the precipitation variations since AD 1600. Analysis of the annual accumulation data presented precipitation changes from AD 1600, indicative of wet and dry periods in the past 400 year in the central Tibetan Plateau. Accordingly, the 18th and 20th centuries experienced high precipitation period, whilst the 19th century experienced low precipitation period. Such a feature was consistent with precipitation recorded in ice cores from Dunde and Guliya Glaciers, northern Tibetan Plateau. Besides, the results also pointed to consistency in precipitation-temperature correlation on the northern Tibetan Plateau, in a way that temperature and precipitation were positively correlated. But this feature was contrary to the relationship revealed from Dasuopu ice cores, southern Tibetan Plateau, where temperature and precipitation were negatively correlated. The north-south contrast in precipitation amount and its relationship with temperature may shed light on the reconstruction of Asian monsoon since AD 1600.

  7. δ13C-CH4 in ice core samples

    DEFF Research Database (Denmark)

    Sperlich, Peter

    Ice core records of δ13C-CH4 reflect the variability of CH4 biogeochemistry in response to climate change and show this system is far more complex than expected. The first part of this work is concerned with the development of analytical techniques that allow 1) precise referencing and 2) measure......Ice core records of δ13C-CH4 reflect the variability of CH4 biogeochemistry in response to climate change and show this system is far more complex than expected. The first part of this work is concerned with the development of analytical techniques that allow 1) precise referencing and 2......) measurements of δ13C-CH4 in ice core samples as is required when δ13C-CH4 records that are measured in several laboratories are merged for analysis. Both the referencing and measurement techniques have been compared to further laboratories which proofed the accuracy of the analytical systems. The second part...

  8. δ13C-CH4 in ice core samples

    DEFF Research Database (Denmark)

    Sperlich, Peter

    Ice core records of δ13C-CH4 reflect the variability of CH4 biogeochemistry in response to climate change and show this system is far more complex than expected. The first part of this work is concerned with the development of analytical techniques that allow 1) precise referencing and 2) measure......Ice core records of δ13C-CH4 reflect the variability of CH4 biogeochemistry in response to climate change and show this system is far more complex than expected. The first part of this work is concerned with the development of analytical techniques that allow 1) precise referencing and 2......) measurements of δ13C-CH4 in ice core samples as is required when δ13C-CH4 records that are measured in several laboratories are merged for analysis. Both the referencing and measurement techniques have been compared to further laboratories which proofed the accuracy of the analytical systems. The second part...

  9. Reconstruction of Aerosol Concentration and Composition from Glacier Ice Cores

    Science.gov (United States)

    Vogel, Alexander; Dällenbach, Kaspar; El-Haddad, Imad; Wendl, Isabel; Eichler, Anja; Schwikowski, Margit

    2017-04-01

    Reconstruction of the concentration and composition of natural aerosol in an undisturbed atmosphere enables the evaluation of the understanding of aerosol-climate effects, which is currently based on highly uncertain emission inventories of the biosphere under pre-industrial conditions. Understanding of the natural state of the pre-industrial atmosphere and evaluating the atmospheric perturbations by anthropogenic emissions, and their potential feedbacks, is essential for accurate model predictions of the future climate (Boucher et al., 2013). Here, we present a new approach for the chemical characterization of the organic fraction preserved in cold-glacier ice cores. From this analysis historic trends of atmospheric organic aerosols are reconstructed, allowing new insights on organic aerosol composition and mass in the pre-industrial atmosphere, which can help to improve climate models through evaluation of our current understanding of aerosol radiative effects. We present results from a proof-of-principal study, analyzing an 800 year ice core record from the Lomonosovfonna glacier ice core, drilled in 2009 in Svalbard, Norway, using a setup that has until then only been applied on offline measurements of aerosol filter extracts (Dällenbach et al., 2016): The melted ice was nebulized and dried, such that aerosols are formed from the soluble and insoluble organic and inorganic compounds that are preserved in the ice. To improve the sensitivity, the aerosol stream was then enriched by the application of an online aerosol concentrator, before the aerosol was analyzed by electron ionization within a high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). We were able to demonstrate that this setup is a quantitative method toward nitrate and sulfate when internal inorganic standards of NH415NO3 and (NH4)234SO4 are added to the sample. Comparison between AMS and IC measurements of nitrate and sulfate resulted in an excellent agreement. The analysis of

  10. Could a new ice core offer an insight into the stability of the West Antarctic Ice Sheet during the last interglacial?

    Science.gov (United States)

    Mulvaney, R.; Hindmarsh, R. C.

    2013-12-01

    Vaughan et al., in their 2011 paper 'Potential Seaways across West Antarctica' (Geochem. Geophys. Geosyst., 12, Q10004, doi:10.1029/2011GC003688), offer the intriguing prospect that substantial ice loss from the West Antarctic Ice Sheet during the previous interglacial period might have resulted in the opening of a seaway between the Weddell Sea and the Amundsen Sea. One of their potential seaways passes between the south western corner of the present Ronne Ice Shelf and the Pine Island Bay, through what is currently the course of the Rutford Ice Stream, between the Ellsworth Mountains and the Fletcher Promontory. To investigate whether this seaway could have existed (and to recover a paleoclimate and ice sheet history from the Weddell Sea), a team from the British Antarctic Survey and the Laboratoire de Glaciologie et Géophysique de l'Environnement drilled an ice core from a close to a topographic dome in the ice surface on the Fletcher Promontory in January 2012, reaching the bedrock at 654.3m depth from the surface. The site was selected to penetrate directly through the centre of a Raymond cupola observed in internal radar reflections from the ice sheet, with the intention that this would ensure we obtained the oldest ice available from the Fletcher Promontory. The basal ice sheet temperature measured was -18°C, implying the oldest ice would not have melted away from the base, while the configuration of the Raymond cupola in the radar horizons suggested stability in the ice dome topography during the majority of the Holocene. Our hypothesis is that chemical analysis of the ice core will reveal whether the site was ever relatively close to open sea water or ice shelf in the Rutford channel 20 km distant, rather than the current 700 km distance to sea ice/open water in either the Weddell Sea or the Amundsen Sea. While we do not yet have the chemistry data to test this hypothesis, in this poster we will discuss whether there is in reality any potential local

  11. JWST NIRCam WFSS Ice Feature Spectroscopy in Nearby Molecular Cores

    Science.gov (United States)

    Chu, Laurie; Hodapp, Klaus W.; Rieke, Marcia J.; Meyer, Michael; Greene, Thomas P.; JWST NIRCam Science Team

    2017-06-01

    In molecular clouds above a few magnitudes of total visual extinction, some components of the molecular gas freeze out on the surfaces of dust grains. These ice mantles around dust grains are the site of complex surface chemistry that leads to the formation of simple organic molecules in these mantles. The icy surfaces also facilitate the coaggulation of the dust particles, setting the stage for grain growth and ultimately the formation of planetary bodies.As part of the JWST NIRCam GTO program, we plan to observe a selection of small molecular cores using the wide field grism spectroscopy mode of NIRCam.This poster presents the results of a preliminary study of several candidate molecular cores using UKIRT, Spitzer IRAC, IRTF SpeX, Keck MOSFIRE and Subaru MOIRCS data.After the prelimary studies we have selected three molecular cores in different evolutionary stages for the GTO program: B68, a quiescent molecular core, LDN 694-2, a collapsing pre-stellar core, and B335, a protostellar core. All these cores are seen against a dense background of stars in the inner Galaxy and offer the opportunity for spatially well resolved mapping of the ice feature distribution. We will obtain slitless grism spectroscopy in six filters covering the features of H2O, CO2, CO, CH3OH, and the XCN feature. Simulations using aXeSIM have shown that spectrum overlap will occur in a fraction of the spectra, but will not be a prohibitive problem.Our poster will discuss the details of observations planned out in the APT system.

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

    DEFF Research Database (Denmark)

    Hvenegård-Lassen, Kirsten

    2016-01-01

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

  13. Boreal fire records in Northern Hemisphere ice cores: a review

    Science.gov (United States)

    Legrand, Michel; McConnell, Joseph; Fischer, Hubertus; Wolff, Eric W.; Preunkert, Susanne; Arienzo, Monica; Chellman, Nathan; Leuenberger, Daiana; Maselli, Olivia; Place, Philip; Sigl, Michael; Schüpbach, Simon; Flannigan, Mike

    2016-10-01

    Here, we review different attempts made since the early 1990s to reconstruct past forest fire activity using chemical signals recorded in ice cores extracted from the Greenland ice sheet and a few mid-northern latitude, high-elevation glaciers. We first examined the quality of various inorganic (ammonium, nitrate, potassium) and organic (black carbon, various organic carbon compounds including levoglucosan and numerous carboxylic acids) species proposed as fire proxies in ice, particularly in Greenland. We discuss limitations in their use during recent vs. pre-industrial times, atmospheric lifetimes, and the relative importance of other non-biomass-burning sources. Different high-resolution records from several Greenland drill sites and covering various timescales, including the last century and Holocene, are discussed. We explore the extent to which atmospheric transport can modulate the record of boreal fires from Canada as recorded in Greenland ice. Ammonium, organic fractions (black and organic carbon), and specific organic compounds such as formate and vanillic acid are found to be good proxies for tracing past boreal fires in Greenland ice. We show that use of other species - potassium, nitrate, and carboxylates (except formate) - is complicated by either post-depositional effects or existence of large non-biomass-burning sources. The quality of levoglucosan with respect to other proxies is not addressed here because of a lack of high-resolution profiles for this species, preventing a fair comparison. Several Greenland ice records of ammonium consistently indicate changing fire activity in Canada in response to past climatic conditions that occurred during the last millennium and since the last large climatic transition. Based on this review, we make recommendations for further study to increase reliability of the reconstructed history of forest fires occurring in a given region.

  14. IceChrono1: a probabilistic model to compute a common and optimal chronology for several ice cores

    Science.gov (United States)

    Parrenin, Frédéric; Bazin, Lucie; Capron, Emilie; Landais, Amaëlle; Lemieux-Dudon, Bénédicte; Masson-Delmotte, Valérie

    2016-04-01

    Polar ice cores provide exceptional archives of past environmental conditions. The dating of ice cores and the estimation of the age scale uncertainty are essential to interpret the climate and environmental records that they contain. It is however a complex problem which involves different methods. Here, we present IceChrono1, a new probabilistic model integrating various sources of chronological information to produce a common and optimized chronology for several ice cores, as well as its uncertainty. IceChrono1 is based on the inversion of three quantities: the surface accumulation rate, the Lock-In Depth (LID) of air bubbles and the thinning function. The chronological information integrated into the model are: models of the sedimentation process (accumulation of snow, densification of snow into ice and air trapping, ice flow), ice and air dated horizons, ice and air depth intervals with known durations, Δdepth observations (depth shift between synchronous events recorded in the ice and in the air) and finally air and ice stratigraphic links in between ice cores. The optimization is formulated as a least squares problem, implying that all densities of probabilities are assumed to be Gaussian. It is numerically solved using the Levenberg-Marquardt algorithm and a numerical evaluation of the model's Jacobian. IceChrono follows an approach similar to that of the Datice model which was recently used to produce the AICC2012 chronology for 4 Antarctic ice cores and 1 Greenland ice core. IceChrono1 provides improvements and simplifications with respect to Datice from the mathematical, numerical and programming point of views. The capabilities of IceChrono is demonstrated on a case study similar to the AICC2012 dating experiment. We find results similar to those of Datice, within a few centuries, which is a confirmation of both IceChrono and Datice codes. We also test new functionalities with respect to the original version of Datice: observations as ice intervals

  15. Using high resolution tritium profiles to quantify the effects of melt on two Spitsbergen ice cores

    NARCIS (Netherlands)

    van der Wel, L.G.; Streurman, H.J.; Isaksson, E.; Helsen, M.M.; van de Wal, R.S.W.; Martma, T.; Pohjola, V.A.; Moore, J.C.; Meijer, H.A.J.

    2011-01-01

    Ice cores from small ice caps provide valuable climatic information, additional to that of Greenland and Antarctica. However, their integrity is usually compromised by summer meltwater percolation. To determine to what extent this can affect such ice cores, we performed high-resolution tritium measu

  16. Using high resolution tritium profiles to quantify the effects of melt on two Spitsbergen ice cores

    NARCIS (Netherlands)

    van der Wel, L.G.; Streurman, H.J.; Isaksson, E.; Helsen, M.M.; van de Wal, R.S.W.; Martma, T.; Pohjola, V.A.; Moore, J.C.; Meijer, H.A.J.

    2011-01-01

    Ice cores from small ice caps provide valuable climatic information, additional to that of Greenland and Antarctica. However, their integrity is usually compromised by summer meltwater percolation. To determine to what extent this can affect such ice cores, we performed high-resolution tritium measu

  17. Using high resolution tritium profiles to quantify the effects of melt on two Spitsbergen ice cores

    NARCIS (Netherlands)

    van der Wel, L.G.; Streurman, H.J.; Isaksson, E.; Helsen, M.M.; van de Wal, R.S.W.; Martma, T.; Pohjola, V.A.; Moore, J.C.; Meijer, H.A.J.

    2011-01-01

    Ice cores from small ice caps provide valuable climatic information, additional to that of Greenland and Antarctica. However, their integrity is usually compromised by summer meltwater percolation. To determine to what extent this can affect such ice cores, we performed high-resolution tritium

  18. Measurement of fracture toughness of an ice core from Antarctica

    Directory of Open Access Journals (Sweden)

    J. Christmann

    2014-09-01

    Full Text Available The critical fracture toughness is a material parameter describing the resistance of a cracked body to further crack extension. It is an important parameter to simulate and predict the break-up behaviour of ice shelves from calving of single icebergs to the disintegration of entire ice shelves over a wide range of length scales. The fracture toughness values are calculated with equations that are derived from an elastic stress analysis. Additionally, an X-ray computer tomography (CT scanner was used to identify the density as a function of depth. The critical fracture toughness of 91 Antarctic inland ice samples with densities between 840 to 870 kg m−3 has been determined by applying a four-point-bending technique on single edge v-notched beam samples. The examined ice core was drilled 70 m north of Kohnen Station, Dronnning Maud Land (75°00' S, 00°04' E, 2882 m. Supplementary data are available at doi:10.1594/PANGAEA.835321.

  19. THE TROPICAL CONNECTION BETWEEN THE ATLANTIC SECTOR ICE CORES AND THE NORTH PACIFIC MT LOGAN ICE CORE

    Science.gov (United States)

    Fisher, D. A.

    2009-12-01

    The stable isotope record from the Mt Logan, Yukon, Canada ice core spans the late Glacial to present and shows very large and sudden variations in O18 during the Holocene . It is hypothesized that they are driven by changes in the water sources ,which in turn, are determined by the state of ENSO. There seems to be no correlations between the Logan ice core isotope record and those from the North Atlantic (Greenland and Eastern Canadian Arctic). Using the stacked and co-dated Greenland and Eastern Canadian Arctic ice core records from the Holocene, it is possible to reproduce the Logan isotope record by subtracting the stacked Atlantic record from itself with an 1100 year lag. The correlations obtainable are -0.43 for 50 year average series. This correlation is significant at the 99.8 % level . The 1100 lag has also been found in previous studies comparing the Greenland to Antarctic ice cores (Stocker and Johnsen,2003). It is argued that such a lagged difference series is a proxy for the difference between the ocean water surface and deep temperatures in the tropical Pacific . ENSO’s amplitude is driven by this temperature difference, (Sun 2000). When the deep water is too warm, then the difference is too small to produce ENSO oscillations and strong tropical easterly winds persist (ie strong and constant La Nina). The ice core records from Mt Logan , Greenland and Eastern Arctic Canada all point to a similar history of ENSO oscillation strength. Prior to ~ 4200 BP the strong and constant La Nina tended to drive the tropical Pacific winds and moisture across to produce strong and reliable monsoons. Since 4200 BP the “modern” and variable pattern has been in place. There was a smaller scale shift about 1840 AD . For about a couple of centuries prior to 1840 AD , La Nina was in charge and after there were the oscillations that are thought of as normal. If the 1100 year lag between surface and bottom temperatures is true and if the bottom temperatures are echoes

  20. Ice cores and calcite precipitates from alpine ice caves as useful proxies in paleoclimate reconstructions

    Science.gov (United States)

    Colucci, Renato R.; Barbante, Carlo; Bertò, Michele; Dreossi, Giuliano; Festi, Daniela; Forte, Emanuele; Gabrieli, Jacopo; Guglielmin, Mauro; Lenaz, Davide; Luetscher, Marc; Maggi, Valter; Princivalle, Francesco; Schwikowski, Margit; Stenni, Barbara; Žebre, Manja

    2017-04-01

    In the last years a growing set of research campaigns have been undertaken in the European southeastern Alps. The aim of such interest is mainly due to the peculiar climatic conditions of this area, allowing the existence of periglacial and glacial evidence at the lowest altitude in the Alps. The reason for such "anomaly" is likely ascribable to very high mean annual precipitation and local topoclimatic amplifications. In the frame of this research, in the fall 2013 a 7.8 m long ice-core has been extracted from a permanent cave ice deposit located in the area of Mt. Canin (2,587 masl) in the Julian Alps. The ice-core has been cut and analysed in terms of: a) oxygen and hydrogen isotope composition; b); black carbon and dust concentrations; c) water conductivity; d) mineralogical analyses via X-ray powder diffraction. In the fall 2016, in the same area, a set of 1.0 m long horizontal ice cores have been extracted in another ice cave deposit, intercepting a preserved layer of coarse cryogenic cave carbonates (CCCcoarse). Such original finding represents the first alpine evidence of in situ CCCcoarse and the first occurrence from the southern side of the Alps. A unique opportunity to better understand the processes associated with the formation of CCCcoarse and the well-preserved status of samples allow planning, besides U/Th datings, several different analyses which may be associated with the precipitation of CCC. Subglacial calcite crusts, widespread in the area, represents a further proxy able to help understanding the evolution of climate during the holocene in this alpine sector. In the light of accelerated climate change we discuss here the potential of this still untapped and fragile cryospheric archives for paleoclimatic reconstructions in high elevated areas of the Alps.

  1. An ice core record of net snow accumulation and seasonal snow chemistry at Mt. Waddington, southwest British Columbia, Canada

    Science.gov (United States)

    Neff, P. D.; Steig, E. J.; Clark, D. H.; McConnell, J. R.; Pettit, E. C.; Menounos, B.

    2011-12-01

    We recovered a 141 m ice core from Combatant Col (51.39°N, 125.22°W, 3000 m asl) on the flank of Mt. Waddington, southern Coast Mountains, British Columbia, Canada. Aerosols and other impurities in the ice show unambiguous seasonal variations, allowing for annual dating of the core. Clustered melt layers, originating from summer surface heating, also aid in the dating of the core. Seasonality in water stable isotopes is preserved throughout the record, showing little evidence of diffusion at depth, and serves as an independent verification of the timescale. The annual signal of deuterium excess is especially well preserved. The record of lead deposition in the core agrees with those of ice cores from Mt. Logan and from Greenland, with a sharp drop-off in concentration in the 1970s and early 1980s, further validating the timescales. Despite significant summertime melt at this mid-latitude site, these data collectively reveal a continuous and annually resolved 36-year record of snow accumulation. We derived an accumulation time series from the Mt. Waddington ice core, after correcting for ice flow. Years of anomalously high or low snow accumulation in the core correspond with extremes in precipitation data and geopotential height anomalies from reanalysis data that make physical sense. Specifically, anomalously high accumulation years at Mt. Waddington correlate with years where "Pineapple Express" atmospheric river events bring large amounts of moisture from the tropical Pacific to western North America. The Mt. Waddington accumulation record thus reflects regional-scale climate. These results demonstrate the potential of ice core records from temperate glaciers to provide meaningful paleoclimate information. A longer core to bedrock (250-300 m) at the Mt. Waddington site could yield ice with an age of several hundred to 1000 years.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-11-01

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

  3. East Antarctic ice sheet stability recorded in a high-elevation ice-cored moraine

    Science.gov (United States)

    Bader, Nicole A.; Licht, Kathy J.; Kaplan, Michael R.; Kassab, Christine; Winckler, Gisela

    2017-03-01

    Till in an extensive blue ice moraine in the central Transantarctic Mountains at Mt. Achernar shows relatively continuous deposition by East Antarctic derived ice throughout the last glacial cycle. The most recently exposed material along the active margin of the Law Glacier (Zone 1) has hummocky topography that transitions into to a relatively flat region (Zone 2), followed by a series of ∼2 m high continuous, parallel/sub-parallel ridges and troughs (Zones 3-5). The entire moraine is ice-cored. Past surface changes of data, the U-Pb zircon data from till across all zones show little variability and are consistent with a Beacon Supergroup source, as samples show significant populations from the Proterozoic, ∼550-600 Ma and ∼950-1270 Ma, as well as the late Archean ∼2700-2770 Ma. The Mackellar, Fairchild, and lower Buckley Formations are interpreted as dominant sources of the detrital zircons. The zircon data lack the spatio-temporal variability indicated by the pebble fraction because the local Ferrar dolerite is not zircon bearing, highlighting the broader importance of using multiple techniques when interpreting provenance changes over time. Rather than reflecting major changes in ice flow path over time, the provenance changes are interpreted to indicate relative stability of the East Antarctic ice sheet, as the Law Glacier tapped into and eroded successively lower stratigraphic units of the Beacon Supergroup. This has important implications for interpreting offshore provenance records.

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

    Science.gov (United States)

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

    2014-08-01

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

  5. Small scale folding observed in the NEEM ice core

    Science.gov (United States)

    Jansen, Daniela; Llorens, Maria-Gema; Westhoff, Julien; Steinbach, Florian; Bons, Paul D.; Kipfstuhl, Sepp; Griera, Albert; Weikusat, Ilka

    2015-04-01

    Disturbances on the centimeter scale in the layering of the NEEM ice core (North Greenland) can be mapped by means of visual stratigraphy as long as the ice does have a visual layering, such as, for example, cloudy bands. Different focal depths of the visual stratigraphy method allow, to a certain extent, a three dimensional view of the structures. In this study we present a structural analysis of the visible folds, discuss characteristics and frequency and present examples of typical fold structures. With this study we aim to quantify the potential impact of small scale folding on the integrity of climate proxy data. We also analyze the structures with regard to the stress environment under which they formed. The structures evolve from gentle waves at about 1700 m to overturned z-folds with increasing depth. Occasionally, the folding causes significant thickening of layers. Their shape indicates that they are passive features and are probably not initiated by rheology differences between layers. Layering is heavily disturbed and tracing of single layers is no longer possible below a depth of 2160 m. Lattice orientation distributions for the corresponding core sections were analyzed where available in addition to visual stratigraphy. The data show axial-plane parallel strings of grains with c.axis orientations that deviate from that of the matrix, which has more or less a single-maximum fabric at the depth where the folding occurs. We conclude from these data that folding is a consequence of deformation along localized shear planes and kink bands. The findings are compared with results from other deep ice cores. The observations presented are supplemented by microstructural modeling using a crystal plasticity code that reproduces deformation, applying a Fast Fourier Transform (FFT), coupled with ELLE to include dynamic recrystallization processes. The model results reproduce the development of bands of grains with a tilted orientation relative to the single maximum

  6. A 60 000 year Greenland stratigraphic ice core chronology

    Directory of Open Access Journals (Sweden)

    K. K. Andersen

    2007-11-01

    Full Text Available The Greenland Ice Core Chronology 2005 (GICC05 is a time scale based on annual layer counting of high-resolution records from Greenland ice cores. Whereas the Holocene part of the time scale is based on various records from the DYE-3, the GRIP, and the NorthGRIP ice cores, the glacial part is solely based on NorthGRIP records. Here we present an 18 kyr extension of the time scale such that GICC05 continuously covers the past 60 kyr. The new section of the time scale places the onset of Greenland Interstadial 12 (GI-12 at 46.9±1.0 kyr b2k (before year AD 2000, the North Atlantic Ash Zone 2 layer in GI-15 at 55.4±1.2 kyr b2k, and the onset of GI-17 at 59.4±1.3 kyr b2k. The error estimates are derived from the accumulated number of uncertain annual layers and can be regarded as 1σ uncertainties. In the 40–60 kyr interval the new time scale has a discrepancy with the Meese-Sowers GISP2 time scale of up to 2.4 kyr, whereas GICC05 compares well to the dating of the Hulu Cave record with absolute age differences of less than 800 years throughout the 60 kyr period. The new time scale is generally in close agreement with other independently dated records and reference horizons, such as the Laschamp geomagnetic excursion and the Kleegruben speleothem record from the Austrian Alps, suggesting high accuracy of both event durations and absolute age estimates.

  7. A 60 000 year Greenland stratigraphic ice core chronology

    Directory of Open Access Journals (Sweden)

    A. Svensson

    2008-03-01

    Full Text Available The Greenland Ice Core Chronology 2005 (GICC05 is a time scale based on annual layer counting of high-resolution records from Greenland ice cores. Whereas the Holocene part of the time scale is based on various records from the DYE-3, the GRIP, and the NorthGRIP ice cores, the glacial part is solely based on NorthGRIP records. Here we present an 18 ka extension of the time scale such that GICC05 continuously covers the past 60 ka. The new section of the time scale places the onset of Greenland Interstadial 12 (GI-12 at 46.9±1.0 ka b2k (before year AD 2000, the North Atlantic Ash Zone II layer in GI-15 at 55.4±1.2 ka b2k, and the onset of GI-17 at 59.4±1.3 ka b2k. The error estimates are derived from the accumulated number of uncertain annual layers. In the 40–60 ka interval, the new time scale has a discrepancy with the Meese-Sowers GISP2 time scale of up to 2.4 ka. Assuming that the Greenland climatic events are synchronous with those seen in the Chinese Hulu Cave speleothem record, GICC05 compares well to the time scale of that record with absolute age differences of less than 800 years throughout the 60 ka period. The new time scale is generally in close agreement with other independently dated records and reference horizons, such as the Laschamp geomagnetic excursion, the French Villars Cave and the Austrian Kleegruben Cave speleothem records, suggesting high accuracy of both event durations and absolute age estimates.

  8. An Ice Core Perspective on Aleutian Low Variability over the Common Era

    Science.gov (United States)

    Osterberg, E. C.; Winski, D.; Kreutz, K. J.; Wake, C. P.; Ferris, D. G.; Campbell, S.; Introne, D.

    2016-12-01

    The Aleutian Low (ALow) is the dominant feature of atmospheric circulation in the North Pacific, strongly influencing wintertime temperature, precipitation and wind patterns in Alaska and the Yukon Territory, as well as further downstream in North America via atmospheric teleconnections. Changes in ALow strength are known to impact marine ecosystems by contributing to the multi-decadal sea-surface temperature mode in the North Pacific known as the Pacific Decadal Oscillation (PDO). Meteorological records show that in addition to distinct PDO-like variability, the ALow has intensified over the 20th century. However, ALow variability prior to the instrumental period remains unclear due to generally poor correlations among published ALow and PDO reconstructions, including the Mt. Logan ice core ALow record. An improved understanding of past ALow variability is critical for evaluating natural ALow forcing mechanisms, placing the 20th century intensification in context, and improving ALow projections under increased anthropogenic forcing. Here we combine ALow-sensitive time series from the new Denali ice core and the Mt. Logan ice core to develop a high-resolution (1-3 year) multi-ice-core record of ALow variability over the past 1500 years. The Denali ice core was collected from the summit plateau (3900 m) of Mt. Hunter in 2013, and was sampled using the Dartmouth continuous melter system with discrete sampling for major ion (IC), trace element (ICP-MS), and stable isotope ratios (Picarro), as well as continuous flow analyses for dust size and concentration (Klotz Abakus). We focus here on the sea-salt sodium time series, and calibrate our record over the 20th century with reanalysis wind speed and pressure data. The Denali sodium record of ALow strength strongly resembles the Mt. Logan ALow record, with both showing a recent intensification of the ALow that started in the late 1600s and continues into the 20th century. Both records reveal that the ALow was stronger

  9. Fire in Ice: Glacial-Interglacial biomass burning in the NEEM ice core

    Science.gov (United States)

    Zennaro, Piero; Kehrwald, Natalie; Zangrando, Roberta; Gambaro, Andrea; Barbante, Carlo

    2014-05-01

    Earth is an intrinsically flammable planet. Fire is a key Earth system process with a crucial role in biogeochemical cycles, affecting carbon cycle mechanisms, land-surface properties, atmospheric chemistry, aerosols and human activities. However, human activities may have also altered biomass burning for thousands of years, thus influencing the climate system. We analyse the specific marker levoglucosan to reconstruct past fire events in ice cores. Levoglucosan (1,6-anhydro-β-D-glucopyranose) is an organic compound that can be only released during the pyrolysis of cellulose at temperatures > 300°C. Levoglucosan is a major fire product in the fine fraction of woody vegetation combustion, can be transported over regional to global distances, and is deposited on the Greenland ice sheet. The NEEM, Greenland ice core (77 27'N, 51 3'W, 2454 masl) documents past fire activity changes from the present back to the penultimate interglacial, the Eemian. Here we present a fire activity reconstruction from both North American and Eurasian sources over the last 120,000 yrs based on levoglucosan signatures in the NEEM ice core. Biomass burning significantly increased over the boreal Northern Hemisphere since the last glacial, resulting in a maximum between 1.5 and 3.5 kyr BP yet decreasing from ~2 kyr BP until the present. Major climate parameters alone cannot explain the observed trend and thus it is not possible to rule out the hypothesis of early anthropogenic influences on fire activity. Over millennial timescales, temperature influences Arctic ice sheet extension and vegetation distribution at Northern Hemisphere high latitudes and may have altered the distance between NEEM and available fuel loads. During the last Glacial, the combination of dry and cold climate conditions, together with low boreal insolation and decreased atmospheric carbon dioxide levels may have also limited the production of available biomass. Diminished boreal forest extension and the southward

  10. Climatic indicators in an ice core from the Yukon [abstract

    OpenAIRE

    Holdsworth, G; Fogarasi, S.; Krouse, H. R.; M. Nosal

    1988-01-01

    EXTRACT (SEE PDF FOR FULL ABSTRACT): Stable isotope data obtained from snow and ice cores retrieved from an altitude of 5340m on Mt. Logan (60°30'N; 140°36'W) indicate that "isotopic seasons" are not generally in phase with calendar seasons. The former are phase lagged with respect to the latter by up to several months and appear to be correlated with SST'S and ocean heat transfer curves and/or the position of the Aleutian low rather than with air temperature or the temperature difference...

  11. Climatic and environmental changes over the last millennium recorded in the Malan ice core from the northern Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Ninglian; YAO Tandong; PU Jianchen; ZHANG Yongliang; SUN Weizhen

    2006-01-01

    In this paper, climatic and environmental changes were reconstructed since 1129A.D.based on the Malan ice core from Hol Xil, the northern Tibetan Plateau. The record of δ18O in the Malan ice core indicated that the warm-season air temperature variations displayed a general increase trend, the 20th-century warming was within the range of natural climate variability, and the warmest century was the 17th century while the warmest decade was the 1610s, over the entire study period. The "Medieval Warm Epoch" and "Little Ice Age" were also reflected by the ice core record.The dust ratio in the Malan ice core is a good proxy for dust event frequency. The 870-year record of the dust ratio showed that dust events occurred much frequently in the 19th century. Comparing the variations of δ18O and the dust ratio, it is found that there was a strong negative correlation between them on the time scales of 101 - 102 years. By analyses of all the climatic records of ice cores and tree rings from the northern Tibetan Plateau, it was revealed that dust events were more frequent in the cold and dry periods than in the warm and wet periods.

  12. Tropical Ice Core Records: Evidence for Asynchronous Glaciation on Milankovitch Time Scales

    Science.gov (United States)

    Thompson, L. G.

    2001-12-01

    Ice core records are available from selected high altitude, low and mid-latitude ice caps. Comparisons are made among the histories from the Tibetan Plateau, the tropical Andes of South America, and Kilimanjaro in East Africa. Three of these records (Guliya in China, Huascarán in Peru, and Sajama in Bolivia) contain ice deposited during the Last Glacial Stage (LGS). The oxygen isotopic ratios (δ 18O) of this ice suggest significant tropical cooling ( ~5° C). Comparison of a global array of cores reveals large-scale similarities as well as important regional differences. The δ 18O shift from Early Holocene to LGM is 5.4‰ on Sajama, 6.3‰ on Huascarán, ~5.3‰ in central Greenland, 6.6‰ at Byrd Station in Antarctica and 5.4‰ at Vostok also in Antarctica. These records all show similar isotopic depletion, reflecting significant global cooling at the Late Glacial Maximum (LGM). As continental ice sheets form only in high latitudes (>40° ), those regions have provided most of the evidence for the pulsing of Quaternary glaciations. In low latitudes, glaciers are restricted to the high mountains and only recently have enough long tropical ice core histories become available to investigate the timing of glaciations there. Long ice cores recovered to bedrock at 7 high-altitude (>5300 m) sites on three continents are investigated for synchroneity of their glaciation histories. The cores from Huascarán in Peru at 9° S and Sajama in Bolivia at 18° S contain continuous records back into the LGS. Both glaciers clearly survived the early Holocene warm period (9 to 6 ka B.P.), but neither contains a long record of glacial stage climate back to the previous interglacial. Rather, the published records from Huascarán and Sajama extend back ~19 kyr and 25 kyr, respectively. Hence, both mountaintops, among the highest in South America, appear to have been ice free during a time considered significantly colder than the Holocene. The records from Dasuopu (28° N) and

  13. Temperature and methane records over the last 2 ka in Dasuopu ice core

    Institute of Scientific and Technical Information of China (English)

    PU; Jianchen; (

    2002-01-01

    : The recover of ice cores at the elevation of 7000 m in Qinghai-Tibetan plateau and its significance, J. Glaciology & Geocryology (in Chinese), 1998, 20(1): 1-2.[15]Yao Tandong, Pu Jianchen, Wang Ninglian et al., A new type of ice formation zone found in the Himalayas, Chinese Science Bulletin, 1999, 44(5): 469-473.[16]Xu Baiqing, Yao Tandong, A study on the air bubble formation process at the elevation of 7100 m in Dasuopu glacier, J. Glaciology & Geocryology (in Chinese), 1999, 21(2): 115-120.[17]Yao, T. D., Duan, K. Q., Tian, L. D., Glacial accumulation record in the Dasuopu ice core and Indian summer monsoon rainfall in the past 400 years, Science in China (in Chinese), Ser. D, 2000, 30(6): 619-627.[18]Thompson, L. G., Yao, T., Mosley-Thompson, E. et al., A High-resolution Millennial Record of the South Asian Monsoon from Himalayan Ice Cores, Science, 2000, 289(5486): 1916-1920.[19]Huang Cuilan, Yao Tandong, Pu Jianchen et al., Environmental information recorded in shallow ice core of Dasuopu glacier in the Qinghai-Tibetan Plateau, Chinese Science Bulletin, 1998, 43(22): 1935-1936.[20]Duan Keqin, Wang Ninglian, Li Yuefang, Accumulation in Dasuopu ice core in Qinghai-Tibet Plateau and solar activity, Chinese Science Bulletin, 2000, 45(11): 1038-1041.[21]Duan, K.Q., Yao, T. D., Modern environment and climate recorded in the Dasuopu ice core, in Formation and Evolution, Environmental Changes and Sustainable Development on the Tibetan Plateau (ed. Zheng Du et al), Beijing: Academic Press, 54-61.[22]Huo Wenmian, Yao Tandong, Li Yuefang, Inceasing atmospheric pollution revealed by Pb record of a 7000-m ice core, Chinese Science Bulletin, 1999, 44(14): 1309-1312.[23]Raynaud, D., Chappellaz, J., The record of atmospheric methane, in Atmospheric Methane: Sources, Sinks, and Role in the Global Change, NATO ASI Series (ed. Khalil, M. A. K.), Berlin, Heidelberg: Springer-Verlag, 1993, 113: 38-59.[24]Wang Mingxing, Atmospheric Chemistry

  14. Deconvolution-based resolution enhancement of chemical ice core records obtained by continuous flow analysis

    DEFF Research Database (Denmark)

    Rasmussen, Sune Olander; Andersen, Katrine K.; Johnsen, Sigfus Johann;

    2005-01-01

    Continuous flow analysis (CFA) has become a popular measuring technique for obtaining high-resolution chemical ice core records due to an attractive combination of measuring speed and resolution. However, when analyzing the deeper sections of ice cores or cores from low-accumulation areas, there ...

  15. Recent Increases in Snow Accumulation and Decreases in Sea-Ice Concentration Recorded in a Coastal NW Greenland Ice Core

    Science.gov (United States)

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

    2013-12-01

    A significant rise in summer temperatures over the past several decades has led to widespread retreat of the Greenland Ice Sheet (GIS) margin and surrounding sea ice. Recent observations from geodetic stations and GRACE show that ice mass loss progressed from South Greenland up to Northwest Greenland by 2005 (Khan et al., 2010). Observations from meteorological stations at the U.S. Thule Air Force Base, remote sensing platforms, and climate reanalyses indicate a 3.5C mean annual warming in the Thule region and a 44% decrease in summer (JJAS) sea-ice concentrations in Baffin Bay from 1980-2010. Mean annual precipitation near Thule increased by 12% over this interval, with the majority of the increase occurring in fall (SON). To improve projections of future ice loss and sea-level rise in a warming climate, we are currently developing multi-proxy records (lake sediment cores, ice cores, glacial geologic data, glaciological models) of Holocene climate variability and cryospheric response in NW Greenland, with a focus on past warm periods. As part of our efforts to develop a millennial-length ice core paleoclimate record from the Thule region, we collected and analyzed snow pit samples and short firn cores (up to 20 m) from the coastal region of the GIS (2Barrel site; 76.9317 N, 63.1467 W) and the summit of North Ice Cap (76.938 N, 67.671 W) in 2011 and 2012, respectively. The 2Barrel ice core was sampled using a continuous ice core melting system at Dartmouth, and subsequently analyzed for major anion and trace element concentrations and stable water isotope ratios. Here we show that the 2Barrel ice core spanning 1990-2010 records a 25% increase in mean annual snow accumulation, and is positively correlated (r = 0.52, p<0.01) with ERA-Interim precipitation. The 2Barrel annual sea-salt Na concentration is strongly correlated (r = 0.5-0.8, p<0.05) with summer and fall sea-ice concentrations in northern Baffin Bay near Thule (Figure 1). We hypothesize that the positive

  16. Precipitation variations recorded in Guliya ice core in the past 400 years

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the Guliya ice core records, the precipitation in the past 400 years was retrieved. Its rela tions with other regions were also analyzed. The results demonstrated that there were two high-precipitation periods and two low-precipitation periods in Guliya ice core since 1571 AD. The average precipitation in the two high-precipitation periods was 42 mm (21%) higher than that in the two low-precipitation periods. The precipitation recorded in the Guliya ice core was consistent with that in Dunde ice core. The variation trends of precipitation in the Guliya ice core and the northern hemisphere are similar. During the extremely wet years in the northern hemisphere, the precipitation recorded in the Guliya ice core was two times the long-term average. However, the annual precipitation was 38% less than that of the long-term average in extremely dry years.

  17. Denali Ice Core Record of North Pacific Hydroclimate, Temperature and Atmospheric Circulation over the Past Millennium

    Science.gov (United States)

    Osterberg, E. C.; Wake, C. P.; Kreutz, K. J.; Winski, D.; Ferris, D. G.; Introne, D.; Campbell, S.; Birkel, S. D.

    2015-12-01

    While tree ring and lake sediment core studies have revealed a great deal about North Pacific (e.g. Alaska) surface temperature variability over the past millennium, we do not have an equivalent understanding of North Pacific hydroclimate variability or temperatures at high elevations. A millennial-length precipitation proxy record is needed to place late 20th century Alaskan precipitation increases into longer context, and to evaluate hydroclimate changes during the Little Ice Age and Medieval Climate Anomaly. High-elevation summer temperature records would be valuable for understanding the sensitivity of Alaskan glaciers to past warm and cool periods. Here we present an overview of the new Denali Ice Core record collected from the summit plateau (4000 m a.s.l.) of Mt. Hunter (63° N, 151° W) in Denali National Park, Alaska. Two parallel ice cores were collected to bedrock (208 m in length) in May-June 2013, sampled using the Dartmouth continuous melter system, and analyzed for major ions, trace elements, particle concentration and size distribution, and stable isotope ratios at Dartmouth and the Universities of Maine and New Hampshire. The cores are dated using robust annual oscillations in dust elements, methanesulfonate, ammonium, and stable isotopes, and validated using major volcanic eruptions recorded as sulfate, chloride and heavy metal spikes, and the 1963 nuclear weapons testing 137Cs spike. Preliminary analyses indicate a significant increase in both summer temperature and annual accumulation over the 20th century, and significant relationships with major ocean-atmospheric modes including the Pacific Decadal Oscillation. We compare the new Denali record to the Eclipse Icefield and Mt. Logan ice core records and develop composite records of North Pacific hydroclimate and atmospheric circulation variability over the past millennium.

  18. Ice cores and SeaRISE: What we do (and don't) know

    Science.gov (United States)

    Alley, Richard B.

    1991-01-01

    Ice core analyses are needed in SeaRISE to learn what the West Antarctic ice sheet and other marine ice sheets were like in the past, what climate changes led to their present states, and how they behave. The major results of interest to SeaRISE from previous ice core analyses in West Antarctic are that the end of the last ice age caused temperature and accumulation rate increases in inland regions, leading to ice sheet thickening followed by thinning to the present.

  19. Radiocarbon analyses along the EDML ice core in Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Wal, R.S.W. van de; Veen, C. van der [Utrecht Univ. (Netherlands). Inst. for Marine and Atmospheric research; Meijer, H.A.J.; De Rooij, M. [Univ. of Groningen (Netherlands). Center for Isotope Research

    2007-02-15

    Samples, 17 in total, from the EDML core drilled at Kohnen station Antarctica are analysed for {sup 14}CO and {sup 14}CO{sub 2} with a dry-extraction technique in combination with accelerator mass spectrometry. Results of the in situ produced {sup 14}CO fraction show a very low concentration of in situ produced {sup 14}CO. Despite these low levels in carbon monoxide, a significant in situ production is observed in the carbon dioxide fraction. For the first time we found background values for the ice samples which are equal to line blanks. The data set is used to test a model for the production of {sup 14}C in the ice matrix, in combination with a degassing as {sup 14}CO{sub 2} and possibly as {sup 14}CO into the air bubbles. Application of the model, for which no independent validation is yet possible, offers the opportunity to use radiocarbon analysis as dating technique for the air bubbles in the ice. Assigning an arbitrary error of 25% to the calculation of the in situ production leads to age estimates, after correction for the in situ production, which are in agreement with age estimates based on a volcanic layer match of EDML to the Dome C timescale in combination with a correction for firn diffusion.

  20. Accumulation in Dasuopu ice core in Qinghai-Tibet Plateau and solar activity

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The time series of accumulation in recent 300 years correlated well with solar activity in Dasuopu ice core. Results of spectrum analysis on the accumulation time series of the Dasuopu ice core shows that there are some periods that coincide with the periods of solar activity. By comparing the long-time change trend of the accumulation in the Dasuopu ice core with various kinds of indexes of solar activity intensity, a negative correlation is found between the trend and solar activity.

  1. Deep Radiostratigraphy of the East Antarctic Plateau: Connecting the Dome C and Vostok Ice Core Sites

    Science.gov (United States)

    Cavitte, Marie G. P.; Blankenship, Donald D.; Young, Duncan A.; Schroeder, Dustin M.; Parrenin, Frederic; Lemeur, Emmanuel; Macgregor, Joseph A.; Siegert, Martin J.

    2016-01-01

    Several airborne radar-sounding surveys are used to trace internal reflections around the European Project for Ice Coring in Antarctica Dome C and Vostok ice core sites. Thirteen reflections, spanning the last two glacial cycles, are traced within 200 km of Dome C, a promising region for million-year-old ice, using the University of Texas Institute for Geophysics High-Capacity Radar Sounder. This provides a dated stratigraphy to 2318 m depth at Dome C. Reflection age uncertainties are calculated from the radar range precision and signal-to-noise ratio of the internal reflections. The radar stratigraphy matches well with the Multichannel Coherent Radar Depth Sounder (MCoRDS) radar stratigraphy obtained independently. We show that radar sounding enables the extension of ice core ages through the ice sheet with an additional radar-related age uncertainty of approximately 1/3-1/2 that of the ice cores. Reflections are extended along the Byrd-Totten Glacier divide, using University of Texas/Technical University of Denmark and MCoRDS surveys. However, core-to-core connection is impeded by pervasive aeolian terranes, and Lake Vostok's influence on reflection geometry. Poor radar connection of the two ice cores is attributed to these effects and suboptimal survey design in affected areas. We demonstrate that, while ice sheet internal radar reflections are generally isochronal and can be mapped over large distances, careful survey planning is necessary to extend ice core chronologies to distant regions of the East Antarctic ice sheet.

  2. Assessing Stationarity in Ice Core Record-Sea Level Pressure Relationships for Yukon Territory Ice Core Records

    Science.gov (United States)

    Kelsey, E. P.; Wake, C. P.; Osterberg, E. C.

    2014-12-01

    We assess the stationarity of the relationship between Northern Hemisphere winter (Dec-Feb) sea-level pressure (SLP) and proxy time series (major ions, accumulation, and stable isotopes) from the Eclipse (3017 m asl) and the Mt. Logan Prospector-Russell Col (PRCol; 5340 m asl) ice cores from Yukon, Canada. We develop a novel spatial calibration procedure to identify ranges of ice core values that are associated with consistent winter SLP anomaly patterns. Each ice core variable time series was ranked and divided into groups of 13 years each. We assess stationarity by splitting the 1872-2001 analysis period in half (1872-1936 and 1937-2001) and comparing the locations and magnitudes of SLP anomaly patterns during the two periods for each group of ice core values. Northern Hemisphere monthly mean SLP from the 20th Century Reanalysis dataset are used. The high accumulation rate (1.38 m a-1) at Eclipse allows us to analyze 6-month seasonal mean values (Oct-Mar and Apr-Sep), whereas annual mean values are used from PRCol where the accumulation rate is lower (0.40 m a-1). The Eclipse cold season accumulation and PRCol annual mean sodium concentrations (Na+) exhibit the strongest correlations with winter SLP anomaly patterns. In particular, the lowest and highest 20% annual Na+ values at PRCol and lowest 10% cold season accumulation values at Eclipse exhibit stationarity with consistent SLP anomaly patterns in the North Pacific for all three time periods. A weaker Aleutian Low consistently occurred in the central to eastern North Pacific for the lowest Na+ years at PRCol and lowest accumulation cold seasons at Eclipse, although these groups of years are mostly independent. A stronger Aleutian Low occurs in the North Pacific for the highest Na+ years at PRCol. A stationary SLP anomaly pattern is not observed through all three time periods for high cold season accumulation at Eclipse. Application of this calibration procedure with other traditional calibration and

  3. Water isotopic ratios from a continuously melted ice core sample

    Directory of Open Access Journals (Sweden)

    V. Gkinis

    2011-06-01

    Full Text Available A new technique for on-line high resolution isotopic analysis of liquid water, tailored for ice core studies is presented. We build an interface between an Infra Red Cavity Ring Down Spectrometer (IR-CRDS and a Continuous Flow Analysis (CFA system. The system offers the possibility to perform simultaneuous water isotopic analysis of δ18O and δD on a continuous stream of liquid water as generated from a continuously melted ice rod. Injection of sub μl amounts of liquid water is achieved by pumping sample through a fused silica capillary and instantaneously vaporizing it with 100 % efficiency in a home made oven at a temperature of 170 °C. A calibration procedure allows for proper reporting of the data on the VSMOW scale. We apply the necessary corrections based on the assessed performance of the system regarding instrumental drifts and dependance on humidity levels. The melt rates are monitored in order to assign a depth scale to the measured isotopic profiles. Application of spectral methods yields the combined uncertainty of the system at below 0.1 ‰ and 0.5 ‰ for δ18O and δD, respectively. This performance is comparable to that achieved with mass spectrometry. Dispersion of the sample in the transfer lines limits the resolution of the technique. In this work we investigate and assess these dispersion effects. By using an optimal filtering method we show how the measured profiles can be corrected for the smoothing effects resulting from the sample dispersion. Considering the significant advantages the technique offers, i.e. simultaneuous measurement of δ18O and δD, potentially in combination with chemical components that are traditionally measured on CFA systems, notable reduction on analysis time and power consumption, we consider it as an alternative to traditional isotope ratio mass spectrometry with the possibility to be deployed for field ice core studies. We present data acquired in the

  4. Water isotopic ratios from a continuously melted ice core sample

    Directory of Open Access Journals (Sweden)

    V. Gkinis

    2011-11-01

    Full Text Available A new technique for on-line high resolution isotopic analysis of liquid water, tailored for ice core studies is presented. We built an interface between a Wavelength Scanned Cavity Ring Down Spectrometer (WS-CRDS purchased from Picarro Inc. and a Continuous Flow Analysis (CFA system. The system offers the possibility to perform simultaneuous water isotopic analysis of δ18O and δD on a continuous stream of liquid water as generated from a continuously melted ice rod. Injection of sub μl amounts of liquid water is achieved by pumping sample through a fused silica capillary and instantaneously vaporizing it with 100% efficiency in a~home made oven at a temperature of 170 °C. A calibration procedure allows for proper reporting of the data on the VSMOW–SLAP scale. We apply the necessary corrections based on the assessed performance of the system regarding instrumental drifts and dependance on the water concentration in the optical cavity. The melt rates are monitored in order to assign a depth scale to the measured isotopic profiles. Application of spectral methods yields the combined uncertainty of the system at below 0.1‰ and 0.5‰ for δ18O and δD, respectively. This performance is comparable to that achieved with mass spectrometry. Dispersion of the sample in the transfer lines limits the temporal resolution of the technique. In this work we investigate and assess these dispersion effects. By using an optimal filtering method we show how the measured profiles can be corrected for the smoothing effects resulting from the sample dispersion. Considering the significant advantages the technique offers, i.e. simultaneuous measurement of δ18O and δD, potentially in combination with chemical components that are traditionally measured on CFA systems, notable reduction on analysis time and power consumption, we consider it as an alternative to traditional isotope ratio mass spectrometry with the possibility to

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

    Directory of Open Access Journals (Sweden)

    J. Schwander

    2012-04-01

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

  6. Methane and nitrous oxide in the ice core record.

    Science.gov (United States)

    Wolff, Eric; Spahni, Renato

    2007-07-15

    Polar ice cores contain, in trapped air bubbles, an archive of the concentrations of stable atmospheric gases. Of the major non-CO2 greenhouse gases, methane is measured quite routinely, while nitrous oxide is more challenging, with some artefacts occurring in the ice and so far limited interpretation. In the recent past, the ice cores provide the only direct measure of the changes that have occurred during the industrial period; they show that the current concentration of methane in the atmosphere is far outside the range experienced in the last 650,000 years; nitrous oxide is also elevated above its natural levels. There is controversy about whether changes in the pre-industrial Holocene are natural or anthropogenic in origin. Changes in wetland emissions are generally cited as the main cause of the large glacial-interglacial change in methane. However, changing sinks must also be considered, and the impact of possible newly described sources evaluated. Recent isotopic data appear to finally rule out any major impact of clathrate releases on methane at these time-scales. Any explanation must take into account that, at the rapid Dansgaard-Oeschger warmings of the last glacial period, methane rose by around half its glacial-interglacial range in only a few decades. The recent EPICA Dome C (Antarctica) record shows that methane tracked climate over the last 650,000 years, with lower methane concentrations in glacials than interglacials, and lower concentrations in cooler interglacials than in warmer ones. Nitrous oxide also shows Dansgaard-Oeschger and glacial-interglacial periodicity, but the pattern is less clear.

  7. Fire in ice: two millennia of boreal forest fire history from the Greenland NEEM ice core

    Science.gov (United States)

    Zennaro, P.; Kehrwald, N.; McConnell, J. R.; Schüpbach, S.; Maselli, O. J.; Marlon, J.; Vallelonga, P.; Leuenberger, D.; Zangrando, R.; Spolaor, A.; Borrotti, M.; Barbaro, E.; Gambaro, A.; Barbante, C.

    2014-10-01

    Biomass burning is a major source of greenhouse gases and influences regional to global climate. Pre-industrial fire-history records from black carbon, charcoal and other proxies provide baseline estimates of biomass burning at local to global scales spanning millennia, and are thus useful to examine the role of fire in the carbon cycle and climate system. Here we use the specific biomarker levoglucosan together with black carbon and ammonium concentrations from the North Greenland Eemian (NEEM) ice cores (77.49° N, 51.2° W; 2480 m a.s.l) over the past 2000 years to infer changes in boreal fire activity. Increases in boreal fire activity over the periods 1000-1300 CE and decreases during 700-900 CE coincide with high-latitude NH temperature changes. Levoglucosan concentrations in the NEEM ice cores peak between 1500 and 1700 CE, and most levoglucosan spikes coincide with the most extensive central and northern Asian droughts of the past millennium. Many of these multi-annual droughts are caused by Asian monsoon failures, thus suggesting a connection between low- and high-latitude climate processes. North America is a primary source of biomass burning aerosols due to its relative proximity to the Greenland Ice Cap. During major fire events, however, isotopic analyses of dust, back trajectories and links with levoglucosan peaks and regional drought reconstructions suggest that Siberia is also an important source of pyrogenic aerosols to Greenland.

  8. Measurement of the fracture toughness of polycrystalline bubbly ice from an Antarctic ice core

    Directory of Open Access Journals (Sweden)

    J. Christmann

    2015-05-01

    Full Text Available The critical fracture toughness is a material parameter describing the resistance of a cracked body to further crack extension. It is an important parameter for simulating and predicting the breakup behavior of ice shelves from the calving of single icebergs to the disintegration of entire ice shelves over a wide range of length scales. The fracture toughness values are calculated with equations that are derived from an elastic stress analysis. Additionally, an X-ray computer tomography (CT scanner was used to identify the density as a function of depth. The critical fracture toughness of 91 Antarctic bubbly ice samples with densities between 840 and 870 kg m−3 has been determined by applying a four-point bending technique on single-edge v-notched beam samples. The examined ice core was drilled 70 m north of Kohnen Station, Dronnning Maud Land (75°00' S, 00°04' E; 2882 m. Supplementary data are available at doi:10.1594/PANGAEA.835321.

  9. Drilling, processing and first results for Mount Johns ice core in West Antarctica Ice Sheet

    Directory of Open Access Journals (Sweden)

    Franciele Schwanck

    Full Text Available ABSTRACT: An ice core, 92.26 m in length, was collected near the ice divide of the West Antarctica ice sheet during the 2008/2009 austral summer. This paper described the fieldwork at the Mount Johns site (79º55'S; 94º23'W and presented the first results of the upper 45.00 m record covering approximately 125 years (1883 - 2008, dated by annual layer counting and volcanic reference horizons. Trace element concentrations in 2,137 samples were determined using inductively coupled plasma mass spectrometry. The concentrations obtained for Al, Ba, Ca, Fe, K, Mg, Mn, Na, Sr and Ti are controlled by climate variations, the transport distance, and the natural sources of these aerosols. Natural dust contributions, mainly derived from the arid areas of Patagonia and Australia, are important sources for aluminum, barium, iron, manganese and titanium. Marine aerosols from sea ice and transported by air masses are important sources of sodium and magnesium. Calcium, potassium and strontium showed considerable inputs of both continental dust and marine aerosols.

  10. Seismic wave propagation in anisotropic ice – Part 1: Elasticity tensor and derived quantities from ice-core properties

    Directory of Open Access Journals (Sweden)

    A. Diez

    2014-08-01

    Full Text Available A preferred orientation of the anisotropic ice crystals influences the viscosity of the ice bulk and the dynamic behaviour of glaciers and ice sheets. Knowledge about the distribution of crystal anisotropy, to understand its contribution to ice dynamics, is mainly provided by crystal orientation fabric (COF data from ice cores. However, the developed anisotropic fabric does not only influence the flow behaviour of ice, but also the propagation of seismic waves. Two effects are important: (i sudden changes in COF lead to englacial reflections and (ii the anisotropic fabric induces an angle dependency on the seismic velocities and, thus, also recorded traveltimes. A framework is presented here to connect COF data with the elasticity tensor to determine seismic velocities and reflection coefficients for cone and girdle fabrics from ice-core data. We connect the microscopic anisotropy of the crystals with the macroscopic anisotropy of the ice mass, observable with seismic methods. Elasticity tensors for different fabrics are calculated and used to investigate the influence of the anisotropic ice fabric on seismic velocities and reflection coefficients, englacially as well as for the ice-bed contact. Our work, therefore, provides a contribution to remotely determine the state of bulk ice anisotropy.

  11. The Mount Logan (Yukon) Ice Cores: Preliminary Results

    Science.gov (United States)

    Fisher, D. A.

    2004-05-01

    Three ice cores were taken at different elevations on or near My Logan in the years 2001 and 2002. The summit core (PRCol) comes from the summit plateau ( 5340 masl, length 187 m to bedrock, mean temperature -29 C ) and was done by the Geological Survey of Canada. The NIPR group cored 210m on the flanks of the mountain at King Col (4200 masl mean temperature -16C) and the UNH group cored 20 km from the mountain at Eclipse "Dome" (3015 masl,length 345 m mean temperature -5C) . The three cores were done cooperatively by GSC, NIPR and UNH and cover nominally 30 ka, 1 ka and 2ka respectively . Located very close to the Gulf of Alaska these core records are thought to reflect the climate history of the Pacific Ocean and having three widely spaced elevations, the sites "see" different distances to different sources. The lowest site (Eclipse) has excellent seasonals but a very muted δ 18O history with no obvious little ice age, whereas the most recent 1ka of the PRCol summit sites contains two very large and sudden δ 18O and d (deuterium excess) shifts at 1850 AD and ~ 800 AD. The δ 18O shifts which happen from one year to the next are about 4 o/oo . The summit site (PRCol) δ 18O response is "backwards", ie the Little Ice Age δ 18O values are 4 o/oo more positive than recent ones. The PRCol δ 18O and d suggest that the source water can either be ëlocalí (Gulf of Alaska) or very distant (tropics) . The Eclipse site seems only to get the local water . A massive dust storm originating in central Asia (Gobi) in April 2001 dumped a visible layer all over the St Elias Mountains and this layer was sampled, to provide a calibration "Asian dust event". The satellite and isotoic signatures both agreed that Gobi was the source. The PRCol record covers the Holocene and well back into the ice age. The transition is defined by a sudden ECM shift on the flanks of a more gradual O18 shift. Acknowledgements. Logan consortium consists of : Geological Survey of Canada : Jocelyne

  12. Climatic and insolation control on the high-resolution total air content in the NGRIP ice core

    Science.gov (United States)

    Eicher, Olivier; Baumgartner, Matthias; Schilt, Adrian; Schmitt, Jochen; Schwander, Jakob; Stocker, Thomas F.; Fischer, Hubertus

    2016-10-01

    Because the total air content (TAC) of polar ice is directly affected by the atmospheric pressure and temperature, its record in polar ice cores was initially considered as a proxy for past ice sheet elevation changes. However, the Antarctic ice core TAC record is known to also contain an insolation signature, although the underlying physical mechanisms are still a matter of debate. Here we present a high-resolution TAC record over the whole North Greenland Ice Core Project ice core, covering the last 120 000 years, which independently supports an insolation signature in Greenland. Wavelet analysis reveals a clear precession and obliquity signal similar to previous findings on Antarctic TAC, with a different insolation history. In our high-resolution record we also find a decrease of 4-6 % (4-5 mL kg-1) in TAC as a response to Dansgaard-Oeschger events (DO events). TAC starts to decrease in parallel to increasing Greenland surface temperature and slightly before CH4 reacts to the warming but also shows a two-step decline that lasts for several centuries into the warm interstadial. The TAC response is larger than expected considering only changes in air density by local temperature and atmospheric pressure as a driver, pointing to a transient firnification response caused by the accumulation-induced increase in the load on the firn at bubble close-off, while temperature changes deeper in the firn are still small.

  13. Dansgaard-Oeschger cycles observed in the Greenland ReCAP ice core project

    Science.gov (United States)

    Kjær, Helle Astrid; Vallelonga, Paul; Vinther, Bo; Simonsen, Marius; Maffezzoli, Niccoló; Gkinis, Vasileios; Svensson, Anders; Jensen, Camilla Marie; Dallmayr, Remi; Spolaor, Andrea; Edwards, Ross

    2017-04-01

    The new REnland ice CAP (RECAP) ice core was drilled in summer 2015 in Greenland and measured by means of Continuous flow analysis (CFA) during the last 3 months of 2015. The Renland ice core was obtained as part of the ReCAP project, extending 584.11 meters to the bottom of the Renland ice cap located in east Greenland. The unique position on a mountain saddle above 2000 meters altitude, but close to the coast, ensures that the Renland ice core offers high accumulation, but also reaches far back in time. Results show that despite the short length the RECAP ice core holds ice all the way back to the past warm interglacial period, the Eemian. The glacial section is strongly thinned and covers on 20 meters of the ReCAP core, but nonetheless due to the high resolution of the measurements all 25 expected DO events could be identified. The record was analyzed for multiple elements including the water isotopes, forest fire tracers NH4+ and black carbon, insoluble dust particles by means of Abakus laser particle counter and the dust ion Ca2+, sea salt Na+, and sea ice proxies as well as acidity useful for finding volcanic layers to date the core. Below the glacial section another 20 meters of warm Eemian ice have been analysed. Here we present the chemistry results as obtained by continuous flow analysis (CFA) and compare the glacial section with the chemistry profile from other Greenland ice cores.

  14. Ultra-sensitive Flow Injection Analysis (FIA) determination of calcium in ice cores at ppt level.

    Science.gov (United States)

    Traversi, R; Becagli, S; Castellano, E; Maggi, V; Morganti, A; Severi, M; Udisti, R

    2007-07-02

    A Flow Injection Analysis (FIA) spectrofluorimetric method for calcium determination in ice cores was optimised in order to achieve better analytical performances which would make it suitable for reliable calcium measurements at ppt level. The method here optimised is based on the formation of a fluorescent compound between Ca and Quin-2 in buffered environment. A careful evaluation of operative parameters (reagent concentration, buffer composition and concentration, pH), influence of interfering species possibly present in real samples and potential favourable effect of surfactant addition was carried out. The obtained detection limit is around 15 ppt, which is one order of magnitude lower than the most sensitive Flow Analysis method for Ca determination currently available in literature and reproducibility is better than 4% for Ca concentrations of 0.2 ppb. The method was validated through measurements performed in parallel with Ion Chromatography on 200 samples from an alpine ice core (Lys Glacier) revealing an excellent fit between the two chemical series. Calcium stratigraphy in Lys ice core was discussed in terms of seasonal pattern and occurrence of Saharan dust events.

  15. Holocene paleotemperature signals based on polar firn water isotope diffusion studies from two Greenland ice cores.

    Science.gov (United States)

    Gkinis, Vasileios; Terkelsen Holme, Christian; Møllesøe Vinther, Bo

    2017-04-01

    Polar ice cores provide a wealth of paleoclimatic information that is characterised by high temporal resolution and continuity, with water isotopic ratios of polar precipitation (δ18O, δD) being one of the most prominent proxies for past temperatures. In particular, ice cores from Greenland, record the series of abrupt stadial - interstadial transitions during the last Glacial, pinpointing in time, abrupt temperature transitions adjoined by similar accumulation trends. While the signal to noise ratio of the isotopic signal clearly allows the observation of sizable climate changes during the Glacial, the situation differs considerably when one looks into the Holocene. With the exception of the 8.2ky event, the signal to noise ratio of δ18O over the Holocene is extremely low, suggesting negligible temperature changes during this period. This is contrary to signals obtained by other proxies from marine and terrestrial records from high latitudes. In this study we bypass the discussion that deals with the various processes that can negatively affect paleotemperature reconstructions based on the δ18O proxy from ice cores. Based on two ultra-high resolution and high precision isotopic records covering the last 20,000 years from the NorthGRIP and NEEM ice cores we make use of the available spectral information to infer polar firn paleotemperatures using a coupled densification - firn water isotope diffusion model. The processes involved in the densification of firn and the diffusion of water isotopes that takes place after deposition and until the pore close-off are temperature-dependent and do not present the limitations of the normal δ18O thermometer. We show here how this approach reveals significant temperature changes over the Holocene. We compare the signals of the two records and pay particular attention to the indications of a mid-Holocene climatic shift towards colder temperatures that is apparent in both temperature reconstructions.

  16. Characterizing black carbon in rain and ice cores using coupled tangential flow filtration and transmission electron microscopy

    Directory of Open Access Journals (Sweden)

    A. Ellis

    2015-06-01

    Full Text Available Antarctic ice cores have been used to study the history of black carbon (BC, but little is known with regards to the physical and chemical characteristics of these particles in the remote atmosphere. Characterization remains limited by ultra-trace concentrations in ice core samples and the lack of adequate methods to isolate the particles unaltered from the melt water. To investigate the physical and chemical characteristics of these particles, we have developed a tangential flow filtration (TFF method combined with transmission electron microscopy (TEM. Tests using ultrapure water and polystyrene latex particle standards resulted in excellent blanks and significant particle recovery. This approach has been applied to melt water from Antarctic ice cores as well as tropical rain from Darwin, Australia with successful results: TEM analysis revealed a variety of BC particle morphologies, insoluble coatings, and the attachment of BC to mineral dust particles. The TFF-based concentration of these particles has proven to give excellent results for TEM studies of BC particles in Antarctic ice cores and can be used for future studies of insoluble aerosols in rainwater and ice core samples.

  17. Statistical extraction of volcanic sulphate from non-Polar ice cores

    NARCIS (Netherlands)

    Moore, J.C.; Beaudon, E.; Kang, S.; Divine, D.; Isaksson, E.; Pohjola, V.A.; van de Wal, R.S.W.

    2012-01-01

    Ice cores from outside the Greenland and Antarctic ice sheets are difficult to date because of seasonal melting and multiple sources (terrestrial, marine, biogenic and anthropogenic) of sulfates deposited onto the ice. Here we present a method of volcanic sulfate extraction that relies on fitting

  18. Statistical extraction of volcanic sulphate from non-Polar ice cores

    NARCIS (Netherlands)

    Moore, J.C.; Beaudon, E.; Kang, S.; Divine, D.; Isaksson, E.; Pohjola, V.A.; van de Wal, R.S.W.

    2012-01-01

    Ice cores from outside the Greenland and Antarctic ice sheets are difficult to date because of seasonal melting and multiple sources (terrestrial, marine, biogenic and anthropogenic) of sulfates deposited onto the ice. Here we present a method of volcanic sulfate extraction that relies on fitting su

  19. Effect of periodic melting on geochemical and isotopic signals in an ice core from Lomonosovfonna, Svalbard

    NARCIS (Netherlands)

    Pohjola, V.A.; Moore, J.C.; Isaksson, E.; Jauhiainen, T.; Wal, R.S.W. van de; Martma, T.; Meijer, H.A.J.; Vaikmäe, R.

    2002-01-01

    [1] We examine the quality of atmospherically deposited ion and isotope signals in an ice core taken from a periodically melting ice field, Lomonosovfonna in central Spitsbergen, Svalbard. The aim is to determine the degree to which the signals are altered by periodic melting of the ice. We use thre

  20. Effect of periodic melting on geochemical and isotopic signals in an ice core from Lomonosovfonna, Svalbard

    NARCIS (Netherlands)

    Pohjola, V.A.; Moore, J.C.; Isaksson, E.; Jauhiainen, T.; Wal, R.S.W. van de; Martma, T.; Meijer, H.A.J.; Vaikmäe, R.

    2002-01-01

    [1] We examine the quality of atmospherically deposited ion and isotope signals in an ice core taken from a periodically melting ice field, Lomonosovfonna in central Spitsbergen, Svalbard. The aim is to determine the degree to which the signals are altered by periodic melting of the ice. We use thre

  1. Holocene biomass burning recorded in polar and low-latitude ice cores

    Science.gov (United States)

    Kehrwald, N. M.; Zennaro, P.; Zangrando, R.; Gabrielli, P.; Thompson, L. G.; Gambaro, A.; Barbante, C.

    2011-12-01

    Ice cores contain specific molecular markers including levoglucosan (1,6-anhydro-β-D-glucopyranose) and other pyrochemical evidence that provides much-needed information on the role of fire in regions with no existing data of past fire activity. Levoglucosan is a cellulose combustion product produced at burning temperatures of 300°C or greater. We first trace fire emissions from a boreal forest source in the Canadian Shield through transport and deposition at Summit, Greenland. Atmospheric and surface samples suggest that levoglucosan in snow can record biomass burning events up to 1000s of kilometers away. Levoglucosan does degrade by interacting with hydroxyl radicals in the atmosphere, but it is emitted in large quantities, allowing the use as a biomass burning tracer. These quantified atmospheric biomass burning emissions and associated parallel oxalate and levoglucosan peaks in snow pit samples validates levoglucosan as a proxy for past biomass burning in snow records and by extension in ice cores. The temporal and spatial resolution of chemical markers in ice cores matches the core in which they are measured. The longest temporal resolution extends back approximately eight glacial cycles in the EPICA Dome C ice core, but many ice cores provide high-resolution Holocene records. The spatial resolution of chemical markers in ice cores depends on the core location where low-latitude ice cores primarily reflect regional climate parameters, and polar ice cores integrate hemispheric signals. Here, we compare levoglucosan flux measured during the late Holocene in the Kilimanjaro (3°04.6'S; 37°21.2'E, 5893 masl) and NEEM, Greenland (77°27' N; 51°3'W, 2454 masl) ice cores. We contrast the Holocene results with levoglucosan flux across the past 600,000 years in the EPICA Dome C (75°06'S, 123°21'E, 3233 masl) ice core.

  2. Optimization of High-Resolution Continuous Flow Analysis for Transient Climate Signals in Ice Cores

    DEFF Research Database (Denmark)

    Bigler, Matthias; Svensson, Anders; Kettner, Ernesto

    2011-01-01

    meltwater conductivity detection modules. The system is optimized for high- resolution determination of transient signals in thin layers of deep polar ice cores. Based on standard measurements and by comparing sections of early Holocene and glacial ice from Greenland, we find that the new system features...... a depth resolution in the ice of a few millimeters which is considerably better than other CFA systems. Thus, the new system can resolve ice strata down to 10 mm thickness and has the potential of identifying annual layers in both Greenland and Antarctic ice cores throughout the last glacial cycle....

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

  4. Water isotopic ratios from a continuously melted ice core sample

    CERN Document Server

    Gkinis, V; Blunier, T; Bigler, M; Schüpbach, S; Kettner, E; Johnsen, S J

    2014-01-01

    A new technique for on-line high resolution isotopic analysis of liquid water, tailored for ice core studies is presented. We built an interface between a Wavelength Scanned Cavity Ring Down Spectrometer (WS-CRDS) purchased from Picarro Inc. and a Continuous Flow Analysis (CFA) system. The system offers the possibility to perform simultaneous water isotopic analysis of $\\delta^{18}$O and $\\delta$D on a continuous stream of liquid water as generated from a continuously melted ice rod. Injection of sub ${\\mu}$l amounts of liquid water is achieved by pumping sample through a fused silica capillary and instantaneously vaporizing it with 100% efficiency in a home made oven. A calibration procedure allows for proper reporting of the data on the VSMOW--SLAP scale. Application of spectral methods yields the combined uncertainty of the system at below 0.1 permil and 0.5 permil for $\\delta^{18}$O and $\\delta$D, respectively. This performance is comparable to that achieved with mass spectrometry. Dispersion of the sampl...

  5. New revelations on the nature of organic matter in ice cores

    Science.gov (United States)

    Grannas, Amanda M.; Hockaday, William C.; Hatcher, Patrick G.; Thompson, Lonnie G.; Mosley-Thompson, Ellen

    2006-02-01

    Analysis of organic species stored in ice cores provides a unique opportunity to obtain information about the environment of the past. Because of the trace nature of the organic components of interest, studying these species in molecular level detail within ice cores can be an analytical challenge. Using Fourier transform ion cyclotron resonance mass spectrometry with electrospray ionization, we have characterized, at an unprecedented molecular level, the organic material in an ice core collected from Franz Josef Land (Russia). Several thousand distinct molecular species are identified and provide clues to the principal sources of the organic matter. Humic-like substances have been identified in both modern and ancient ice, despite the remote marine setting of the ice field. Species containing sulfur heteroatoms are far more abundant in the modern ice, indicating that anthropogenic sulfur emissions are also present in the high-molecular weight organic compounds preserved in ice.

  6. Greenland ice core evidence for spatial and temporal variability of the Atlantic Multidecadal Oscillation

    NARCIS (Netherlands)

    Chylek, P.; Folland, C.K.; Frankcombe, L.M.; Dijkstra, H.A.; Lesins, G.; Dubey, M.

    2012-01-01

    [1] The Greenland δ18O ice core record is used as a proxy for Greenland surface air temperatures and to interpret Atlantic Multidecadal Oscillation (AMO) variability. An analysis of annual δ18O data from six Arctic ice cores (five from Greenland and one from Canada's Ellesmere Island) suggests a sig

  7. Greenland ice core evidence for spatial and temporal variability of the Atlantic Multidecadal Oscillation

    NARCIS (Netherlands)

    Chylek, P.; Folland, C.K.; Frankcombe, L.M.|info:eu-repo/dai/nl/304829838; Dijkstra, H.A.|info:eu-repo/dai/nl/073504467; Lesins, G.; Dubey, M.

    2012-01-01

    [1] The Greenland δ18O ice core record is used as a proxy for Greenland surface air temperatures and to interpret Atlantic Multidecadal Oscillation (AMO) variability. An analysis of annual δ18O data from six Arctic ice cores (five from Greenland and one from Canada's Ellesmere Island) suggests a

  8. Phase relationships between orbital forcing and the composition of air trapped in Antarctic ice cores

    Directory of Open Access Journals (Sweden)

    L. Bazin

    2015-04-01

    Full Text Available Orbital tuning is central for ice core chronologies beyond annual layer counting, available back to 60 ka (i.e. thousand of years before 1950 for Greenland ice cores. While several complementary orbital tuning tools have recently been developed using δ18Oatm, δO2/N2 and air content with different orbital targets, quantifying their uncertainties remains a challenge. Indeed, the exact processes linking variations of these parameters, measured in the air trapped in ice, to their orbital targets are not yet fully understood. Here, we provide new series of δO2/N2 and δ18Oatm data encompassing Marine Isotopic Stage (MIS 5 (between 100–160 ka and the oldest part (380–800 ka of the East Antarctic EPICA Dome C (EDC ice core. For the first time, the measurements over MIS 5 allow an inter-comparison of δO2/N2 and δ18Oatm records from three East Antarctic ice core sites (EDC, Vostok and Dome F. This comparison highlights a site-specific relationship between δO2/N2 and its local summer solstice insolation. Such a relationship increases the uncertainty associated with the use of δO2/N2 as a tool for orbital tuning. Combining records of δ18Oatm and δO2/N2 from Vostok and EDC, we evidence a loss of orbital signature for these two parameters during periods of minimum eccentricity (∼400, ∼720–800 ka. Our dataset reveals a time-varying lag between δO2/N2 and δ18Oatm over the last 800 ka that we interpret as variations of the lag between δ18Oatm and precession. Large lags of ∼5 ka are identified during Terminations I and II, associated with strong Heinrich events. On the opposite, minimal lags (∼1–2 ka are identified during four periods characterized by high eccentricity, intermediate ice volume and no Heinrich events (MIS 6–7, the end of MIS 9, MIS 15 and MIS 17. We therefore suggest that the occurrence of Heinrich events influences the response of δ18Oatm to precession.

  9. Mt. Logan Ice Core Record of North Pacific Holocene Climate Variability

    Science.gov (United States)

    Osterberg, E. C.; Mayewski, P. A.; Fisher, D. A.; Kreutz, K. J.; Handley, M. J.; Sneed, S. B.

    2006-12-01

    A >12,000 year-long, continuous, high-resolution (sub-annual to multi-decadal) ice core record from the summit plateau (5300 m asl) of Mt. Logan, Yukon, Canada, reveals large, abrupt fluctuations in North Pacific climate throughout the Holocene with a 1-2 ky periodicity. Co-registered major ion, trace element and stable isotope time series reveal a strong inverse relationship between precipitation δ18O and atmospheric seasalt and dust concentrations over multi-decadal to millennial periods (rMt. Logan represent changes in moisture source region between dominantly cold North Pacific waters (more zonal circulation; enriched stable isotope values) and warmer subtropical waters (more meridional circulation; depleted stable isotope values). Consequently, Holocene millennial-scale stable isotope fluctuations in the Mt. Logan core have a larger amplitude (6-9‰ for δ18O) than those found in Greenland and Canadian Arctic ice core records (e.g. 2-3‰ for GISP2 δ18O). Over the instrumental period (1948-1998), higher Mt. Logan dust concentrations are strongly associated with enhanced springtime cyclonic activity over East Asian desert source regions (rMt. Logan seasalt aerosol concentrations are related to the wintertime strength of the Aleutian Low pressure center (r<-0.45, p<0.001). We use these calibrated proxy relationships to propose a conceptual model of North Pacific atmospheric circulation during the Holocene.

  10. Towards multi-decadal to multi-millennial ice core records from coastal west Greenland ice caps

    Science.gov (United States)

    Das, Sarah B.; Osman, Matthew B.; Trusel, Luke D.; McConnell, Joseph R.; Smith, Ben E.; Evans, Matthew J.; Frey, Karen E.; Arienzo, Monica; Chellman, Nathan

    2017-04-01

    The Arctic region, and Greenland in particular, is undergoing dramatic change as characterized by atmospheric warming, decreasing sea ice, shifting ocean circulation patterns, and rapid ice sheet mass loss, but longer records are needed to put these changes into context. Ice core records from the Greenland ice sheet have yielded invaluable insight into past climate change both regionally and globally, and provided important constraints on past surface mass balance more directly, but these ice cores are most often from the interior ice sheet accumulation zone, at high altitude and hundreds of kilometers from the coast. Coastal ice caps, situated around the margins of Greenland, have the potential to provide novel high-resolution records of local and regional maritime climate and sea surface conditions, as well as contemporaneous glaciological changes (such as accumulation and surface melt history). But obtaining these records is extremely challenging. Most of these ice caps are unexplored, and thus their thickness, age, stratigraphy, and utility as sites of new and unique paleoclimate records is largely unknown. Access is severely limited due to their high altitude, steep relief, small surface area, and inclement weather. Furthermore, their relatively low elevation and marine moderated climate can contribute to significant surface melting and degradation of the ice stratigraphy. We recently targeted areas near the Disko Bay region of central west Greenland where maritime ice caps are prevalent but unsampled, as potential sites for new multi-decadal to multi-millennial ice core records. In 2014 & 2015 we identified two promising ice caps, one on Disko Island (1250 m. asl) and one on Nuussuaq Peninsula (1980 m. asl) based on airborne and ground-based geophysical observations and physical and glaciochemical stratigraphy from shallow firn cores. In spring 2015 we collected ice cores at both sites using the Badger-Eclipse electromechanical drill, transported by a medley

  11. A method for determination of methyl chloride concentration in air trapped in ice cores.

    Science.gov (United States)

    Saito, Takuya; Yokouchi, Yoko; Aoki, Shuji; Nakazawa, Takakiyo; Fujii, Yoshiyuki; Watanabe, Okitsugu

    2006-05-01

    A method for measuring the concentration of methyl chloride (CH3Cl) in air trapped in an ice core was developed. The method combines the air extraction by milling the ice core samples under vacuum and the analysis of the extracted air with a cryogenic preconcentration/gas chromatograph/mass spectrometry system. The method was applied to air from Antarctic ice core samples estimated to have been formed in the pre-industrial and/or early industrial periods. The overall precision of the method deduced from duplicate ice core analyses was estimated to be better than +/-20 pptv. The measured CH3Cl concentration of 528+/-26 pptv was similar to the present-day concentration in the remote atmosphere as well as the CH3Cl concentration over the past 300 years obtained from Antarctic firn air and ice core analyses.

  12. Temperature and methane records over the last 2 ka in Dasuopu ice core

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    High resolution δ18O and methane records over the last 2ka have been reconstructed from Dasuopu ice core recovered from the Himalayas. Analysis shows that the δ18O record correlates well with the Northern Hemispheric temperature, Dunde ice core record, and with temperature record in eastern China. The warming trend detected in δ18O record from the last century is similar to that during the Medieval warm period. There is a dramatic increasing in methane concentration in the Dasuopu ice core, which reached 1031 nmol@mol-1 in 1997. Moreover, methane concentration in the Dasuopu ice core is about 15%-20% higher than that in Antarctica and Greenland. There is a positive correlation between methane concentration and δ18O in Dasuopu ice core.

  13. Where might we find evidence of a Last Interglacial West Antarctic Ice Sheet collapse in Antarctic ice core records?

    Science.gov (United States)

    Bradley, S. L.; Siddall, M.; Milne, G. A.; Masson-Delmotte, V.; Wolff, E.

    2012-05-01

    Abundant indirect evidence suggests that the West Antarctic Ice Sheet (WAIS) reduced in size during the Last Interglacial (LIG) compared to the Holocene. This study explores this possibility by comparing, for the first time, ice core stable isotope records for the LIG with output from a glacio-isostatic adjustment (GIA) model. The results show that ice core records from East Antarctica are remarkably insensitive to vertical movement of the solid land motion driven by a simulated hypothetical collapse of the WAIS. However, new and so far unexplored sites are identified which are sensitive to the isostatic signal associated with WAIS collapse and so ice core proxy data from these sites would be effective in testing this hypothesis further.

  14. Climatological significance of an ice core net-accumulation record at Mt. Qomolangma (Everest)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An ice core record at Mt. Qomolangma (Everest) since 1954 reveals a sharp decline in net-accumulation in the 1960s, and the annual net-accumulation during the 1970s to the beginning of the 1990s is only half of that at the end of the 1950s. The decreased net-accumulation is coincident with glacier retreat, which is associated with recent temperature increase in the region that intensified the ablation. Under the background of global warming, such glacier variation trends will aggravate.

  15. Microbial activity and phylogeny in ice cores retrieved from Lake Paula, a newly detected freshwater lake in Antarctica

    Science.gov (United States)

    Sattler, Birgit I.; Waldhuber, Sebastian; Fischer, Helgard; Semmler, Hans; Sipiera, Paul P.; Psenner, Roland

    2004-11-01

    A permanent ice covered water body, called Lake Paula, was detected in Patriot Hills in the West Antarctic and sampled for the first time ever for microbial life. The ice sheet measured approximately 2,5m thickness and the water body has a depth of about 10m. The lake is situated near a moraine which partly ablates from snow and provides meltwater from the slopes to the lake during austral summer. These running waters which are kept liquid by the heating up of the dark soil are penetrating the lower ice cover and thus softening up the lakeside part if the ice core. It is inoculated by nutrients, active microbes and diatoms of terrestrial origin. A distinct gradient concerning bacterial numbers, biomass and production which is 10 fold at the ice-water interface compared to the exposed part is observable. Temperature sensitivity of the embedded microbes reflect the gradient as well: Bacteria isolated from the upper part showed growth optima at 10°C, the lower part at 25°C, phylogenetic properties done by 16s rDNA reveal distinct communities depending on their vertical position, some clones are similar to those retrieved in Lake Vostok ice cores. These results offer the conclusion that even in this harsh environment like the Antarctic continent a dynamic system like microbial ice aggregates can be sustained as long as the supply of liquid water which is essential for an active bacterial metabolism is provided at least for a small time frame.

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

    Directory of Open Access Journals (Sweden)

    J. Schwander

    2012-08-01

    Full Text Available We compare a variety of methods for estimating the gas/ice depth offset (Δdepth at EPICA Dome C (EDC, East Antarctica. (1 Purely based on modelling efforts, Δdepth can be estimated combining a firn densification with an ice flow model. (2 The diffusive column height can be estimated from δ15N and converted to Δdepth using an ice flow model and assumptions about past average firn density and thickness of the convective zone. (3 Ice and gas synchronisation of the EDC ice core to the GRIP, EDML and TALDICE ice cores shifts the ice/gas offset problem into higher accumulation ice cores where it can be more accurately evaluated. (4 Finally, the bipolar seesaw hypothesis allows us to synchronise the ice isotopic record with the gas CH4 record, the later being taken as a proxy of Greenland temperature. The general agreement of method 4 with methods 2 and 3 confirms that the bipolar seesaw antiphase happened during the last 140 kyr. Applying method 4 to the deeper section of the EDC core confirms that the ice flow is complex and can help to improve our reconstruction of the thinning function and thus, of the EDC age scale. We confirm that method 1 overestimates the glacial Δdepth at EDC and we suggest that it is due to an overestimation of the glacial lock-in depth (LID by the firn densification model. In contrast, we find that method 1 very likely underestimates Δdepth during Termination II, due either to an underestimated thinning function or to an underestimated LID. Finally, method 2 gives estimates within a few metres of methods 3 and 4 during the last deglacial warming, suggesting that the convective zone at Dome C cannot have been very large at this time, if it existed at all.

  17. The Search for Transient Astrophysical Neutrino Emission with IceCube-DeepCore

    Science.gov (United States)

    Aartsen, M. G.; Abraham, K.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Altmann, D.; Anderson, T.; Ansseau, I.; Archinger, M.; Arguelles, C.; Arlen, T. C.; Auffenberg, J.; Bai, X.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Becker, K.-H.; Beiser, E.; BenZvi, S.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brayeur, L.; Bretz, H.-P.; Buzinsky, N.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Cowen, D. F.; Cruz Silva, A. H.; Daughhetee, J.; Davis, J. C.; Day, M.; de André, J. P. A. M.; De Clercq, C.; del Pino Rosendo, E.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dumm, J. P.; Dunkman, M.; Eagan, R.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fahey, S.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Felde, J.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Flis, S.; Fösig, C.-C.; Fuchs, T.; Gaisser, T. K.; Gaior, R.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Gier, D.; Gladstone, L.; Glagla, M.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Góra, D.; Grant, D.; Groh, J. C.; Groß, A.; Ha, C.; Haack, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Hansen, E.; Hansmann, B.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Holzapfel, K.; Homeier, A.; Hoshina, K.; Huang, F.; Huber, M.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jero, K.; Jurkovic, M.; Kappes, A.; Karg, T.; Karle, A.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kemp, J.; Kheirandish, A.; Kiryluk, J.; Kläs, J.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Konietz, R.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, G.; Kroll, M.; Kunnen, J.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lesiak-Bzdak, M.; Leuermann, M.; Leuner, J.; Lu, L.; Lünemann, J.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Maruyama, R.; Mase, K.; Matis, H. S.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meli, A.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Middell, E.; Middlemas, E.; Mohrmann, L.; Montaruli, T.; Morse, R.; Nahnhauer, R.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke, A.; Olivas, A.; Omairat, A.; O'Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Paul, L.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Pütz, J.; Quinnan, M.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Reimann, R.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Richter, S.; Riedel, B.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Saba, S. M.; Sabbatini, L.; Sander, H.-G.; Sandrock, A.; Sandroos, J.; Sarkar, S.; Schatto, K.; Scheriau, F.; Schimp, M.; Schmidt, T.; Schmitz, M.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schulte, L.; Seckel, D.; Seunarine, S.; Smith, M. W. E.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stahlberg, M.; Stamatikos, M.; Stanev, T.; Stanisha, N. A.; Stasik, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Ström, R.; Strotjohann, N. L.; Sullivan, G. W.; Sutherland, M.; Taavola, H.; Taboada, I.; Tatar, J.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Turcati, A.; Unger, E.; Usner, M.; Vallecorsa, S.; Vandenbroucke, J.; van Eijndhoven, N.; Vanheule, S.; van Santen, J.; Veenkamp, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandkowsky, N.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zoll, M.; IceCube Collaboration

    2016-01-01

    We present the results of a search for astrophysical sources of brief transient neutrino emission using IceCube and DeepCore data acquired between 2012 May 15 and 2013 April 30. While the search methods employed in this analysis are similar to those used in previous IceCube point source searches, the data set being examined consists of a sample of predominantly sub-TeV muon-neutrinos from the Northern Sky (-5° < δ < 90°) obtained through a novel event selection method. This search represents a first attempt by IceCube to identify astrophysical neutrino sources in this relatively unexplored energy range. The reconstructed direction and time of arrival of neutrino events are used to search for any significant self-correlation in the data set. The data revealed no significant source of transient neutrino emission. This result has been used to construct limits at timescales ranging from roughly 1 s to 10 days for generic soft-spectra transients. We also present limits on a specific model of neutrino emission from soft jets in core-collapse supernovae.

  18. An Optical Dye Method for Continuous Determination of Acidity in Ice Cores.

    Science.gov (United States)

    Kjær, Helle Astrid; Vallelonga, Paul; Svensson, Anders; Elleskov L Kristensen, Magnus; Tibuleac, Catalin; Winstrup, Mai; Kipfstuhl, Sepp

    2016-10-04

    The pH of polar ice is important for the stability and mobility of impurities in ice cores and can be strongly influenced by volcanic eruptions or anthropogenic emissions. We present a simple optical method for continuous determination of acidity in ice cores based on spectroscopically determined color changes of two common pH-indicator dyes, bromophenol blue, and chlorophenol red. The sealed-system method described here is not equilibrated with CO2, making it simpler than existing methods for pH determination in ice cores and offering a 10-90% peak response time of 45 s and a combined uncertainty of 9%. The method is applied to Holocene ice core sections from Greenland and Antarctica and compared to standard techniques such as electrical conductivity measurement (ECM) conducted on the solid ice, and electrolytic meltwater conductivity, EMWC. Acidity measured in the Greenland NGRIP ice core shows good agreement with acidity calculated from ion chromatography. Conductivity and dye-based acidity Hdye(+) are found to be highly correlated in the Greenland NEGIS firn core (75.38° N, 35.56° W), with all signals greater than 3σ variability coinciding with either volcanic eruptions or possible wild fire activity. In contrast, the Antarctic Roosevelt Island ice core (79.36° S, 161.71° W) features an anticorrelation between conductivity and Hdye(+), likely due to strong influence of marine salts.

  19. Technique for continuous high-resolution analysis of trace substances in firn and ice cores

    Energy Technology Data Exchange (ETDEWEB)

    Roethlisberger, R.; Bigler, M.; Hutterli, M.; Sommer, S.; Stauffer, B.; Junghans, H.G.; Wagenbach, D.

    2000-01-15

    The very successful application of a CFA (Continuous flow analysis) system in the GRIP project (Greenland Ice Core Project) for high-resolution ammonium, calcium, hydrogen peroxide, and formaldehyde measurements along a deep ice core led to further development of this analysis technique. The authors included methods for continuous analysis technique. The authors included methods for continuous analysis of sodium, nitrate, sulfate, and electrolytical conductivity, while the existing methods have been improved. The melting device has been optimized to allow the simultaneous analysis of eight components. Furthermore, a new melter was developed for analyzing firn cores. The system has been used in the frame of the European Project for Ice Coring in Antarctica (EPICA) for in-situ analysis of several firn cores from Dronning Maud Land, Antarctica, and for the new ice core drilled at Dome C, Antarctica.

  20. Reassessment of the Upper Fremont Glacier ice-core chronologies by synchronizing of ice-core-water isotopes to a nearby tree-ring chronology

    Science.gov (United States)

    Chellman, Nathan J.; McConnell, Joseph R.; Arienzo, Monica; Pederson, Gregory T.; Aarons, Sarah; Csank, Adam

    2017-01-01

    The Upper Fremont Glacier (UFG), Wyoming, is one of the few continental glaciers in the contiguous United States known to preserve environmental and climate records spanning recent centuries. A pair of ice cores taken from UFG have been studied extensively to document changes in climate and industrial pollution (most notably, mid-19th century increases in mercury pollution). Fundamental to these studies is the chronology used to map ice-core depth to age. Here, we present a revised chronology for the UFG ice cores based on new measurements and using a novel dating approach of synchronizing continuous water isotope measurements to a nearby tree-ring chronology. While consistent with the few unambiguous age controls underpinning the previous UFG chronologies, the new interpretation suggests a very different time scale for the UFG cores with changes of up to 80 years. Mercury increases previously associated with the mid-19th century Gold Rush now coincide with early-20th century industrial emissions, aligning the UFG record with other North American mercury records from ice and lake sediment cores. Additionally, new UFG records of industrial pollutants parallel changes documented in ice cores from southern Greenland, further validating the new UFG chronologies while documenting the extent of late 19th and early 20th century pollution in remote North America.

  1. Caldicellulosiruptor Core and Pangenomes Reveal Determinants for

    Energy Technology Data Exchange (ETDEWEB)

    Blumer-Schuette, Sara E. [North Carolina State University; Giannone, Richard J [ORNL; Zurawski, Jeffrey V [North Carolina State University; Ozdemir, Inci [North Carolina State University; Ma, Qin [University of Georgia, Athens, GA; Yin, Yanbin [University of Georgia, Athens, GA; Xu, Ying [University of Georgia, Athens, GA; Kataeva, Irena [University of Georgia, Athens, GA; Poole, Farris [University of Georgia, Athens, GA; Adams, Michael W. W. [University of Georgia, Athens, GA; Hamilton-Brehm, Scott [ORNL; Elkins, James G [ORNL; Larimer, Frank W [ORNL; Land, Miriam L [ORNL; Hauser, Loren John [ORNL; Cottingham, Robert W [ORNL; Hettich, Robert {Bob} L [ORNL; Kelly, Robert M [North Carolina State University

    2012-01-01

    Extremely thermophilic bacteria of the genus Caldicellulosiruptor utilize carbohydrate components of plant cell walls, including cellulose and hemicellulose, facilitated by a diverse set of glycoside hydrolases (GHs). From a biofuel perspective, this capability is crucial for deconstruction of plant biomass into fermentable sugars. While all species from the genus grow on xylan and acidpretreated switchgrass, growth on crystalline cellulose is variable. The basis for this variability was examined using microbiological, genomic, and proteomic analyses of eight globally diverse Caldicellulosiruptor species. The open Caldicellulosiruptor pangenome (4,009 open reading frames [ORFs]) encodes 106 GHs, representing 43 GH families, but only 26 GHs from 17 families are included in the core (noncellulosic) genome (1,543 ORFs). Differentiating the strongly cellulolytic Caldicellulosiruptor species from the others is a specific genomic locus that encodes multidomain cellulases from GH families 9 and 48, which are associated with cellulose-binding modules. This locus also encodes a novel adhesin associated with type IV pili, which was identified in the exoproteome bound to crystalline cellulose. Taking into account the core genomes, pangenomes, and individual genomes, the ancestral Caldicellulosiruptor was likely cellulolytic and evolved, in some cases, into species that lost the ability to degrade crystalline cellulose while maintaining the capacity to hydrolyze amorphous cellulose and hemicellulose.

  2. Extraction of Ice Sheet Layers from Two Intersected Radar Echograms Near Neem Ice Core in Greenland

    Science.gov (United States)

    Xiong, S.; Muller, J.-P.

    2016-06-01

    Accumulation of snow and ice over time result in ice sheet layers. These can be remotely sensed where there is a contrast in electromagnetic properties, which reflect variations of the ice density, acidity and fabric orientation. Internal ice layers are assumed to be isochronous, deep beneath the ice surface, and parallel to the direction of ice flow. The distribution of internal layers is related to ice sheet dynamics, such as the basal melt rate, basal elevation variation and changes in ice flow mode, which are important parameters to model the ice sheet. Radar echo sounder is an effective instrument used to study the sedimentology of the Earth and planets. Ice Penetrating Radar (IPR) is specific kind of radar echo sounder, which extends studies of ice sheets from surface to subsurface to deep internal ice sheets depending on the frequency utilised. In this study, we examine a study site where folded ice occurs in the internal ice sheet south of the North Greenland Eemian ice drilling (NEEM) station, where two intersected radar echograms acquired by the Multi-channel Coherent Radar Depth Sounder (MCoRDS) employed in the NASA's Operation IceBridge (OIB) mission imaged this folded ice. We propose a slice processing flow based on a Radon Transform to trace and extract these two sets of curved ice sheet layers, which can then be viewed in 3-D, demonstrating the 3-D structure of the ice folds.

  3. Optimization of high-resolution continuous flow analysis for transient climate signals in ice cores.

    Science.gov (United States)

    Bigler, Matthias; Svensson, Anders; Kettner, Ernesto; Vallelonga, Paul; Nielsen, Maibritt E; Steffensen, Jørgen Peder

    2011-05-15

    Over the past two decades, continuous flow analysis (CFA) systems have been refined and widely used to measure aerosol constituents in polar and alpine ice cores in very high-depth resolution. Here we present a newly designed system consisting of sodium, ammonium, dust particles, and electrolytic meltwater conductivity detection modules. The system is optimized for high-resolution determination of transient signals in thin layers of deep polar ice cores. Based on standard measurements and by comparing sections of early Holocene and glacial ice from Greenland, we find that the new system features a depth resolution in the ice of a few millimeters which is considerably better than other CFA systems. Thus, the new system can resolve ice strata down to 10 mm thickness and has the potential of identifying annual layers in both Greenland and Antarctic ice cores throughout the last glacial cycle.

  4. Multi-proxy fingerprint of Heinrich event 4 in Greenland ice core records

    Directory of Open Access Journals (Sweden)

    M. Guillevic

    2014-03-01

    Full Text Available Glacial climate was characterised by two types of abrupt events. Greenland ice cores record Dansgaard–Oeschger events, marked by abrupt warming in-between cold, stadial phases. Six of these stadials coincide with major Heinrich events (HE, identified from ice-rafted debris (IRD and large excursions in carbon and oxygen stable isotopic ratios in North Atlantic deep sea sediments, documenting major ice sheet collapse events. This finding has led to the paradigm that glacial cold events are induced by the response of the Atlantic Meridional Overturning Circulation to such massive freshwater inputs, supported by sensitivity studies conducted with climate models of various complexities. This mechanism could however never be confirmed or infirmed because the exact timing of Heinrich events and associated low latitude hydrological cycle changes with respect to Greenland stadials has so far remained elusive. Here, we provide the first multi-proxy fingerprint of H4 within Stadial 9 in Greenland ice cores through ice and air proxies of low latitude climate and water cycle changes. Our new dataset demonstrates that Stadial 9 consists of three phases, characterised first by Greenland cooling during 550 ± 60 years (as shown by markers of Greenland temperature δ18O and δ15N, followed by the fingerprint of Heinrich Event 4 as identified from several proxy records (abrupt decrease in 17O excess and Greenland methane sulfonic acid (MSA, increase in CO2 and methane mixing ratio, heavier δ D-CH4 and δ18Oatm, lasting 740 ± 60 years, itself ending approximately 390 ± 50 years prior to abrupt Greenland warming. Preliminary investigations on GS-13 encompassing H5, based on the ice core proxies δ18O, MSA, δ18Oatm, CH4 and CO2 data also reveal a 3 phase structure, as well as the same sequence of events. The decoupling between stable cold Greenland temperature and low latitude HE imprints provides new targets for benchmarking climate model simulations and

  5. The 1500m South Pole Ice Core: Recovering a 40 Ka Environmental Record

    Science.gov (United States)

    Casey, Kimberly Ann; Neumann, Thomas Allen; Fudge, T. J.; Neumann, T. A.; Steig, E. J.; Cavitte, M. G. P.; Blankenship, D. D.

    2014-01-01

    Supported by the US National Science Foundation, a new 1500 m, approximately 40 ka old ice core will be recovered from South Pole during the 2014/15 and 2015/16 austral summer seasons using the new US Intermediate Depth Drill. The combination of low temperatures, relatively high accumulation rates and low impurity concentrations at South Pole will yield detailed records of ice chemistry and trace atmospheric gases. The South Pole ice core will provide a climate history record of a unique area of the East Antarctic plateau that is partly influenced by weather systems that cross the West Antarctic ice sheet. The ice at South Pole flows at approximately 10m a(exp-1) and the South Pole ice-core site is a significant distance from an ice divide. Therefore, ice recovered at depth originated progressively farther upstream of the coring site. New ground-penetrating radar collected over the drill site location shows no anthropogenic influence over the past approximately 50 years or upper 15 m. Depth-age scale modeling results show consistent and plausible annual-layer thicknesses and accumulation rate histories, indicating that no significant stratigraphic disturbances exist in the upper 1500m near the ice-core drill site.

  6. Expression and Characterization of an Ice Binding Protein from a Bacterium Isolated at a Depth of 3,519 Meters in the Vostok Ice Core, Antarctica

    Science.gov (United States)

    Christner, B. C.; Achberger, A.; Brox, T. I.; Skidmore, M. L.

    2011-12-01

    The cryopreservation of microorganisms in ancient glacial ice is possible if lethal levels of macromolecular damage are not incurred and cellular integrity is not compromised via intracellular ice formation or recrystallization. There are numerous examples of cold-adapted species that prevent or limit ice crystal growth by producing ice-binding proteins (IBP). Previously, a bacterium (isolate 3519-10; Flavobacteriaceae family) recovered from a depth of 3,519 meters below the surface in the Vostok ice core was shown to produce and secrete an IBP that inhibits the recrystallization of ice. To explore the phenotypic advantage that IBPs confer to ice-entrapped cells, experiments were designed to examine the expression of 3519-10's IBP gene and protein at different temperatures, assess the effect of the IBP on bacterial viability in ice, and determine how the IBP influences the physical structure of the ice. Total RNA isolated from aerobic cultures grown at temperatures between 4C to 25C and analyzed by reverse transcription-PCR indicated constitutive expression of the IBP gene. Additionally, SDS-PAGE analysis of 3519-10's extracellular proteins revealed a polypeptide corresponding to the predicted size of the 54 kDa IBP at all temperatures tested. The total extracellular protein fraction was subsequently used in assays with Escherichia coli to examine the effect of the IBP on bacterial survival in warm ice (-5C) and after freeze-thaw cycling. In the presence of 100 μg mL-1 of extracellular protein from 3519-10, the survival of E. coli was increased by greater than 100-fold; however, the survival of E. coli suspensions containing the same concentration of bovine serum albumin was not significantly different than controls (pcells and non-IBP producing bacteria, and 10 times as many crystals as in particle-free deionized water. Presumably, the effect that the IBP has on bacterial viability and ice crystal structure is due to its activity as an inhibitor of ice

  7. Expression and partial characterization of an ice binding protein from a bacterium isolated at a depth of 3,519 meters in the Vostok ice core, Antarctica

    Directory of Open Access Journals (Sweden)

    Amanda Marie Achberger

    2011-12-01

    Full Text Available Cryopreservation of microorganisms in ancient glacial ice is possible if lethal levels of macromolecular damage are not incurred and cellular integrity is not compromised via intracellular ice formation or recrystallization. Previously, a bacterium (isolate 3519-10 recovered from a depth of 3,519 meters below the surface in the Vostok ice core was shown to secrete an IBP that inhibits the recrystallization of ice. To explore the advantage that IBPs confer to ice-entrapped cells, experiments were designed to examine the expression of 3519-10’s IBP gene and protein at different temperatures, assess the effect of the IBP on bacterial viability in ice, and determine how the IBP influences the physical structure of the ice. Total RNA isolated from cultures grown between 4 to 25⁰C and analyzed by reverse transcription-PCR indicated constitutive expression of the IBP gene. SDS-PAGE analysis of 3519-10’s extracellular proteins also revealed a polypeptide of the predicted size of the 54 kDa IBP at all temperatures tested. In the presence of 100 µg mL-1 of extracellular protein from 3519-10, the survival of Escherichia coli was increased by greater than 34-fold after freeze-thaw cycling. Microscopic analysis of ice formed in the presence of the IBP indicated that per mm2 field of view, there were ~5 times as many crystals as in ice formed in the presence of washed 3519-10 cells and non-IBP producing bacteria, and ~10 times as many crystals as in filtered deionized water. Presumably, the effect that the IBP has on bacterial viability and ice crystal structure is due to its activity as an inhibitor of ice recrystallization. A myriad of molecular adaptations are likely to play a role in bacterial persistence under frozen conditions, but the ability of 3519-10’s IBP to control ice crystal structure, and thus the liquid vein network within the ice, may provide one explanation for its successful survival deep within the Antarctic ice sheet for

  8. Electrical conductivity measurements from the GISP2 and GRIP Greenland ice cores

    DEFF Research Database (Denmark)

    Dahl-Jensen, Dorthe; Clausen, Henrik Brink; Taylor, K. C.

    1993-01-01

    . Here we present electrical conductivity records for the Greenland Ice Sheet Project 2 (GISP2) and Greenland Ice-core Project (GRIP) ice cores, drilled 28 km apart to enable direct comparison of the results. The upper parts of both records are consistent with previous evidence from other Greenland cores......THE direct-current electrical conductivity of glacial ice depends on its acidity1-3, and can also indicate changes in climate, as ice formed in cold, dusty periods has a high concentration of alkaline dust1,4,5, which significantly reduces the conductivity6,7 compared to warmer, less dusty periods......4,8& #150;12 for a stable Greenland climate during the Holocene, and a series of warm events punctuating the last glacial period. However, there is a significant discrepancy between the two records in the bottom 10% of the cores, calling into question recent reports of climate variability...

  9. Continuous ice-core chemical analyses using inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    McConnell, Joseph R; Lamorey, Gregg W; Lambert, Steven W; Taylor, Kendrick C

    2002-01-01

    Impurities trapped in ice sheets and glaciers have the potential to provide detailed, high temporal resolution proxy information on paleo-environments, atmospheric circulation, and environmental pollution through the use of chemical, isotopic, and elemental tracers. We present a novel approach to ice-core chemical analyses in which an ice-core melter is coupled directly with both an inductively coupled plasma mass spectrometer and a traditional continuous flow analysis system. We demonstrate this new approach using replicated measurements of ice-core samples from Summit, Greenland. With this method, it is possible to readily obtain continuous, exactly coregistered concentration records for a large number of elements and chemical species at ppb and ppt levels and at unprecedented depth resolution. Such very-high depth resolution, multiparameter measurements will significantly expand the use of ice-core records for environmental proxies.

  10. The design and performance of IceCube DeepCore

    Science.gov (United States)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Brown, A. M.; Buitink, S.; Caballero-Mora, K. S.; Carson, M.; Chirkin, D.; Christy, B.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; Cruz Silva, A. H.; D'Agostino, M. V.; Danninger, M.; Daughhetee, J.; Davis, J. C.; De Clercq, C.; Degner, T.; Demirörs, L.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; DeYoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Dunkman, M.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Góra, D.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Heinen, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoffmann, B.; Homeier, A.; Hoshina, K.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobi, E.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Kroll, G.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lünemann, J.; Madsen, J.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Miarecki, S.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Panknin, S.; Paul, L.; Pérez de los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Richman, M.; Rodrigues, J. P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schmidt, T.; Schönwald, A.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strahler, E. A.; Ström, R.; Stüer, M.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; van Eijndhoven, N.; Vandenbroucke, J.; Van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, C.; Xu, D. L.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Zoll, M.

    2012-05-01

    The IceCube neutrino observatory in operation at the South Pole, Antarctica, comprises three distinct components: a large buried array for ultrahigh energy neutrino detection, a surface air shower array, and a new buried component called DeepCore. DeepCore was designed to lower the IceCube neutrino energy threshold by over an order of magnitude, to energies as low as about 10 GeV. DeepCore is situated primarily 2100 m below the surface of the icecap at the South Pole, at the bottom center of the existing IceCube array, and began taking physics data in May 2010. Its location takes advantage of the exceptionally clear ice at those depths and allows it to use the surrounding IceCube detector as a highly efficient active veto against the principal background of downward-going muons produced in cosmic-ray air showers. DeepCore has a module density roughly five times higher than that of the standard IceCube array, and uses photomultiplier tubes with a new photocathode featuring a quantum efficiency about 35% higher than standard IceCube PMTs. Taken together, these features of DeepCore will increase IceCube's sensitivity to neutrinos from WIMP dark matter annihilations, atmospheric neutrino oscillations, galactic supernova neutrinos, and point sources of neutrinos in the northern and southern skies. In this paper we describe the design and initial performance of DeepCore.

  11. Change of bacterial community in the Malan Ice Core and its relation to climate and environment

    Institute of Scientific and Technical Information of China (English)

    XIANG Shurong; YAO Tandong; AN Lizhe; LI Zhen; WU Guangjian; WANG Youqing; XU Baiqing; WANG Junxia

    2004-01-01

    In order to understand the relationship be tween the community structure of bacteria in ice core and the past climate and environment, we initiated the study on the microorganisms in the three selected ice samples from the Malan ice core drilled from the Tibetan Plateau. The 16S ribosomal DNA (rDNA) molecules were directly amplified from the melt water samples, and three 16S rDNA clone libraries were established. Among 94 positive clones, eleven clones with unique restriction pattern were used for partial sequence and compared with eight reported sequences from the same ice core. The phylotypes were divided into 5 groups:alpha, beta, gamma proteobacteria; CFB, and other eubacteria group. Among them, there were many "typical Malan glacial bacteria" pertaining to psychrophilies and new bacteria found in the ice core. At a longer time scale, the concentration distribution of "typical Malan glacial bacteria" with depth showed negative correlation with temperature variations and was coincident with dirty layer. It implied the influence of temperature on the microbial record through impact on the concentrations of the "typical Malan glacial bacteria''. In addition, the nutrition contained in ice was another important factor controlling the distribution of microbial population in ice core section. Moreover, the result displayed an apparent layer distribution of bacterial community in the ice core section, which reflected the microbial response to the past climatic and environmental conditions at the time of deposition.

  12. Proxies and measurement techniques for mineral dust in Antarctic ice cores.

    Science.gov (United States)

    Ruth, Urs; Barbante, Carlo; Bigler, Matthias; Delmonte, Barbara; Fischer, Hubertus; Gabrielli, Paolo; Gaspari, Vania; Kaufmann, Patrik; Lambert, Fabrice; Maggi, Valter; Marino, Federica; Petit, Jean-Robert; Udisti, Roberto; Wagenbach, Dietmar; Wegner, Anna; Wolff, Eric W

    2008-08-01

    To improve quantitative interpretation of ice core aeolian dust records, a systematic methodological comparison was made. This involved methods for water-insoluble particle counting (Coulter counter and laser-sensing particle detector), soluble ion analysis (ion chromatography and continuous flow analysis), elemental analysis (inductively coupled plasma mass spectroscopy at pH 1 and after full acid digestion), and water-insoluble elemental analysis (proton induced X-ray emission). Antarctic ice core samples covering the last deglaciation from the EPICA Dome C (EDC) and the EPICA Dronning Maud Land (EDML) cores were used. All methods correlate very well among each other, but the ratios of glacial age to Holocene concentrations, which are typically a factor approximately 100, differ between the methods by up to a factor of 2 with insoluble particles showing the largest variability. The recovery of ICP-MS measurements depends on the digestion method and is differentfor different elements and during different climatic periods. EDC and EDML samples have similar dust composition, which suggests a common dust source or a common mixture of sources for the two sites. The analyzed samples further reveal a change of dust composition during the last deglaciation.

  13. Two ice-core delta O-18 records from Svalbard illustrating climate and sea-ice variability over the last 400 years

    NARCIS (Netherlands)

    Isaksson, E; Kohler, J; Pohjola, [No Value; Moore, J; Igarashi, M; Karlof, L; Martma, T; Meijer, H; Motoyama, H; Vaikmae, R; van de Wal, RSW; Pohjola, Veijo; Karlöf, Lars; Vaikmäe, Rein; Wal, Roderik S.W. van de; Kohler, 27967

    2005-01-01

    Ice cores from the relatively low-lying ice caps in Svalbard have not been widely exploited in climatic studies owing to uncertainties about the effect of meltwater percolation. However, results from two new Svalbard ice cores, at Lomonosovfonna and Austfonna, have shown that with careful site selec

  14. Seasonal variations of dust record in the Muztagata ice cores

    Institute of Scientific and Technical Information of China (English)

    WU GuangJian; YAO TanDong; XU BaiQing; TIAN LiDe; LI Zhen; DUAN KeQin

    2008-01-01

    Based on the oxygen isotope ratio and microparticle record in ice cores recovered at Mt.Muztagata,Eastern Pamirs,the seasonal variations of atmospheric dust have been reconstructed for the past four decades.High dust concentrations and coarser particle grains have the similar trend with oxygen iso-tope value.Our statistical results indicate that 50%--60% high dust concentration samples occur dur-ing the season with high oxygen isotope values (summer),while low dust storm frequency during spring and winter.Back-trajectory analysis shows that the air mass hitting Muztagata predominately came from West Asia (such as Iran-Afghanistan Plateau) and Central Asia,which are the main dust source area for Muztagata.Dust storms in those source areas most frequently occur during summer (from May to August),while frequent dust storm events in northern China mainly occur during spring (March to May).Regions in the path of Asian dust transport,such as in Japan,the North Pacific,and Greenland,also show high dust concentrations during spring (from March to May).Our results indicate that dust storms have different seasonality in different regions within Asia.

  15. Comparative studies in method for stratigraphical structure measurement of ice cores: Identification of cloudy bands

    Institute of Scientific and Technical Information of China (English)

    Morimasa Takata; Hitoshi Shoji; Atsushi Miyamoto; Kimiko Shimohara

    2003-01-01

    Cloudy bands are typical stratigraphic structure in deep ice core.Detailed recording of cloudy bands is important for dating of ice core since pair of series cloudy band and clear layer is corresponds to annual layer and it sometimes corresponds to volcanic ash layer.We developed two type scanners, transmitted light method and laser tomograph method for the stratigraphic study.Measurements were carried out for NGRIP deep ice core, which containing many cloudy bands, using the two type scanners and digital camera.We discussed about the possibility of identification of cloudy bands by each method and about advantage and disadvantage of measurements and their results.

  16. Tracing the sources of particles in the East Rongbuk ice core from Mt. Qomolangma

    Institute of Scientific and Technical Information of China (English)

    XU JianZhong; HOU ShuGui; CHEN FuKun; REN JiaWen; QIN DaHe

    2009-01-01

    Sr-Nd-Pb isotopic tracer was applied, for the first time, to identifying the sources of the particles in the East Rongbuk ice core from Mt. Qomalangma (Everest). The results show that the particles in the dirty layers originate mainly from local sources, while the particles in the non-dirty layers are consistent with the features of dust from the arid regions in northwestern India. The HYSPLIT model shows that the air trajectory goes first through northwestern India before reaching the drilling site of ice core when dust storms occur in northwestern India, confirming northwestern India as a possible source of dust in the East Rongbuk ice core.

  17. Sensitivity of interglacial Greenland temperature and δ18O: ice core data, orbital and increased CO2 climate simulations

    Directory of Open Access Journals (Sweden)

    D. Swingedouw

    2011-09-01

    preliminary comparison with other models. This suggests that further simulations and detailed inter-model comparisons are also likely to be of benefit. Comparisons with Greenland ice core stable isotope data reveals that IPSL-CM4/LMDZiso simulations strongly underestimate the amplitude of the ice core signal during the last interglacial, which could reach +8–10 °C at fixed-elevation. While the model-data mismatch may result from missing positive feedbacks (e.g. vegetation, it could also be explained by a reduced elevation of the central Greenland ice sheet surface by 300–400 m.

  18. Exploring ice core drilling chips from a cold Alpine glacier for cosmogenic radionuclide (10Be) analysis

    Science.gov (United States)

    Zipf, Lars; Merchel, Silke; Bohleber, Pascal; Rugel, Georg; Scharf, Andreas

    Ice cores offer unique multi-proxy paleoclimate records, but provide only very limited sample material, which has to be carefully distributed for various proxy analyses. Beryllium-10, for example, is analysed in polar ice cores to investigate past changes of the geomagnetic field, solar activity, and the aerosol cycle, as well as to more accurately date the material. This paper explores the suitability of a drilling by-product, the so-called drilling chips, for 10Be-analysis. An ice core recently drilled at a cold Alpine glacier is used to directly compare 10Be-data from ice core samples with corresponding drilling chips. Both sample types have been spiked with 9Be-carrier and identically treated to chemically isolate beryllium. The resulting BeO has been investigated by accelerator mass spectrometry (AMS) for 10Be/9Be-ratios to calculate 10Be-concentrations in the ice. As a promising first result, four out of five sample-combinations (ice core and drilling chips) agree within 2-sigma uncertainty range. However, further studies are needed in order to fully demonstrate the potential of drilling chips for 10Be-analysis in alpine and shallow polar ice cores.

  19. New focuses of polar ice-core study: NEEM and Dome A

    Institute of Scientific and Technical Information of China (English)

    REN JiaWen; XIAO CunDe; HOU ShuGui; LI YuanSheng; SUN Bo

    2009-01-01

    Ice core records from polar regions are of great value to study long-term climate and environmental change. Greenland ice-core records are celebrated for their high resolution and have provided very important knowledge for understanding the late Quaternary palaeoclimate, especially in reference to millennial-scale abrupt climatic flips during the last glaciation. Recently, a new project to retrieve a deep ice-core from Greenland known as NEEM for North Greenland Eemian Ice Drilling, has been launched with the main target being the last interglacial period. The new core will help us understand further details of climate changes during a period of warmth as the present. Antarctic ice cores have a unique advantage in providing recovery of longer time-scale paleclimate information and hence are regarded as a crucial pillar to examine climatic cycles on the time-scale of Earth-orbital phenomena.Since the bottom ice in Dome A is estimated to be older than a million years, a deep drilling there becomes a new focus for ice core studies.

  20. How Will Sea Ice Loss Affect the Greenland Ice Sheet? On the Puzzling Features of Greenland Ice-Core Isotopic Composition

    Science.gov (United States)

    Pausata, Francesco S. R.; Legrande, Allegra N.; Roberts, William H. G.

    2016-01-01

    The modern cryosphere, Earth's frozen water regime, is in fast transition. Greenland ice cores show how fast theses changes can be, presenting evidence of up to 15 C warming events over timescales of less than a decade. These events, called Dansgaard/Oeschger (D/O) events, are believed to be associated with rapid changes in Arctic sea ice, although the underlying mechanisms are still unclear. The modern demise of Arctic sea ice may, in turn, instigate abrupt changes on the Greenland Ice Sheet. The Arctic Sea Ice and Greenland Ice Sheet Sensitivity (Ice2Ice Chttps://ice2ice.b.uib.noD) initiative, sponsored by the European Research Council, seeks to quantify these past rapid changes to improve our understanding of what the future may hold for the Arctic. Twenty scientists gathered in Copenhagen as part of this initiative to discuss the most recent observational, technological, and model developments toward quantifying the mechanisms behind past climate changes in Greenland. Much of the discussion focused on the causes behind the changes in stable water isotopes recorded in ice cores. The participants discussed sources of variability for stable water isotopes and framed ways that new studies could improve understanding of modern climate. The participants also discussed how climate models could provide insights into the relative roles of local and nonlocal processes in affecting stable water isotopes within the Greenland Ice Sheet. Presentations of modeling results showed how a change in the source or seasonality of precipitation could occur not only between glacial and modern climates but also between abrupt events. Recent fieldwork campaigns illustrate an important role of stable isotopes in atmospheric vapor and diffusion in the final stable isotope signal in ice. Further, indications from recent fieldwork campaigns illustrate an important role of stable isotopes in atmospheric vapor and diffusion in the final stable isotope signal in ice. This feature complicates

  1. Signals of Antarctic Circum-polar Wave over the Southern Indian Ocean as recorded in an Antarctica ice core

    Institute of Scientific and Technical Information of China (English)

    XIAO Cunde; CHENG Yanjie; REN Jiawen; LU Longhua; LI Zhongqin; QIN Dahe; ZHOU Xiuji

    2005-01-01

    Oxygen stable isotopic and ionic records, covering a period of 1745-1996, are recovered in DT001 ice core drilled in Princess Elizabeth Land, East Antarctica. Using empirical orthogonal function (EOF) analysis of the annually resolved glaciochemical time series, we find the first EOF (EOF1) represents sea-salt aerosols and is the proxy of sea level pressure (SLP) over a quasi-stationary low in the Southern Indian Ocean (SIO).δ18O represents the sea surface temperature (SST) of the same ocean area. In the past two decades, four climatic waves as represented by SLP and SST proxies are found in the DT001 ice core, which in coincident with four Antarctic Circum-polar Waves (ACW) as revealed by NCEP/NCAR reanalysis. The phase difference between SST and SLP in the ice core is also coincident with that in ACW. Both ice-core record and reanalysis suggest that there were no signals of ACW during 1958-1980, none during the overall recording period between 1745-1996, as there is no regular phase difference between SST and SLP. The ACW signal after early 1980s is probably attributable to the climate shift occurring over Antarctic Peninsula-Drake Passage region.

  2. Towards a new common Greenland Ice Core Chronology for the last 5000 years

    Science.gov (United States)

    Winstrup, Mai; Olander Rasmussen, Sune; Møllesøe Vinther, Bo; Cook, Eliza; Svensson, Anders; McConnell, Joe; Steffensen, Jørgen Peder

    2017-04-01

    Since the development of the Greenland Ice Core Chronology 2005 (GICC05), it has been widely used as a reference chronology in paleoclimate research. However, recent research (Sigl et al, 2015) demonstrated that this timescale has small, but significant, issues over historical time. These discrepancies was found by counting annual layers in high-resolution chemistry records from the NEEM S1 shallow core, and confirmed by linking via 10Be marker horizons to the layer-counted WAIS Divide ice core, Antarctica, and accurately-dated tree-ring series. This work showed that a revision of GICC05 is required prior to 1250AD. We here refine and extend this work. Layer-counting in a single core will always involve some uncertainty, and we hence use data from multiple Greenland ice cores, for which high-resolution impurity records recently have been measured. These ice cores have been synchronized using volcanic marker horizons, and the layer-counting is performed automatically using the StratiCounter algorithm (Winstrup et al, 2012), while ensuring that the number of layers between volcanic horizons are the same in all cores. Based on this extended multiple-core data set, we are further able to extend the new Greenland timescale another few thousand years back in time. This will, among others, provide a new ice-core date for the catastrophic volcanic eruption ( 1600 BC) that destroyed the Greek Minoan culture, an important time marker in Greek history.

  3. Dynamics of Crystal Formation in the Greenland NorthGRIP Ice Core

    CERN Document Server

    Mathiesen, J; Jensen, M H; Levinsen, M; Olesen, P; Dahl-Jensen, D; Svensson, A; Mathiesen, Joachim; Ferkinghoff-Borg, Jesper; Jensen, Mogens H.; Levinsen, Mogens; Olesen, Poul; Dahl-Jensen, Dorthe; Svensson, Anders

    2003-01-01

    The North Greenland Ice Core Project (NorthGRIP) provides paleoclimatic information back to at least 115 kyr before present [Dahl-Jensen et al., 2002]. Each year, precipitation on the ice sheet covers it with a new layer of snow, which gradually transforms into ice crystals as the layer sinks into the ice sheet. The size distribution of ice crystals has been measured at selected depths in the upper 880 m of the NorthGRIP ice core [Svensson et al., 2003b], which cover a time span of 5300 years. The distributions change with time toward a universal curve, indicating a common underlying physical process in the formation of crystals. We identify this process as an interplay between fragmentation of the crystals and diffusion of their grain boundaries. The process is described by a two-parameter differential equation to which we obtain the exact solution. The solution is in excellent agreement with the experimentally observed distributions.

  4. An improved continuous flow analysis system for high-resolution field measurements on ice cores.

    Science.gov (United States)

    Kaufmann, Patrik R; Federer, Urs; Hutterli, Manuel A; Bigler, Matthias; Schüpbach, Simon; Ruth, Urs; Schmitt, Jochen; Stocker, Thomas F

    2008-11-01

    Continuous flow analysis (CFA) is a well-established method to obtain information about impurity contents in ice cores as indicators of past changes in the climate system. A section of an ice core is continuously melted on a melter head supplying a sample water flow which is analyzed online. This provides high depth and time resolution of the ice core records and very efficient sample decontamination as only the inner part of the ice sample is analyzed. Here we present an improved CFA system which has been totally redesigned in view of a significantly enhanced overall efficiency and flexibility, signal quality, compactness, and ease of use. These are critical requirements especially for operations of CFA during field campaigns, e.g., in Antarctica or Greenland. Furthermore, a novel deviceto measure the total air content in the ice was developed. Subsequently, the air bubbles are now extracted continuously from the sample water flow for subsequent gas measurements.

  5. Diversity of 16S rDNA and environmental factor influencing microorganisms in Malan ice core

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The research on extrempholic microorganisms in glacial low-temperature environment receives more attention than ever before. Due to the successive chronological records in ice core, it is important to initiate microbiological studies on ice core samples. 23 samples from one ice core, drilled from central Qinghai-Tibetan Plateau, were analyzed. The number of total microorganisms and culturable microorganisms in different layers showed that it related with the content of dust in ice. It is suggested that the distribution of microorganisms in ice depends on the transportation of materials during glacier development. The bacteria diversity in Malan Glacier was analyzed by 16S rDNA sequencing methods, which showed that many sequences were similar to known psychrophilic bacteria.

  6. Carbonaceous particles in Muztagh Ata ice core, West Kunlun Mountains, China

    Institute of Scientific and Technical Information of China (English)

    LIU XianQin; XU BaiQing; YAO TanDong; WANG NingLian; WU GuangJian

    2008-01-01

    Carbonaceous particles concentrations of OC and EC are determined using a two-step gas chroma-tography system in Muztagh Ata ice core covering the time period of 1955-2000. Over the period rep-resented by the core, OC and EC concentrations appear to have changed significantly, varied in the range of 17.7-216.7 and 6.5-124.6, and averaged 61.8, 32.9 ng·g-1, respectively. The average concen-tration of EC in Muztagh Ata ice core is much lower than that in an Alpine ice core record (100-300 ng·g-1) during the same period, but it is a factor of 14 in Greenland ice core (2.3 ng.g-1), this may induce a strong impact on the snow albedo in the last 46 years in our study area. Observations indicate two periods with obviously high deposition concentrations (1955-1965 and 1974-1989) and two periods with low concentrations (1966-1973 and 1990-1995), as well as a recent increasing trend. By com-paring EC and SO42- concentration variations and deciphering OC/EC ratios recorded in the same ice core, we can judge roughly that the carbonaceous particles deposited in Muztagh Ata ice core were attributed to fossil fuel combustion sources.

  7. Investigating the past and recent δ18O-accumulation relationship seen in Greenland ice cores

    Directory of Open Access Journals (Sweden)

    D. Dahl-Jensen

    2012-12-01

    Full Text Available Decadal means of δ18O and accumulation rates from 52 ice core locations in Greenland are presented. The accumulation rates are derived from annual layers determined in the δ18O curve. Investigation of the δ18O-accumulation relationship across the ice divide reveals a significant Foehn effect with anticorrelation of δ18O and accumulation rate on the lee side of the divide in Southern Greenland, while no effect is seen in Central Greenland. Furthermore, the sensitivity of accumulation rate to changes in temperature is found to be smaller in Northern Greenland than in the central and southern parts. Four records in the data set contain sufficient recent data that the period of observed temperature rise from the 1990s and onwards can be investigated. All four records are from locations close to the ice divide in Northern Greenland and while three of them show increased temperatures, no conclusive statement can be made about the accumulation rate from these data.

  8. Search for Transient Astrophysical Neutrino Emission with IceCube-DeepCore

    CERN Document Server

    Aartsen, M G; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Ahrens, M; Altmann, D; Anderson, T; Ansseau, I; Archinger, M; Arguelles, C; Arlen, T C; Auffenberg, J; Bai, X; Barwick, S W; Baum, V; Bay, R; Beatty, J J; Tjus, J Becker; Becker, K -H; Beiser, E; BenZvi, S; Berghaus, P; Berley, D; Bernardini, E; Bernhard, A; Besson, D Z; Binder, G; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Börner, M; Bos, F; Bose, D; Böser, S; Botner, O; Braun, J; Brayeur, L; Bretz, H -P; Buzinsky, N; Casey, J; Casier, M; Cheung, E; Chirkin, D; Christov, A; Clark, K; Classen, L; Coenders, S; Cowen, D F; Silva, A H Cruz; Daughhetee, J; Davis, J C; Day, M; de André, J P A M; De Clercq, C; Rosendo, E del Pino; Dembinski, H; De Ridder, S; Desiati, P; de Vries, K D; de Wasseige, G; de With, M; DeYoung, T; Díaz-Vélez, J C; di Lorenzo, V; Dumm, J P; Dunkman, M; Eagan, R; Eberhardt, B; Ehrhardt, T; Eichmann, B; Euler, S; Evenson, P A; Fadiran, O; Fahey, S; Fazely, A R; Fedynitch, A; Feintzeig, J; Felde, J; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Fösig, C -C; Fuchs, T; Gaisser, T K; Gaior, R; Gallagher, J; Gerhardt, L; Ghorbani, K; Gier, D; Gladstone, L; Glagla, M; Glüsenkamp, T; Goldschmidt, A; Golup, G; Gonzalez, J G; Góra, D; Grant, D; Groh, J C; Groß, A; Ha, C; Haack, C; Ismail, A Haj; Hallgren, A; Halzen, F; Hansen, E; Hansmann, B; Hanson, K; Hebecker, D; Heereman, D; Helbing, K; Hellauer, R; Hickford, S; Hignight, J; Hill, G C; Hoffman, K D; Hoffmann, R; Holzapfel, K; Homeier, A; Hoshina, K; Huang, F; Huber, M; Huelsnitz, W; Hulth, P O; Hultqvist, K; In, S; Ishihara, A; Jacobi, E; Japaridze, G S; Jero, K; Jurkovic, M; Kappes, A; Karg, T; Karle, A; Kauer, M; Keivani, A; Kelley, J L; Kemp, J; Kheirandish, A; Kiryluk, J; Kläs, J; Klein, S R; Kohnen, G; Koirala, R; Kolanoski, H; Konietz, R; Köpke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Krings, K; Kroll, G; Kroll, M; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Lanfranchi, J L; Larson, M J; Lesiak-Bzdak, M; Leuermann, M; Leuner, J; Lu, L; Lünemann, J; Madsen, J; Maggi, G; Mahn, K B M; Maruyama, R; Mase, K; Matis, H S; Maunu, R; McNally, F; Meagher, K; Medici, M; Meli, A; Menne, T; Merino, G; Meures, T; Miarecki, S; Middell, E; Middlemas, E; Mohrmann, L; Montaruli, T; Morse, R; Nahnhauer, R; Naumann, U; Neer, G; Niederhausen, H; Nowicki, S C; Nygren, D R; Obertacke, A; Olivas, A; Omairat, A; O'Murchadha, A; Palczewski, T; Pandya, H; Pankova, D V; Paul, L; Pepper, J A; Heros, C Pérez de los; Pfendner, C; Pieloth, D; Pinat, E; Posselt, J; Price, P B; Przybylski, G T; Pütz, J; Quinnan, M; Raab, C; Rädel, L; Rameez, M; Rawlins, K; Reimann, R; Relich, M; Resconi, E; Rhode, W; Richman, M; Richter, S; Riedel, B; Robertson, S; Rongen, M; Rott, C; Ruhe, T; Ryckbosch, D; Saba, S M; Sabbatini, L; Sander, H -G; Sandrock, A; Sandroos, J; Sarkar, S; Schatto, K; Scheriau, F; Schimp, M; Schmidt, T; Schmitz, M; Schoenen, S; Schöneberg, S; Schönwald, A; Schulte, L; Seckel, D; Seunarine, S; Smith, M W E; Soldin, D; Song, M; Spiczak, G M; Spiering, C; Stahlberg, M; Stamatikos, M; Stanev, T; Stanisha, N A; Stasik, A; Stezelberger, T; Stokstad, R G; Stößl, A; Ström, R; Strotjohann, N L; Sullivan, G W; Sutherland, M; Taavola, H; Taboada, I; Tatar, J; Ter-Antonyan, S; Terliuk, A; Tešić, G; Tilav, S; Toale, P A; Tobin, M N; Toscano, S; Tosi, D; Tselengidou, M; Turcati, A; Unger, E; Usner, M; Vallecorsa, S; Vandenbroucke, J; van Eijndhoven, N; Vanheule, S; van Santen, J; Veenkamp, J; Vehring, M; Voge, M; Vraeghe, M; Walck, C; Wallace, A; Wallraff, M; Wandkowsky, N; Weaver, Ch; Wendt, C; Westerhoff, S; Whelan, B J; Whitehorn, N; Wiebe, K; Wiebusch, C H; Wille, L; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, D L; Xu, X W; Xu, Y; Yanez, J P; Yodh, G; Yoshida, S; Zoll, M

    2015-01-01

    We present the results of a search for astrophysical sources of brief transient neutrino emission using IceCube and DeepCore data acquired between May 15th 2012 and April 30th 2013. While the search methods employed in this analysis are similar to those used in previous IceCube point source searches, the data set being examined consists of a sample of predominantly sub-TeV muon neu- trinos from the Northern Sky (-5$^{\\circ}$ < {\\delta} < 90$^{\\circ}$ ) obtained through a novel event selection method. This search represents a first attempt by IceCube to identify astrophysical neutrino sources in this relatively unexplored energy range. The reconstructed direction and time of arrival of neutrino events is used to search for any significant self-correlation in the dataset. The data revealed no significant source of transient neutrino emission. This result has been used to construct limits at timescales ranging from roughly 1$\\,$s to 10 days for generic soft-spectra transients. We also present limits on a s...

  9. Physical analysis of an Antarctic ice core-towards an integration of micro- and macrodynamics of polar ice.

    Science.gov (United States)

    Weikusat, Ilka; Jansen, Daniela; Binder, Tobias; Eichler, Jan; Faria, Sérgio H; Wilhelms, Frank; Kipfstuhl, Sepp; Sheldon, Simon; Miller, Heinrich; Dahl-Jensen, Dorthe; Kleiner, Thomas

    2017-02-13

    Microstructures from deep ice cores reflect the dynamic conditions of the drill location as well as the thermodynamic history of the drill site and catchment area in great detail. Ice core parameters (crystal lattice-preferred orientation (LPO), grain size, grain shape), mesostructures (visual stratigraphy) as well as borehole deformation were measured in a deep ice core drilled at Kohnen Station, Dronning Maud Land (DML), Antarctica. These observations are used to characterize the local dynamic setting and its rheological as well as microstructural effects at the EDML ice core drilling site (European Project for Ice Coring in Antarctica in DML). The results suggest a division of the core into five distinct sections, interpreted as the effects of changing deformation boundary conditions from triaxial deformation with horizontal extension to bedrock-parallel shear. Region 1 (uppermost approx. 450 m depth) with still small macroscopic strain is dominated by compression of bubbles and strong strain and recrystallization localization. Region 2 (approx. 450-1700 m depth) shows a girdle-type LPO with the girdle plane being perpendicular to grain elongations, which indicates triaxial deformation with dominating horizontal extension. In this region (approx. 1000 m depth), the first subtle traces of shear deformation are observed in the shape-preferred orientation (SPO) by inclination of the grain elongation. Region 3 (approx. 1700-2030 m depth) represents a transitional regime between triaxial deformation and dominance of shear, which becomes apparent in the progression of the girdle to a single maximum LPO and increasing obliqueness of grain elongations. The fully developed single maximum LPO in region 4 (approx. 2030-2385 m depth) is an indicator of shear dominance. Region 5 (below approx. 2385 m depth) is marked by signs of strong shear, such as strong SPO values of grain elongation and strong kink folding of visual layers. The details of structural

  10. Physical analysis of an Antarctic ice core-towards an integration of micro- and macrodynamics of polar ice*

    Science.gov (United States)

    Weikusat, Ilka; Jansen, Daniela; Binder, Tobias; Eichler, Jan; Faria, Sérgio H.; Wilhelms, Frank; Kipfstuhl, Sepp; Sheldon, Simon; Miller, Heinrich; Dahl-Jensen, Dorthe; Kleiner, Thomas

    2017-02-01

    Microstructures from deep ice cores reflect the dynamic conditions of the drill location as well as the thermodynamic history of the drill site and catchment area in great detail. Ice core parameters (crystal lattice-preferred orientation (LPO), grain size, grain shape), mesostructures (visual stratigraphy) as well as borehole deformation were measured in a deep ice core drilled at Kohnen Station, Dronning Maud Land (DML), Antarctica. These observations are used to characterize the local dynamic setting and its rheological as well as microstructural effects at the EDML ice core drilling site (European Project for Ice Coring in Antarctica in DML). The results suggest a division of the core into five distinct sections, interpreted as the effects of changing deformation boundary conditions from triaxial deformation with horizontal extension to bedrock-parallel shear. Region 1 (uppermost approx. 450 m depth) with still small macroscopic strain is dominated by compression of bubbles and strong strain and recrystallization localization. Region 2 (approx. 450-1700 m depth) shows a girdle-type LPO with the girdle plane being perpendicular to grain elongations, which indicates triaxial deformation with dominating horizontal extension. In this region (approx. 1000 m depth), the first subtle traces of shear deformation are observed in the shape-preferred orientation (SPO) by inclination of the grain elongation. Region 3 (approx. 1700-2030 m depth) represents a transitional regime between triaxial deformation and dominance of shear, which becomes apparent in the progression of the girdle to a single maximum LPO and increasing obliqueness of grain elongations. The fully developed single maximum LPO in region 4 (approx. 2030-2385 m depth) is an indicator of shear dominance. Region 5 (below approx. 2385 m depth) is marked by signs of strong shear, such as strong SPO values of grain elongation and strong kink folding of visual layers. The details of structural observations are

  11. Chemical compositions of solid particles present in the Greenland NEEM ice core over the last 110,000 years

    Science.gov (United States)

    Oyabu, Ikumi; Iizuka, Yoshinori; Fischer, Hubertus; Schüpbach, Simon; Gfeller, Gideon; Svensson, Anders; Fukui, Manabu; Steffensen, Jørgen Peder; Hansson, Margareta

    2015-09-01

    This study reports the chemical composition of particles present along Greenland's North Greenland Eemian Ice Drilling (NEEM) ice core, back to 110,000 years before present. Insoluble and soluble particles larger than 0.45 µm were extracted from the ice core by ice sublimation, and their chemical composition was analyzed using scanning electron microscope and energy dispersive X-ray spectroscopy and micro-Raman spectroscopy. We show that the dominant insoluble components are silicates, whereas NaCl, Na2SO4, CaSO4, and CaCO3 represent major soluble salts. For the first time, particles of CaMg(CO3)2 and Ca(NO3)2•4H2O are identified in a Greenland ice core. The chemical speciation of salts varies with past climatic conditions. Whereas the fraction of Na salts (NaCl + Na2SO4) exceeds that of Ca salts (CaSO4 + CaCO3) during the Holocene (0.6-11.7 kyr B.P.), the two fractions are similar during the Bølling-Allerød period (12.9-14.6 kyr B.P.). During cold climate such as over the Younger Dryas (12.0-12.6 kyr B.P.) and the Last Glacial Maximum (15.0-26.9 kyr B.P.), the fraction of Ca salts exceeds that of Na salts, showing that the most abundant ion generally controls the salt budget in each period. High-resolution analyses reveal changing particle compositions: those in Holocene ice show seasonal changes, and those in LGM ice show a difference between cloudy bands and clear layers, which again can be largely explained by the availability of ionic components in the atmospheric aerosol body of air masses reaching Greenland.

  12. Analysis of the characteristics of microorganisms packed in the ice core of Malan Glacier, Tibet, China

    Institute of Scientific and Technical Information of China (English)

    张晓君; 姚檀栋; 马晓军; 王宁练

    2001-01-01

    Glacier is a special medium which can conserve a long time chronological information of microorganism. As a preliminary research, from Ice Core3 of Malan glacier (91°45.3’ E, 35°48.4’ N; drilled at 5620 m a.s.l. ), we successfully isolated live microorganisms. 75 strains of bacteria in 10 genera and 6 strains of actinomycetes in 2 genera were isolated from 23 samples. 32 strains bacteria were identified to be Bacillus and 25 strains were B.circulans, B.firmus, B.subtilis and 6. alvei. The genera of bacteria in Malan ice core were similar to that in Greenland and Antarctic ice core. We cannot isolate fungi and alga from Malan ice core, although they are widely distributed in Greenland and Antarctica.

  13. Direct North-South synchronization of abrupt climate change record in ice cores using beryllium 10

    Directory of Open Access Journals (Sweden)

    G. M. Raisbeck

    2007-05-01

    Full Text Available A new, decadally resolved record of the 10Be peak at 41 kyr from the EPICA Dome C ice core (Antarctica is used to match it with the same peak in the GRIP ice core (Greenland. This permits a direct synchronisation of the climatic variations around 41 kyr BP, independent of uncertainties related to the ice age-gas age difference in ice cores. Dansgaard-Oeschger event 10 is in the period of best synchronisation and is found to be coeval with an Antarctic temperature maximum. Simulations using a thermal bipolar seesaw model agree reasonably well with the observed relative climate chronology in these two cores. They also reproduce three Antarctic warming events between A1 and A2.

  14. Direct north-south synchronization of abrupt climate change record in ice cores using Beryllium 10

    Directory of Open Access Journals (Sweden)

    G. M. Raisbeck

    2007-09-01

    Full Text Available A new, decadally resolved record of the 10Be peak at 41 kyr from the EPICA Dome C ice core (Antarctica is used to match it with the same peak in the GRIP ice core (Greenland. This permits a direct synchronisation of the climatic variations around this time period, independent of uncertainties related to the ice age-gas age difference in ice cores. Dansgaard-Oeschger event 10 is in the period of best synchronisation and is found to be coeval with an Antarctic temperature maximum. Simulations using a thermal bipolar seesaw model agree reasonably well with the observed relative climate chronology in these two cores. They also reproduce three Antarctic warming events observed between A1 and A2.

  15. Visual-Stratigraphic Dating of the GISP2 Ice Core: Basis, Reproducibility, and Application

    Science.gov (United States)

    Alley, R. B.; Shuman, C. A.; Meese, D. A.; Gow, A. J.; Taylor, K. C.; Cuffey, K. M.; Fitzpatrick, J. J.; Grootes, P. M.; Zielinski, G. A.; Ram, M.; Spinelli, G.; Elder, B.

    1997-01-01

    Annual layers are visible in the Greenland Ice Sheet Project 2 ice core from central Greenland, allowing rapid dating of the core. Changes in bubble and grain structure caused by near-surface, primarily summertime formation of hoar complexes provide the main visible annual marker in the Holocene, and changes in "cloudiness" of the ice correlated with dustiness mark Wisconsinan annual cycles; both markers are evident and have been intercalibrated in early Holocene ice. Layer counts are reproducible between different workers and for one worker at different times, with 1% error over century-length times in the Holocene. Reproducibility is typically 5% in Wisconsinan ice-age ice and decreases with increasing age and depth. Cumulative ages from visible stratigraphy are not significantly different from independent ages of prominent events for ice older than the historical record and younger than approximately 50,000 years. Visible observations are not greatly degraded by "brittle ice" or many other core-quality problems, allowing construction of long, consistently sampled time series. High accuracy requires careful study of the core by dedicated observers.

  16. Ice core record of rising lead pollution in the North Pacific atmosphere

    Science.gov (United States)

    Osterberg, E.; Mayewski, P.; Kreutz, K.; Fisher, D.; Handley, M.; Sneed, S.; Zdanowicz, C.; Zheng, J.; Demuth, M.; Waskiewicz, M.; Bourgeois, J.

    2008-03-01

    A high-resolution, 8000 year-long ice core record from the Mt. Logan summit plateau (5300 m asl) reveals the initiation of trans-Pacific lead (Pb) pollution by ca. 1730, and a >10-fold increase in Pb concentration (1981-1998 mean = 68.9 ng/l) above natural background (5.6 ng/l) attributed to rising anthropogenic Pb emissions from Asia. The largest rise in North Pacific Pb pollution from 1970-1998 (end of record) is contemporaneous with a decrease in Eurasian and North American Pb pollution as documented in ice core records from Greenland, Devon Island, and the European Alps. The distinct Pb pollution history in the North Pacific is interpreted to result from the later industrialization and less stringent abatement measures in Asia compared to North America and Eurasia. The Mt. Logan record shows evidence for both a rising Pb emissions signal from Asia and a trans-Pacific transport efficiency signal related to the strength of the Aleutian Low.

  17. Carbonyl sulfide hydrolysis in polar ice cores and the feasibility of recovering a paleoatmospheric history

    Science.gov (United States)

    Nicewonger, M. R.; Aydin, K. M.; Saltzman, E. S.; Fudge, T. J.; Waddington, E. D.; Verhulst, K. R.

    2012-12-01

    Carbonyl sulfide (COS) is the most abundant sulfur gas in the atmosphere with a current tropospheric mean level of 484 parts per trillion [Montzka et al., 2007]. The major sources of COS are biomass burning, oceanic emissions of COS, and the atmospheric oxidation of precursor sulfur compounds CS2 and DMS emitted from the oceans and soils. The major losses of atmospheric COS are uptake by vegetation and soil. The uptake of COS by terrestrial vegetation provides a link between the global budget of COS and the carbon cycle. We measured COS in polar ice cores from four Antarctic sites: Taylor Dome, Siple Dome, South Pole, and West Antarctic Ice Sheet Divide. The COS samples ranged in age from 0.2-42 ky BP. There are large differences between the measurements from the various sites during overlapping time periods. COS levels in ice from the warmer sites (Siple Dome and WAIS-D) are considerably lower than those from the colder sites (Taylor Dome and South Pole). This result suggests that the difference reflects COS loss to hydrolysis within the ice core bubbles. The kinetics of COS hydrolysis in aqueous solution have been studied, but there is no information about reaction rates in ice. A 1-dimensional heat and ice flow model was used to determine the temperature history for each ice core sample. Assuming a pseudo-first order Arrhenius rate equation for COS loss in ice, we can correct each ice core sample for post-depositional COS loss. The temperature histories are used with an objective minimization algorithm to determine the optimal kinetic parameters for COS loss to obtain agreement between ice core measurements from different sites. The results indicate that the ice core data from all sites can be reconciled with a single COS atmospheric history. The uncertainty in this history becomes large in warm ice at longer time scales. This study suggests that reconstructing paleoatmospheric COS will require measurements in ice cores from sites with cold surface temperatures

  18. Improved dating of a mid-fifteenth century volcanic marker in ice cores

    Science.gov (United States)

    Cole-Dai, J.; Ferris, D. G.; McConnell, J. R.; Sigl, M.; Gao, C.

    2013-12-01

    Ice cores are dated with a variety of techniques with varying degrees of accuracy and precision. Recent advances in ice core chemical analysis have enabled high resolution (i.e., sub-annual) measurements that allow many ice cores to be dated with the technique of annual layer counting (ALC). Dating by ALC, when applied to appropriate ice cores, provides accuracy and precision that are not possible with other dating techniques. Two recent ice cores, one from Antarctica and one from Greenland and dated with the ALC technique, yield an 800 year (1200-2007 C.E.) bipolar record of explosive volcanic eruptions. The age uncertainties of volcanic signals in the period of 1400-2007 are no more than ×1 year. A prominent volcanic signal in the 15th century appears in the layers of 1459-1461 of both ice cores, indicating an eruption date of 1458. The mid-15th century eruption of the Kuwae volcano in the tropical Pacific is believed to be the most explosive in the last 700 years and to have impacted global climate. Examination of previous ice core records found 1454-1457 to be the date range of the prominent volcanic signal, presumed to be from the Kuwae eruption, in most Antarctica ice cores. This led to the suggestion that 1452 or 1453 is the probable eruption date for Kuwae. The new bipolar record places 1458×1 as the date of the eruption responsible for the prominent volcanic signal. The date of 1458 appears to be an improvement of the previously suggested date (1452 or 1453) for the eruption responsible for the prominent volcanic signal in the mid-15th century. However, the presence of another, less prominent signal at 1453-1454 in the new bipolar record makes it difficult at this point to attribute either signal to the Kuwae eruption, although current evidence suggests the later (1458) eruption is probably that of Kuwae.

  19. Driver of the interannual variations of isotope in ice core from the middle of Tibetan Plateau

    Science.gov (United States)

    Shao, Lili; Tian, Lide; Cai, Zhongyin; Cui, Jiangpeng; Zhu, Dayun; Chen, Yanhui; Palcsu, László

    2017-05-01

    Understanding the climatic significance of stable isotope in precipitation and ice cores on the Tibetan Plateau (TP) is of critical for the paleoclimate rebuilding. However, there is a gap between the seasonal control of precipitation and long-term isotope record from ice core. Here we present a well-dated ice core isotope record from the middle of the TP (mid-TP). Isotope variations in the past decades from this ice core show strong anti-phase relation with Southern Oscillation Index, confirming unequivocally that the large scale atmospheric circulation through the El Nino Southern Oscillation cycle, rather local climate parameters, controls the interannual signal in ice cores from the mid-TP. Results also show that the cloud top height in the northern Indian Ocean is in association with the interannual variations, confirming the same mechanism controlling the precipitation δ18O in southwest Asia and southeast Asia. The study will improve the understanding of the interannual change of Tibetan Plateau ice core isotope signal, and also the hydrological cycle in the southwest Asian region.

  20. Change in ice rheology during climate variations – implications for ice flow modelling and dating of the EPICA Dome C core

    Directory of Open Access Journals (Sweden)

    G. Durand

    2007-01-01

    Full Text Available The study of the distribution of crystallographic orientations (i.e., the fabric along ice cores provides information on past and current ice flow in ice-sheets. Besides the usually observed formation of a vertical single maximum fabric, the EPICA Dome C ice core (EDC shows an abrupt and unexpected strengthening of its fabric during termination II around 1750 m depth. Such strengthening has already been observed for sites located on an ice-sheet flank. This suggests that horizontal shear could occur along the EDC core. Moreover, the change in the fabric leads to a modification of the effective viscosity between neighbouring ice layers. Through the use of an anisotropic ice flow model, we quantify the change in effective viscosity and investigate its implication for ice flow and dating.

  1. Sea ice as a source of sea salt aerosol to Greenland ice cores: a model-based study

    Science.gov (United States)

    Rhodes, Rachael H.; Yang, Xin; Wolff, Eric W.; McConnell, Joseph R.; Frey, Markus M.

    2017-08-01

    Growing evidence suggests that the sea ice surface is an important source of sea salt aerosol and this has significant implications for polar climate and atmospheric chemistry. It also suggests the potential to use ice core sea salt records as proxies for past sea ice extent. To explore this possibility in the Arctic region, we use a chemical transport model to track the emission, transport, and deposition of sea salt from both the open ocean and the sea ice, allowing us to assess the relative importance of each. Our results confirm the importance of sea ice sea salt (SISS) to the winter Arctic aerosol burden. For the first time, we explicitly simulate the sea salt concentrations of Greenland snow, achieving values within a factor of two of Greenland ice core records. Our simulations suggest that SISS contributes to the winter maxima in sea salt characteristic of ice cores across Greenland. However, a north-south gradient in the contribution of SISS relative to open-ocean sea salt (OOSS) exists across Greenland, with 50 % of winter sea salt being SISS at northern sites such as NEEM (77° N), while only 10 % of winter sea salt is SISS at southern locations such as ACT10C (66° N). Our model shows some skill at reproducing the inter-annual variability in sea salt concentrations for 1991-1999, particularly at Summit where up to 62 % of the variability is explained. Future work will involve constraining what is driving this inter-annual variability and operating the model under different palaeoclimatic conditions.

  2. Recent North West Greenland climate variability documented by NEEM shallow ice cores

    Science.gov (United States)

    Masson-Delmotte, Valérie; Steen-Larsen, Hans-Christian; Popp, Trevor; Vinther, Bo; Oerter, Hans; Ortega, Pablo; White, Jim; Orsi, Anais; Falourd, Sonia; Minster, Benedicte; Jouzel, Jean; Landais, Amaelle; Risi, Camille; Werner, Martin; Swingedouw, Didier; Fettweis, Xavier; Gallée, Hubert; Sveinbjornsdottir, Arny; Gudlaugsdottir, Hera; Box, Jason

    2014-05-01

    Short water stable isotope records obtained from NEEM ice cores (North West Greenland) have been shown to be sensitive to NW Greenland temperature variations, and sea-ice extent in the Baffin Bay area (Steen-Larsen et al, JGR, 2011), with maximum snowfall deposition during summer, therefore providing information complementary to other Greenland ice core records. At the NEEM deep drilling camp, several snow pits and shallow ice cores have been retrieved and analysed at high resolution (seasonal to annual) for water stable isotopes using mass spectrometry and laser instruments in order to document recent climate variability, complementing and facilitating the interpretation of the long records obtained from the deep ice core which extends back to the last interglacial period (NEEM, Nature, 2013). The different pits and shallow ice core records allow to document the signal to noise ratio and to produce a robust stack back to 1750, and up to 2011. The stack record of annual mean d18O depicts a recent isotopic enrichment in parallel with the Greenland warming inferred from coastal weather stations, and shows that many features of decadal variations are in fact well captured by the low resolution profiles measured along the deep ice core data. Recent variations can therefore be compared to long-term trends and centennial variations of the last Holocene, documented at about 5 year resolution. For the past decades to centuries, the NEEM isotopic records are compared with estimations and simulations of local temperature for different seasons, results from NEEM borehole temperature inversions, d18O records from other Greenland ice cores, large scale modes of variability (NAO and AMO) and with simulations from atmospheric general circulation models equiped with water stable isotopes.

  3. Ice cores from Arctic sub-polar glaciers : Chronology and post-depositional processes deduced from radioactivity measurements

    NARCIS (Netherlands)

    Pinglot, J.F.; Vaikmae, R.A.; Kamiyama, K.; Igarashi, M.; Fritsche, D.; Wilhalms, F.; Koerner, R.; Henderson, L.; Isaksson, E.; Winther, J.G.; van de Wal, R.S.W.; Fournier, M; Bouisset, P.; Meijer, H.A.J.

    2003-01-01

    The response of Arctic ice masses to climate change is studied using ice cores containing information on past climatic and environmental features. Interpretation of this information requires accurate chronological data. Absolute dating of ice cores from sub-polar Arctic glaciers is possible using

  4. Ice cores from Arctic sub-polar glaciers : Chronology and post-depositional processes deduced from radioactivity measurements

    NARCIS (Netherlands)

    Pinglot, J.F.; Vaikmae, R.A.; Kamiyama, K.; Igarashi, M.; Fritsche, D.; Wilhalms, F.; Koerner, R.; Henderson, L.; Isaksson, E.; Winther, J.G.; van de Wal, R.S.W.; Fournier, M; Bouisset, P.; Meijer, H.A.J.

    2003-01-01

    The response of Arctic ice masses to climate change is studied using ice cores containing information on past climatic and environmental features. Interpretation of this information requires accurate chronological data. Absolute dating of ice cores from sub-polar Arctic glaciers is possible using we

  5. Using high-resolution tritium profiles to quantify the effects of melt on two Spitsbergen ice cores

    NARCIS (Netherlands)

    Wel, L.G. van der; Streurman, H.J.; Isaksson, E.; Helsen, M.M.; Wal, R.S.W. van de; Martma, T.; Pohjola, V.A.; Moore, J.C.; Meijer, H.A.J.

    2011-01-01

    Ice cores from small ice caps provide valuable climatic information, additional to that of Greenland and Antarctica. However, their integrity is usually compromised by summer meltwater percolation. To determine to what extent this can affect such ice cores, we performed high-resolution tritium measu

  6. Ice cores from Arctic sub-polar glaciers : Chronology and post-depositional processes deduced from radioactivity measurements

    NARCIS (Netherlands)

    Pinglot, J.F.; Vaikmae, R.A.; Kamiyama, K.; Igarashi, M.; Fritsche, D.; Wilhalms, F.; Koerner, R.; Henderson, L.; Isaksson, E.; Winther, J.G.; van de Wal, R.S.W.; Fournier, M; Bouisset, P.; Meijer, H.A.J.

    2003-01-01

    The response of Arctic ice masses to climate change is studied using ice cores containing information on past climatic and environmental features. Interpretation of this information requires accurate chronological data. Absolute dating of ice cores from sub-polar Arctic glaciers is possible using we

  7. Using high-resolution tritium profiles to quantify the effects of melt on two Spitsbergen ice cores

    NARCIS (Netherlands)

    Wel, L.G. van der; Streurman, H.J.; Isaksson, E.; Helsen, M.M.; Wal, R.S.W. van de; Martma, T.; Pohjola, V.A.; Moore, J.C.; Meijer, H.A.J.

    2011-01-01

    Ice cores from small ice caps provide valuable climatic information, additional to that of Greenland and Antarctica. However, their integrity is usually compromised by summer meltwater percolation. To determine to what extent this can affect such ice cores, we performed high-resolution tritium measu

  8. Using high-resolution tritium profiles to quantify the effects of melt on two Spitsbergen ice cores

    NARCIS (Netherlands)

    Wel, L.G. van der; Streurman, H.J.; Isaksson, E.; Helsen, M.M.; Wal, R.S.W. van de; Martma, T.; Pohjola, V.A.; Moore, J.C.; Meijer, H.A.J.

    2011-01-01

    Ice cores from small ice caps provide valuable climatic information, additional to that of Greenland and Antarctica. However, their integrity is usually compromised by summer meltwater percolation. To determine to what extent this can affect such ice cores, we performed high-resolution tritium

  9. Tree ring effects and ice core acidities clarify the volcanic record of the first millennium

    OpenAIRE

    M. G. L. Baillie; McAneney, J

    2015-01-01

    In 2012 Plummer et al., in presenting the volcanic chronology of the Antarctic Law Dome ice core, chose to list connections to acid layers in other ice cores and also possible chronological coincidences between ice acid dates and the precise dates of frost damage, and/or reduced growth in North American bristlecone pines. We disagree with the chronological links indicated by Plummer et al. for the period before AD 700, and in this paper we show that a case can be made that b...

  10. Optimization of High-Resolution Continuous Flow Analysis for Transient Climate Signals in Ice Cores

    DEFF Research Database (Denmark)

    Bigler, Matthias; Svensson, Anders; Kettner, Ernesto

    2011-01-01

    Over the past two decades, continuous flow analysis (CFA) systems have been refined and widely used to measure aerosol constituents in polar and alpine ice cores in very high-depth resolution. Here we present a newly designed system consisting of sodium, ammonium, dust particles, and electrolytic...... meltwater conductivity detection modules. The system is optimized for high- resolution determination of transient signals in thin layers of deep polar ice cores. Based on standard measurements and by comparing sections of early Holocene and glacial ice from Greenland, we find that the new system features...

  11. A High-Resolution Continuous Flow Analysis System for Polar Ice Cores

    DEFF Research Database (Denmark)

    Dallmayr, Remi; Goto-Azuma, Kumiko; Kjær, Helle Astrid

    2016-01-01

    of Polar Research (NIPR) in Tokyo. The system allows the continuous analysis of stable water isotopes and electrical conductivity, as well as the collection of discrete samples from both inner and outer parts of the core. This CFA system was designed to have sufficiently high temporal resolution to detect...... signals of abrupt climate change in deep polar ice cores. To test its performance, we used the system to analyze different climate intervals in ice drilled at the NEEM (North Greenland Eemian Ice Drilling) site, Greenland. The quality of our continuous measurement of stable water isotopes has been...

  12. Laser altimetry reveals complex pattern of Greenland Ice Sheet dynamics

    NARCIS (Netherlands)

    Csatho, Beata M.; Schenk, Anton F.; van der Veen, Cornelis J.; Babonis, Gregory; Duncan, Kyle; Rezvanbehbahani, Soroush; van den Broeke, Michiel R.; Simonsen, Sebastian B.; Nagarajan, Sudhagar; van Angelen, Jan H.

    2014-01-01

    We present a new record of ice thickness change, reconstructed at nearly 100,000 sites on the Greenland Ice Sheet (GrIS) from laser altimetry measurements spanning the period 1993-2012, partitioned into changes due to surface mass balance (SMB) and ice dynamics. We estimate a mean annual GrIS mass l

  13. Geostatistical analysis and isoscape of ice core derived water stable isotope records in an Antarctic macro region

    Science.gov (United States)

    Hatvani, István Gábor; Leuenberger, Markus; Kohán, Balázs; Kern, Zoltán

    2017-09-01

    Water stable isotopes preserved in ice cores provide essential information about polar precipitation. In the present study, multivariate regression and variogram analyses were conducted on 22 δ2H and 53 δ18O records from 60 ice cores covering the second half of the 20th century. Taking the multicollinearity of the explanatory variables into account, as also the model's adjusted R2 and its mean absolute error, longitude, elevation and distance from the coast were found to be the main independent geographical driving factors governing the spatial δ18O variability of firn/ice in the chosen Antarctic macro region. After diminishing the effects of these factors, using variography, the weights for interpolation with kriging were obtained and the spatial autocorrelation structure of the dataset was revealed. This indicates an average area of influence with a radius of 350 km. This allows the determination of the areas which are as yet not covered by the spatial variability of the existing network of ice cores. Finally, the regional isoscape was obtained for the study area, and this may be considered the first step towards a geostatistically improved isoscape for Antarctica.

  14. Direct linking of Greenland and Antarctic ice cores at the Toba eruption (74 ka BP)

    Science.gov (United States)

    Svensson, A.; Bigler, M.; Fischer, H.; Johnsen, S. J.; Kipfstuhl, S.; Parrenin, F.; Rasmussen, S. O.; Steffensen, J. P.; Vinther, B. M.; Wegner, A.

    2012-04-01

    The Toba eruption that occurred some 74 ka ago in Sumatra, Indonesia, is among the largest volcanic events on Earth over the last 2 million years. Tephra from this eruption has been spread over vast areas in Asia where it constitutes a major reference horizon close to the Marine Isotope Stage 3/4 (MIS 3/4) boundary. Up to now, no tephra has been associated with Toba neither in Greenland nor in Antarctic ice cores, but based on Toba tephra identified in marine records from the Arabian Sea it is very likely that Greenland ice core acidity spikes related to Toba occur towards the end of Greenland Interstadial 20 (GI-20). Furthermore, the linking of Greenland and Antarctic ice cores by gas records suggests that the Antarctica counterpart should be situated between Antarctic Isotope Maxima (AIM) 19 and 20. In this work we suggest a direct synchronization of Greenland (NGRIP) and Antarctic (EDML) ice cores based on matching of a pattern of bi-polar volcanic spikes and annual layer counting in both cores around 74 ka BP. The synchronization pattern covers some 2000 years in GI-20 and AIM 19/20 and includes 5 major and several minor acidity peaks that are recognized in both ice cores. The most prominent acidity spikes in this time interval that occur towards the end of GI-20, are those thought to originate from Toba, but the proposed linking is independent of the source of the volcanic spikes. Although the linking of Greenland and Antarctic ice cores around Toba is already quite well constrained by matching of gas records, the relative phasing between ice cores from the two hemispheres still has some uncertainty related to the offset in the age of ice and air bubbles in the ice cores (delta-gas age). The identification of a direct Toba synchronization may help to determine the exact phasing of inter-hemispheric climate during this period and to constrain delta-gas ages. It also provides a way to place paleo-environmental records other than ice cores into a precise climatic

  15. Investigation of a deep ice core from the Elbrus Western Plateau, the Caucasus, Russia

    Directory of Open Access Journals (Sweden)

    V. Mikhalenko

    2015-07-01

    NH4+ and is 1455 mm w.e. for the last 140 years. Using annual layer counting also for the dating of the ice core, a good agreement with the absolute markers of the tritium 1963 bomb test time horizon located at the core depth of 50.7 m w.e. and the sulfate peak of the Katmai eruption (1912 at 87.7 m w.e. was obtained. According to mathematical modeling results, the bottom ice age at the maximal glacier depth is predicted to be about 660 years BP. As the 2009 borehole was situated downstream of this point, the estimated bottom ice age of the drilling site does not exceed 350–400 years BP. Taking into account the information that we have acquired on the Western Plateau Elbrus glacier and first results of the ice core analysis, these data can be used to reconstruct the atmospheric history of the European region.

  16. Assessment of diffusive isotopic fractionation in polar firn, and application to ice core trace gas records

    DEFF Research Database (Denmark)

    Buizert, C.; Sowers, T.; Blunier, T.

    2013-01-01

    from ice cores; (5) arguably gives more accurate results than a combined firn densification-firn air transport modeling study would. We apply the method to records of CH, CO and NO mixing ratios, and we find that the correction is particularly important for C - . We apply the correction to C - records......During rapid variations of the atmospheric mixing ratio of a trace gas, diffusive transport in the porous firn layer atop ice sheets and glaciers alters the isotopic composition of that gas relative to the overlying atmosphere. Records of past atmospheric trace gas isotopic composition from ice...... cores and firn need to be corrected for this diffusive fractionation artifact. We present a novel, semi-empirical method to accurately estimate the magnitude of the diffusive fractionation in the ice core record. Our method (1) consists of a relatively simple analytical calculation; (2) requires only...

  17. The role of variability in atmospheric circulation and Greenland precipitation for interpreting ice core records

    Science.gov (United States)

    Faber, Anne-Katrine; Li, Camille

    2017-04-01

    Ice cores from Greenland contain the layers of snowfall accumulated throughout each year. Variability in snowfall accumulation can therefore influence the climatic signal recorded in the ice cores. This study uses reanalysis data from ERA-Interim (1979-2015) to investigate how atmospheric circulation patterns can drive precipitation and accumulation variability on the Greenland Ice Sheet. This is examined by comparing the spatial and temporal variability in precipitation amount and frequency with specific phases of atmospheric patterns such as the North Atlantic Circulation (NAO) as well as with the position of the North Atlantic jet stream. Results show that large-scale atmospheric conditions associated with high precipitation events in northwestern Greenland (near the ice core site NEEM) differ from the atmospheric conditions associated with high precipitation events in northeastern Greenland (near the ice core site EGRIP). The relationship between the large-scale conditions and moisture transport paths are investigated to determine how this precipitation variability arises. A further understanding of the atmospheric circulation patterns role in the precipitation variability and high precipitation events can help to improve the interpretation of the ice core records for past and present-day climates.

  18. A Method for Continuous (239)Pu Determinations in Arctic and Antarctic Ice Cores.

    Science.gov (United States)

    Arienzo, M M; McConnell, J R; Chellman, N; Criscitiello, A S; Curran, M; Fritzsche, D; Kipfstuhl, S; Mulvaney, R; Nolan, M; Opel, T; Sigl, M; Steffensen, J P

    2016-07-05

    Atmospheric nuclear weapons testing (NWT) resulted in the injection of plutonium (Pu) into the atmosphere and subsequent global deposition. We present a new method for continuous semiquantitative measurement of (239)Pu in ice cores, which was used to develop annual records of fallout from NWT in ten ice cores from Greenland and Antarctica. The (239)Pu was measured directly using an inductively coupled plasma-sector field mass spectrometer, thereby reducing analysis time and increasing depth-resolution with respect to previous methods. To validate this method, we compared our one year averaged results to published (239)Pu records and other records of NWT. The (239)Pu profiles from the Arctic ice cores reflected global trends in NWT and were in agreement with discrete Pu profiles from lower latitude ice cores. The (239)Pu measurements in the Antarctic ice cores tracked low latitude NWT, consistent with previously published discrete records from Antarctica. Advantages of the continuous (239)Pu measurement method are (1) reduced sample preparation and analysis time; (2) no requirement for additional ice samples for NWT fallout determinations; (3) measurements are exactly coregistered with all other chemical, elemental, isotopic, and gas measurements from the continuous analytical system; and (4) the long half-life means the (239)Pu record is stable through time.

  19. Anthropogenic emissions and combustion products recorded in a Colle Gnifetti ice core

    Science.gov (United States)

    Gabrieli, J.; Kehrwald, N. M.; Zennaro, P.; Lim, S.; Laj, P.; Barbante, C.

    2012-12-01

    Ice cores provide direct and highly resolved records of atmospheric parameters that record both climate signals and forcing factors. European Alpine glaciers are located near densely populated and industrialized areas and provide excellent archives of past air pollution. Ice cores to bedrock on Colle Gnifetti, Monte Rosa (45°55'51''N, 07°52'34''E; 4450 m a.s.l.) permit centennial to millennial reconstruction of past regional climate, while snow pit and shallow core studies from the same site allow multiple parameter reconstructions of anthropogenic emissions. Air pollution includes fossil fuel and biomass burning products that influence regional smog and contain trace elements hazardous to human health. Here, we examine a high-resolution suite of anthropogenic and natural emissions (black carbon, levoglucosan, trace elements, heavy metals) and climate proxies (major ions and stable isotopes) in a 12 m Colle Gnifetti ice core to determine seasonal changes in anthropogenic emissions and their interaction with climate parameters. This is the first study to compare black carbon (a fossil fuel and biomass combustion tracer) with levoglucosan (a fire activity biomarker) in a European ice core. The combination of these two proxies can determine changing combustion product sources through time. Our results demonstrate that anthropogenic emissions influence the summer aerosol flux while crustal sources dominate the winter aerosol flux. These ice core chemical data are consistent with observational data and boundary layer dynamics that transport pollutants concentrated in the Po Valley and similar industrial lowland regions to glacier surfaces during the summer.

  20. Deconvolution-based resolution enhancement of chemical ice core records obtained by continuous flow analysis

    DEFF Research Database (Denmark)

    Rasmussen, Sune Olander; Andersen, Katrine K.; Johnsen, Sigfus Johann

    2005-01-01

    Continuous flow analysis (CFA) has become a popular measuring technique for obtaining high-resolution chemical ice core records due to an attractive combination of measuring speed and resolution. However, when analyzing the deeper sections of ice cores or cores from low-accumulation areas......, there is still need for further improvement of the resolution. Here a method for resolution enhancement of CFA data is presented. It is demonstrated that it is possible to improve the resolution of CFA data by restoring some of the detail that was lost in the measuring process, thus improving the usefulness...

  1. Source of major ions from an ice core of the No.12 Glacier in Laohugou Valley,Qilian Mountain

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In June 2006,a 20.12 m shallow ice core was recovered from an elevation of 5,040 m in the northern branch firn basin of No.12 Glacier,Great Snow Mountain,in the western part of Qilian Mountain,China.Isotopes(δ 18 O),major soluble ions,and radionuclide(β-activity) measurements from the ice core revealed a 46-year record(1960-2006).In this paper,the method of sea-salt ion tracer,correlation analysis and trend analysis were used in this research to confirm the source of the chemical composition.The correlation analysis and HYSPLIT backward trajectory analysis suggests that atmospheric soluble dust species dominate the chemical signature.

  2. Microparticle record in the Guliya ice core and its comparison with polar records since the last interglacial

    Institute of Scientific and Technical Information of China (English)

    WU Guangjian; YAO Tandong; L.G. Thompson; LI Zhongqin

    2004-01-01

    Based on the study of oxygen isotope and microparticle in the Guliya ice core, atmospheric dust and environmental changes in the northwest Tibetan Plateau since the last interglacial were revealed. The microparticle record indicates that Iow dust load on the Plateau in the interglacial.Particle concentration increased rapidly when the climate turned into the last glacial and reached the maximum during the MIS 4. In the Last Glacial Maximum, however, the enhancement of microparticle concentration was slight, differing to those in the Antarctic and Greenland. On the orbital timescale, both the temperature on the Tibetan Plateau and summer solar insolation in the Northern Hemisphere had their impact on the microparticle record, but the difference in phase and amplitude also existed. Though having the same dust source, microparticle records in the ice cores on the Tibetan Plateau and the Greenland seem to have different significance.

  3. Synchronisation of the EDML and EDC ice cores for the last 52 kyr by volcanic signature matching

    DEFF Research Database (Denmark)

    Severi, M.; Becagli, S.; Castellano, E.;

    2007-01-01

    A common time scale for the EPICA ice cores from Dome C (EDC) and Dronning Maud Land (EDML) has been established. Since the EDML core was not drilled on a dome, the development of the EDML1 time scale for the EPICA ice core drilled in Dronning Maud Land was based on the creation of a detailed str...

  4. Tree ring effects and ice core acidities clarify the volcanic record of the first millennium

    Science.gov (United States)

    Baillie, M. G. L.; McAneney, J.

    2015-01-01

    In 2012 Plummer et al., in presenting the volcanic chronology of the Antarctic Law Dome ice core, chose to list connections to acid layers in other ice cores and also possible chronological coincidences between ice acid dates and the precise dates of frost damage, and/or reduced growth in North American bristlecone pines. We disagree with the chronological links indicated by Plummer et al. for the period before AD 700, and in this paper we show that a case can be made that better linkages between ice acid and tree ring effects occur for this period if the ice chronologies are systematically moved forward by around 7 years, consistent with a hypothesis published by Baillie in 2008. In the paper we seek to explore the proposition that frost damage rings in North American bristlecone pines are a very useful indicator of the dates of certain large explosive volcanic eruptions; the dating of major eruptions being critical for any clear understanding of volcanic forcing. This paper cannot prove that there is an error in the Greenland Ice Core Chronology 2005 (GICC05), and in equivalent ice chronologies from the Antarctic, however, it does provide a coherent argument for an apparent ice dating offset. If the suggested offset were to prove correct it would be necessary to locate where the error occurs in the ice chronologies and in this regard the dating of the increasingly controversial Icelandic Eldgjá eruption in the AD 930s, and the China/Korean Millennium eruption which occurs some 7 years after Eldgjá, may well be critical. In addition, if the offset were to be substantiated it would have implications for the alleged identification of tephra at 429.3 m in the Greenland GRIP core, currently attributed to the Italian volcano Vesuvius and used as a critical zero error point in the GICC05 chronology.

  5. Fire in ice: two millennia of Northern Hemisphere fire history from the Greenland NEEM ice core

    Directory of Open Access Journals (Sweden)

    P. Zennaro

    2014-02-01

    Full Text Available Biomass burning is a major source of greenhouse gases and influences regional to global climate. Pre-industrial fire-history records from black carbon, charcoal and other proxies provide baseline estimates of biomass burning at local to global scales, but there remains a need for broad-scale fire proxies that span millennia in order to understand the role of fire in the carbon cycle and climate system. We use the specific biomarker levoglucosan, and multi-source black carbon and ammonium concentrations to reconstruct fire activity from the North Greenland Eemian (NEEM ice cores (77.49° N; 51.2° W, 2480 m a.s.l. over the past 2000 years. Increases in boreal fire activity (1000–1300 CE and 1500–1700 CE over multi-decadal timescales coincide with the most extensive central and northern Asian droughts of the past two millennia. The NEEM biomass burning tracers coincide with temperature changes throughout much of the past 2000 years except for during the extreme droughts, when precipitation changes are the dominant factor. Many of these multi-annual droughts are caused by monsoon failures, thus suggesting a connection between low and high latitude climate processes. North America is a primary source of biomass burning aerosols due to its relative proximity to the NEEM camp. During major fire events, however, isotopic analyses of dust, back-trajectories and links with levoglucosan peaks and regional drought reconstructions suggest that Siberia is also an important source of pyrogenic aerosols to Greenland.

  6. Recent change of the ice core accumulation rates on the Qinghai-Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Three ice cores recovered from the Himalayas (i.e. the East Rongbuk Glacier and the Far East Rongbuk Glacier at Mt. Qomolangma (Everest), and the Dasuopu Glacier at Xixiabangma) show a sharp decline in the accumulation rates since the 1950s, which is consistent with the precipitation fluctuation over India and the low northern latitude zone (5°-35°N). Correspondingly, an increasing trend is observed for the ice core accumulations from the central and northern Qingh ai-Tibetan Plateau (i.e. the Xiao Dongkemadi Glacier in the central Tanggula Mountains, the Guliya Ice Cap in the western Kunlun Mountains, and the Dunde Ice Cap in the Qilian Mountains) since the 1950s, which is consistent with the precipi tation fluctuation over the middle-high northern latitude zone (35°-70°N). However, the variation magnitude of the high-elevation ice core accumulations is more significant than that of precipitation at the low-eleva- tion places, suggesti ng its extra sensitivity of high-elevation areas to climatic change. The inter-d ecadal abrupt change of the African-Asian summer monsoon in the1960s may attribute to the recent ice core accumulation change during the recent decades.

  7. The Design and Performance of IceCube DeepCore

    CERN Document Server

    ,

    2011-01-01

    The IceCube neutrino observatory in operation at the South Pole, Antarctica, comprises three distinct components: a large buried array for ultrahigh energy neutrino detection, a surface air shower array, and a new buried component called DeepCore. DeepCore was designed to lower the IceCube neutrino energy threshold by over an order of magnitude, to energies as low as about 10 GeV. DeepCore is situated primarily 2100 m below the surface of the icecap at the South Pole, at the bottom center of the existing IceCube array, and began taking physics data in May 2010. Its location takes advantage of the exceptionally clear ice at those depths and allows it to use the surrounding IceCube detector as a highly efficient active veto against the principal background of downward-going muons produced in cosmic-ray air showers. DeepCore has a module density roughly five times higher than that of the standard IceCube array, and uses photomultiplier tubes with a new photocathode featuring a quantum efficiency about 35% higher...

  8. Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements

    Directory of Open Access Journals (Sweden)

    E. Capron

    2013-05-01

    Full Text Available Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ15N of N2 in air trapped in ice core, assuming that δ15N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI and semi-coastal (TALDICE and EPICA Dronning Maud Land, EDML Antarctic regions. Combined with available ice core air-δ15N measurements from the EPICA Dome C (EDC site, the studied regions encompass a large range of surface accumulation rates and temperature conditions. Our δ15N profiles reveal a heterogeneous response of the firn structure to glacial–interglacial climatic changes. While firn densification simulations correctly predict TALDICE δ15N variations, they systematically fail to capture the large millennial-scale δ15N variations measured at BI and the δ15N glacial levels measured at JRI and EDML – a mismatch previously reported for central East Antarctic ice cores. New constraints of the EDML gas–ice depth offset during the Laschamp event (~41 ka and the last deglaciation do not favour the hypothesis of a large convective zone within the firn as the explanation of the glacial firn model–δ15N data mismatch for this site. While we could not conduct an in-depth study of the influence of impurities in snow for firnification from the existing datasets, our detailed comparison between the δ15N profiles and firn model simulations under different temperature and accumulation rate scenarios suggests that the role of accumulation rate may have been underestimated in the current description of firnification

  9. An improved method for delta 15N measurements in ice cores

    Directory of Open Access Journals (Sweden)

    M. Leuenberger

    2008-02-01

    Full Text Available The use of isotopic ratios of nitrogen gas (δ15N trapped in ice cores as a paleothermometer to characterise abrupt climate changes is becoming a widespread technique. The versatility of the technique could be enhanced, for instance in quantifying small temperature changes during the last glacial period in Antarctic ice cores, by using high precision methods. In this paper, we outline a method for measuring δ15N to a precision of 0.006permil (1σ, n=9 from replicate ice core samples. The high precision results from removing oxygen, carbon dioxide and water vapour from the air extracted from ice cores. The advantage of the technique is that it does not involve correction for isobaric interference due to CO+ ions. We also highlight the importance of oxygen removal from the sample, and how it influences δ15N measurements. The results show that a small amount of oxygen in the sample can be detrimental to achieving an optimum precision in δ15N measurements of atmospheric nitrogen trapped ice core samples.

  10. Improved methodologies for continuous-flow analysis of stable water isotopes in ice cores

    Science.gov (United States)

    Jones, Tyler R.; White, James W. C.; Steig, Eric J.; Vaughn, Bruce H.; Morris, Valerie; Gkinis, Vasileios; Markle, Bradley R.; Schoenemann, Spruce W.

    2017-02-01

    Water isotopes in ice cores are used as a climate proxy for local temperature and regional atmospheric circulation as well as evaporative conditions in moisture source regions. Traditional measurements of water isotopes have been achieved using magnetic sector isotope ratio mass spectrometry (IRMS). However, a number of recent studies have shown that laser absorption spectrometry (LAS) performs as well or better than IRMS. The new LAS technology has been combined with continuous-flow analysis (CFA) to improve data density and sample throughput in numerous prior ice coring projects. Here, we present a comparable semi-automated LAS-CFA system for measuring high-resolution water isotopes of ice cores. We outline new methods for partitioning both system precision and mixing length into liquid and vapor components - useful measures for defining and improving the overall performance of the system. Critically, these methods take into account the uncertainty of depth registration that is not present in IRMS nor fully accounted for in other CFA studies. These analyses are achieved using samples from a South Pole firn core, a Greenland ice core, and the West Antarctic Ice Sheet (WAIS) Divide ice core. The measurement system utilizes a 16-position carousel contained in a freezer to consecutively deliver ˜ 1 m × 1.3 cm2 ice sticks to a temperature-controlled melt head, where the ice is converted to a continuous liquid stream and eventually vaporized using a concentric nebulizer for isotopic analysis. An integrated delivery system for water isotope standards is used for calibration to the Vienna Standard Mean Ocean Water (VSMOW) scale, and depth registration is achieved using a precise overhead laser distance device with an uncertainty of ±0.2 mm. As an added check on the system, we perform inter-lab LAS comparisons using WAIS Divide ice samples, a corroboratory step not taken in prior CFA studies. The overall results are important for substantiating data obtained from LAS

  11. Laser altimetry reveals complex pattern of Greenland Ice Sheet dynamics

    DEFF Research Database (Denmark)

    Csatho, Beata M.; Schenk, Anton F.; van der Veen, Cornelis J.

    2014-01-01

    Significance We present the first detailed reconstruction of surface elevation changes of the Greenland Ice Sheet from NASA’s laser altimetry data. Time series at nearly 100,000 locations allow the characterization of ice sheet changes at scales ranging from individual outlet glaciers to larger d...

  12. High-resolution, continuous method for measurement of acidity in ice cores.

    Science.gov (United States)

    Pasteris, Daniel R; McConnell, Joseph R; Edwards, Ross

    2012-02-07

    The acid content of ice core samples provides information regarding the history of volcanism, biogenic activity, windblown dust, forest fires, and pollution-induced acid rain. A continuous ice core analysis allows for collection of high-resolution data in a very efficient manner, but this technique has not been readily applied to the measurement of pH and acidity in ice cores. The difficulty arises because the sample is highly undersaturated with respect to carbon dioxide (CO(2)) immediately after melting, making it difficult to maintain stable concentrations of dissolved carbon dioxide and carbonic acid (H(2)CO(3)). Here, we present a solution to this problem in the form of a small flow-through bubbling chamber that is supplied with a known concentration of CO(2). The bubbling action allows for quick equilibration while the small size of the chamber limits sample mixing in order to maintain high resolution. Thorough error analysis provides a measurement uncertainty of ±0.20 μM or ±5% of the acidity value, whichever is greater, and the T95 signal response time is determined to be 1.25 min. The performance of the technique is further evaluated with data from a 63-year ice core from northwest Greenland for which all major ion species were also measured. The measured acidity closely matches the acidity derived from a charge balance calculation, indicating that all of the analytes were measured accurately. The performance specifications that we provide are applicable to ice cores with low concentrations of alkaline dust (ice cores that are collected. To date, the method has not been evaluated with samples containing high alkaline dust concentrations, such as Greenland cores from the last glacial period, where measurement could be made difficult by memory effects as particles coat the internal surfaces of the sample stream.

  13. Direct linking of Greenland and Antarctic ice cores at the Toba eruption (74 kyr BP)

    Science.gov (United States)

    Svensson, A.; Bigler, M.; Blunier, T.; Clausen, H. B.; Dahl-Jensen, D.; Fischer, H.; Fujita, S.; Goto-Azuma, K.; Johnsen, S. J.; Kawamura, K.; Kipfstuhl, S.; Kohno, M.; Parrenin, F.; Popp, T.; Rasmussen, S. O.; Schwander, J.; Seierstad, I.; Severi, M.; Steffensen, J. P.; Udisti, R.; Uemura, R.; Vallelonga, P.; Vinther, B. M.; Wegner, A.; Wilhelms, F.; Winstrup, M.

    2012-11-01

    The Toba eruption that occurred some 74 kyr ago in Sumatra, Indonesia, is among the largest volcanic events on Earth over the last 2 million years. Tephra from this eruption has been spread over vast areas in Asia where it constitutes a major time marker close to the Marine Isotope Stage 4/5 boundary. As yet, no tephra associated with Toba has been identified in Greenland or Antarctic ice cores. Based on new accurate dating of Toba tephra from Malaysia and on accurately dated European stalagmites the Toba event is known to occur between the onsets of Greenland Interstadials (GI) 19 and 20. Furthermore, the existing linking of Greenland and Antarctic ice cores by gas records and by the bipolar seesaw hypothesis suggests that the Antarctic counterpart is situated between Antarctic Isotope Maxima (AIM) 19 and 20. In this work we suggest a direct synchronization of Greenland (NGRIP) and Antarctic (EDML) ice cores at the Toba eruption based on matching of a pattern of bipolar volcanic spikes. Annual layer counting between volcanic spikes in both cores allows for a unique match. We first demonstrate this bipolar matching technique at the already synchronized Laschamp geomagnetic excursion (41 kyr BP) before we apply it to the suggested Toba interval. The Toba synchronization pattern covers some 2000 yr in GI-20 and AIM 19/20 and includes nine acidity peaks that are recognized in both ice cores. The suggested bipolar Toba synchronization has decadal precision. It thus allows a determination of the exact phasing of inter-hemispheric climate in a time interval of poorly constrained ice core records, and it allows for a discussion of the climatic impact of the Toba eruption in a global perspective. Furthermore, our bipolar match provides a way to place paleo-environmental records other than ice cores into a precise climatic context.

  14. Direct linking of Greenland and Antarctic ice cores at the Toba eruption (74 kyr BP

    Directory of Open Access Journals (Sweden)

    A. Svensson

    2012-11-01

    Full Text Available The Toba eruption that occurred some 74 kyr ago in Sumatra, Indonesia, is among the largest volcanic events on Earth over the last 2 million years. Tephra from this eruption has been spread over vast areas in Asia where it constitutes a major time marker close to the Marine Isotope Stage 4/5 boundary. As yet, no tephra associated with Toba has been identified in Greenland or Antarctic ice cores. Based on new accurate dating of Toba tephra from Malaysia and on accurately dated European stalagmites the Toba event is known to occur between the onsets of Greenland Interstadials (GI 19 and 20. Furthermore, the existing linking of Greenland and Antarctic ice cores by gas records and by the bipolar seesaw hypothesis suggests that the Antarctic counterpart is situated between Antarctic Isotope Maxima (AIM 19 and 20.

    In this work we suggest a direct synchronization of Greenland (NGRIP and Antarctic (EDML ice cores at the Toba eruption based on matching of a pattern of bipolar volcanic spikes. Annual layer counting between volcanic spikes in both cores allows for a unique match. We first demonstrate this bipolar matching technique at the already synchronized Laschamp geomagnetic excursion (41 kyr BP before we apply it to the suggested Toba interval. The Toba synchronization pattern covers some 2000 yr in GI-20 and AIM 19/20 and includes nine acidity peaks that are recognized in both ice cores.

    The suggested bipolar Toba synchronization has decadal precision. It thus allows a determination of the exact phasing of inter-hemispheric climate in a time interval of poorly constrained ice core records, and it allows for a discussion of the climatic impact of the Toba eruption in a global perspective. Furthermore, our bipolar match provides a way to place paleo-environmental records other than ice cores into a precise climatic context.

  15. Low time resolution analysis of polar ice cores cannot detect impulsive nitrate events

    CERN Document Server

    Smart, D F; Melott, A L; Laird, C M

    2015-01-01

    Ice cores are archives of climate change and possibly large solar proton events (SPEs). Wolff et al. (2012) used a single event, a nitrate peak in the GISP2-H core, which McCracken et al. (2001a) time associated with the poorly quantified 1859 Carrington event, to discredit SPE-produced, impulsive nitrate deposition in polar ice. This is not the ideal test case. We critique the Wolff et al. analysis and demonstrate that the data they used cannot detect impulsive nitrate events because of resolution limitations. We suggest re-examination of the top of the Greenland ice sheet at key intervals over the last two millennia with attention to fine resolution and replicate sampling of multiple species. This will allow further insight into polar depositional processes on a sub-seasonal scale, including atmospheric sources, transport mechanisms to the ice sheet, post-depositional interactions, and a potential SPE association.

  16. Continuous methane measurements from a late Holocene Greenland ice core

    DEFF Research Database (Denmark)

    Rhodes, R.H.; Mitchell, L.E.; Brook, E.J.

    2013-01-01

    that these oscillations result from staggered bubble close-off between seasonal layers of contrasting density during time periods of sustained multi-year atmospheric methane change. Secondly, we report the detection of abrupt (20-100. cm depth interval), high amplitude (35-80. ppb excess) methane spikes in the NEEM ice...

  17. Influence of regional precipitation patterns on stable isotopes in ice cores from the central Himalayas

    Directory of Open Access Journals (Sweden)

    H. Pang

    2013-05-01

    Full Text Available Several ice cores have been recovered from the Dasuopu Glacier and the East Rongbuk (ER Glacier in the central Himalayas since the 1990s. Although the distance between the ER and the Dasuopu ice core drilling sites is only ∼125 km, the stable isotopic record (δ18O or δD of the ER core is interpreted as a precipitation proxy while the Dasuopu core as a temperature proxy. Thus, the climatological significance of the stable isotopic records of these Himalayan ice cores remains a subject of debate. Based on analysis of regional precipitation patterns over the region, we find that the different interpretations of the Dasuopu and Everest isotopic records may not be contradictive. The north–south and west–east seesaws of the Indian Summer Monsoon (ISM precipitation are primarily responsible for precipitation falling at the ER site, which results in a negative correlation between the ER δ18O or δD record and precipitation amount along the southern slope of the central Himalayas, corresponding to the "amount effect". In addition to the ISM precipitation, non-summer monsoonal precipitation associated with winter westerlies also significantly contributes to precipitation falling at the Dasuopu site, which may cause a positive correlation between the Dasuopu stable isotopic record and temperature, in response to the "temperature effect". Our results have important implications for interpreting the stable isotopic ice core records recovered from different climatological regimes of the Himalayas.

  18. Arctic ice core records of vanillic acid from Siberia, Greenland, and Svalbard

    Science.gov (United States)

    Grieman, M. M.; Saltzman, E. S.; McConnell, J.; Fritzsche, D.; Opel, T.; Isaksson, E. D.; Schwikowski, M.

    2015-12-01

    Biomass burning is a major source for atmospheric gases and aerosols, and an important part of the global carbon cycle and radiation budget. The factors controlling centennial and millennial variability in regional to global biomass burning dynamics are not well understood because there are few well-dated proxy records only. We are exploring ice core records of organic compounds resulting from incomplete combustion of lignin as tracers for biomass burning. In this study we investigate the distribution of vanillic acid (VA) in Arctic ice cores. VA is a major product of conifer combustion, but may also be produced from angiosperms. VA was measured in ice core samples using ion chromatography with electrospray MS/MS detection. Here we present measurements of vanillic acid in three Arctic ice cores from Siberia (Akademii Nauk; 0-3 kyr bp), northern Greenland (Tunu; 0-1.75 kyr bp), and Svalbard (Lomonosovfonna; 0-0.75 kyr bp). The Siberian record exhibits 3 strong centennial scale maxima (1200-600 BC, AD 300-800, and AD 1450-1700). All three cores exhibit a smaller feature around 1250, with a subsequent decline in Greenland and Svalbard. VA levels in Greenland and Svalbard are generally smaller than those in Siberia. These results suggest strong regional input from Northern Eurasian sources (i.e. boreal forests) to the Siberian core, and lower Arctic-wide "background" levels at the other sites.

  19. Assimilation of Sonic Velocity and Thin Section Measurements from the NEEM Ice Core

    Science.gov (United States)

    Hay, Michael; Pettit, Erin; Kluskiewicz, Dan; Waddington, Edwin

    2016-04-01

    We examine the measurement of crystal orientation fabric (COF) in ice cores using thin sections and sound-wave velocities, focusing on the NEEM core in Greenland. Ice crystals have substantial plastic anisotropy, with shear orthogonal to the crystallographic c-axis occuring far more easily than deformation in other orientations. Due to strain-induced grain-rotation, COFs can become highly anisotropic, resulting in bulk anisotropic flow. Thin-section measurements taken from ice cores allow sampling of the crystal fabric distribution. Thin-section measurements, however, suffer from sampling error, as they sample a small amount of ice, usually on the order of a hundred grans. They are typically only taken at intervals of several meters, which means that meter-scale variations in crystal fabric are difficult to capture. Measuring sonic velocities in ice cores provides an alternate method of determining crystal fabric. The speed of vertical compression waves is affected by the vertical clustering of c-axes, but is insensitive to azimuthal fabric anisotropy. By measuring splitting between the fast and slow shear-wave directions, information on the azimuthal distribution of orientations can be captured. Sonic-velocity measurements cannot capture detailed information on the orientation distribution of the COF, but they complement thin-section measurements with several advantages. Sonic-logging measurements can be taken at very short intervals, eliminating spatial gaps. In addition, sonic logging samples a large volume of ice with each measurement, reducing sampling error. Our logging tool has a depth resolution of around 3m/s, and can measure velocity features on the order of 1m/s. Here, we show the results of compression-wave measurements at NEEM. We also combine sonic-velocity measurements and thin-section measurements to produce a more accurate and spatially-complete representation of ice-crystal orientations in the vicinity of the NEEM core.

  20. Assimilation of Sonic Velocity and Thin-Section Measurements from the NEEM Ice-Core

    Science.gov (United States)

    Hay, M.; Pettit, E. C.; Waddington, E. D.

    2016-12-01

    We examine the measurement of crystal orientation fabric (COF) in ice cores using thin sections and sound-wave velocities, focusing on the NEEM core in Greenland. Ice crystals have substantial plastic anisotropy, with shear orthogonal to the crystallographic c-axis occurring far more easily than deformation in other orientations. Due to strain-induced grain-rotation, COFs can become highly anisotropic, resulting in bulk anisotropic flow. Thin-section measurements taken from ice cores allow sampling of the crystal fabric distribution. Thin-section measurements, however, suffer from sampling error, as they sample a small amount of ice, usually on the order of a hundred grans. They are typically only taken at intervals of several meters, which means that meter-scale variations in crystal fabric are difficult to capture. Measuring sonic velocities in ice cores provides an alternate method of determining crystal fabric. The speed of vertical compression waves is affected by the vertical clustering of c-axes, but is insensitive to azimuthal fabric anisotropy. By measuring splitting between the fast and slow shear-wave directions, information on the azimuthal distribution of orientations can be captured. Sonic-velocity measurements cannot capture detailed information on the orientation distribution of the COF, but they complement thin-section measurements with several advantages. Sonic-logging measurements can be taken at very short intervals, eliminating spatial gaps. In addition, sonic logging samples a large volume of ice with each measurement, reducing sampling error. Our logging tool has a depth resolution of around 3m/s, and can measure velocity features on the order of 1m/s. Here, we show the results of compression-wave measurements at NEEM. We also assimilate the sonic measurements with the thin-section data using a Bayesian inference procedure. This procedure allows us to combine the respective strengths of the two fabric measurement methods, to produce a more

  1. The features of Drosophila core promoters revealed by statistical analysis

    Directory of Open Access Journals (Sweden)

    Trifonov Edward N

    2006-06-01

    Full Text Available Abstract Background Experimental investigation of transcription is still a very labor- and time-consuming process. Only a few transcription initiation scenarios have been studied in detail. The mechanism of interaction between basal machinery and promoter, in particular core promoter elements, is not known for the majority of identified promoters. In this study, we reveal various transcription initiation mechanisms by statistical analysis of 3393 nonredundant Drosophila promoters. Results Using Drosophila-specific position-weight matrices, we identified promoters containing TATA box, Initiator, Downstream Promoter Element (DPE, and Motif Ten Element (MTE, as well as core elements discovered in Human (TFIIB Recognition Element (BRE and Downstream Core Element (DCE. Promoters utilizing known synergetic combinations of two core elements (TATA_Inr, Inr_MTE, Inr_DPE, and DPE_MTE were identified. We also establish the existence of promoters with potentially novel synergetic combinations: TATA_DPE and TATA_MTE. Our analysis revealed several motifs with the features of promoter elements, including possible novel core promoter element(s. Comparison of Human and Drosophila showed consistent percentages of promoters with TATA, Inr, DPE, and synergetic combinations thereof, as well as most of the same functional and mutual positions of the core elements. No statistical evidence of MTE utilization in Human was found. Distinct nucleosome positioning in particular promoter classes was revealed. Conclusion We present lists of promoters that potentially utilize the aforementioned elements/combinations. The number of these promoters is two orders of magnitude larger than the number of promoters in which transcription initiation was experimentally studied. The sequences are ready to be experimentally tested or used for further statistical analysis. The developed approach may be utilized for other species.

  2. Nitrate ions spikes in ice cores are not suitable proxies for solar proton events

    CERN Document Server

    Duderstadt, Katharine A; Jackman, Charles H; Randall, Cora E; Schwadron, Nathan A; Solomon, Stanley C; Spence, Harlan E; Yudin, Valery A

    2015-01-01

    Nitrate ion spikes in polar ice cores are contentiously used to estimate the intensity, frequency, and probability of historical solar proton events, quantities that are needed to prepare for potentially society-crippling space weather events. We use the Whole Atmosphere Community Climate Model to calculate how large an event would have to be to produce enough odd nitrogen throughout the atmosphere to be discernible as nitrate peaks at the Earth's surface. These hypothetically large events are compared with probability of occurrence estimates derived from measured events, sunspot records, and cosmogenic radionuclides archives. We conclude that the fluence and spectrum of solar proton events necessary to produce odd nitrogen enhancements equivalent to the spikes of nitrate ions in Greenland ice cores are unlikely to have occurred throughout the Holocene, confirming that nitrate ions in ice cores are not suitable proxies for historical individual solar proton events.

  3. A method for analysis of vanillic acid in polar ice cores

    Directory of Open Access Journals (Sweden)

    M. M. Grieman

    2014-07-01

    Full Text Available Biomass burning generates a wide range of organic compounds that are transported via aerosols to the polar ice sheets. Vanillic acid is a product of conifer lignin combustion, which has previously been observed in laboratory and ambient biomass burning aerosols. In this study a method was developed for analysis of vanillic acid in melted polar ice core samples. Vanillic acid was chromatographically separated using reversed phase LC and detected using electrospray triple quadrupole mass spectrometry (ESI-MS/MS. Using a 100 μL injection loop and analysis time of 4 min, we obtained a detection limit (S : N = 2 of 58 ppt (parts per trillion by mass and an analytical precision of ±10 %. Measurements of vanillic acid in Arctic ice core samples from the Siberian Akademii Nauk core are shown as an example application of the method.

  4. Relationship between calcium and atmospheric dust recorded in Guliya ice core

    Institute of Scientific and Technical Information of China (English)

    YAO Tandong; WU Guangjian; PU Jianchen; JIAO Keqin; HUANG Cuilan

    2004-01-01

    By the analyses of Guliya ice core on the Tibetan Plateau, it was found that the calcium (Ca2+) originated from the terrestrial source is the main cation of soluble aerosol and a good proxy of the atmospheric component and environment in the mountain ice core located in the mid-low latitude arid regions. Evident variation of Ca2+ concentration has been found in the Guliya ice core since the Last Interglaciation with two relatively strong increase periods and two weak increase periods. These variations are generally related to climatic changes: high Ca2+ concentration periods coincide with cold periods and low Ca2+ concentration periods coincide with warm periods. However, Ca2+ concentration does not always decrease (increase) with climate warming (cooling). The magnitude and phase of Ca2+ concentration does not always match temperature either. The changes of atmospheric circulation, land surface condition and atmospheric humidity might be important factors which influence Ca2+ concentration besides temperature.

  5. Atmospheric methane and nitrous oxide of the Late Pleistocene from Antarctic ice cores.

    Science.gov (United States)

    Spahni, Renato; Chappellaz, Jérôme; Stocker, Thomas F; Loulergue, Laetitia; Hausammann, Gregor; Kawamura, Kenji; Flückiger, Jacqueline; Schwander, Jakob; Raynaud, Dominique; Masson-Delmotte, Valérie; Jouzel, Jean

    2005-11-25

    The European Project for Ice Coring in Antarctica Dome C ice core enables us to extend existing records of atmospheric methane (CH4) and nitrous oxide (N2O) back to 650,000 years before the present. A combined record of CH4 measured along the Dome C and the Vostok ice cores demonstrates, within the resolution of our measurements, that preindustrial concentrations over Antarctica have not exceeded 773 +/- 15 ppbv (parts per billion by volume) during the past 650,000 years. Before 420,000 years ago, when interglacials were cooler, maximum CH4 concentrations were only about 600 ppbv, similar to lower Holocene values. In contrast, the N2O record shows maximum concentrations of 278 +/- 7 ppbv, slightly higher than early Holocene values.

  6. Identification of major proton fluence events from nitrates in polar ice cores.

    Science.gov (United States)

    Shea, M A; Smart, D F; Dreschhoff, G A

    1999-06-01

    Large transient concentrations of nitrates in polar ice cores have been identified as the signature of some major solar proton fluence events between 1940 and 1991. We review this solar proton proxy identification technique using nitrate concentration measurements in ice cores from the Arctic and Antarctic. Using this identification technique we go back in time in an attempt to identify major solar proton events during the past several centuries. There is a very large nitrate increase corresponding to the Carrington flare of 1859 evident in the Arctic ice core. Other significant nitrate increases may indicate that major solar proton events occurred toward the end of the last century. The problems associated with this new technique of using nitrates as proxies to identify solar proton events are discussed.

  7. The 1200 year composite ice core record of Aleutian Low intensification

    Science.gov (United States)

    Osterberg, E. C.; Winski, D. A.; Kreutz, K. J.; Wake, C. P.; Ferris, D. G.; Campbell, S.; Introne, D.; Handley, M.; Birkel, S.

    2017-07-01

    Future changes in North Pacific wintertime climate will be largely determined by the response of the Aleutian Low (ALow) pressure system to anthropogenic forcing. Although the ALow has intensified over the twentieth century, global climate model projections of future ALow variability are equivocal. In order to evaluate decadal to centennial ALow forcing mechanisms and provide context for the modern intensification, here we combine a new Denali ice core (Alaska) sea-salt sodium record with the Mount Logan ice core (Yukon) sodium record to develop a composite 1200 year record of ALow variability. The composite record indicates that the recent secular ALow intensification began circa 1741 and is unprecedented in magnitude and duration over the past millennium. North Pacific ice core snow accumulation and stable isotope records are consistent with this interpretation. The ALow intensification is associated with warming tropical Pacific sea surface temperatures, consistent with dynamic theory and instrumental correlations.

  8. A centrifugal ice microtome for measurements of atmospheric CO2 on air trapped in polar ice cores

    Directory of Open Access Journals (Sweden)

    H. Fischer

    2012-10-01

    Full Text Available For atmospheric CO2 reconstructions using ice cores, the technique to release the trapped air from the ice samples is crucial for the precision and accuracy of the measurements. We present here a new dry extraction technique in combination with a new gas analytical system that together show significant improvements with respect to current systems. Ice samples (3–15 g are pulverized using a novel Centrifugal Ice Microtome (CIM by shaving the ice in a cooled vacuum chamber (−27 °C in which no friction occurs due to the use of magnetic bearings. Both, the shaving principle of the CIM and the use of magnetic bearings have not been applied so far in this field. Shaving the ice samples produces finer ice powder and releases a minimum of 90% of the trapped air compared to 50%–70% when needle crushing is employed. In addition, the friction-free motion with an optimized design to reduce contaminations of the inner surfaces of the device result in a reduced system offset of about 2.0 ppmv compared to 4.9ppmv. The gas analytical part shows a factor two higher precision than our corresponding part of the previous system and all processes except the loading and cleaning of the CIM now run automatically. Compared to our previous system the new system shows a 3 times better measurement reproducibility of about 1.1 ppmv (1σ which is similar to the best reproducibility of other systems applied in this field. With this high reproducibility, replicate measurements are not required anymore for most prospective measurement campaigns resulting in a possible output of 12–20 measurements per day compared to a maximum of 6 with other systems.

  9. Development of melting system for Measurement of trace elements and ions in ice core

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sang Bum; Lee, Khang Hyun; Hur, Soon Do; Soyol-Erene, Tseren-Ochir; Kim, Sun Mee; Chung, Ji Woong; Jun, Seong Joon [Korea Polar Research Institute, KIOST, Incheon (Korea, Republic of); Hong, Sung Min [Dept. of Ocean Sciences, Inha University, Incheon (Korea, Republic of); Kang, Chang Hee [Dept. of Chemistry and Research Institute for Basic Sciences, Jeju National University, Jeju (Korea, Republic of)

    2015-04-15

    We present a titanium (Ti) melting head divided into three zones as an improved melting system for decontaminating ice-core samples. This system was subjected to performance tests using short ice-core samples (4 × 4 cm{sup 2}, ⁓5 cm long). The procedural blanks (PBs) and detection limits of ionic species, with the exception of math formula, were comparable with published values, but for elements the experimental procedures should be refined to obtain valid Zn concentrations due to the PB of ⁓90.0 ± 16.2 ng/L. The improved melting system efficiently decontaminated the samples, as verified by the concentration profiles of elements and ions in the melted samples from the three melting-head zones. The recovery of trace elements in ice-core samples was ⁓70–120% at ⁓100 ng/L in artificial ice cores. Because of the memory effects between ice-core samples melted in series, the melting system should be rinsed at least 5–6 times (in a total volume of ⁓2.5 mL deionized water) after each melting procedure. Finally, as an application of this technique, trace elements were measured in ice-core samples recovered from the East Rongbuk Glacier, Mount Everest, (28°03′N, 86°96′E, 6518 m a.s.l.), and the concentrations of trace elements following mechanical chiseling and the melting method were compared.

  10. Chronology of Pu isotopes and 236U in an Arctic ice core.

    Science.gov (United States)

    Wendel, C C; Oughton, D H; Lind, O C; Skipperud, L; Fifield, L K; Isaksson, E; Tims, S G; Salbu, B

    2013-09-01

    In the present work, state of the art isotopic fingerprinting techniques are applied to an Arctic ice core in order to quantify deposition of U and Pu, and to identify possible tropospheric transport of debris from former Soviet Union test sites Semipalatinsk (Central Asia) and Novaya Zemlya (Arctic Ocean). An ice core chronology of (236)U, (239)Pu, and (240)Pu concentrations, and atom ratios, measured by accelerator mass spectrometry in a 28.6m deep ice core from the Austfonna glacier at Nordaustlandet, Svalbard is presented. The ice core chronology corresponds to the period 1949 to 1999. The main sources of Pu and (236)U contamination in the Arctic were the atmospheric nuclear detonations in the period 1945 to 1980, as global fallout, and tropospheric fallout from the former Soviet Union test sites Novaya Zemlya and Semipalatinsk. Activity concentrations of (239+240)Pu ranged from 0.008 to 0.254 mBq cm(-2) and (236)U from 0.0039 to 0.053 μBq cm(-2). Concentrations varied in concordance with (137)Cs concentrations in the same ice core. In contrast to previous published results, the concentrations of Pu and (236)U were found to be higher at depths corresponding to the pre-moratorium period (1949 to 1959) than to the post-moratorium period (1961 and 1962). The (240)Pu/(239)Pu ratio ranged from 0.15 to 0.19, and (236)U/(239)Pu ranged from 0.18 to 1.4. The Pu atom ratios ranged within the limits of global fallout in the most intensive period of nuclear atmospheric testing (1952 to 1962). To the best knowledge of the authors the present work is the first publication on biogeochemical cycles with respect to (236)U concentrations and (236)U/(239)Pu atom ratios in the Arctic and in ice cores. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Chemical compositions of past soluble aerosols reconstructed from NEEM (Greenland) and Dome C (Antarctica) ice cores

    Science.gov (United States)

    Oyabu, Ikumi; Iizuka, Yoshinori; Fukui, Manabu; Fischer, Hubertus; Schüpbach, Simon; Gfeller, Gideon; Mulvaney, Robert; Hansson, Margareta

    2015-04-01

    Polar ice core preserve past atmospheric aerosols, which is a useful proxy for understanding the interaction between climate changes and atmospheric aerosols. One useful technique for reconstructing past soluble aerosols from ice core is the determination of dissolved ion species. However, since salts and acids melt into ions, chemical compositions of soluble aerosols in the ice cores have not been cleared. To clarify the temporal variations in the chemical compositions of past soluble aerosols, this study investigated chemical compositions of soluble particles preserved in the NEEM (Greenland) and Dome C (Antarctica) ice cores using new method 'ice-sublimation method'. The ice-sublimation method can extract soluble salts particles as a solid state without melting. The ice core samples are selected from the sections from the last termination (the Last Glacial Maximum (LGM) to Holocene) of Dome C (inland Antarctica) and NEEM ice cores. Using ice-sublimation method, soluble salts particles were extracted. Chemical components of extracted particles were analysed by scanning electron microscope and energy dispersive spectroscopy, and micro-Raman spectroscopy. The major components of soluble salts particles in the Dome C ice core are CaSO4, Na2SO4 and NaCl. The CaSO4 and NaCl fractions were high in the first half of the last termination, whereas the Na2SO4 fraction is high in the latter half of the last termination. The major components of soluble salts particles in the NEEM ice core are CaCO3, CaSO4, NaCl and Na2SO4. The fractions of CaCO3, CaSO4 and NaCl were high in LGM, whereas those of NaCl and Na2SO4 were high in Holocene. The changes in the salts compositions in Dome C ice core are mainly controlled by concentration of terrestrial material (Ca2+). In the first half of the last termination, most of the terrestrial material (CaCO3) reacted with H2SO4 but some of sea-salt (NaCl) was not reacted with H2SO4 due to high Ca2+ concentration. As a result, the CaSO4 and Na

  12. Carbonaceous aerosol tracers in ice-cores record multi-decadal climate oscillations.

    Science.gov (United States)

    Seki, Osamu; Kawamura, Kimitaka; Bendle, James A P; Izawa, Yusuke; Suzuki, Ikuko; Shiraiwa, Takayuki; Fujii, Yoshiyuki

    2015-09-28

    Carbonaceous aerosols influence the climate via direct and indirect effects on radiative balance. However, the factors controlling the emissions, transport and role of carbonaceous aerosols in the climate system are highly uncertain. Here we investigate organic tracers in ice cores from Greenland and Kamchatka and find that, throughout the period covered by the records (1550 to 2000 CE), the concentrations and composition of biomass burning-, soil bacterial- and plant wax- tracers correspond to Arctic and regional temperatures as well as the warm season Arctic Oscillation (AO) over multi-decadal time-scales. Specifically, order of magnitude decreases (increases) in abundances of ice-core organic tracers, likely representing significant decreases (increases) in the atmospheric loading of carbonaceous aerosols, occur during colder (warmer) phases in the high latitudinal Northern Hemisphere. This raises questions about causality and possible carbonaceous aerosol feedback mechanisms. Our work opens new avenues for ice core research. Translating concentrations of organic tracers (μg/kg-ice or TOC) from ice-cores, into estimates of the atmospheric loading of carbonaceous aerosols (μg/m(3)) combined with new model constraints on the strength and sign of climate forcing by carbonaceous aerosols should be a priority for future research.

  13. The ice-core record of volcanism: Status and future directions

    Science.gov (United States)

    Sigl, Michael; McConnell, Joseph R.; Chellman, Nathan; Ludlow, Francis; Curran, Mark; Plunkett, Gill; Büntgen, Ulf; Toohey, Matthew; Burke, Andrea; Grieman, Mackenzie

    2016-04-01

    Radiative forcing resulting from stratospheric aerosols produced by major volcanic eruptions is a dominant driver of climate variability in the Earth's past. Accurate knowledge of the climate anomalies resulting from volcanic eruptions provides important information for understanding the global and regional responses of the Earth system to external forcing agents. Based on a unique compilation of newly obtained, high-resolution, ice-core measurements, as well as palaeo-climatic evidence inferred from existing tree-ring records and historical documentary sources, we revised the dating of ice-core based reconstructions of past volcanic eruptions and confirmed the dominant role of explosive volcanism on short-term summer temperature variability throughout the past 2,500 years. Continuous weekly surface snow measurements obtained from Summit, Greenland (2005-2014) further allow placing volcanic sulphate emissions arising from a series of moderate volcanic eruptions during the last decade into a multi-millennial context. While these updated ice core records provide a more accurate constraint on the timing and magnitude of volcanic eruptions, there is also new data emerging on the geographic locations of past eruptions, atmospheric transport of volcanic fallout and climatic consequences (e.g. sea-ice; hydro-climate) from studying volcanic deposits (e.g. extent of volcanic ash deposition), proxy data and historical records. On the basis of selected case studies we will discuss the role volcanic eruptions have played in the Earth's climate system during the past and identify potential additional constraints provided by ice cores.

  14. Historical variations of mercury stable isotope ratios in Arctic glacier firn and ice cores

    Science.gov (United States)

    Zdanowicz, C. M.; Krümmel, E. M.; Poulain, A. J.; Yumvihoze, E.; Chen, J.; Å trok, M.; Scheer, M.; Hintelmann, H.

    2016-09-01

    The concentration and isotopic composition of mercury (Hg) were determined in glacier core samples from Canadian Arctic ice caps dating from preindustrial to recent time (early 21st century). Mean Hg levels increased from ≤ 0.2 ng L-1 in preindustrial time to ~0.8-1.2 ng L-1 in the modern industrial era (last ~200 years). Hg accumulated on Arctic ice caps has Δ199Hg and Δ201Hg that are higher (~ -1 to 2.9‰) than previously reported for Arctic snow impacted by atmospheric Hg depletion events (mostly < -1‰), suggesting that these events contribute little to Hg accumulation on ice caps. The range of δ202Hg, Δ199Hg, and Δ201Hg in glacier cores overlaps with that of Arctic Hg0(g) and of seawater in Baffin Bay and also with that of midlatitude precipitation and industrial Hg sources, including coal and Hg ores. A core from Agassiz ice cap (80.7°N) shows a ~ +1‰ shift in δ202Hg over the nineteenth to twentieth centuries that could reflect changes in the isotopic composition of the atmospheric Hg pool in the High Arctic in response to growing industrial emissions at lower latitudes. This study is the first ever to report on historical variations of Hg stable isotope ratios in Arctic ice cores. Results could help constrain future modeling efforts of the global Hg biogeochemical cycle and the atmosphere's response to changing Hg emissions, past and future.

  15. Neutrino oscillations with IceCube DeepCore and PINGU

    Energy Technology Data Exchange (ETDEWEB)

    DeYoung, T. [Dept. of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Collaboration: IceCube-PINGU Collaboration

    2014-11-18

    The IceCube neutrino telescope was augmented with the DeepCore infill array, completed in the 2010/11 austral summer, to enhance its response to neutrinos below 100 GeV. At these energies, neutrino oscillation effects are visible in the flux of atmospheric neutrinos traversing path lengths comparable to the Earth's diameter. Initial measurements of muon neutrino disappearance parameters using data from DeepCore are presented, as well as an estimate of potential future precision. In addition, plans for a Precision IceCube Next Generation Upgrade (PINGU), which could permit determination of the neutrino mass hierarchy within the coming decade, are discussed.

  16. High-resolution Greenland Ice Core data show abrupt climate change happens in few years

    DEFF Research Database (Denmark)

    Steffensen, Jørgen Peder; Andersen, Katrine Krogh; Bigler, Matthias

    2008-01-01

    The last two abrupt warmings at the onset of our present warm interglacial period, interrupted by the Younger Dryas cooling event, were investigated at high temporal resolution from the North Greenland Ice Core Project ice core. The deuterium excess, a proxy of Greenland precipitation moisture......, reflecting the wetting of Asian deserts. A northern shift of the Intertropical Convergence Zone could be the trigger of these abrupt shifts of Northern Hemisphere atmospheric circulation, resulting in changes of 2 to 4 kelvin in Greenland moisture source temperature from one year to the next....

  17. Proxies and measurement techinques for mineral dust in antarctic ice cores

    DEFF Research Database (Denmark)

    Ruth..[], Urs; Bigler, Matthias

    2008-01-01

    To improve quantitative interpretation of ice core aeolian dust records, a systematic methodological comparison was made. This involved methods for water-insoluble particle counting (Coulter counter and laser-sensing particle detector), soluble ion analysis (ion chromatography and continuous flow...... analysis), elemental analysis (inductively coupled plasma mass spectroscopy at pH 1 and after full acid digestion), and water-insoluble elemental analysis (proton induced X-ray emission). Antarctic ice core samples covering the last deglaciation from the EPICA Dome C (EDC) and the EPICA Dronning Maud Land...

  18. Surface mass balance and water stable isotopes derived from firn cores on three ice rises, Fimbul Ice Shelf, Antarctica

    Science.gov (United States)

    Vega, Carmen P.; Schlosser, Elisabeth; Divine, Dmitry V.; Kohler, Jack; Martma, Tõnu; Eichler, Anja; Schwikowski, Margit; Isaksson, Elisabeth

    2016-11-01

    Three shallow firn cores were retrieved in the austral summers of 2011/12 and 2013/14 on the ice rises Kupol Ciolkovskogo (KC), Kupol Moskovskij (KM), and Blåskimen Island (BI), all part of Fimbul Ice Shelf (FIS) in western Dronning Maud Land (DML), Antarctica. The cores were dated back to 1958 (KC), 1995 (KM), and 1996 (BI) by annual layer counting using high-resolution oxygen isotope (δ18O) data, and by identifying volcanic horizons using non-sea-salt sulfate (nssSO42-) data. The water stable isotope records show that the atmospheric signature of the annual snow accumulation cycle is well preserved in the firn column, especially at KM and BI. We are able to determine the annual surface mass balance (SMB), as well as the mean SMB values between identified volcanic horizons. Average SMB at the KM and BI sites (0.68 and 0.70 mw. e. yr-1) was higher than at the KC site (0.24 mw. e. yr-1), and there was greater temporal variability as well. Trends in the SMB and δ18O records from the KC core over the period of 1958-2012 agree well with other previously investigated cores in the area, thus the KC site could be considered the most representative of the climate of the region. Cores from KM and BI appear to be more affected by local meteorological conditions and surface topography. Our results suggest that the ice rises are suitable sites for the retrieval of longer firn and ice cores, but that BI has the best preserved seasonal cycles of the three records and is thus the most optimal site for high-resolution studies of temporal variability of the climate signal. Deuterium excess data suggest a possible effect of seasonal moisture transport changes on the annual isotopic signal. In agreement with previous studies, large-scale atmospheric circulation patterns most likely provide the dominant influence on water stable isotope ratios preserved at the core sites.

  19. Surface water mass composition changes captured by cores of Arctic land-fast sea ice

    Science.gov (United States)

    Smith, I. J.; Eicken, H.; Mahoney, A. R.; Van Hale, R.; Gough, A. J.; Fukamachi, Y.; Jones, J.

    2016-04-01

    In the Arctic, land-fast sea ice growth can be influenced by fresher water from rivers and residual summer melt. This paper examines a method to reconstruct changes in water masses using oxygen isotope measurements of sea ice cores. To determine changes in sea water isotope composition over the course of the ice growth period, the output of a sea ice thermodynamic model (driven with reanalysis data, observations of snow depth, and freeze-up dates) is used along with sea ice oxygen isotope measurements and an isotopic fractionation model. Direct measurements of sea ice growth rates are used to validate the output of the sea ice growth model. It is shown that for sea ice formed during the 2011/2012 ice growth season at Barrow, Alaska, large changes in isotopic composition of the ocean waters were captured by the sea ice isotopic composition. Salinity anomalies in the ocean were also tracked by moored instruments. These data indicate episodic advection of meteoric water, having both lower salinity and lower oxygen isotopic composition, during the winter sea ice growth season. Such advection of meteoric water during winter is surprising, as no surface meltwater and no local river discharge should be occurring at this time of year in that area. How accurately changes in water masses as indicated by oxygen isotope composition can be reconstructed using oxygen isotope analysis of sea ice cores is addressed, along with methods/strategies that could be used to further optimize the results. The method described will be useful for winter detection of meteoric water presence in Arctic fast ice regions, which is important for climate studies in a rapidly changing Arctic. Land-fast sea ice effective fractionation coefficients were derived, with a range of +1.82‰ to +2.52‰. Those derived effective fractionation coefficients will be useful for future water mass component proportion calculations. In particular, the equations given can be used to inform choices made when

  20. Automated ice-core layer-counting with strong univariate signals

    Directory of Open Access Journals (Sweden)

    J. J. Wheatley

    2012-11-01

    Full Text Available We present an automated process for determining the annual layer chronology of an ice-core with a strong annual signal, utilising the hydrogen peroxide record from an Antarctic Peninsula ice-core as a test signal on which to count annual cycles and explain the methods. The signal is de-trended and normalised before being split into sections with a deterministic cycle count and those that need more attention. Possible reconstructions for the uncertain sections are determined which could be used as a visual aid for manual counting, and a simple method for assigning probability measures to each reconstruction is discussed. The robustness of this process is explored by applying it to versions of two different chemistry signals from the same stretch of the NGRIP (North Greenland Ice Core Project ice-core, which shows more variation in annual layer thickness, with and without thinning to mimic poorer quality data. An adapted version of these methods is applied to the more challenging non-sea-salt sulphur signal from the same Antarctic Peninsula core from which the hydrogen peroxide signal was taken. These methods could readily be adapted for use on much longer datasets, thereby reducing manual effort and providing a robust automated layer-counting methodology.

  1. Identifying deformation mechanisms in the NEEM ice core using EBSD measurements

    Science.gov (United States)

    Kuiper, Ernst-Jan; Weikusat, Ilka; Drury, Martyn R.; Pennock, Gill M.; de Winter, Matthijs D. A.

    2015-04-01

    Deformation of ice in continental sized ice sheets determines the flow behavior of ice towards the sea. Basal dislocation glide is assumed to be the dominant deformation mechanism in the creep deformation of natural ice, but non-basal glide is active as well. Knowledge of what types of deformation mechanisms are active in polar ice is critical in predicting the response of ice sheets in future warmer climates and its contribution to sea level rise, because the activity of deformation mechanisms depends critically on deformation conditions (such as temperature) as well as on the material properties (such as grain size). One of the methods to study the deformation mechanisms in natural materials is Electron Backscattered Diffraction (EBSD). We obtained ca. 50 EBSD maps of five different depths from a Greenlandic ice core (NEEM). The step size varied between 8 and 25 micron depending on the size of the deformation features. The size of the maps varied from 2000 to 10000 grid point. Indexing rates were up to 95%, partially by saving and reanalyzing the EBSP patterns. With this method we can characterize subgrain boundaries and determine the lattice rotation configurations of each individual subgrain. Combining these observations with arrangement/geometry of subgrain boundaries the dislocation types can be determined, which form these boundaries. Three main types of subgrain boundaries have been recognized in Antarctic (EDML) ice core¹². Here, we present the first results obtained from EBSD measurements performed on the NEEM ice core samples from the last glacial period, focusing on the relevance of dislocation activity of the possible slip systems. Preliminary results show that all three subgrain types, recognized in the EDML core, occur in the NEEM samples. In addition to the classical boundaries made up of basal dislocations, subgrain boundaries made of non-basal dislocations are also common. ¹Weikusat, I.; de Winter, D. A. M.; Pennock, G. M.; Hayles, M

  2. A 21 000-year record of fluorescent organic matter markers in the WAIS Divide ice core

    Science.gov (United States)

    D'Andrilli, Juliana; Foreman, Christine M.; Sigl, Michael; Priscu, John C.; McConnell, Joseph R.

    2017-05-01

    Englacial ice contains a significant reservoir of organic material (OM), preserving a chronological record of materials from Earth's past. Here, we investigate if OM composition surveys in ice core research can provide paleoecological information on the dynamic nature of our Earth through time. Temporal trends in OM composition from the early Holocene extending back to the Last Glacial Maximum (LGM) of the West Antarctic Ice Sheet Divide (WD) ice core were measured by fluorescence spectroscopy. Multivariate parallel factor (PARAFAC) analysis is widely used to isolate the chemical components that best describe the observed variation across three-dimensional fluorescence spectroscopy (excitation-emission matrices; EEMs) assays. Fluorescent OM markers identified by PARAFAC modeling of the EEMs from the LGM (27.0-18.0 kyr BP; before present 1950) through the last deglaciation (LD; 18.0-11.5 kyr BP), to the mid-Holocene (11.5-6.0 kyr BP) provided evidence of different types of fluorescent OM composition and origin in the WD ice core over 21.0 kyr. Low excitation-emission wavelength fluorescent PARAFAC component one (C1), associated with chemical species similar to simple lignin phenols was the greatest contributor throughout the ice core, suggesting a strong signature of terrestrial OM in all climate periods. The component two (C2) OM marker, encompassed distinct variability in the ice core describing chemical species similar to tannin- and phenylalanine-like material. Component three (C3), associated with humic-like terrestrial material further resistant to biodegradation, was only characteristic of the Holocene, suggesting that more complex organic polymers such as lignins or tannins may be an ecological marker of warmer climates. We suggest that fluorescent OM markers observed during the LGM were the result of greater continental dust loading of lignin precursor (monolignol) material in a drier climate, with lower marine influences when sea ice extent was higher and

  3. Accumulation reconstruction and water isotope analysis for 1736-1997 of an ice core from the Ushkovsky volcano, Kamchatka, and their relationships to North Pacific climate records

    Science.gov (United States)

    Sato, T.; Shiraiwa, T.; Greve, R.; Seddik, H.; Edelmann, E.; Zwinger, T.

    2014-02-01

    An ice core was retrieved in June 1998 from the Gorshkov crater glacier at the top of the Ushkovsky volcano, in central Kamchatka. This ice core is one of only two recovered from Kamchatka so far, thus filling a gap in the regional instrumental climate network. Hydrogen isotope (δD) analyses and past accumulation reconstructions were conducted for the top 140.7 m of the core, spanning 1736-1997. Two accumulation reconstruction methods were developed and applied with the Salamatin and the Elmer/Ice firn-ice dynamics models, revealing a slightly increasing or nearly stable trend, respectively. Wavelet analysis shows that the ice core records have significant decadal and multi-decadal variabilities at different times. Around 1880 the multi-decadal variability of δD became lost and its average value increased by 6‰. The multi-decadal variability of reconstructed accumulation rates changed at around 1850. Reconstructed accumulation variations agree with ages of moraines in Kamchatka. Ice core signals were significantly correlated with North Pacific sea surface temperature (SST) and surface temperature (2 m temperature). δD correlates with the North Pacific Gyre Oscillation (NPGO) index after the climate regime shift in 1976/1977, but not before that. Therefore, our findings imply that the ice core record contains various information on the local, regional and large-scale climate variability in the North Pacific region. Understanding all detailed mechanisms behind the time-dependent connections between these climate patterns is challenging and requires further efforts towards multi-proxy analysis and climate modelling.

  4. Nitrate and chloride in Antarctic ice cores - postdepositional effects and the preservation of atmospheric signals (Invited)

    Science.gov (United States)

    Pasteris, D.; McConnell, J. R.; Edwards, R.; Isaksson, E. D.; Albert, M. R.

    2013-12-01

    Continuous nitrate and chloride measurements have been made from an array of ice cores located in interior Dronning Maud Land that cover the last 2000 years. The average snow accumulation rates at the ice core sites range from 2.7 to 10 cm weq yr-1, which has enabled the study of how accumulation rate affects the preservation and diffusion of nitrate and chloride in the snow. High-resolution dating of the ice cores by tie-point matching with the WAIS Divide ice core has allowed the effects of temporal changes in accumulation rate to also be observed. Results show a strong linear dependence of nitrate concentration on site-average accumulation rate, suggesting that fresh snow concentrations and reemission rates of nitrate from the snowpack are homogenous across the study area. Bulk chloride to sodium ratios over scales greater than 1 m are close to bulk sea salt composition at all of the sites, suggesting that little net gain or loss of volatile chloride has occurred. However, the chloride signal is heavily diffused relative to sodium and the extent of diffusion does not increase with depth in the ice cores, suggesting that it is a near-surface phenomenon. Possible mechanisms behind the observed chloride diffusion pattern will be discussed. Lastly, a sustained decline in nitrate concentration occurred during the Little Ice Age (LIA, 1500-1900 C.E.), but the high-resolution snow accumulation records show that it is not caused by a decrease in accumulation rate during that time. The nitrate record is highly correlated with published methane isotope data from Antarctica (δ13CH4), suggesting that the decline during the LIA was caused by a decrease in a biomass burning nitrate source. Average nitrate concentration versus site-average inverse accumulation rate Composite time series of nitrate (thick black line), δ13CH4 (thin red line with diamonds), and black carbon (dashed black line).

  5. Microparticles, soil, derived chemical components and sea salt in the Hans Tausen Ice Cap ice core from Peary Island, North Greenland

    DEFF Research Database (Denmark)

    Steffensen, J.P.; Andersen, M.L.S; Stampe, Mia

    2001-01-01

    due to melt water run-off. Sea salt concentrations show little variation with depth, and our results indicate, that the sea salt in Hans Tausen ice is from remote sources. The North Polar Sea has not been a significant source of sea salt in the life time of the Hans Tausen ice cap. All our results...... are consistent with the hypothesis that the Hans Tausen ice cap was formed sometime during the Holocene: It started as a small ice cap of superimposed ice with heavy melting and strong influence of local dust sources. With time the ice cap grew, both horizontally and vertically, the surface got colder with less......Selected segments of the 344 m deep ice core from Hans Tausen ice cap in Peary Land, North Greenland have been stratigraphically analyzed for chemical impurities and insoluble microparticles (Dust). Two different components of the microparticles have been identified by their different...

  6. Air fractionation in plate-like inclusions within the EPICA-DML deep ice core

    Science.gov (United States)

    Nedelcu, A.; Faria, S. H.; Kipfstuhl, S.; Schmidt, B.; Kuhs, W. F.

    2009-04-01

    On ice samples from the ice core recovered in the frame of the European Project for Ice Coring in Antarctica at the deep drilling site in Dronning Maud Land (75°00S; 00°04E) micro-Raman spectrochemical analysis was applied to typical relaxation features appearing after the extraction of an ice core. Essentially, these relaxation microinclusions are little planar polygonal cavities possessing hexagonal symmetry i.e. thin negative crystals lying on the basal plane of the hosting ice crystallite. Usually named plate-like inclusions, PLIs, they tend to change their aspect ratio becoming in general rounder, thicker or thinner depending on the equilibrium established between the structure-composition of the ice and the minute environmental temperature-pressure conditions around a specific PLI, but still preserving a very large aspect ratio (typically 20:1). Muguruma and others (1966) and Mae (1968) have reported studies on plate hexagonal voids, i.e. PLIs, produced (only) in tensile deformation tests of natural and artificial single ice crystals while the first report of PLIs in Antarctic ice cores was presented by Gow (1971). In spite of these early studies and the abundance of PLIs in stored ice core samples, extended investigations of these relaxation features are scarce. We present the results of the first successful study of the chemical composition of PLIs using microfocus Raman spectroscopy (Nedelcu and others, in press). We observe that the relaxation features contain mainly O2 and N2 in their interior, with N2/O2 ratios smaller than 3.7 (the nowadays atmospheric air N2/O2 ratio), indicating a general oxygen enrichment that is not so different from O2 enrichments reported in other investigations on polar ice samples (Nakahara and others, 1988, Ikeda and others, 1999). These results seem to lend support to the current hypothesis that O2 diffuses faster than N2 through the ice matrix (Ikeda-Fukazawa and others, 2001, 2005; Severinghaus and Battle, 2006). More

  7. Preliminary evidence indicating Dome A(Antarctica) satisfying preconditions for drilling the oldest ice core

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Lowest temperature and snow accumulation rate are preconditions for retrieving the oldest ice core from the polar ice sheets.The 10-m depth firn temperature at Dome A,the summit of the Antaretie Ice Sheet,recorded by an automatic weather station(AWS)was-58.3℃in 2005 and-58.2℃in 2006,respectively.The 10-m firn temperature is an approximation of the annual mean air temperature(AMAT),and this is the lowest AMAT that has been recorded on the surface of the Earth.The stable isotopic ratios(δ18O and δD)of surface snow at Dome A are also lower than at other ice sheet domes along the East Antarctic Ice Divide such as Dome C,Dome F,Dome B and Vostok.These facts indicate that Dome A is the"pole of cold"on the Earth.The total amount of snow accumulation rate in 2005 and 2006 was only 0.16 cm,equaling 0.016 m water equivalent per year,the lowest precipitation ever recorded from Antarctica.Preliminary evidences indicate that Dome A is a candidate site for recovering the oldest ice core.

  8. Phylogenetic analysis of anaerobic psychrophilic enrichment cultures obtained from a greenland glacier ice core

    Science.gov (United States)

    Sheridan, Peter P.; Miteva, Vanya I.; Brenchley, Jean E.

    2003-01-01

    The examination of microorganisms in glacial ice cores allows the phylogenetic relationships of organisms frozen for thousands of years to be compared with those of current isolates. We developed a method for aseptically sampling a sediment-containing portion of a Greenland ice core that had remained at -9 degrees C for over 100,000 years. Epifluorescence microscopy and flow cytometry results showed that the ice sample contained over 6 x 10(7) cells/ml. Anaerobic enrichment cultures inoculated with melted ice were grown and maintained at -2 degrees C. Genomic DNA extracted from these enrichments was used for the PCR amplification of 16S rRNA genes with bacterial and archaeal primers and the preparation of clone libraries. Approximately 60 bacterial inserts were screened by restriction endonuclease analysis and grouped into 27 unique restriction fragment length polymorphism types, and 24 representative sequences were compared phylogenetically. Diverse sequences representing major phylogenetic groups including alpha, beta, and gamma Proteobacteria as well as relatives of the Thermus, Bacteroides, Eubacterium, and Clostridium groups were found. Sixteen clone sequences were closely related to those from known organisms, with four possibly representing new species. Seven sequences may reflect new genera and were most closely related to sequences obtained only by PCR amplification. One sequence was over 12% distant from its closest relative and may represent a novel order or family. These results show that phylogenetically diverse microorganisms have remained viable within the Greenland ice core for at least 100,000 years.

  9. Vertical quantitative and dominant population distribution of the bacteria isolated from the Muztagata ice core

    Institute of Scientific and Technical Information of China (English)

    XIANG; Shurong; YAO; Tandong; AN; Lizhe; WU; Guangjian; XU

    2005-01-01

    Vertical distribution of the main bacteria isolated from the Muztagata ice core (about 22.4 m) was investigated by means of cultivation and 16S rRNA sequence analysis. The results showed that the amount of culturable bacteria fluctuated with ice core depth, and was more in dirty layer than in clean ice, which suggested the close corresponding relationship between high input of the bacteria deposited by wind and snowflow and dirty layer. Most of the bacteria were psychrophiles and psychrotolerants, including α- and γ-proteobacteria, Cryobacterium psychrophilum, CFB (Cytophaga-Flavobacterium-Bacteroides) group, high-G+C gram-positive bacteria (HGC). Acinetobacter sp. And HGC repeatly occurred in different ice depths, and their quantitative distribution was consistent with the change of the total amount of culturable bacteria with depth, which suggested the main bio-indicator; while Flavobacterium, Cryobacterium psychrophilum, and α-proteobacteria, also functioned as a secondary indicator of climatic and environmental changes. This study is the first report concerning continuous quantitative variation and pattern of the main culturable bacteria in ice core section.

  10. The methane record of Daansgard-Oeschger event 17 in Vostok 4G-2 ice core: effects of layered bubble trapping and smoothing

    Science.gov (United States)

    Fourteau, Kévin; Faïn, Xavier; Martinerie, Patricia; Landais, Amaëlle; Ekaykin, Alexey A.; Lipenkov, Vladimir Ya.; Chappellaz, Jérôme

    2017-04-01

    This work aims to characterise and quantify the modification and loss of past atmospheric information recorded in ice cores due to gas trapping mechanisms. For this purpose a very high resolution methane record of the DO event 17 in Vostok 4G-2 ice core has been measured by continuous flow analysis and laser spectroscopy. This is the first time that the gas of a very low accumulation core, about 1.3cm.yr-1 ice equivalent, is measured using a continuous method. The measurements reveal numerous anomalous layers a couple of centimetres thick. These anomalous layers differ in methane mixing ratio from adjacent layers by about plus or minus 50ppbv. Their amplitude and uneven distribution along the ice core can be reproduced by a simple layered bubble trapping model. After removing the layering anomalies, the DO 17 recorded in the Vostok core is clearly smoother than in the WAIS Divide record, a much higher accumulation rate site. This is consistent with previous observations and general understanding, since high accumulation firns sink and densify faster and the trapping phase of gases is less spread over time. However the smoothing of the DO event in the Vostok ice core turns out to be less important and to contain higher frequencies than expected. Finally we developed a method to infer the gas age distribution enclosed in ice cores by comparison with a high frequency atmospheric scenario, such as the WAIS Divide record. This approach allows to constrain gas age distributions in climatic conditions which have no modern analogue.

  11. 喜马拉雅地区纳木那尼的化学离子特征%Glaciochemical records from Naimona'Nyi ice core in the Himalayas

    Institute of Scientific and Technical Information of China (English)

    刘勇勤; 姚檀栋; 田立德

    2006-01-01

    A 6-m ice core was recovered in 2004 from the Naimona'Nyi Glacier, the middle Himalayas. Empirical orthogonal function (EOF) analysis on the major ion reveals that EOF1 represents the variations of majority of ions which may be originated from crustal aerosols. Comparing the calcium concentrations from the Naimona'Nyi with these from Dasuopu, East Rongbuk and Guliya ice cores, it is observed that calcium, a good indicator of the input of crustal aerosol in snow, concentrates mostly in the Guliya ice core located on the northern Tibetan Plateau, and gradually decreases from west to east in the Himalayas.

  12. Detailed history of atmospheric trace elements from the Quelccaya ice core (Southern Peru) during the last 1200 years

    Science.gov (United States)

    Uglietti, C.; Gabrielli, P.; Thompson, L. G.

    2013-12-01

    The recent increase in trace element concentrations, for example Cr, Cu, Zn, Ag, Pb, Bi, and U, in polar snow and ice has provided compelling evidence of a hemispheric change in atmospheric composition since the nineteenth century. This change has been concomitant with the expansion of the Industrial Revolution and points towards an anthropogenic source of trace elements in the atmosphere. There are very few low latitude trace element ice core records and these are believed to be sensitive to perturbations of regional significance. To date, these records have not been used to document a preindustrial anthropogenic impact on atmospheric composition at low latitudes. Ice cores retrieved from the tropical Andes are particularly interesting because they have the potential to reveal detailed information about the evolution and environmental consequences of mineral exploitation related to the Pre Inca Civilizations, the Inca Empire (1438-1533 AD) and the subsequent Spanish invasion and dominance (1532-1833 AD). The chemical record preserved in the ice of the Quelccaya ice cap (southern Peruvian Andes) offers the exceptional opportunity to geochemically constrain the composition of the tropical atmosphere at high resolution over the last ~1200 years. Quantification of twenty trace elements (Ag, Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Rb, Sb, Sn, Ti, Tl, U, V, and Zn) was performed by ICP-SFMS over 105 m of the Quelccaya North Dome core (5600 m asl, 128.57 m) by analyzing 2450 samples. This provides the first atmospheric trace element record in South America spanning continuously and at high resolution for the time period between 1990 and 790 AD. Ag, As, Bi, Cd, Cr, Co, Cu, Mn, Mo, Sb, Sn, Pb and Zn show increases in concentration and crustal enrichment factor starting at different times between 1450 and 1550 AD, in concomitance with the expansions of the Inca Empire and, subsequently, the Spanish Empire well before the inception of the Industrial Revolution. This

  13. An extended climate archive from the Eastern Alpine ice coring site of Mt Ortles

    Science.gov (United States)

    Dreossi, Giuliano; Carturan, Luca; De Blasi, Fabrizio; Paolo, Gabrielli; Spolaor, Andrea; Jacopo, Gabrieli; Barbante, Carlo; Seppi, Roberto; Dinale, Roberto; Zanoner, Thomas; Stenni, Barbara; Fontana Giancarlo, Dalla; Thompson, Lonnie G.

    2016-04-01

    Oxygen and hydrogen stable isotope content of ice cores has been extensively used for temperature reconstruction. The most elevated glaciers of the Alpine area have been utilized for ice coring for more than four decades, but the scarcity of drilling projects in the Eastern Alps and of isotopic records covering a long time period for the entire Alpine region suggest that the paleoclimatic potential of this mountain area is still largely unexploited. In autumn 2011 four deep cores were drilled on Mt Ortles, South Tyrol, Italy, at 3859 m a.s.l. An extensive reconstructed temperature record for the Ortles summit, based on the surrounding meteorological station data, is available for the last 150 years, while an automatic weather station had been operating from 2011 to 2015 in proximity of the drilling site. A preliminary age scale has been utilized for dating the two cores for which the isotopic record is available (core #1 and #2), creating an Ortles stacked record and comparing the Ortles data to temperatures and to other Alpine isotope records. The comparison among different ice core locations shows some similarities in the observed fluctuations, despite the considerable distance between the sites and the substantial geographical variability of temperature, precipitation and moisture source patterns characterizing the Alps.

  14. Synchronizing the North American Varve Chronology with Greenland ice core records using meteoric 10Be flux

    Science.gov (United States)

    DeJong, B.; Balco, G.; Ridge, J. C.; Rood, D. H.; Bierman, P. R.

    2012-12-01

    The North American Varve Chronology (NAVC) is a floating 5700-year sequence of glacial lake varves deposited in the Connecticut River Valley of the northeast US ~18,000-12,500 years ago. The NAVC is an annually resolved record of regional climate and ice-marginal processes at 40-45° N latitude, near the margin of the retreating Laurentide Ice Sheet (LIS). NAVC deposition occurred at the same time as rapid and abrupt Arctic and North Atlantic climate changes that took place during the last deglaciation. An age estimate for the NAVC based on radiocarbon dated plant macrofossils in individual varves implies a relationship between ice-marginal events recorded by the NAVC and climate events recorded in Greenland ice cores. For example, the retreat rate of the LIS up the Connecticut River Valley increased during the Bolling warming in Greenland, a readvance of the LIS margin took place during the Older Dryas cold period, and a correlation between an outburst flood from glacial Lake Iroquois and the Intra-Allerod Cold Period supports the hypothesis that the flood affected North Atlantic thermohaline circulation. On the other hand, a doubling of the ice-margin retreat rate recorded by the NAVC around 16,000 years ago coincides with a relatively cold period in Greenland. Our goal is to investigate the precise time relationship between these events by synchronizing the NAVC with the Greenland ice core time scale using atmospherically-produced 10Be. Existing 10Be flux records, including those from Greenland ice cores, exhibit solar variability on a range of time scales. Because this variability is globally synchronous, a 10Be flux record for the NAVC can, in principle, be used to align NAVC and ice core timescales. We are generating such a record at present. First, we are analyzing short varve sections at high temporal resolution to evaluate the magnitude of solar variability signals; a single section analyzed so far displays interannual variability with a period consistent

  15. Abundance, viability and diversity of the indigenous microbial populations at different depths of the NEEM Greenland ice core

    OpenAIRE

    Miteva, Vanya; Rinehold, Kaitlyn; Sowers, Todd; Sebastian, Aswathy; Brenchley, Jean

    2015-01-01

    The 2537-m-deep North Greenland Eemian Ice Drilling (NEEM) core provided a first-time opportunity to perform extensive microbiological analyses on selected, recently drilled ice core samples representing different depths, ages, ice structures, deposition climates and ionic compositions. Here, we applied cultivation, small subunit (SSU) rRNA gene clone library construction and Illumina next-generation sequencing (NGS) targeting the V4–V5 region, to examine the microbial abundance, viability an...

  16. Annually resolved ice core records of tropical climate variability over the past ~1800 years.

    Science.gov (United States)

    Thompson, L G; Mosley-Thompson, E; Davis, M E; Zagorodnov, V S; Howat, I M; Mikhalenko, V N; Lin, P-N

    2013-05-24

    Ice cores from low latitudes can provide a wealth of unique information about past climate in the tropics, but they are difficult to recover and few exist. Here, we report annually resolved ice core records from the Quelccaya ice cap (5670 meters above sea level) in Peru that extend back ~1800 years and provide a high-resolution record of climate variability there. Oxygen isotopic ratios (δ(18)O) are linked to sea surface temperatures in the tropical eastern Pacific, whereas concentrations of ammonium and nitrate document the dominant role played by the migration of the Intertropical Convergence Zone in the region of the tropical Andes. Quelccaya continues to retreat and thin. Radiocarbon dates on wetland plants exposed along its retreating margins indicate that it has not been smaller for at least six millennia.

  17. Neutrino Mass Ordering Studies with PINGU and IceCube/DeepCore

    CERN Document Server

    Wren, Steven

    2016-01-01

    The Precision IceCube Next Generation Upgrade (PINGU) is a proposed extension to the IceCube detector. The design of PINGU would augment the existing 86 strings with an additional 40 with the main goal of determining the neutrino mass ordering (NMO). Preliminary studies of the NMO can start with IceCube/DeepCore, a sub-array of more densely- packed strings in operation since 2011. This detector has a neutrino energy threshold of roughly 10 GeV and allows for high-statistics datasets of atmospheric neutrinos to be collected. This data provides a unique opportunity to better understand the systematic effects involved in making the NMO measurement by comparing the simulation studies to real data. These proceedings will present the current status of these studies in Monte Carlo simulations with projected DeepCore sensitivity for the NMO.

  18. Atmospheric neutrino results from IceCube-DeepCore and plans for PINGU

    Science.gov (United States)

    Koskinen, D. Jason; IceCube-Gen2 collaboration

    2017-09-01

    The IceCube neutrino observatory at the South Pole is the largest operating neutrino detector in the world and spans a wide range of science topics, from astronomy at the PeV-scale to particle physics at the GeV-scale. We present results from the search for a light, O(1) eV2, sterile neutrino using the large IceCube array and, separately, using the lower energy extension DeepCore sub-array. Additionally, we review the atmospheric neutrino results and expected sensitivities related to oscillation physics (νµ disappearance and ντ appearance) as well as new limits on non-standard interactions. Continuing the success of the IceCube-DeepCore physics program, a proposed next generation in-fill detector with increased sensitivity to neutrinos of O(1) GeV will be covered.

  19. Multilayer formation and evaporation of deuterated ices in prestellar and protostellar cores

    CERN Document Server

    Taquet, Vianney; Sipilä, Olli

    2014-01-01

    Extremely large deuteration of several molecules has been observed towards prestellar cores and low-mass protostars for a decade. New observations performed towards low-mass protostars suggest that water presents a lower deuteration in the warm inner gas than in the cold external envelope. We coupled a gas-grain astrochemical model with a one-dimension model of collapsing core to properly follow the formation and the deuteration of interstellar ices as well as their subsequent evaporation in the low-mass protostellar envelopes with the aim of interpreting the spatial and temporal evolutions of their deuteration. The astrochemical model follows the formation and the evaporation of ices with a multilayer approach and also includes a state-of-the-art deuterated chemical network by taking the spin states of H$_2$ and light ions into account. Because of their slow formation, interstellar ices are chemically heterogeneous and show an increase of their deuterium fractionation towards the surface. The differentiation...

  20. Radiocarbon analyses along the EDML ice core in Antarctica

    NARCIS (Netherlands)

    van de Wal, R.S.W.; Meijer, H.A.J.; van Rooij, M.; van der Veen, C.

    2007-01-01

    Samples, 17 in total, from the EDML core drilled at Kohnen station Antarctica are analysed for 14CO and 14CO2 with a dry-extraction technique in combination with accelerator mass spectrometry. Results of the in situ produced 14CO fraction show a very low concentration of in situ produced 14CO. Despi

  1. Radiocarbon analyses along the EDML ice core in Antarctica

    NARCIS (Netherlands)

    Van de Wal, R. S. W.; Meijer, H. A. J.; De Rooij, M.; Van der Veen, C.

    2007-01-01

    Samples, 17 in total, from the EDML core drilled at Kohnen station Antarctica are analysed for (CO)-C-14 and (CO2)-C-14 with a dry-extraction technique in combination with accelerator mass spectrometry. Results of the in situ produced (CO)-C-14 fraction show a very low concentration of in situ produ

  2. Dust records from three ice cores: relationships to spring atmospheric circulation over the Northern Hemisphere

    Science.gov (United States)

    Kang, Shichang; Mayewski, Paul A.; Yan, Yuping; Qin, Dahe; Yao, Tandong; Ren, Jiawen

    Non-sea-salt Mg 2+ (nssMg 2+) records from three Northern Hemisphere ice cores (Mt. Everest, Himalayas; Mt. Logan, Yukon Territory; and 20D, southern Greenland) are presented as a proxy of atmospheric dust. NssMg 2+ concentrations of both Mt. Everest and 20D ice core have increased since the 20th century. Relationships between the three ice core annual nssMg 2+ series and instrumental sea-level pressure (SLP) series of spring (March-April-May) are investigated for the last century (AD 1899-1996), in order to develop an understanding of dust aerosol transport over the Northern Hemisphere during the spring season. On a hemispheric scale, an enhanced spring Arctic High weakens dust aerosol transport from central Asia to subarctic regions (e.g., southern Greenland and Yukon Territory), but strengthens transport of dust to the Himalaya (e.g., Mt. Everest). An intensification of the Siberian High may strengthen transport of dust aerosols to Greenland, and an enhancement of the Tibetan High strengthens transport to Himalaya and Yukon regions in spring. A stronger spring Azores High favors dust transport to both the Himalayas and south Greenland. On a regional scale, a deepened spring Icelandic Low and Aleutian Low increases transport of dust aerosols to Greenland and the Yukon Territory, respectively. Understanding these transport patterns is significant for the interpretation of ice core records and reconstruction of atmospheric circulation using longer records.

  3. 9,400 years of cosmic radiation and solar activity from ice cores and tree rings

    National Research Council Canada - National Science Library

    Friedhelm Steinhilber; Jose A. Abreu; Jürg Beer; Irene Brunner; Marcus Christl; Hubertus Fischer; Ulla Heikkilä; Peter W. Kubik; Mathias Mann; Ken G. McCracken; Heinrich Miller; Hiroko Miyahara; Hans Oerter; Frank Wilhelms

    2012-01-01

    .... Cosmic-ray produced radionuclides, such as ¹⁰Be and ¹⁴C which are stored in polar ice cores and tree rings, offer the unique opportunity to reconstruct the history of cosmic radiation and solar activity over many millennia...

  4. Climate variation since the Last Interglaciation recorded in the Guliya ice core

    Institute of Scientific and Technical Information of China (English)

    姚檀栋; L.G.Thompson; 施雅风; 秦大河; 焦克勤; 杨志红; 田立德; E.M.Thompson

    1997-01-01

    The climatic and environmental variations since the Last Interglaciation are reconstructed based on the study of the upper 268 m of the 309-m-long Guliya ice core. Five stages can be distinguished since the Last Interglaciation from the δ18O record in the Guliya ice core: Stage 1 (Deglaciation), Stage 2 (the Last Glacial Maximum), Stage 3 (interstadial), Stage 4 (interstadial in the early glacial maximum) and Stage 5 (the Last Interglaciation). Stage 5 can be divided further into 5 substages; a, b, c, d, e. The δ18O record in the Guliya ice core indicates clearly the close correlation between the temperature variation on the Tibetan Plateau and the solar activities. The study indicates that the solar activity is a main forcing to the climatic variation on the Tibetan Plateau. Through a comparison of the ice core record in Guliya with that in the Greenland and the Antarctic, it can be found that the variation of large temperature variation events in different parts of the world is generally the same, b

  5. Reconstruct Environmental Change through Reading Oxalate Records from the Ice Core

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ CAS scientists have made progress in investigating the past atmospheric changes by retrieving oxalate records from an ice core of Tianshan glaciers. An analysis shows that the variation of the organic acid mirrors the history of the regional economic development as well as environment protection in the west China over the past 40 years.

  6. Formate and acetate records in the Muztagata ice core,Northwest Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Junxia; YAO Tandong; XU Baiqing; WU Guangjian; XIANG Shurong

    2004-01-01

    Formate and acetate concentrations are measured in a 22.56 m-depth ice core recovered in Mt. Muztagata Glacier, northwest Tibetan Plateau. The mean concentrations for formate and acetate in this ice core are 186.6±160.1 and 136.4±133.9 rng/g, respectively. Study shows that there is a positive correlation between formate and nitrate, suggesting both continental origins. However, no significant relationship has been found between formate and acetate, though they both have obvious periodical variations. Because Mt. Muztagata lies in the mid-latitude and is correlative to the nearby human activities, formate and acetate concentrations are higher than those in Greenland and Antarctica. During recent decades, the increase of formate concentration in the Muztagata ice core and formaldehyde production shows a close correlation. We preliminarily presume that the high formate concentration in the Muztagata ice core is concerned with the thriving of house decoration in which excess formaldehyde was used.

  7. 10Be climate fingerprints during the Eemian in the NEEM ice core, Greenland

    Science.gov (United States)

    Sturevik-Storm, Anna; Aldahan, Ala; Possnert, Göran; Berggren, Ann-Marie; Muscheler, Raimund; Dahl-Jensen, Dorthe; Vinther, Bo M.; Usoskin, Ilya

    2014-09-01

    Several deep Greenland ice cores have been retrieved, however, capturing the Eemian period has been problematic due to stratigraphic disturbances in the ice. The new Greenland deep ice core from the NEEM site (77.45°N, 51.06°W, 2450 m.a.s.l) recovered a relatively complete Eemian record. Here we discuss the cosmogenic 10Be isotope record from this core. The results show Eemian average 10Be concentrations about 0.7 times lower than in the Holocene which suggests a warmer climate and approximately 65-90% higher precipitation in Northern Greenland compared to today. Effects of shorter solar variations on 10Be concentration are smoothed out due to coarse time resolution, but occurrence of a solar maximum at 115.26-115.36 kyr BP is proposed. Relatively high 10Be concentrations are found in the basal ice sections of the core which may originate from the glacial-interglacial transition and relate to a geomagnetic excursion about 200 kyr BP.

  8. North Pacific Atmospheric Circulation and Tropical Teleconnections Over the Past 1500 Years From a Mt. Logan Ice Core

    Science.gov (United States)

    Osterberg, E. C.; Mayewski, P. A.; Kreutz, K. J.; Fisher, D. A.; Maasch, K.; Sneed, S. B.

    2007-12-01

    A calibrated 1500 year-long glaciochemical proxy record for the strength of the wintertime (November-March) Aleutian Low (ALOW) from the Mt. Logan summit (PR Col; 5300 m a.s.l.) ice core [Na+] time series reveals a strong ALOW from ca. 650-900 A.D., ca. 1300-1550 A.D., and ca. 1700-1998 A.D., and a weaker ALOW from ca. 900-1300 A.D. and ca. 1550-1700 A.D. The proxy record was calibrated to instrumental sea-level pressure data using standard regression techniques, and verified using statistical, spectral, and spatial correlation analyses. The Mt. Logan ALOW proxy record shows strong similarities with sea surface temperature, precipitation, and glacier extent proxy records from the Pacific basin sensitive to the El Niño-Southern Oscillation, indicating a robust coupling between high-latitude and tropical Pacific climate during the late Holocene. The Medieval Warm Period was characterized by more persistent La Niña-like conditions (weak ALOW), while the Little Ice Age (LIA) was characterized by at least two intervals of more persistent El Niño-like conditions (strong ALOW; 1300-1550 A.D., 1700-1998 A.D.). The LIA intensification of the ALOW is similar to the LIA intensification of the Icelandic Low in the North Atlantic (based on the GISP2, Greenland ice core [Na+] calibrated proxy record) and the Amundsen Sea Low in the high-latitude South Pacific (based on the Siple Dome, West Antarctica ice core [Na+] calibrated proxy record).

  9. Laser ablation inductively coupled plasma mass spectrometry: a new tool for trace element analysis in ice cores.

    Science.gov (United States)

    Reinhardt, H; Kriews, M; Miller, H; Schrems, O; Lüdke, C; Hoffmann, E; Skole, J

    2001-07-01

    A new method for the detection of trace elements in polar ice cores using laser ablation with subsequent inductively coupled plasma mass spectrometry analysis is described. To enable direct analysis of frozen ice samples a special laser ablation chamber was constructed. Direct analysis reduces the risk of contamination. The defined removal of material from the ice surface by means of a laser beam leads to higher spatial resolution (300-1000 microm) in comparison to investigations with molten ice samples. This is helpful for the detection of element signatures in annual layers of ice cores. The method was applied to the successful determination of traces for the elements Mg, Al, Fe, Zn, Cd, Pb, some rare-earth elements (REE) and minor constituents such as Ca and Na in ice cores. These selected elements serve as tracer elements for certain sources and their element signatures detected in polar ice cores can give hints to climate changes in the past. We report results from measurements of frozen ice samples, the achievable signal intensities, standard deviations and calibration graphs as well as the first signal progression of 205Pb in an 8,000-year-old ice core sample from Greenland. In addition, the first picture of a crater on an ice surface burnt by an IR laser made by cryogenic scanning electron microscopy is presented.

  10. Chronology of Pu isotopes and {sup 236}U in an Arctic ice core

    Energy Technology Data Exchange (ETDEWEB)

    Wendel, C.C., E-mail: cato.wendel@umb.no [Isotope Laboratory, Department of Plant and Environmental Sciences, Agricultural University of Norway, P.O. Box 5003, N-1432 Aas (Norway); Oughton, D.H., E-mail: deborah.oughton@umb.no [Isotope Laboratory, Department of Plant and Environmental Sciences, Agricultural University of Norway, P.O. Box 5003, N-1432 Aas (Norway); Lind, O.C., E-mail: ole-christian.lind@umb.no [Isotope Laboratory, Department of Plant and Environmental Sciences, Agricultural University of Norway, P.O. Box 5003, N-1432 Aas (Norway); Skipperud, L., E-mail: lindis.skipperud@umb.no [Isotope Laboratory, Department of Plant and Environmental Sciences, Agricultural University of Norway, P.O. Box 5003, N-1432 Aas (Norway); Fifield, L.K., E-mail: keith.fifield@anu.edu.au [Department of Nuclear Physics, Australian National University, Canberra ACT 0200 (Australia); Isaksson, E., E-mail: elisabeth.isaksson@npolar.no [Norwegian Polar Institute, Fram Centre, Hjalmar Johansens Gate 14, N9296 Tromsø (Norway); Tims, S.G., E-mail: steve.tims@anu.edu.au [Department of Nuclear Physics, Australian National University, Canberra ACT 0200 (Australia); Salbu, B., E-mail: brit.salbu@umb.no [Isotope Laboratory, Department of Plant and Environmental Sciences, Agricultural University of Norway, P.O. Box 5003, N-1432 Aas (Norway)

    2013-09-01

    In the present work, state of the art isotopic fingerprinting techniques are applied to an Arctic ice core in order to quantify deposition of U and Pu, and to identify possible tropospheric transport of debris from former Soviet Union test sites Semipalatinsk (Central Asia) and Novaya Zemlya (Arctic Ocean). An ice core chronology of {sup 236}U, {sup 239}Pu, and {sup 240}Pu concentrations, and atom ratios, measured by accelerator mass spectrometry in a 28.6 m deep ice core from the Austfonna glacier at Nordaustlandet, Svalbard is presented. The ice core chronology corresponds to the period 1949 to 1999. The main sources of Pu and {sup 236}U contamination in the Arctic were the atmospheric nuclear detonations in the period 1945 to 1980, as global fallout, and tropospheric fallout from the former Soviet Union test sites Novaya Zemlya and Semipalatinsk. Activity concentrations of {sup 239+240}Pu ranged from 0.008 to 0.254 mBq cm{sup −2} and {sup 236}U from 0.0039 to 0.053 μBq cm{sup −2}. Concentrations varied in concordance with {sup 137}Cs concentrations in the same ice core. In contrast to previous published results, the concentrations of Pu and {sup 236}U were found to be higher at depths corresponding to the pre-moratorium period (1949 to 1959) than to the post-moratorium period (1961 and 1962). The {sup 240}Pu/{sup 239}Pu ratio ranged from 0.15 to 0.19, and {sup 236}U/{sup 239}Pu ranged from 0.18 to 1.4. The Pu atom ratios ranged within the limits of global fallout in the most intensive period of nuclear atmospheric testing (1952 to 1962). To the best knowledge of the authors the present work is the first publication on biogeochemical cycles with respect to {sup 236}U concentrations and {sup 236}U/{sup 239}Pu atom ratios in the Arctic and in ice cores. - Highlights: • Concentrations and atom ratios of Pu and {sup 236}U determined in an Arctic ice core. • Concentrations of U and Pu found to be higher pre- than post-moratorium. • U and Pu concentrations

  11. A Pleistocene ice core record of atmospheric O2 concentrations

    Science.gov (United States)

    Stolper, D. A.; Bender, M. L.; Dreyfus, G. B.; Yan, Y.; Higgins, J. A.

    2016-09-01

    The history of atmospheric O2 partial pressures (PO2) is inextricably linked to the coevolution of life and Earth’s biogeochemical cycles. Reconstructions of past PO2 rely on models and proxies but often markedly disagree. We present a record of PO2 reconstructed using O2/N2 ratios from ancient air trapped in ice. This record indicates that PO2 declined by 7 per mil (0.7%) over the past 800,000 years, requiring that O2 sinks were ~2% larger than sources. This decline is consistent with changes in burial and weathering fluxes of organic carbon and pyrite driven by either Neogene cooling or increasing Pleistocene erosion rates. The 800,000-year record of steady average carbon dioxide partial pressures (PCO2) but declining PO2 provides distinctive evidence that a silicate weathering feedback stabilizes PCO2 on million-year time scales.

  12. ISOTOPIC REGIME OF SUBGLACIAL LAKE VOSTOK ON EVIDENCE FROM DEEP ICE CORE STUDIES

    Directory of Open Access Journals (Sweden)

    A. A. Ekaykin

    2012-01-01

    Full Text Available On the 5th of February 2012 the long-lasting project of deep ice drilling at Russian Antarctic station of Vostok was completed by the penetration to the subglacial lake at the depth of 3769.3 m. The study of the ice core representing the frozen lake water and obtained as a result of the drilling, has allowed to make preliminary conclusions on the lake hydrological regime before its direct studies. In this work we present the new isotopic data (dD and d18O from the 5G-2 ice core from the depth interval 3600–3720 m. The measurements were performed in the recently established Climate and Environment Research Laboratory of Arctic and Antarctic Research Institute (St. Petersburg,Russia. The comparison of the new isotope profile with the previously published 5G-1 data (3540–3650 m demonstrates a good reproducibility, which means a satisfying quality of the measurements. The analysis of the whole available lake ice thickness isotope profile (3540–3720 m has allowed to obtain a new information on theLakeVostok’s hydrological regime. Based on the isotopic behavior, the lake ice core is divided into three sections. The first (3540–3619 m corresponds to the so-called «lake ice 1», the ice containing visible mineral inclusions that was formed close to the western lake shore. The isotopic variability in this section was formed due to the changing conditions and mechanisms of the ice formation (ice accretion rate, concentrations of the frazil ice crystals and frozen water pockets. The second (3619–3647 m is characterized by a weak correlation between deuterium and oxygen 18, which is interpreted as an influence of the hydrothermal activity on the lake’s isotopic regime. In the third section (3647–3720 m, formed over the deep basin in the southern part of the lake, the isotopic variability is reduced due to the relatively stable steady-state conditions of the ice formation. At the same time, the signature of the lake water isotopic

  13. North Pacific Climate Variability in Ice Core Accumulation Records From Eclipse Icefield, Yukon, Canada

    Science.gov (United States)

    Yalcin, K.; Wake, C. P.; Kreutz, K. J.

    2005-12-01

    Three annually dated ice cores from Eclipse Icefield, Yukon, Canada provide records of net accumulation spanning the last 100 to 500 years. The ice cores were dated by annual layer counting verified by reference horizons provided by radioactive fallout and volcanic eruptions. Annual layers become progressively thinner with depth in the Eclipse ice cores, requiring reconstruction of original annual layer thicknesses by correcting for ice creep. An empirical approach was used that is based on the observed layer thicknesses from annual layer counting of the Eclipse ice cores. Accumulation records are highly reproducible with 73% of the signal shared between the three cores. The accumulation time-series shows considerable decadal scale variability that can be related to climate regimes that characterize the North Pacific. For example, periods of high accumulation are noted from 1470-1500, 1540-1560, and 1925-1975. Periods of low accumulation are observed between 1500-1540, 1680-1780, and 1875-1925. The strongest multi-year drop in accumulation is seen between 1979 and 1984, although there are isolated years with lower accumulation. This drop in accumulation is possibly related to the 1977 regime shift in the Pacific Decadal Oscillation. However, PDO regime shifts are not always reflected in the accumulation time series, implying a non-linear response or modulation by other modes of climate variability such as ENSO. Its is noteworthy that the Eclipse accumulation time series is out of phase with the accumulation time series from nearby Mount Logan on all time scales for reasons to be investigated.

  14. Aerial photographs reveal late-20th-century dynamic ice loss in northwestern greenland

    DEFF Research Database (Denmark)

    Kjær, Kurt H.; Khan, Shfaqat Abbas; Korsgaard, Niels J

    2012-01-01

    Global warming is predicted to have a profound impact on the Greenland Ice Sheet and its contribution to global sea-level rise. Recent mass loss in the northwest of Greenland has been substantial. Using aerial photographs, we produced digital elevation models and extended the time record of recent...... observed marginal dynamic thinning back to the mid-1980s. We reveal two independent dynamic ice loss events on the northwestern Greenland Ice Sheet margin: from 1985 to 1993 and 2005 to 2010, which were separated by limited mass changes. Our results suggest that the ice mass changes in this sector were...... primarily caused by short-lived dynamic ice loss events rather than changes in the surface mass balance. This finding challenges predictions about the future response of the Greenland Ice Sheet to increasing global temperatures....

  15. Aerial Photographs Reveal Late-20th-Century Dynamic Ice Loss in Northwestern Greenland

    Science.gov (United States)

    Kjær, Kurt H.; Khan, Shfaqat A.; Korsgaard, Niels J.; Wahr, John; Bamber, Jonathan L.; Hurkmans, Ruud; van den Broeke, Michiel; Timm, Lars H.; Kjeldsen, Kristian K.; Bjørk, Anders A.; Larsen, Nicolaj K.; Jørgensen, Lars Tyge; Færch-Jensen, Anders; Willerslev, Eske

    2012-08-01

    Global warming is predicted to have a profound impact on the Greenland Ice Sheet and its contribution to global sea-level rise. Recent mass loss in the northwest of Greenland has been substantial. Using aerial photographs, we produced digital elevation models and extended the time record of recent observed marginal dynamic thinning back to the mid-1980s. We reveal two independent dynamic ice loss events on the northwestern Greenland Ice Sheet margin: from 1985 to 1993 and 2005 to 2010, which were separated by limited mass changes. Our results suggest that the ice mass changes in this sector were primarily caused by short-lived dynamic ice loss events rather than changes in the surface mass balance. This finding challenges predictions about the future response of the Greenland Ice Sheet to increasing global temperatures.

  16. Recent climate tendencies on an East Antarctic ice shelf inferred from a shallow firn core network

    Science.gov (United States)

    Schlosser, E; Anschütz, H; Divine, D; Martma, T; Sinisalo, A; Altnau, S; Isaksson, E

    2014-01-01

    Nearly three decades of stable isotope ratios and surface mass balance (SMB) data from eight shallow firn cores retrieved at Fimbul Ice Shelf, East Antarctica, in the Austral summers 2009–2011 have been investigated. An additional longer core drilled in 2000/2001 extends the series back to the early eighteenth century. Isotope ratios and SMB from the stacked record of all cores were also related to instrumental temperature data from Neumayer Station on Ekström Ice Shelf. Since the second half of the twentieth century, the SMB shows a statistically significant negative trend, whereas the δ18O of the cores shows a significant positive trend. No trend is found in air temperature at the nearest suitable weather station, Neumayer (available since 1981). This does not correspond to the statistically significant positive trend in Southern Annular Mode (SAM) index, which is usually associated with a cooling of East Antarctica. SAM index and SMB are negatively correlated, which might be explained by a decrease in meridional exchange of energy and moisture leading to lower precipitation amounts. Future monitoring of climate change on the sensitive Antarctic ice shelves is necessary to assess its consequences for sea level change. Key Points Mass balance and stable oxygen isotope ratios from shallow firn cores Decreasing trend in surface mass balance, no trend in stable isotopes Negative correlation between SAM and SMB PMID:25821663

  17. Continuous and discrete measurements of atmospheric methane from an ice core from Roosevelt Island, East Ross Sea, Antarctica

    Science.gov (United States)

    Blunier, T.; Simonsen, M. F.; Brook, E.; Lee, J.; Vallelonga, P. T.; Bertler, N. A. N.

    2014-12-01

    A new ice core from Roosevelt Island was drilled for the Roosevelt Island Climate Evolution (RICE) project to establish the history of deglaciation of the Ross Sea. Evidence of glacial retreat in the Ross Sea Embayment shows that deglaciation happened in several stages of rapid collapse and persisted well after the melting of the Northern Hemisphere ice sheets was complete. The drill location on a small island surrounded by sea ice makes dating the core a challenge. We present a timescale for Roosevelt Island using mixing ratios of methane in air preserved within the ice core measured continuously with a Picarro laser spectrometer as well as in high-resolution with gas chromatography (GC). Discrete data from GC analysis over the top 400m of core replicate both the magnitude and variations from other high-resolution ice core records from WAIS Divide, Law Dome, GISP2 and NEEM S1. Both the continuous and discrete methane records of the RICE core were matched to these established records and provide an accurate and consistent depth-age relationship for the past 3.6kyr. The deeper part of the core was measured continuously in July 2014. First inspection of the data suggests that the oldest section of the core reaches into the previous interglacial (Eemian). We will present preliminary evaluated continuous methane data for the deeper part of the core together with a first time scale for the Roosevelt Island ice core.

  18. Latest results on atmospheric neutrino oscillations from IceCube/DeepCore

    Science.gov (United States)

    de André, J. P. A. M.; IceCube Collaboration

    2016-05-01

    The IceCube Neutrino Observatory, located at the South Pole, is the world’s largest neutrino detector. DeepCore, the low energy extension for IceCube, with a threshold of about ten GeV is well suited to study neutrino oscillations using neutrinos produced in the Earth’s atmosphere and traveling distances as large as the Earth’s diameter before being detected. Using these neutrinos DeepCore makes measurements of the neutrino oscillation parameters θ23 and |Δm 2 32| with precisions approaching that of dedicated experiments, and based on preliminary studies these results can still be further improved. These new studies as well as the current results obtained in DeepCore are discussed here.

  19. Giant solar flares in Antarctic ice. [nitrate ions in ice core samples

    Science.gov (United States)

    Stothers, R.

    1980-01-01

    A new hypothesis proposes an explanation for the presence of four prominent spikes in a long time record of the NO3(-) concentration inside the Antarctic ice. This solar flare hypothesis suggests that the ionizing radiation necessary in the spike formation could have come from extremely powerful solar flares. It is proposed that these flares would have occurred during the times of the largest maxima in the solar cycle. The solar flare hypothesis is compared with the supernova hypothesis.

  20. Objective identification of climate states from Greenland ice cores for the last glacial period

    Directory of Open Access Journals (Sweden)

    D. J. Peavoy

    2010-06-01

    Full Text Available We present statistical methods to systematically determine climate regimes for the last glacial period using three temperature proxy records from Greenland: measurements of δ18O from the Greenland Ice Sheet Project 2 (GISP2, the Greenland Ice Core Project (GRIP and the North Greenland Ice Core Project (NGRIP. By using Bayesian model comparison methods we find that, in two out of three data sets, a model with 3 states is very strongly supported. We interpret these states as corresponding to: a gradual cooling regime due to iceberg influx in the North Atlantic, sudden temperature decrease due to increased freshwater influx following ice sheet collapse and to the Dansgaard-Oeschger events associated with sudden rebound temperature increase after the thermohaline circulation recovers its full flux. We find that these models are far superior to those that differentiate between states based on absolute temperature differences only, which questions the appropriateness of defining stadial and interstadial climate states. We investigate the recurrence properties of these climate regimes and find that the only significant periodicity is within the Greenland Ice Sheet Project 2 data at 1450 years in agreement with previous studies.

  1. Direct linking of Greenland and Antarctic ice cores at the Toba eruption (74 ka BP

    Directory of Open Access Journals (Sweden)

    A. Svensson

    2013-03-01

    Full Text Available The Toba eruption that occurred some 74 ka ago in Sumatra, Indonesia, is among the largest volcanic events on Earth over the last 2 million years. Tephra from this eruption has been spread over vast areas in Asia, where it constitutes a major time marker close to the Marine Isotope Stage 4/5 boundary. As yet, no tephra associated with Toba has been identified in Greenland or Antarctic ice cores. Based on new accurate dating of Toba tephra and on accurately dated European stalagmites, the Toba event is known to occur between the onsets of Greenland interstadials (GI 19 and 20. Furthermore, the existing linking of Greenland and Antarctic ice cores by gas records and by the bipolar seesaw hypothesis suggests that the Antarctic counterpart is situated between Antarctic Isotope Maxima (AIM 19 and 20. In this work we suggest a direct synchronization of Greenland (NGRIP and Antarctic (EDML ice cores at the Toba eruption based on matching of a pattern of bipolar volcanic spikes. Annual layer counting between volcanic spikes in both cores allows for a unique match. We first demonstrate this bipolar matching technique at the already synchronized Laschamp geomagnetic excursion (41 ka BP before we apply it to the suggested Toba interval. The Toba synchronization pattern covers some 2000 yr in GI-20 and AIM-19/20 and includes nine acidity peaks that are recognized in both ice cores. The suggested bipolar Toba synchronization has decadal precision. It thus allows a determination of the exact phasing of inter-hemispheric climate in a time interval of poorly constrained ice core records, and it allows for a discussion of the climatic impact of the Toba eruption in a global perspective. The bipolar linking gives no support for a long-term global cooling caused by the Toba eruption as Antarctica experiences a major warming shortly after the event. Furthermore, our bipolar match provides a way to place palaeo-environmental records other than ice cores into a

  2. An 80-year summer temperature history from the Xiao Dongkemadi ice core in the central Tibetan Plateau and its association with atmospheric circulation

    Science.gov (United States)

    Li, Xiangying; Ding, Yongjian; Yu, Zhongbo; Mika, Sillanpää; Liu, Shiyin; Shangguan, Donghui; Lu, Chengyang

    2015-02-01

    The climate significance of oxygen isotopes from the central Tibetan Plateau (cTP) ice cores is a debated issue because of large scale atmospheric circulation. A high-resolution δ18O record was recovered from the Xiao Dongkemadi (XD) ice core, which expanded the spatial coverage of δ18O data in this region. Annual average δ18O correlated significantly with nearby MJJAS air temperatures, suggesting the δ18O can be used as a proxy to reconstruct regional climate change. The reconstructed temperature anomaly is related to the regional and global warming trends, and the greater warming amplitude since 1970s is related to the elevation dependency of the warming signal. The close relationship of the warming to variations in glacier mass balances and discharge reveal that recent warming has led to obvious glacier shrinkage and runoff increase. Correlation analysis suggests that monsoon and westerly moisture substantially influence the cTP ice core records, along with an increase in their level of contribution to the XD core accumulation in recent decades, and confirms a teleconnection of regional climate of the cTP ice cores with climate parameters in the Indian and North Atlantic Oceans.

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

    Institute of Scientific and Technical Information of China (English)

    XU; Baiqing

    2001-01-01

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

  4. Evidence for cold events in the early Holocene from the Guliya ice core, Tibetan Plateau, China

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Evidence for the "8.2 ka cold event" has been provided mostly from the circum-North Atlantic area. However, whether this cold event occurred in other places is a key to understanding its cause. Here, we provide the evidence for the "8.2 ka cold event" from the Guliya ice core in the northwest Tibetan Plateau, and it was found that the peak cooling (~8.3-8.2 ka) in this ice core was about 7.8-10℃, which was larger than the cooling in the North Atlantic region. The primary causes for this episode were diminished solar activity and weakened thermohaline circulation. Moreover, another weak cold event, centered about 9.4 ka, was also recorded in the Guliya ice core record. These two cold events were concurrent with the ice-rafting episodes in the North Atlantic during the early Holocene, which implies that the millennial-scale climatic cyclicity might exist in the Tibetan Plateau as well as in the North Atlantic.

  5. Anthropogenic trace metals in an ice core at Vestfonna, Svalbard, Norway

    Institute of Scientific and Technical Information of China (English)

    Sumito Matoba; Hideaki Motoyama; Hideki Narita; Okitsugu Watanabe

    2003-01-01

    A 211 m depth ice core observation was carried out at the top of the Vestfonna Ice Cap in Nordaustlandet, Svalbard, Norway in 1995.Chronology of the ice core was determined by tritium analysis and comparison to the volcanic eruption of Laki; the resulting accumulation rate is 0.34-0.35 m water eq.*yr-1 for the last 400 year.Concentrations of Al, V, Cr, Fe, Cu, Zn, As, Ag, Cd, Pb and U in an ice core have been determined by an inductively coupled plasma mass spectrometry (ICP-MS) with a desolvated micro-concentric nebulizer, which is a recent development and can achieve high sensitivity with low uptake rate of 60 mL/min.The concentrations of Pb, Cu, and Zn had increased from 1940s declined from 1970s to present.However, the profiles of Pb, Cu, and Zn were different and they seem to be influenced by the difference of sources.Since the ratios between Cu, Pb, and Zn in Svalbard is similar to that in French Alps, the source area of these elements is estimated to be Europe.

  6. Variation of culturable bacteria along depth in the East Rongbuk ice core, Mt. Everest

    Directory of Open Access Journals (Sweden)

    Liang Shen

    2012-05-01

    Full Text Available Ice melt water from a 22.27 m ice core which was drilled from the East Rongbuk Glacier, Mt. Everest was incubation in two incubation ways: plate melt water directly and enrichment melt water prior plate, respectively. The abundance of cultivable bacteria ranged from 0–295 CFU mL−1 to 0–1720 CFU mL−1 in two incubations with a total of 1385 isolates obtained. Comparing to direct cultivation, enrichment cultivation recovered more bacteria. Pigment-producing bacteria accounted for an average of 84.9% of total isolates. Such high percentage suggested that pigment production may be an adaptive physiological feature for the bacteria in ice core to cope with strong ultraviolet radiation on the glacier. The abundances of cultivable bacteria and pigment-producing isolates varied synchronously along depth: higher abundance in the middle and lower at the top and bottom. It indicated that the middle part of the ice core was hospitable for the microbial survival. Based on the physiological properties of the colonies, eighty-nine isolates were selected for phylogenetic analysis. Obtained 16S rRNA gene sequences fell into four groups: Firmicutes, Alpha-Proteobacteria, Gamma-Proteobacteria, and Actinobacteria, with the Firmicutes being dominant. Microbial compositions derived from direct and enrichment cultivations were not overlapped. We suggest that it is a better way to explore the culturable microbial diversity in ice core by combining the approaches of both direct and enrichment cultivation.

  7. Multi-decadal variability in the Greenland ice core records obtained using intrinsic timescale decomposition

    Science.gov (United States)

    Zhou, Jiansong; Tung, Ka-Kit; Li, King-Fai

    2016-08-01

    By performing a new adaptive time series decomposition on the composite average of multiple ice core records obtained from the Arctic and Greenland, we extracted a robust quasi-oscillatory signal with a period of ~70 years throughout the preceding millennium, and showed that it is strongly connected to the Atlantic Multidecadal Oscillation (AMO). In the same decomposition there exists the Greenland signature of the Little Ice Age and Medieval Warm Period. Throughout the warm and cold periods the AMO properties remained robust. It implies that the evolution of the AMO has its own coherent mechanism and was little affected by these large climatic excursions.

  8. Simultaneous stable isotope analysis of methane and nitrous oxide on ice core samples

    Directory of Open Access Journals (Sweden)

    C. J. Sapart

    2011-12-01

    Full Text Available Methane and nitrous oxide are important greenhouse gases which show a strong increase in atmospheric mixing ratios since pre-industrial time as well as large variations during past climate changes. The understanding of their biogeochemical cycles can be improved using stable isotope analysis. However, high-precision isotope measurements on air trapped in ice cores are challenging because of the high susceptibility to contamination and fractionation.

    Here, we present a dry extraction system for combined CH4 and N2O stable isotope analysis from ice core air, using an ice grating device. The system allows simultaneous analysis of δD(CH4 or δ13C(CH4, together with δ15N(N2O, δ18O(N2O and δ15N(NO+ fragment on a single ice core sample, using two isotope mass spectrometry systems. The optimum quantity of ice for analysis is about 600 g with typical "Holocene" mixing ratios for CH4 and N2O. In this case, the reproducibility (1σ is 2.1‰ for δD(CH4, 0.18‰ for δ13C(CH4, 0.51‰ for δ15N(N2O, 0.69‰ for δ18O(N2O and 1.12‰ for δ15N(NO+ fragment. For smaller amounts of ice the standard deviation increases, particularly for N2O isotopologues. For both gases, small-scale intercalibrations using air and/or ice samples have been carried out in collaboration with other institutes that are currently involved in isotope measurements of ice core air. Significant differences are shown between the calibration scales, but those offsets are consistent and can therefore be corrected for.

  9. Past temperature reconstructions from deep ice cores: relevance for future climate change

    Directory of Open Access Journals (Sweden)

    V. Masson-Delmotte

    2006-01-01

    Full Text Available Ice cores provide unique archives of past climate and environmental changes based only on physical processes. Quantitative temperature reconstructions are essential for the comparison between ice core records and climate models. We give an overview of the methods that have been developed to reconstruct past local temperatures from deep ice cores and highlight several points that are relevant for future climate change. We first analyse the long term fluctuations of temperature as depicted in the long Antarctic record from EPICA Dome C. The long term imprint of obliquity changes in the EPICA Dome C record is highlighted and compared to simulations conducted with the ECBILT-CLIO intermediate complexity climate model. We discuss the comparison between the current interglacial period and the long interglacial corresponding to marine isotopic stage 11, ~400 kyr BP. Previous studies had focused on the role of precession and the thresholds required to induce glacial inceptions. We suggest that, due to the low eccentricity configuration of MIS 11 and the Holocene, the effect of precession on the incoming solar radiation is damped and that changes in obliquity must be taken into account. The EPICA Dome C alignment of terminations I and VI published in 2004 corresponds to a phasing of the obliquity signals. A conjunction of low obliquity and minimum northern hemisphere summer insolation is not found in the next tens of thousand years, supporting the idea of an unusually long interglacial ahead. As a second point relevant for future climate change, we discuss the magnitude and rate of change of past temperatures reconstructed from Greenland (NorthGRIP and Antarctic (Dome C ice cores. Past episodes of temperatures above the present-day values by up to 5°C are recorded at both locations during the penultimate interglacial period. The rate of polar warming simulated by coupled climate models forced by a CO2 increase of 1% per year is compared to ice-core

  10. 30-Year Satellite Record Reveals Accelerated Arctic Sea Ice Loss, Antarctic Sea Ice Trend Reversal

    Science.gov (United States)

    Cavalieri, Donald J.; Parkinson, C. L.; Vinnikov, K. Y.

    2003-01-01

    Arctic sea ice extent decreased by 0.30 plus or minus 0.03 x 10(exp 6) square kilometers per decade from 1972 through 2002, but decreased by 0.36 plus or minus 0.05 x 10(exp 6) square kilometers per decade from 1979 through 2002, indicating an acceleration of 20% in the rate of decrease. In contrast to the Arctic, the Antarctic sea ice extent decreased dramatically over the period 1973-1977, then gradually increased, with an overall 30-year trend of -0.15 plus or minus 0.08 x 10(exp 6) square kilometers per 10yr. The trend reversal is attributed to a large positive anomaly in Antarctic sea ice extent observed in the early 1970's.

  11. Towards understanding North Pacific climate variabilty with instrumental and ice core records

    Science.gov (United States)

    Kelsey, Eric P.

    Reconstructing climate variability prior to the instrumental era is critical to advance our understanding of the Earth's climate system. Although many paleoclimate records from the North Atlantic basin have been studied, relatively few paleoclimate records have been recovered in the North Pacific leaving a gap in our knowledge concerning North Pacific climate variability. The Eclipse and Mount Logan Prospector-Russell ice cores are favorably located in the St. Elias Mountains, Yukon, Canada to document North Pacific climate variability over the late Holocene. Detailed analysis reveals a consistent relationship of surface air temperature (SAT) anomalies associated with extreme Arctic Oscillation (AO) and Pacific-North America (PNA) index values, and a consistent relationship of North Pacific sea level pressure (SLP) anomalies associated with extreme Mt. Logan annual [Na+] and Eclipse cold season accumulation values. Spatial SAT anomaly patterns are most consistent for AO and PNA index values ≥1.5 and ≤-1.5 during the period 1872-2010. The highest and lowest ˜10% of Eclipse warm and cold season stable isotopes are associated with distinct atmospheric circulation patterns. The most-fractionated isotope values occur with a weaker Aleutian Low, and the least-fractionated isotope values occur with an amplification of the Aleutian Low and northwestern North American ridge. The assumption of stationarity between ice core records and sea-level pressure was tested for the Eclipse cold season accumulation and Mt. Logan annual sodium concentration records for 1872-2001. A stationary relationship was found for ≥95% of years when Mt. Logan sodium concentrations were ≤1.32 microg/L, with positive SLP anomalies in the eastern North Pacific. This high frequency supports the use of low sodium values at Mt. Logan for a reconstruction of SLP prior to 1872. Negative SLP anomalies in the North Pacific occurred for extreme high sodium concentration years and positive SLP

  12. A new ice core proxy of continental weathering and its feedback with atmospheric CO2

    Science.gov (United States)

    Schmitt, J.; Seth, B.; Köhler, P.; Willenbring, J. K.; Fischer, H.

    2012-04-01

    The analysis of CO2 and its stable carbon isotopes from ice cores revealed large changes of atmospheric CO2 which are closely related to a reorganisation of the global ocean circulation, marine processes and minor contributions in the terrestrial carbon storage. These components dominate the large CO2 amplitudes during glacial/interglacial terminations. Yet, on longer orbital time scales, CO2 is also modulated by the alkalinity of the ocean system. The net alkalinity influx to the ocean is driven by silicate weathering, which draws down atmospheric CO2 and provides alkalinity in the form of bicarbonate ions. Conversely, alkalinity is lost during coral reef growth and when CaCO3 is buried in marine sediments. On orbital time scales, these fluxes are assumed to be almost balanced as atmospheric CO2 and its climatic effects feed back on the weathering rates providing a negative feedback loop. Besides these basic concepts, little is known about the magnitude of weathering rate fluctuations on orbital time scales. To date, proxies from marine sediments and Fe-Mn crusts that faithfully record the ocean composition over glacial interglacial cycles do not quantify the total weathering fluxes to the ocean but only indicate that the style of weathering or the source area of sediment has changed. Due to large spatial heterogeneity, individual field site measurements do not elucidate global fluxes of weathering products to the ocean and how those might affect atmospheric CO2 concentrations. Here, we use a novel approach using the pptv-level trace gas CF4, which can be analysed in air trapped in ice cores. CF4 is a trace impurity in granites and other plutonic rocks, and during weathering this gas escapes into the atmosphere. In preindustrial times, weathering of granitic rocks was the only natural source of CF4. Because CF4 is inert to destruction processes in the tropo- and stratospheres, its only sink is destruction by UV radiation in the mesosphere. This chemical inertness

  13. Formation of Glycerol through Hydrogenation of CO Ice under Prestellar Core Conditions

    Science.gov (United States)

    Fedoseev, G.; Chuang, K.-J.; Ioppolo, S.; Qasim, D.; van Dishoeck, E. F.; Linnartz, H.

    2017-06-01

    Observational studies reveal that complex organic molecules (COMs) can be found in various objects associated with different star formation stages. The identification of COMs in prestellar cores, i.e., cold environments in which thermally induced chemistry can be excluded and radiolysis is limited by cosmic rays and cosmic-ray-induced UV photons, is particularly important as this stage sets up the initial chemical composition from which ultimately stars and planets evolve. Recent laboratory results demonstrate that molecules as complex as glycolaldehyde and ethylene glycol are efficiently formed on icy dust grains via nonenergetic atom addition reactions between accreting H atoms and CO molecules, a process that dominates surface chemistry during the “CO freeze-out stage” in dense cores. In the present study we demonstrate that a similar mechanism results in the formation of the biologically relevant molecule glycerol—HOCH2CH(OH)CH2OH—a three-carbon-bearing sugar alcohol necessary for the formation of membranes of modern living cells and organelles. Our experimental results are fully consistent with a suggested reaction scheme in which glycerol is formed along a chain of radical-radical and radical-molecule interactions between various reactive intermediates produced upon hydrogenation of CO ice or its hydrogenation products. The tentative identification of the chemically related simple sugar glyceraldehyde—HOCH2CH(OH)CHO—is discussed as well. These new laboratory findings indicate that the proposed reaction mechanism holds much potential to form even more complex sugar alcohols and simple sugars.

  14. An ultra-clean technique for accurately analysing Pb isotopes and heavy metals at high spatial resolution in ice cores with sub-pg g(-1) Pb concentrations.

    Science.gov (United States)

    Burn, Laurie J; Rosman, Kevin J R; Candelone, Jean-Pierre; Vallelonga, Paul; Burton, Graeme R; Smith, Andrew M; Morgan, Vin I; Barbante, Carlo; Hong, Sungmin; Boutron, Claude F

    2009-02-23

    Measurements of Pb isotope ratios in ice containing sub-pg g(-1) concentrations are easily compromised by contamination, particularly where limited sample is available. Improved techniques are essential if Antarctic ice cores are to be analysed with sufficient spatial resolution to reveal seasonal variations due to climate. This was achieved here by using stainless steel chisels and saws and strict protocols in an ultra-clean cold room to decontaminate and section ice cores. Artificial ice cores, prepared from high purity water were used to develop and refine the procedures and quantify blanks. Ba and In, two other important elements present at pg g(-1) and fg g(-1) concentrations in Polar ice, were also measured. The final blank amounted to 0.2+/-0.2 pg of Pb with (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of 1.16+/-0.12 and 2.35+/-0.16, respectively, 1.5+/-0.4 pg of Ba and 0.6+/-2.0 fg of In, most of which probably originates from abrasion of the steel saws by the ice. The procedure was demonstrated on a Holocene Antarctic ice core section and was shown to contribute blanks of only approximately 5%, approximately 14% and approximately 0.8% to monthly resolved samples with respective Pb, Ba and In concentrations of 0.12 pg g(-1), 0.3 pg g(-1) and 2.3 fg g(-1). Uncertainties in the Pb isotopic ratio measurements were degraded by only approximately 0.2%.

  15. An ice-core-based record of biomass burning in the Arctic and Subarctic, 1750 1980

    Science.gov (United States)

    Whitlow, S.; Mayewski, P.; Dibb, J.; Holdsworth, G.; Twickler, M.

    1994-07-01

    Ammonium records from 3 ice cores, 20D and GISP2 (Greenland) and Mt. Logan (Yukon), covering the period from 1750 to the 1980s are analyzed. For each data set, samples with NH4+ concentrations greater than one standard deviation above the mean value also tend to be enriched in NO3 and K+, similar to the chemical composition of aerosols from aged biomass burning plumes. We believe the NH4+ spikes originate from biomass burning events. There is not a one to one correspondence between documented large fires and NH4+ spikes, nor are specific annual layers with elevated NH4+ concentrations often found in more than one core. However, frequency of NH4+ spikes increase during periods of more extensive and intensive biomass burning in the NH4+ source areas for the ice core sites. The 20D and GISP2 records are characterized by increased spike frequency from 1790 to 1810 and from 1830 to 1910. This latter time coincides with a period of increased biomass burning documented in the historical fire records for northern North America. In contrast to both Greenland ice core records, the Mt. Logan NH4+ record shows periods of increased spike frequency from 1770 1790, 1810 1830, 1850 1870 and 1930 1980. The poor agreement between the Mt. Logan record and the records from Greenland suggests that another source area, perhaps Siberia, may be the dominant summertime source area for NH4+ spikes in Mt. Logan snow.

  16. Recent climate tendencies on an East Antarctic ice shelf inferred from a shallow firn core network.

    Science.gov (United States)

    Schlosser, E; Anschütz, H; Divine, D; Martma, T; Sinisalo, A; Altnau, S; Isaksson, E

    2014-06-16

    Nearly three decades of stable isotope ratios and surface mass balance (SMB) data from eight shallow firn cores retrieved at Fimbul Ice Shelf, East Antarctica, in the Austral summers 2009-2011 have been investigated. An additional longer core drilled in 2000/2001 extends the series back to the early eighteenth century. Isotope ratios and SMB from the stacked record of all cores were also related to instrumental temperature data from Neumayer Station on Ekström Ice Shelf. Since the second half of the twentieth century, the SMB shows a statistically significant negative trend, whereas the δ(18)O of the cores shows a significant positive trend. No trend is found in air temperature at the nearest suitable weather station, Neumayer (available since 1981). This does not correspond to the statistically significant positive trend in Southern Annular Mode (SAM) index, which is usually associated with a cooling of East Antarctica. SAM index and SMB are negatively correlated, which might be explained by a decrease in meridional exchange of energy and moisture leading to lower precipitation amounts. Future monitoring of climate change on the sensitive Antarctic ice shelves is necessary to assess its consequences for sea level change.

  17. Applications of a rapid endospore viability assay for monitoring UV inactivation and characterizing arctic ice cores.

    Science.gov (United States)

    Shafaat, Hannah S; Ponce, Adrian

    2006-10-01

    We have developed a rapid endospore viability assay (EVA) in which endospore germination serves as an indicator for viability and applied it to (i) monitor UV inactivation of endospores as a function of dose and (ii) determine the proportion of viable endospores in arctic ice cores (Greenland Ice Sheet Project 2 [GISP2] cores; 94 m). EVA is based on the detection of dipicolinic acid (DPA), which is released from endospores during germination. DPA concentrations were determined using the terbium ion (Tb3+)-DPA luminescence assay, and germination was induced by L-alanine addition. The concentrations of germinable endospores were determined by comparison to a standard curve. Parallel EVA and phase-contrast microscopy experiments to determine the percentage of germinable spores yielded comparable results (54.3% +/- 3.8% and 48.9% +/- 4.5%, respectively), while only 27.8% +/- 7.6% of spores produced CFU. EVA was applied to monitor the inactivation of spore suspensions as a function of UV dose, yielding reproducible correlations between EVA and CFU inactivation data. The 90% inactivation doses were 2,773 J/m2, 3,947 J/m2, and 1,322 J/m2 for EVA, phase-contrast microscopy, and CFU reduction, respectively. Finally, EVA was applied to quantify germinable and total endospore concentrations in two GISP2 ice cores. The first ice core contained 295 +/- 19 germinable spores/ml and 369 +/- 36 total spores/ml (i.e., the percentage of germinable endospores was 79.9% +/- 9.3%), and the second core contained 131 +/- 4 germinable spores/ml and 162 +/- 17 total spores/ml (i.e., the percentage of germinable endospores was 80.9% +/- 8.8%), whereas only 2 CFU/ml were detected by culturing.

  18. Comparison of St. Elias Ice Core Accumulation Records and Their Relationships to Climate Indices

    Science.gov (United States)

    Yalcin, K.; Osterberg, E.; Mayewski, P.; Wake, C.; Kreutz, K.; Holdsworth, G.

    2006-12-01

    Recently recovered ice cores from the St Elias Mountains (Yukon) spanning an elevation range of three (Eclipse Icefield) to more than five kilometers (Mount Logan) offer a unique three-dimensional view of paleoclimate and environmental change in the North Pacific region. The record of net accumulation as deduced from the reconstruction of observed annual layer thicknesses in these cores offers a direct view of moisture flux at various altitudes in the St. Elias. However, a potentially large uncertainty in the representativeness of ice core accumulation records exists due to spatial variability in snow accumulation rates. The availability of multiple cores allows us to address this issue. Accumulation records from Eclipse (three cores) are highly reproducible with 78% of the signal shared between the three cores. The proportion of shared signal between accumulation records from the Logan plateau (Prospector-Russell Col and Northwest Col) is lower (52%). In this work we will compare the Eclipse and Logan accumulation records to each other to understand the spatial variability in net accumulation over time at different altitudes. The possible influence of dating errors on these results will be explored using leads and lags of 1-2 years. We also compare our accumulation records to indices of atmospheric circulation (e.g., strength of the Aleutian Low, the Pacific Decadal Oscillation, the El-Nino Southern Oscillation, Arctic Oscillation) to quantify relationships between snow accumulation and large-scale atmospheric circulation features on time-scales of variability ranging from years to centuries.

  19. Depletion of chlorine into HCl ice in a protostellar core

    CERN Document Server

    Kama, M; Lopez-Sepulcre, A; Wakelam, V; Dominik, C; Ceccarelli, C; Lanza, M; Lique, F; Ochsendorf, B B; Lis, D C; Caballero, R N; Tielens, A G G M

    2014-01-01

    The freezeout of gas-phase species onto cold dust grains can drastically alter the chemistry and the heating-cooling balance of protostellar material. In contrast to well-known species such as carbon monoxide (CO), the freezeout of various carriers of elements with abundances $<10^{-5}$ has not yet been well studied. Our aim here is to study the depletion of chlorine in the protostellar core, OMC-2 FIR 4. We observed transitions of HCl and H2Cl+ towards OMC-2 FIR 4 using the Herschel Space Observatory and Caltech Submillimeter Observatory facilities. Our analysis makes use of state of the art chlorine gas-grain chemical models and newly calculated HCl-H$_{2}$ hyperfine collisional excitation rate coefficients. A narrow emission component in the HCl lines traces the extended envelope, and a broad one traces a more compact central region. The gas-phase HCl abundance in FIR 4 is 9e-11, a factor of only 0.001 that of volatile elemental chlorine. The H2Cl+ lines are detected in absorption and trace a tenuous fo...

  20. Ice cores record significant 1940s Antarctic warmth related to tropical climate variability.

    Science.gov (United States)

    Schneider, David P; Steig, Eric J

    2008-08-26

    Although the 20th Century warming of global climate is well known, climate change in the high-latitude Southern Hemisphere (SH), especially in the first half of the century, remains poorly documented. We present a composite of water stable isotope data from high-resolution ice cores from the West Antarctic Ice Sheet. This record, representative of West Antarctic surface temperature, shows extreme positive anomalies in the 1936-45 decade that are significant in the context of the background 20th Century warming trend. We interpret these anomalies--previously undocumented in the high-latitude SH--as indicative of strong teleconnections in part driven by the major 1939-42 El Niño. These anomalies are coherent with tropical sea-surface temperature, mean SH air temperature, and North Pacific sea-level pressure, underscoring the sensitivity of West Antarctica's climate, and potentially its ice sheet, to large-scale changes in the global climate.

  1. Link of volcanic activity and climate change in Altai studied in the ice core from Belukha Mountain

    OpenAIRE

    N. S. Malygina; T. V. Barlyaeva; T. S. Papina

    2013-01-01

    In the present research we discuss a role of volcanic activity in Altai thermal regime. Here we analyses the sulfate and temperature data reconstructed from the natural paleoarchive – ice core from the Belukha Mountain saddle. Sulfate ice-core reconstructions can serve as volcanic markers. The both – sulfate and temperature reconstructions – are for the last 750 years. As the characteristic of volcanic activity we consider Volcanic Explosivity Index (VEI), Dust Veil Index (DVI) and Ice core v...

  2. Post-depositional migration and signal reconstruction of methanesulfonic acid (MSA) in polar ice cores

    Science.gov (United States)

    Osman, Matthew; Das, Sarah B.; Marchal, Olivier; Evans, Matthew J.

    2017-04-01

    Methanesulfonic acid (MSA; CH3SO3H) in polar ice cores is a unique proxy of marine primary productivity, synoptic atmospheric transport, and regional sea ice behavior. However, MSA can be unstable within the ice column, leading to uncertainties surrounding the integrity of its paleoclimatic signal. Here, we use ice core records coupled with forward and inverse numerical models to investigate the post-depositional processes affecting the migration of MSA within the firn and ice column, and attempt to reconstruct the original signal in the ice column. The forward model, detailing the vertical diffusive transport of soluble impurities through supercooled liquid pathways, allows us to systematically assess the contribution of varying influences on the post-depositional migration of MSA. Our results show that two site-specific variables in particular, i) snow accumulation rate, and ii) seasonal concentration gradients of Na+(typically the highest concentration sea salt), may be sufficient to reasonably predict the timing and magnitude of MSA migration within the ice column. However, at present the temporal accuracy of the forward MSA migration model remains limited by inadequate constraints on the diffusion coefficient of MSA, DMS-. Specifically, we find that previous estimates of DMS-are unable to reproduce, within significant uncertainty, the progressive phase alignment of the MSA and Na+signals observed in real Antarctic ice cores. To attempt to correct for the effects of post-depositional migration, we combine recent high-resolution West Antarctic MSA data using sequential methods from optimal control theory (a Kalman filter and a related fixed-interval smoother) to reconstruct and provide uncertainty estimates on the original, pre-migrated MSA profile. We find that although the reconstructed MSA profile provides a reasonable estimate of the original MSA signal, the large uncertainties associated with this reconstructed signal cannot be objectively discriminated

  3. The Southern Hemisphere at glacial terminations: insights from the Dome C ice core

    Directory of Open Access Journals (Sweden)

    R. Röthlisberger

    2008-12-01

    Full Text Available The many different proxy records from the European Project for Ice Coring in Antarctica (EPICA Dome C ice core allow for the first time a comparison of nine glacial terminations in great detail. Despite the fact that all terminations cover the transition from a glacial maximum into an interglacial, there are large differences between single terminations. For some terminations, Antarctic temperature increased only moderately, while for others, the amplitude of change at the termination was much larger. For the different terminations, the rate of change in temperature is more similar than the magnitude or duration of change. These temperature changes were accompanied by vast changes in dust and sea salt deposition all over Antarctica.

    Here we investigate the phasing between a South American dust proxy (non-sea-salt calcium flux, nssCa2+, a sea ice proxy (sea salt sodium flux, ssNa+ and a proxy for Antarctic temperature (deuterium, δD. In particular, we look into whether a similar sequence of events applies to all terminations, despite their different characteristics. All proxies are derived from the EPICA Dome C ice core, resulting in a relative dating uncertainty between the proxies of less than 20 years.

    At the start of the terminations, the temperature (δD increase and dust (nssCa2+ flux decrease start synchronously. The sea ice proxy (ssNa+ flux, however, only changes once the temperature has reached a particular threshold, approximately 5°C below present day temperatures (corresponding to a δD value of −420‰. This reflects to a large extent the limited sensitivity of the sea ice proxy during very cold periods with large sea ice extent. At terminations where this threshold is not reached (TVI, TVIII, ssNa+ flux shows no changes. Above this threshold, the sea ice proxy is closely coupled to the Antarctic temperature, and interglacial levels are reached at the same

  4. The southern hemisphere at glacial terminations: insights from the Dome C ice core

    Directory of Open Access Journals (Sweden)

    R. Röthlisberger

    2008-06-01

    Full Text Available The many different proxy records from the European Project for Ice Coring in Antarctica (EPICA Dome C ice core allow for the first time a comparison of nine glacial terminations in great detail. Despite the fact that all terminations cover the transition from a glacial maximum into an interglacial, there are large differences between single terminations. For some terminations, Antarctic temperature increased only moderately, while for others, the amplitude of change at the termination was much larger. For the different terminations, the rate of change in temperature is more similar than the magnitude or duration of change. These temperature changes were accompanied by vast changes in dust and sea salt deposition all over Antarctica.

    Here we investigate the phasing between a South American dust proxy (non-sea-salt calcium flux, nssCa, a sea ice proxy (sea salt sodium flux, ssNa and a proxy for Antarctic temperature (deuterium, δD. In particular, we look into whether a similar sequence of events applies to all terminations, despite their different characteristics. All proxies are derived from the EPICA Dome C ice core, resulting in a relative dating uncertainty between the proxies of less than 20 years.

    At the start of the terminations, the temperature (δD increase and dust (nssCa flux decrease start synchronously. The sea ice proxy (ssNa flux, however, only changes once the temperature has reached a particular threshold, approximately 5°C below present day temperatures (corresponding to a δD value of –420‰. This reflects to a large extent the limited sensitivity of the sea ice proxy during very cold periods with large sea ice extent. At terminations where this threshold is not reached (TVI, TVIII, ssNa flux shows no changes. Above this threshold, the sea ice proxy is closely coupled to the Antarctic temperature, and interglacial levels are reached at the same time for both ssNa and δD.

  5. Sensitivity of interglacial Greenland temperature and δ18O to orbital and CO2 forcing: climate simulations and ice core data

    Directory of Open Access Journals (Sweden)

    J. Sjolte

    2011-05-01

    results implies that other mechanisms could also play a role. This suggests that further simulations and detailed inter-model comparisons are also likely to be of benefit. Comparisons with Greenland ice core stable isotope data reveals that IPSL/LMDZiso simulations strongly underestimate the amplitude of the ice core signal during the last interglacial, which could reach +8–10 °C at fixed-elevation. While the model-data mismatch may result from missing positive feedbacks (e.g. vegetation, it could also be explained by a reduced elevation of the central Greenland ice sheet surface by 300–400 m.

  6. Post-depositional migration and preservation of methanesulfonic acid (MSA) in polar ice cores

    Science.gov (United States)

    Osman, M.; Marchal, O.; Guo, W.; Das, S. B.; Evans, M. J.

    2015-12-01

    Methanesulfonic acid (MSA; CH3SO3-) in ice cores is a unique, high-resolution proxy of regional sea ice behavior, marine primary productivity, and synoptic climatology. Significant uncertainties remain, however, in both our understanding of the production and transfer of MSA to the ice sheet, as well as its preservation over time, compromising the paleoclimatological utility of the proxy. Here we apply a numerical modeling approach to quantitatively investigate the post-depositional processes affecting MSA migration and preservation within the firn and ice column, building on recent observational and theoretical studies. Our model allows us to evaluate the timing and magnitude of the vertical movement of MSA in response to varying influences, including the competing effects of 1) concentration gradients of sea-salts typically deposited asynchronously to MSA, 2) snow accumulation and densification rates, and 3) in situ temperature gradients. We first test the model against a recently collected ice core from a high accumulation site in coastal West Antarctica, where monthly-resolved MSA records show an abrupt shift from a summer-to-winter maximum in MSA at ~23m depth (ρ ≈ 650 kg/m3), near the firn-ice transition. We find our model to be a robust predictor of the observed migrational features in this record, capturing both (i) the abrupt shift in summer-to-winter maximal concentrations of MSA (steady state ≈ 3.2 yrs), and (ii) the depression of the seasonal amplitude at depth. Further, our modeling results suggest post-depositional effects can lead to substantial interannual alteration of the MSA signal, contrary to previous assumptions that MSA migration is confined within annual layers at high accumulation sites. Using a broad range of polar MSA records and their associated, site-specific environmental conditions, we will evaluate the fidelity of subannual to interannual variability of MSA records and systematically determine the factors conducive to its

  7. Multilayer formation and evaporation of deuterated ices in prestellar and protostellar cores

    Energy Technology Data Exchange (ETDEWEB)

    Taquet, Vianney; Charnley, Steven B. [Astrochemistry Laboratory and The Goddard Center for Astrobiology, Mailstop 691, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20770 (United States); Sipilä, Olli [Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki (Finland)

    2014-08-10

    Extremely large deuteration of several molecules has been observed toward prestellar cores and low-mass protostars for a decade. New observations performed toward low-mass protostars suggest that water presents a lower deuteration in the warm inner gas than in the cold external envelope. We coupled a gas-grain astrochemical model with a one-dimensional model of a collapsing core to properly follow the formation and the deuteration of interstellar ices as well as their subsequent evaporation in the low-mass protostellar envelopes with the aim of interpreting the spatial and temporal evolutions of their deuteration. The astrochemical model follows the formation and the evaporation of ices with a multilayer approach and also includes a state-of-the-art deuterated chemical network by taking the spin states of H{sub 2} and light ions into account. Because of their slow formation, interstellar ices are chemically heterogeneous and show an increase of their deuterium fractionation toward the surface. The differentiation of the deuteration in ices induces an evolution of the deuteration within protostellar envelopes. The warm inner region is poorly deuterated because it includes the whole molecular content of ices, while the deuteration predicted in the cold external envelope scales with the highly deuterated surface of ices. We are able to reproduce the observed evolution of water deuteration within protostellar envelopes, but we are still unable to predict the super-high deuteration observed for formaldehyde and methanol. Finally, the extension of this study to the deuteration of complex organics, important for the prebiotic chemistry, shows good agreement with the observations, suggesting that we can use the deuteration to retrace their mechanisms and their moments of formation.

  8. Anthropogenic signals recorded in an ice core from Eclipse Icefield, Yukon Territory, Canada

    Science.gov (United States)

    Yalcin, Kaplan; Wake, Cameron P.

    Trends in the annual flux of sulfate and nitrate in a new ice core collected at an elevation of 3017 m on Eclipse Icefield, 45 km northeast of Mt. Logan were examined to determine the effect of anthropogenic activity on precipitation chemistry in the remote northwest North America mid-troposphere. The annual flux of both sulfate and nitrate at Eclipse began increasing in the 1940s, demonstrating, for the first time, the anthropogenic sulfate and nitrate pollution of the northwest North American Arctic in an ice core from this region. Comparison of the Eclipse record with regional emission estimates for total sulfur and nitrogen oxides suggests that Eurasia is the dominant source of pollutants reaching Eclipse. The available data does not permit a confident assessment of the relative importance of European versus Soviet emissions in producing the observed trends in sulfate and nitrate at Eclipse.

  9. Long memory effect of past climate change in Vostok ice core records

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Yuuki, E-mail: yyama@ed.yama.tus.ac.jp [Department of Mechanical Engineering, Tokyo University of Science, Yamaguchi (Japan); Kitahara, Naoki [Department of Electronics and Computer Science, Tokyo University of Science, Yamaguchi (Japan); Kano, Makoto [Department of Mechanical Engineering, Tokyo University of Science, Yamaguchi (Japan)

    2012-03-20

    Time series analysis of Vostok ice core data has been done for understanding of palaeoclimate change from a stochastic perspective. The Vostok ice core is one of the proxy data for palaeoclimate in which local temperature and precipitation rate, moisture source conditions, wind strength and aerosol fluxes of marine, volcanic, terrestrial, cosmogenic and anthropogenic origin are indirectly stored. Palaeoclimate data has a periodic feature and a stochastic feature. For the proxy data, spectrum analysis and detrended fluctuation analysis (DFA) were conducted to characterize periodicity and scaling property (long memory effect) in the climate change. The result of spectrum analysis indicates there exist periodicities corresponding to the Milankovitch cycle in past climate change occurred. DFA clarified time variability of scaling exponents (Hurst exponent) is associated with abrupt warming in past climate.

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The concentrations of CH4 in the atmosphere over the past 2000 years have been deduced by extracting and analyzing the air in bubbles embedded in the Dasuopu ice core, Qinghai-Tibetan Plateau. Upon analyzing 57 ice core samples we found that the concentration of CH4 200 years ago and earlier was 0.85 m mol·mol-1 or about 40% of present atmospheric CH4 levels over Qinghai-Tibetan Plateau. A rapid and significant increase of atmospheric CH4 started about 200-250 a ago. For a given age before 19th century, the Dasuopu CH4 concentrations were about 15%-20% higher than those in Antarctic and Greenland references. It was also found that the Dasuopu CH4 concentrations changed more frequently, and its fluctuations could reflect the temperature change sensitively.

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

    Science.gov (United States)

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

    2014-05-01

    Microstructure analysis of ice cores is vital to understand the processes controlling the flow of ice on the microscale. To quantify the microstructural variability (and thus occurring processes) on centimeter, meter and kilometer scale along deep polar ice cores, a large number of sections has to be analyzed. In the last decade, two different methods have been applied: On the one hand, transmission optical microscopy of thin sections between crossed polarizers yields information on the distribution of crystal c-axes. On the other hand, reflection optical microscopy of polished and controlled sublimated section surfaces allows to characterize the high resolution properties of a single grain boundary, e.g. its length, shape or curvature (further developed by [1]). Along the entire NEEM ice core (North-West Greenland, 2537 m length) drilled in 2008-2011 we applied both methods to the same set of vertical sections. The data set comprises series of six consecutive 6 x 9 cm2 sections in steps of 20 m - in total about 800 images. A dedicated method for automatic processing and matching both image types has recently been developed [2]. The high resolution properties of the grain boundary network are analyzed. Furthermore, the automatic assignment of c-axis misorientations to visible sublimation grooves enables us to quantify the degree of similarity between the microstructure revealed by both analysis techniques. The reliability to extract grain boundaries from both image types as well as the appearance of sublimation groove patterns exhibiting low misorientations is investigated. X-ray Laue diffraction measurements (yielding full crystallographic orientation) have validated the sensitivity of the surface sublimation method for sub-grain boundaries [3]. We introduce an approach for automatic extraction of sub-grain structures from sublimation grooves. A systematic analysis of sub-grain boundary densities indicates a possible influence of high impurity contents (amongst

  12. Search for sterile neutrinos with IceCube DeepCore

    Energy Technology Data Exchange (ETDEWEB)

    Terliuk, Andrii [DESY, Platanenallee 6, 15738 Zeuthen (Germany); Collaboration: IceCube-Collaboration

    2016-07-01

    The DeepCore detector is a sub-array of the IceCube Neutrino Observatory that lowers the energy threshold for neutrino detection down to approximately 10 GeV. DeepCore is used for a variety of studies including atmospheric neutrino oscillations. The standard three-neutrino oscillation paradigm is tested using the DeepCore detector by searching for an additional light, sterile neutrino with a mass on the order of 1 eV. Sterile neutrinos do not interact with the ordinary matter, however they can be mixed with the three active neutrino states. Such mixture changes the picture of standard neutrino oscillations for atmospheric neutrinos with energies below 100 GeV. The capabilities of DeepCore detector to measure such sterile neutrino mixing will be presented in this talk.

  13. Constraining recent lead pollution sources in the North Pacific using ice core stable lead isotopes

    Science.gov (United States)

    Gross, B. H.; Kreutz, K. J.; Osterberg, E. C.; McConnell, J. R.; Handley, M.; Wake, C. P.; Yalcin, K.

    2012-08-01

    Trends and sources of lead (Pb) aerosol pollution in the North Pacific rim of North America from 1850 to 2001 are investigated using a high-resolution (subannual to annual) ice core record recovered from Eclipse Icefield (3017 masl; St. Elias Mountains, Canada). Beginning in the early 1940s, increasing Pb concentration at Eclipse Icefield occurs coevally with anthropogenic Pb deposition in central Greenland, suggesting that North American Pb pollution may have been in part or wholly responsible in both regions. Isotopic ratios (208Pb/207Pb and 206Pb/207Pb) from 1970 to 2001 confirm that a portion of the Pb deposited at Eclipse Icefield is anthropogenic, and that it represents a variable mixture of East Asian (Chinese and Japanese) emissions transported eastward across the Pacific Ocean and a North American component resulting from transient meridional atmospheric flow. Based on comparison with source material Pb isotope ratios, Chinese and North American coal combustion have likely been the primary sources of Eclipse Icefield Pb over the 1970-2001 time period. The Eclipse Icefield Pb isotope composition also implies that the North Pacific mid-troposphere is not directly impacted by transpolar atmospheric flow from Europe. Annually averaged Pb concentrations in the Eclipse Icefield ice core record show no long-term trend during 1970-2001; however, increasing208Pb/207Pb and decreasing 206Pb/207Pb ratios reflect the progressive East Asian industrialization and increase in Asian pollutant outflow. The post-1970 decrease in North American Pb emissions is likely necessary to explain the Eclipse Icefield Pb concentration time series. When compared with low (lichen) and high (Mt. Logan ice core) elevation Pb data, the Eclipse ice core record suggests a gradual increase in pollutant deposition and stronger trans-Pacific Asian contribution with rising elevation in the mountains of the North Pacific rim.

  14. Re-evaluating the 1257 AD eruption using annually-resolved ice core chemical analyses

    Science.gov (United States)

    Simonsen, M. F.; Kjær, H. A.; Vallelonga, P. T.; Neff, P. D.; Bertler, N. A. N.; Svensson, A.; Seierstad, I.; Albert, P. G.; Bourne, A. J.; Kurbatov, A.

    2014-12-01

    The source of the 1257 AD volcanic eruption has recently been proposed to be Samalas in Indonesia. The eruption was one of the largest of the Holocene and has been recorded in ice cores in both hemispheres from sulfate and acidity measurements. The estimate of its sulfate load varies from 2 to 8 times that of Tambora. This is also the only volcano for which tephras have been assigned in ice cores from both Antarctica and Greenland (GISP2). Due to this unique assignment of a bipolar tephra layer in ice cores, the origins of the sulfate and tephras have been disputed and it has been proposed that at least one of the tephras was due to an additional volcanic eruption local to either Greenland or Antarctica. We have re-evaluated the acid and tephra deposition from the 1257 AD volcano in two ice cores, one from Greenland (NGRIP. 75.1° N, 42.3° W) and one from Antarctica (RICE, Roosevelt Island. 79.36° S, -161.71° W). Annually-resolved continuous flow analysis (CFA) measurements determined relevant parameters such as melt water conductivity, sulphate and acidity. The acidity peak at RICE (~20 uM H+) is approximately double that found at NGRIP (10 uM H+). The only visible tephra layer found in the corresponding depth range was deposited at 1250 AD, 9 years before the acidity peak. The high resolution of the data offers a precise evaluation of the delay between the deposition of tephra and acid (sulfate) in each hemisphere. The comparison between poles allows some evaluation of the spread of deposition from the volcanic eruption.

  15. Effects of sudden mixing in the solar core on solar neutrinos and ice ages.

    Science.gov (United States)

    Ezer, D.; Cameron, A. G. W.

    1972-01-01

    Some numerical experiments with a solar model have been conducted in connection with the hypothesis regarding the effects of mixing in the solar core. Questions concerning a plausible mechanism by which such a mixing could be produced are explored. The variation of solar luminosity throughout the numerical experiments is shown. In connection with a great change in luminosity after a second mixing, it is suggested that the earth is presently undergoing an ice age.

  16. A High-Resolution Continuous Flow Analysis System for Polar Ice Cores

    DEFF Research Database (Denmark)

    Dallmayr, Remi; Goto-Azuma, Kumiko; Kjær, Helle Astrid;

    2016-01-01

    of Polar Research (NIPR) in Tokyo. The system allows the continuous analysis of stable water isotopes and electrical conductivity, as well as the collection of discrete samples from both inner and outer parts of the core. This CFA system was designed to have sufficiently high temporal resolution to detect......In recent decades, the development of continuous flow analysis (CFA) technology for ice core analysis has enabled greater sample throughput and greater depth resolution compared with the classic discrete sampling technique. We developed the first Japanese CFA system at the National Institute...

  17. Isotopic composition of the ice cores obtained on the Western Plateau of the Mt Elbrus

    Directory of Open Access Journals (Sweden)

    A. V. Kozachek

    2015-01-01

    Full Text Available The results of the isotopic investigations of several ice cores obtained at the Western Plateau of Mt. Elbrus (the Caucasus are presented. There is a distinct seasonal cycle in the isotopic composition record in these cores. Mean annual and seasonal values of the isotopic composition and accumulation rate were reconstructed for 89 years (1924–2012. These values were compared with the available regional meteorological data and the atmospheric circulation characteristics. It was shown that in the summer season the isotopic composition reflects the local temperature while in winter it depends on the atmospheric circulation.

  18. Events of abrupt change ofIndian monsoon recorded in Dasuopu ice core fromHimalayas

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Three ice cores distributed across Dasuopu glacier in Himalayas were recovered. A 400-year net annual accumulation record reconstructed from one of the cores reflects the major precipitation trend in the central Himalayas. This record is related closely to the Indian monsoon precipitation. Wavelet and moving T-test were applied to the 400-year-long Dasuopu accumulation record, and significant staggered variability and abrupt change of the record on interannual to centennial time scales are identified. Finally the possible reason for abrupt change of the accumulation record is discussed.

  19. Measurement of neutrino oscillations in atmospheric neutrinos with the IceCube DeepCore detector

    Energy Technology Data Exchange (ETDEWEB)

    Yanez Garza, Juan Pablo

    2014-06-02

    The study of neutrino oscillations is an active field of research. During the last couple of decades many experiments have measured the effects of oscillations, pushing the field from the discovery stage towards an era of precision and deeper understanding of the phenomenon. The IceCube Neutrino Observatory, with its low energy subarray, DeepCore, has the possibility of contributing to this field. IceCube is a 1 km{sup 3} ice Cherenkov neutrino telescope buried deep in the Antarctic glacier. DeepCore, a region of denser instrumentation in the lower center of IceCube, permits the detection of neutrinos with energies as low as 10 GeV. Every year, thousands of atmospheric neutrinos around these energies leave a strong signature in DeepCore. Due to their energy and the distance they travel before being detected, these neutrinos can be used to measure the phenomenon of oscillations. This work starts with a study of the potential of IceCube DeepCore to measure neutrino oscillations in different channels, from which the disappearance of ν{sub μ} is chosen to move forward. It continues by describing a novel method for identifying Cherenkov photons that traveled without being scattered until detected direct photons. These photons are used to reconstruct the incoming zenith angle of muon neutrinos. The total energy of the interacting neutrino is also estimated. In data taken in 343 days during 2011-2012, 1487 neutrino candidates with an energy between 7 GeV and 100 GeV are found inside the DeepCore volume. Compared to the expectation from the atmospheric neutrino flux without oscillations, this corresponds to a deficit of about 500 muon neutrino events. The oscillation parameters that describe the data best are sin{sup 2}(2θ{sub 23})=1(>0.94 at 68 % C.L.) and vertical stroke Δm{sup 2}{sub 32} vertical stroke =2.4{sub -0.4}{sup +0.6}.10{sup -3} eV{sup 2}, which are in agreement with the results reported by other experiments. The simulation follows the data closely

  20. Continuous flow analysis method for determination of dissolved reactive phosphorus in ice cores.

    Science.gov (United States)

    Kjær, Helle Astrid; Vallelonga, Paul; Svensson, Anders; Kristensen, Magnus Elleskov L; Tibuleac, Catalin; Bigler, Matthias

    2013-01-01

    Phosphorus (P) is an essential macronutrient for all living organisms. Phosphorus is often present in nature as the soluble phosphate ion PO4(3-) and has biological, terrestrial, and marine emission sources. Thus PO4(3-) detected in ice cores has the potential to be an important tracer for biological activity in the past. In this study a continuous and highly sensitive absorption method for detection of dissolved reactive phosphorus (DRP) in ice cores has been developed using a molybdate reagent and a 2-m liquid waveguide capillary cell (LWCC). DRP is the soluble form of the nutrient phosphorus, which reacts with molybdate. The method was optimized to meet the low concentrations of DRP in Greenland ice, with a depth resolution of approximately 2 cm and an analytical uncertainty of 1.1 nM (0.1 ppb) PO4(3-). The method has been applied to segments of a shallow firn core from Northeast Greenland, indicating a mean concentration level of 2.74 nM (0.26 ppb) PO4(3-) for the period 1930-2005 with a standard deviation of 1.37 nM (0.13 ppb) PO4(3-) and values reaching as high as 10.52 nM (1 ppb) PO4(3-). Similar levels were detected for the period 1771-1823. Based on impurity abundances, dust and biogenic particles were found to be the most likely sources of DRP deposited in Northeast Greenland.

  1. A brief history of ice core science over the last 50 yr

    Science.gov (United States)

    Jouzel, J.

    2013-11-01

    For about 50 yr, ice cores have provided a wealth of information about past climatic and environmental changes. Ice cores from Greenland, Antarctica and other glacier-covered regions now encompass a variety of time scales. However, the longer time scales (e.g. at least back to the Last Glacial period) are covered by deep ice cores, the number of which is still very limited: seven from Greenland, with only one providing an undisturbed record of a part of the last interglacial period, and a dozen from Antarctica, with the longest record covering the last 800 000 yr. This article aims to summarize this successful adventure initiated by a few pioneers and their teams and to review key scientific results by focusing on climate (in particular water isotopes) and climate-related (e.g. greenhouse gases) reconstructions. Future research is well taken into account by the four projects defined by IPICS. However, it remains a challenge to get an intact record of the Last Interglacial in Greenland and to extend the Antarctic record through the mid-Pleistocene transition, if possible back to 1.5 Ma.

  2. 9,400 years of cosmic radiation and solar activity from ice cores and tree rings.

    Science.gov (United States)

    Steinhilber, Friedhelm; Abreu, Jose A; Beer, Jürg; Brunner, Irene; Christl, Marcus; Fischer, Hubertus; Heikkilä, Ulla; Kubik, Peter W; Mann, Mathias; McCracken, Ken G; Miller, Heinrich; Miyahara, Hiroko; Oerter, Hans; Wilhelms, Frank

    2012-04-17

    Understanding the temporal variation of cosmic radiation and solar activity during the Holocene is essential for studies of the solar-terrestrial relationship. Cosmic-ray produced radionuclides, such as (10)Be and (14)C which are stored in polar ice cores and tree rings, offer the unique opportunity to reconstruct the history of cosmic radiation and solar activity over many millennia. Although records from different archives basically agree, they also show some deviations during certain periods. So far most reconstructions were based on only one single radionuclide record, which makes detection and correction of these deviations impossible. Here we combine different (10)Be ice core records from Greenland and Antarctica with the global (14)C tree ring record using principal component analysis. This approach is only possible due to a new high-resolution (10)Be record from Dronning Maud Land obtained within the European Project for Ice Coring in Antarctica in Antarctica. The new cosmic radiation record enables us to derive total solar irradiance, which is then used as a proxy of solar activity to identify the solar imprint in an Asian climate record. Though generally the agreement between solar forcing and Asian climate is good, there are also periods without any coherence, pointing to other forcings like volcanoes and greenhouse gases and their corresponding feedbacks. The newly derived records have the potential to improve our understanding of the solar dynamics and to quantify the solar influence on climate.

  3. Interpreting H2O isotope variations in high-altitude ice cores using a cyclone model

    Science.gov (United States)

    Holdsworth, Gerald

    2008-04-01

    Vertical profiles of isotope (δ18O or δD) values versus altitude (z) from sea level to high altitude provide a link to cyclones, which impact most ice core sites. Cyclonic structure variations cause anomalous variations in ice core δ time series which may obscure the basic temperature signal. Only one site (Mount Logan, Yukon) provides a complete δ versus z profile generated solely from data. At other sites, such a profile has to be constructed by supplementing field data. This requires using the so-called isotopic or δ thermometer which relates δ to a reference temperature (T). The construction of gapped sections of δ versus z curves requires assuming a typical atmospheric lapse rate (dT/dz), where T is air temperature, and using the slope (dδ/dT) of a site-derived δ thermometer to calculate dδ/dz. Using a three-layer model of a cyclone, examples are given to show geometrically how changes in the thickness of the middle, mixed layer leads to the appearance of anomalous δ values in time series (producing decalibration of the δ thermometer there). The results indicate that restrictions apply to the use of the δ thermometer in ice core paleothermometry, according to site altitude, regional meteorology, and climate state.

  4. Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period

    National Research Council Canada - National Science Library

    Capron, E; Landais, A; Chappellaz, J; Schilt, A; Buiron, D; Dahl-Jensen, D; Johnsen, S. J; Jouzel, J; Lemieux-Dudon, B; Loulergue, L; Leuenberger, M; Masson-Delmotte, V; Meyer, H; Oerter, H; Stenni, B

    2010-01-01

    Since its discovery in Greenland ice cores, the millennial scale climatic variability of the last glacial period has been increasingly documented at all latitudes with studies focusing mainly on Marine Isotopic Stage 3 (MIS 3...

  5. Archive of Geosample Data and Information from the University of Wisconsin Ice Island T3 Core Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — From 1963 to 1972, 349 piston cores were collected from the Arctic Ocean using Ice Island T3 as a sampling platform and sent to the University of Wisconsin-Madison...

  6. Comparative evaluation of the indigenous microbial diversity vs. drilling fluid contaminants in the NEEM Greenland ice core.

    Science.gov (United States)

    Miteva, Vanya; Burlingame, Caroline; Sowers, Todd; Brenchley, Jean

    2014-08-01

    Demonstrating that the detected microbial diversity in nonaseptically drilled deep ice cores is truly indigenous is challenging because of potential contamination with exogenous microbial cells. The NEEM Greenland ice core project provided a first-time opportunity to determine the origin and extent of contamination throughout drilling. We performed multiple parallel cultivation and culture-independent analyses of five decontaminated ice core samples from different depths (100-2051 m), the drilling fluid and its components Estisol and Coasol, and the drilling chips collected during drilling. We created a collection of diverse bacterial and fungal isolates (84 from the drilling fluid and its components, 45 from decontaminated ice, and 66 from drilling chips). Their categorization as contaminants or intrinsic glacial ice microorganisms was based on several criteria, including phylogenetic analyses, genomic fingerprinting, phenotypic characteristics, and presence in drilling fluid, chips, and/or ice. Firmicutes and fungi comprised the dominant group of contaminants among isolates and cloned rRNA genes. Conversely, most Proteobacteria and Actinobacteria originating from the ice were identified as intrinsic. This study provides a database of potential contaminants useful for future studies of NEEM cores and can contribute toward developing standardized protocols for contamination detection and ensuring the authenticity of the microbial diversity in deep glacial ice.

  7. An annual layer counted ice-core chronology from EDML, Antarctica, over the termination of the last glacial

    Science.gov (United States)

    Winstrup, Mai; Vinther, Bo M.; Svensson, Anders M.; Clausen, Henrik B.; Rasmussen, Sune O.; Fudge, Tj; Steig, Eric J.; Wegner, Anna; Kipfstuhl, Sepp

    2013-04-01

    Accurate and consistent timescales for paleoclimate records are crucial for advancing our understanding of the governing mechanisms and inter-hemispheric coupling involved in rapid climate change. For ice cores, very high-resolution chronologies can be established far back in time by identifying and counting annual layers in the ice core records. This is in particular true for the Greenland ice cores, for which the relatively high accumulation rates act to preserve the annual signal to great depths. The Greenland Ice Core Chronology 2005 (GICC05) is based on annual layer counts in data records from multiple Greenland ice cores, and it reaches back to 60 kyr BP. In Antarctica, only few ice core locations have sufficiently high accumulation rates for the annual signal in the ice core data to be maintained back into the last glacial. An annual layer counted timescale (WDC06A-7) reaching back to 30 kyr BP was recently completed for WAIS Divide, West Antarctica. Overall, the timescale is in good agreement with GICC05 within their respective uncertainties. Over the last glacial termination, however, significant discrepancies exist between the two chronologies, which cannot be reconciled within the specified uncertainty of the respective annual layer counts. Here, we present an independent annual layer counted chronology for the EPICA ice core from Dronning Maud Land (EDML), Antarctica, over the termination of the last glacial (10-15 kyr BP). The chronology is based on the annual signal visible in high-resolution impurity records and electrical conductivity measurements (liquid conductivity, DEP). The timescale is constructed using a novel Bayesian framework for multi-parameter annual layer counting in ice core records, which originates from sophisticated speech-recognition algorithms. It provides an objective estimate of the most likely number of layers within a section, as well as a confidence interval judging the uncertainty involved in layer identification. Resulting

  8. Reconciling radiocarbon and ice core timescales over the Holocene - Cosmogenic radionuclides as synchronization tools

    Science.gov (United States)

    Muscheler, R.; Adolphi, F.; Mekhaldi, F.

    2015-12-01

    The atmospheric production rates of cosmogenic radionuclides, such as 14C and 10Be, vary globally due to external processes, namely the solar and geomagnetic modulation of the galactic cosmic ray flux as well as solar proton events. This signature is recorded in various archives such as ice cores (10Be) and tree-rings (14C). Hence, cosmogenic radionuclides offer a means to continuously assess timescale differences between two of the most widely used timescales in paleoclimatology - the radiocarbon and the ice core timescales. Short lived solar proton events additionally provide distinct marker horizons that allow synchronization of discrete horizons at annual precision. We will present a cosmogenic radionuclide based synchronization of the Greenland ice core timescale (GICC05, Svensson et al., 2008) and the radiocarbon timescale (IntCal13, Reimer et al., 2013) over the Holocene. This synchronization allows radiocarbon dated and ice core paleoclimate records to be compared on a common timescale at down to sub-decadal precision. We will compare these results to independent discrete isochrones obtained from tephrochronology and solar proton events. In addition, we will discuss implications for the accuracy and uncertainty estimates of GICC05 over the Holocene. Reimer, P. J., Bard, E., Bayliss, A., Beck, J. W., Blackwell, P. G., Bronk Ramsey, C., Buck, C. E., Cheng, H., Edwards, R. L., Friedrich, M., Grootes, P. M., Guilderson, T. P., Haflidason, H., Hajdas, I., Hatté, C., Heaton, T. J., Hoffmann, D. L., Hogg, A. G., Hughen, K. A., Kaiser, K. F., Kromer, B., Manning, S. W., Niu, M., Reimer, R. W., Richards, D. A., Scott, E. M., Southon, J. R., Staff, R. A., Turney, C. S. M., and van der Plicht, J.: IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0-50,000 Years cal BP, Radiocarbon, 55, 1869-1887, 10.2458/azu_js_rc.55.16947, 2013. Svensson, A., Andersen, K. K., Bigler, M., Clausen, H. B., Dahl-Jensen, D., Davies, S. M., Johnsen, S. J., Muscheler, R., Parrenin

  9. A 290-a record of atmospheric circulation over the North Pacific from a Mt. Logan ice core, Yukon Territory

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Calibrations between sodium (Na+) concentrations from a Mt. Logan ice core and sea level pressure (SLP) series show that Na+ concentrations are closely correlated with the autumn-time (SeptemberOctober-November) Aleutian low (AleuLow). A deepening of the AleuLow strengthens the transport of sea-salt aerosols from the North Pacific to the Mt. Logan region. The Mt. Logan Na+ record is used to develop a 292 a (1688~1979) reconstruction of the AleuLow revealing a dramatic intensification of atmospheric circulation over the North Pacific region since the 20th century. Mean SLP of the AleuLow was about 1 hPa lower during the 20th century than during prior periods. The strongest deepening of the AleuLow appeared in the 1950s. Significant correlations are also found between the Mt. Logan AleuLow proxy series and the Pacific decadal oscillation (PDO) and Pacific circulation (PC) index during the 20th century. Evolutionary spectral analysis of the proxy record shows significant periodicities from 15 to 30 a consistent with PDO fluctuations and the bidecadal oscillation of North Pacific atmosphere-ocean circulation. A period of 11 a in the AleuLow record may be associated with the Schwabe 11-a cycle of sunspot activity. Additional longer ice core records from this region will aid in the efforts to further understand the climatic change over the North Pacific region.

  10. Ice core from Akademii Nauk ice cap, Severnaya Zemlya (Russian Arctic), dated with a Nye model modified for a growing glacier

    Science.gov (United States)

    Fritzsche, Diedrich; Opel, Thomas; Meyer, Hanno

    2010-05-01

    From 1999 to 2001 a 724 m deep ice core has been drilled from surface to bedrock close to summit of the Akademii Nauk ice cap, Severnaya Zemlya (Russian Arctic), within a joint German-Russian project. The analysis of stable water isotopes and major ion concentration in high resolution were used for reconstruction of past climate and environmental changes. The upper 304 m of the core were dated by counting annual stable isotope cycles considering radioactive (1986, 1963) and volcanic events (1956, 1912, 1783, 1259) as reference horizons. The resulting depth-age relationship and the corresponding annual-layer thickness imply that the ice cap was not in dynamic steady state but had been growing until recent times. That does not comply with requirements of a standard Nye or Dansgaard-Johnson flow model approach. To take into account the peculiarities of Akademii Nauk ice cap a Nye model was modified by adding a growing term according to the found relationship between annual layer thickness and depth. Using the volcanoes identified an average increase of altitude of about 0.08 m w.e. per year was calculated since AD 1259. The model enables us to reconstruct the altitude changes of the ice cap with time and to consider an altitude effect to correct the stable isotope values and to explain decreasing sea-salt ion data. Using the suggested model annual layer thickness can be decompressed to accumulation rates at the altitude where the precipitation was originally deposited. The model can also be used for dating deeper parts of ice core where volcanoes are not identified up to now. Applying this model, the ice core has an age of about 2 500 years, much less than claimed for an older core from Akademii Nauk ice cap. Consequently, the ice cap is much younger and only of Late Holocene age, as also assumed for most Arctic ice caps and glaciers outside Greenland. However, the lowest part of Akademii Nauk ice cap is probably a remnant of an older ice cap stage.

  11. δ18O record and temperature change over the past 100 years in ice cores on the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    YAO; Tandong; GUO; Xuejun; Lonnie; Thompson; DUAN; Keqin; WANG; Ninglian; PU; Jianchen; XU; Baiqing; YANG; Xiaoxin; SUN; Weizhen

    2006-01-01

    The 213 m ice core from the Puruogangri Ice Field on the Tibetan Plateau facilitates the study of the regional temperature changes with its δ18O record of the past 100 years. Here we combine information from this core with that from the Dasuopu ice core (from the southern Tibetan Plateau), the Guliya ice core (from the northwestern Plateau) and the Dunde ice core (from the northeastern Plateau) to learn about the regional differences in temperature change across the Tibetan Plateau. The δ18O changes vary with region on the Plateau, the variations being especially large between South and North and between East and West. Moreover, these four ice cores present increasing δ18O trends, indicating warming on the Tibetan Plateau over the past 100 years. A comparative study of Northern Hemisphere (NH) temperature changes, the δ18O-reflected temperature changes on the Plateau, and available meteorological records show consistent trends in overall warming during the past 100 years.

  12. Abundance, viability and diversity of the indigenous microbial populations at different depths of the NEEM Greenland ice core

    Directory of Open Access Journals (Sweden)

    Vanya Miteva

    2015-02-01

    Full Text Available The 2537-m-deep North Greenland Eemian Ice Drilling (NEEM core provided a first-time opportunity to perform extensive microbiological analyses on selected, recently drilled ice core samples representing different depths, ages, ice structures, deposition climates and ionic compositions. Here, we applied cultivation, small subunit (SSU rRNA gene clone library construction and Illumina next-generation sequencing (NGS targeting the V4–V5 region, to examine the microbial abundance, viability and diversity in five decontaminated NEEM samples from selected depths (101.2, 633.05, 643.5, 1729.75 and 2051.5 m deposited 300–80 000 years ago. These comparisons of the indigenous glacial microbial populations in the ice samples detected significant spatial and temporal variations. Major findings include: (a different phylogenetic diversity of isolates, dominated by Actinobacteria and fungi, compared to the culture-independent diversity, in which Proteobacteria and Firmicutes were more frequent; (b cultivation of a novel alphaproteobacterium; (c dominance of Cyanobacteria among the SSU rRNA gene clones from the 1729.75-m ice; (d identification of Archaea by NGS that are rarely detected in glacial ice; (e detection of one or two dominant but different genera among the NGS sequences from each sample; (f finding dominance of Planococcaceae over Bacillaceae among Firmicutes in the brittle and the 2051.5-m ice. The overall beta diversity between the studied ice core samples examined at the phylum/class level for each approach showed that the population structure of the brittle ice was significantly different from the two deep clathrated ice samples and the shallow ice core.

  13. Centennial mineral dust variability in high-resolution ice core data from Dome C, Antarctica

    Directory of Open Access Journals (Sweden)

    F. Lambert

    2012-03-01

    Full Text Available Ice core data from Antarctica provide detailed insights into the characteristics of past climate, atmospheric circulation, as well as changes in the aerosol load of the atmosphere. We present high-resolution records of soluble calcium (Ca2+, non-sea-salt soluble calcium (nssCa2+, and particulate mineral dust aerosol from the East Antarctic Plateau at a depth resolution of 1 cm, spanning the past 800 000 years. Despite the fact that all three parameters are largely dust-derived, the ratio of nssCa2+ to particulate dust is dependent on the particulate dust concentration itself. We used principal component analysis to extract the joint climatic signal and produce a common high-resolution record of dust flux. This new record is used to identify Antarctic warming events during the past eight glacial periods. The phasing of dust flux and CO2 changes during glacial-interglacial transitions reveals that iron fertilization of the Southern Ocean during the past nine glacial terminations was not the dominant factor in the deglacial rise of CO2 concentrations. Rapid changes in dust flux during glacial terminations and Antarctic warming events point to a rapid response of the southern westerly wind belt in the region of southern South American dust sources on changing climate conditions. The clear lead of these dust changes on temperature rise suggests that an atmospheric reorganization occurred in the Southern Hemisphere before the Southern Ocean warmed significantly.

  14. Global Climate Change: Valuable Insights from Concordant and Discordant Ice Core Histories

    Science.gov (United States)

    Mosley-Thompson, E.; Thompson, L. G.; Porter, S. E.; Goodwin, B. P.; Wilson, A. B.

    2014-12-01

    Earth's ice cover is responding to the ongoing large-scale warming driven in part by anthropogenic forces. The highest tropical and subtropical ice fields are dramatically shrinking and/or thinning and unique climate histories archived therein are now threatened, compromised or lost. Many ice fields in higher latitudes are also experiencing and recording climate system changes although these are often manifested in less evident and spectacular ways. The Antarctic Peninsula (AP) has experienced a rapid, widespread and dramatic warming over the last 60 years. Carefully selected ice fields in the AP allow reconstruction of long histories of key climatic variables. As more proxy climate records are recovered it is clear they reflect a combination of expected and unexpected responses to seemingly similar climate forcings. Recently acquired temperature and precipitation histories from the Bruce Plateau are examined within the context provided by other cores recently collected in the AP. Understanding the differences and similarities among these records provides a better understanding of the forces driving climate variability in the AP over the last century. The Arctic is also rapidly warming. The δ18O records from the Bona-Churchill and Mount Logan ice cores from southeast Alaska and southwest Yukon Territory, respectively, do not record this strong warming. The Aleutian Low strongly influences moisture transport to this geographically complex region, yet its interannual variability is preserved differently in these cores located just 110 km apart. Mount Logan is very sensitive to multi-decadal to multi-centennial climate shifts in the tropical Pacific while low frequency variability on Bona-Churchill is more strongly connected to Western Arctic sea ice extent. There is a natural tendency to focus more strongly on commonalities among records, particularly on regional scales. However, it is also important to investigate seemingly poorly correlated records, particularly

  15. The WAIS-Divide deep ice core WD2014 chronology – Part 2: Methane synchronization (68–31 ka BP and the gas age-ice age difference

    Directory of Open Access Journals (Sweden)

    C. Buizert

    2014-08-01

    Full Text Available The West Antarctic Ice Sheet (WAIS-Divide ice core (WAIS-D is a newly drilled, high-accumulation deep ice core that provides Antarctic climate records of the past ∼68 ka at unprecedented temporal resolution. The upper 2850 m (back to 31.2 ka BP have been dated using annual-layer counting. Here we present a chronology for the deep part of the core (67.8–31.2 ka BP, which is based on stratigraphic matching to annual-layer-counted Greenland ice cores using globally well-mixed atmospheric methane. We calculate the WAIS-D gas age-ice age difference (Δage using a combination of firn densification modeling, ice flow modeling, and a dataset of δ15N-N2, a proxy for past firn column thickness. The largest Δage at WAIS-D occurs during the last glacial maximum, and is 525 ± 100 years. Internally consistent solutions can only be found when assuming little-to-no influence of impurity content on densification rates, contrary to a recently proposed hypothesis. We synchronize the WAIS-D chronology to a linearly scaled version of the layer-counted Greenland Ice Core Chronology (GICC05, which brings the age of Dansgaard-Oeschger (DO events into agreement with the U/Th absolutely dated Hulu speleothem record. The small Δage at WAIS-D provides valuable opportunities to investigate the timing of atmospheric greenhouse gas variations relative to Antarctic climate, as well as the interhemispheric phasing of the bipolar "seesaw".

  16. Mount Logan ice core record of tropical and solar influences on Aleutian Low variability: 500-1998 A.D.

    Science.gov (United States)

    Osterberg, Erich C.; Mayewski, Paul A.; Fisher, David A.; Kreutz, Karl J.; Maasch, Kirk A.; Sneed, Sharon B.; Kelsey, Eric

    2014-10-01

    Continuous, high-resolution paleoclimate records from the North Pacific region spanning the past 1500 years are rare; and the behavior of the Aleutian Low (ALow) pressure center, the dominant climatological feature in the Gulf of Alaska, remains poorly constrained. Here we present a continuous, 1500 year long, calibrated proxy record for the strength of the wintertime (December-March) ALow from the Mount Logan summit (PR Col; 5200 m asl) ice core soluble sodium time series. We show that ice core sodium concentrations are statistically correlated with North Pacific sea level pressure and zonal wind speed. Our ALow proxy record reveals a weak ALow from circa 900-1300 A.D. and 1575-1675 A.D., and a comparatively stronger ALow from circa 500-900 A.D., 1300-1575 A.D., and 1675 A.D. to present. The Mount Logan ALow proxy record shows strong similarities with tropical paleoclimate proxy records sensitive to the El Niño-Southern Oscillation and is consistent with the hypothesis that the Medieval Climate Anomaly was characterized by more persistent La Niña-like conditions while the Little Ice Age was characterized by at least two intervals of more persistent El Niño-like conditions. The Mount Logan ALow proxy record is significantly (p < 0.05) correlated and coherent with solar irradiance proxy records over various time scales, with stronger solar irradiance generally associated with a weaker ALow and La Niña-like tropical conditions. However, a step-like increase in ALow strength during the Dalton solar minimum circa 1820 is associated with enhanced Walker circulation. Furthermore, rising CO2 forcing or internal variability may be masking the twentieth century rise in solar irradiance.

  17. Third Pole Glaciers and Ice Core Records of Past, Present and Future Climate

    Science.gov (United States)

    Thompson, L. G.; Yao, T.; Mosley-Thompson, E. S.; Davis, M. E.

    2011-12-01

    Ice core histories collected over the last two decades from across the Tibetan Plateau and the Himalaya demonstrate the climatic complexity and diversity of the Third Pole (TP) region. Proxy climate records spanning more than 500,000 years have been recovered from the Guliya ice cap in the far northwestern Kunlun Shan, which is dominated by westerly air flow over the Eurasian land mass. Shorter records (central TP, and also in the Himalaya to the south where a monsoonal climate regime dominates and the annual accumulation is high. The Himalayan ice fields are sensitive to fluctuations in the intensity of the South Asian Monsoon and are affected by the rising temperatures in the region. We examine the recent climatic changes to earlier distinctive epochs such as the Medieval Climate Anomaly (~950-1250 AD), the early Holocene "Hypsithermal" (~5 to 9 kyr BP) and the Eemian (~114 -130 kyr BP). The Eemian, the most recent period when Earth was significantly warmer than today, can serve in part as an analog for the coming greenhouse world. One thousand-year records of δ18O variations from four of these ice fields illustrate the effect of the recent warming across the TP. Mean values for much of the 20th Century (AD 1938 to 1987) are compared with those for the prior nine centuries (1000 to 1937 AD). The greatest recent enrichment occurs on the highest elevation site (Dasuopu in the Himalaya), presumably where the greatest warming is occurring. These trends are consistent with instrumental temperature records collected since the 1950s across the TP as well as with IPCC (2007) model predictions of a nearly two-fold vertical amplification of temperatures in the Tropics. A fifth ice field, Naimona'nyi (6100 masl), is not included in the study as recent melting from the top of the glacier has obliterated the upper 40 to 50 years of the record. Evidence confirming this will be presented along with recent mass balance measurements indicating that no net accumulation occurs on

  18. Asian Ice Core Array (AICA): Climate and Environmental Reconstruction of Asia

    Science.gov (United States)

    Grigholm, B.; Mayewski, P. A.; Aizen, V.; Kang, S.; Kaspari, S.; Maasch, K. A.

    2008-12-01

    The large landmass and relief of the Asian continent has a substantial influence on global atmospheric circulation and the regional climate that supports ~2.5 billion people. Recent changes in climate and environmental conditions may lead to desertification and affect water resources, possibly resulting in serious consequences on humans and ecosystems. To put recent changes into context, it is first necessary to have an understanding of past climate and environmental variability. However, instrumental records of climate and environmental variability over the region are sparse and temporally limited. Fortunately, ice cores from high elevation mountain glaciers in Asia can be used to reconstruct atmospheric chemistry and past climate variability spanning seasonal to millennial time scales. The goal of the Asian Ice Core Array (AICA) is to enhance the spatial and temporal understanding of physical and chemical climate variability, establish a baseline for assessing modern climate variability in the context of human activity, and contribute to the prediction of climate variability in Asia. Highly resolved ice core reconstructions of past climate (e.g. atmospheric circulation, temperature, precipitation, and atmospheric chemistry) will utilize continuous, co-registered, and multi-parameter measurements of major ions, trace elements, and stable isotopes (along with selected sections for radionuclide analysis). AICA sites include cores from the Himalayas, Pamir, Tien Shan, Altai, and the Tibetan Plateau. An overview of the AICA project will be presented, in addition to some early results of AICA including reconstructions of the behavior of the summer South Asian monsoon over the Himalayas and the identification of a potential teleconnection between the central Tibetan Plateau and the Pacific Decadal Oscillation (PDO).

  19. Ice-Core Study of the Link between Sea-Salt Aerosol, Sea-Ice Cover and Climate in the Antarctic Peninsula Area

    Energy Technology Data Exchange (ETDEWEB)

    Aristarain, A.J. [Laboratorio de Estratigrafia Glaciar y Geoquimica del Agua y de la Nieve LEGAN, Instituto Antartico Argentino, Mendoza (Argentina); Delmas, R.J. [Laboratoire de Glaciologie et Geophysique de l' Environnement LGGE, Centre National de la Recherche Scientifique, BP 96, 38402 St. Martin d' Heres Cedex (France); Stievenard, M. [Laboratoire des Sciences du Climat et de l' Environnement LSCE, Centre d' Etudes de Saclay, 91191 Gif-sur-Yvette, Cedex (France)

    2004-11-01

    Three ice cores and a set of snow pit samples collected on James Ross Island, Antarctic Peninsula, in 1979, 1981 and 1991 have been analyzed for water stable isotope content D or 18O (isotopic temperature) and major chemical species. A reliable and detailed chronological scale has been established first for the upper 24.5 m of water equivalent (1990-1943) where various data sets can be compared, then extended down to 59.5 m of water equivalent (1847) with the aid of seasonal variations and the sulphate peak reflecting the 1883 Krakatoa volcanic eruption. At James Ross Island, sea-salt aerosol is generally produced by ice-free marine surfaces during the summer months, although some winter sea-salt events have been observed. For the upper part of the core (1990-1943), correlations (positive or negative) were calculated between isotopic temperature, chloride content (a sea-salt indicator), sea-ice extent, regional atmospheric temperature changes and atmospheric circulation. The D and chloride content correlation was then extended back to 1847, making it possible to estimate decadal sea-ice cover fluctuations over the study period. Our findings suggest that ice-core records from James Ross Island reflect the recent warming and sea-ice decrease trends observed in the Antarctic Peninsula area from the mid-1940s.

  20. Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements

    OpenAIRE

    2013-01-01

    Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ15N of N2 in air trapped in ice core, assuming that δ15N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by...

  1. What terrestrial glacial meltwater streams reveal about Greenland ice sheet hydrology

    Science.gov (United States)

    Rennermalm, A. K.; Hammann, A. C.; Moustafa, S.; Smith, L. C.; Pitcher, L. H.; Gleason, C. J.; Chu, V. W.; Yang, K.; Tedesco, M.; van As, D.

    2015-12-01

    Understanding of Greenland ice sheet hydrology can be advanced by better monitoring the discharge of terrestrial glacial meltwater streams. This is demonstrated with an ice sheet watershed study using a unique eight-year long record of pro-glacial discharge data from the Akuliarusiarsuup Kuua River in Southwest Greenland, as well as remote sensing of supraglacial hydrological features, and modeling of watershed runoff. We find strong interannual variability, extreme events, changing meltwater travel time through the melting season, and release of meltwater outside the regular melting season. This reveals that the ice sheet has a complex hydrological system that varies from year to year in response to external forcing and the development of hydrological pathways within and on the surface of the ice sheet.

  2. The effect of multilayer ice chemistry on gas-phase deuteration in starless cores

    CERN Document Server

    Sipilä, O; Taquet, V

    2016-01-01

    Aims. We aim to investigate whether a multilayer ice model can be as successful as a bulk ice model in reproducing the observed abundances of various deuterated gas-phase species toward starless cores. Methods. We calculate abundances for various deuterated species as functions of time adopting fixed physical conditions. We also estimate abundance gradients by adopting a modified Bonnor-Ebert sphere as a core model. In the multilayer ice scenario, we consider desorption from one or several monolayers on the surface. Results. We find that the multilayer model predicts abundances of $\\rm DCO^+$ and $\\rm N_2D^+$ that are about an order of magnitude lower than observed, caused by the trapping of CO and $\\rm N_2$ into the grain mantle. As a result of the mantle trapping, deuteration efficiency in the gas phase increases and we find stronger deuterium fractionation in ammonia than what has been observed. Another distinguishing feature of the multilayer model is that $\\rm D_3^+$ becomes the main deuterated ion at hi...

  3. Non-Target Analyses of organic compounds in ice cores using HPLC-ESI-UHRMS

    Science.gov (United States)

    Zuth, Christoph; Müller-Tautges, Christina; Eichler, Anja; Schwikowski, Margit; Hoffmann, Thorsten

    2015-04-01

    To study the global climatic and environmental changes it is necessary to know the environmental and especially atmospheric conditions of the past. By analysing climate archives, such as for example ice cores, unique environmental information can be obtained. In contrast to the well-established analysis of inorganic species in ice cores, organic compounds have been analysed in ice cores to a much smaller extent. Because of current analytical limitations it has become commonplace to focus on 'total organic carbon' measurements or specific classes of organic molecules, as no analytical methods exist that can provide a broad characterization of the organic material present[1]. On the one hand, it is important to focus on already known atmospheric markers in ice cores and to quantify, where possible, in order to compare them to current conditions. On the other hand, unfortunately a wealth of information is lost when only a small fraction of the organic material is examined. However, recent developments in mass spectrometry in respect to higher mass resolution and mass accuracy enable a new approach to the analysis of complex environmental samples. The qualitative characterization of the complex mixture of water soluble organic carbon (WSOC) in the ice using high-resolution mass spectrometry allows for novel insights concerning the composition and possible sources of aerosol derived WSOC deposited at glacier sites. By performing a non-target analysis of an ice core from the Swiss Alps using previous enrichment by solid-phase extraction (SPE) and high performance liquid chromatography coupled to electrospray ionization and ultra-high resolution mass spectrometry (HPLC-ESI-UHRMS) 475 elemental formulas distributed onto 659 different peaks were detected. The elemental formulas were classified according to their elemental composition into CHO-, CHON-, CHOS-, CHONS-containing compounds and 'others'. Several methods for the analysis of complex data sets of high resolution

  4. Measurement of atmospheric neutrino oscillations with IceCube/DeepCore

    Energy Technology Data Exchange (ETDEWEB)

    Euler, Sebastian; Bissok, Martin; Wallraff, Marius; Wiebusch, Christopher [III. Physikalisches Institut, RWTH Aachen, D-52056 Aachen (Germany); Collaboration: IceCube-Collaboration

    2011-07-01

    IceCube's low-energy optimization DeepCore became operational in May 2010 and is taking data since then. It lowers the energy threshold of IceCube by roughly an order of magnitude. The huge statistics of about 150000 triggered atmospheric muon neutrinos per year and the low energy threshold of about 10 GeV permit to study oscillations. The disappearance probability depends on the neutrino energy and the traveled distance and thus on the zenith angle observed by IceCube. Maximum disappearance is expected at energies of about 25 GeV for vertically upward going neutrinos. For shorter oscillation lengths this flux minimum shifts towards 1 GeV close to the horizon. This study aims for a likelihood analysis of the two experimental observables (zenith and neutrino energy) for a high statistics measurement of the mixing angle {theta}{sub 23} and the mass difference {Delta}m{sup 2}{sub 23}. This talk presents the analysis method and first results from the data taken by IceCube in its 79-string configuration.

  5. A new ice-core record from Lomonosovfonna, Svalbard : viewing the 1920-97 data in relation to present climate and environmental conditions

    NARCIS (Netherlands)

    Isaksson, E; Pohjola, [No Value; Jauhiainen, T; Moore, J; Pinglot, JM; Vaikmae, R; van de Wal, RSW; Ivask, J; Karlof, L; Martma, T; Meijer, HAJ; Mulvaney, R; Thomassen, M; van den Broeke, M

    2001-01-01

    In 1997 a 121 m ice core was retrieved from Lomonosovfonna, the highest ice field in Spitsbergen, Svalbard (1250 m a.s.l.). Radar measurements indicate an ice depth of 126.5 m, and borehole temperature measurements show that the ice is below the melting point, High-resolution sampling of major ions,

  6. River Channel Expansion Reveals Ice Sheet Runoff Variations

    Science.gov (United States)

    Overeem, I.; Hudson, B. D.; Welty, E.; LeWinter, A.; Mikkelsen, A. B.

    2013-12-01

    The Greenland Ice Sheet has been rapidly melting over the last decades. To quantify its contribution to global sea-level rise, we urgently need to understand flux of meltwater into proglacial rivers. Direct measurements of river runoff at the Greenlandic coast are sparse due to the dynamic braided channels with unstable banks, which makes in-situ discharge monitoring challenging. Here, we explore the use of ';inundation-discharge' relationships through analysis of both time-lapse camera imagery and MODIS remote-sensing reflectance data to provide us with a proxy record of river discharge for proglacial systems. We utilize MODIS band6 (mid IR 1628 - 1652 nm). Light in this band is strongly absorbed by water, and reflectance is not sensitive to sediment suspended in the water, making it an appropriate proxy for river braidplain inundation. Our focus is on two Greenlandic river systems; the Watson River near Kangerlussuaq and the Naujat Kuat River near Nuuk, to track band6 reflectance characteristics over all cloud-free days for the summers of 2000-2012. For validation, a ground-based inundation record is assembled from time-lapse imagery overlooking the Watson River for 2012. Exponential inundation-discharge relationships were established using our in-situ discharge records for the Watson River near Kangerlussuaq (2007-2012, R2=0.55) and the Naujat Kuat River near Nuuk (2011-2012, R2 = 0.42). Using these relationships to predict total annual river discharge proves reasonably accurate for most years of the observational record (varying between 96-86%). Interestingly, the extreme melt year of 2012 was not reliably predicted using the established relationship. We compared these predictions against an inundation record from the in-situ time-lapse camera and found that a ground-based observations track extreme discharge events more reliably (R2 = 0.60). This methodology allows us to extend existing river records back beyond the 5 or 2 years of in-situ observations

  7. Exploitation of chemical profiles by conjugate variable analysis: application to the dating of a tropical ice core (Nevado Illimani, Bolivia)

    Science.gov (United States)

    Gay, M.; De Angelis, M.; Lacoume, J.-L.

    2013-06-01

    Ice core dating is a key parameter for the interpretation of the ice archives. However, the relationship between ice depth and age can generally not be easily established and requires to combine a large number of investigations and/or modeling effort. This paper presents a new approach of ice core dating based on conjugate variable (depth and spatial frequency) analysis of chemical profiles. The relationship between the depth of a given ice layer and the date it was deposited is determined using ion concentration depth profiles obtained along a one hundred-meters deep ice core recovered in the summit area of the Nevado Illimani (6350 m a.s.l.), located in the Eastern Bolivian Andes (16°37' S, 67°46' W). The results of Fourier conjugate analysis and wavelet tranforms are first compared. Both methods are applied to nitrate concentration depth profile. The resulting chronologies are checked by comparison with the multi-proxy year-by-year dating published by de Angelis et al. (2003) and with volcanic tie points, demonstrating the efficiency of Fourier conjugate analysis when tracking the natural variability of chemical proxies. The Fourier conjugate analysis is then applied to concentration depth profiles of seven other ions thus providing information on the suitability of each of them for dating studies of tropical Andean ice cores.

  8. Climatic changes on orbital and sub-orbital time scale recorded by the Guliya ice core in Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    姚檀栋; 徐柏青; 蒲健辰

    2001-01-01

    Based on ice core records in the Tibetan Plateau and Greenland, the features and possible causes of climatic changes on orbital and sub-orbital time scale were discussed. Orbital time scale climatic change recorded in ice core from the Tibetan Plateau is typically ahead of that from polar regions, which indicates that climatic change in the Tibetan Plateau might be earlier than polar regions. The solar radiation change is a major factor that dominates the climatic change on orbital time scale. However, climatic events on sub-orbital time scale occurred later in the Tibetan Plateau than in the Arctic Region, indicating a different mechanism. For example, the Younger Dryas and Heinrich events took place earlier in Greenland ice core record than in Guliya ice core record. It is reasonable to propose the hypothesis that these climatic events were affected possibly by the Laurentide Ice Sheet. Therefore, ice sheet is critically important to climatic change on sub-orbital time scale in some ice ages.

  9. Radiocarbon analysis of the EPICA Dome C ice core: no in situ {sup 14}C from the firn observed

    Energy Technology Data Exchange (ETDEWEB)

    Jong, A.F.M. de; Alderliesten, C.; Borg, K. van der E-mail: k.vanderborg@phys.uu.nl; Veen, C. van der; Wal, R.S.W. van de

    2004-08-01

    CO{sub 2} and CO obtained by dry-extraction from ice samples of the EPICA Dome C core were {sup 14}C analysed by AMS. For some of the ice samples there is no evidence for in situ {sup 14}C, indicating the firn did not retain {sup 14}C. The {sup 14}C ages of these samples are too old in comparison with a calibrated ice-flow model, and the concentrations of {sup 14}CO are near zero. For other ice samples, however, in situ {sup 14}C is clearly present, and is likely from post-coring exposure at the Dome C surface. These samples show too young {sup 14}C ages, and distinct concentrations of {sup 14}CO. The accuracy of ages obtained from {sup 14}C analysis of ice samples is discussed.

  10. Identifying and Tracking Individual Updraft Cores using Cluster Analysis: A TWP-ICE case study

    Science.gov (United States)

    Li, X.; Tao, W.; Collis, S. M.; Varble, A.

    2013-12-01

    Cumulus parameterizations in GCMs depend strongly on the vertical velocity structures of convective updraft cores, or plumes. There hasn't been an accurate way of identifying these cores. The majority of previous studies treat the updraft as a single grid column entity, thus missing many intrinsic characteristics, e.g., the size, strength and spatial orientation of an individual core, its life cycle, and the time variations of the entrainment/detrainment rates associated with its life cycle. In this study, we attempt to apply an innovative algorithm based on the centroid-based k-means cluster analysis to improve our understanding of convection and its associated updraft cores. Both 3-D Doppler radar retrievals and cloud-resolving model simulations of a TWP-ICE campaign case during the monsoon period will be used to test and improve this algorithm. This will provide for more in-depth comparisons between CRM simulations and observations that were not possible previously using the traditional piecewise analysis with each updraft column. The first step is to identify the strongest cores (maximum velocity >10 m/s), since they are well defined and produce definite answers when the cluster analysis algorithm is applied. The preliminary results show that the radar retrieved updraft cores are smaller in size and with the maximum velocity located uniformly at higher levels compared with model simulations. Overall, the model simulations produce much stronger cores compared with the radar retrievals. Within the model simulations, the bulk microphysical scheme simulation produces stronger cores than the spectral bin microphysical scheme. Planned researches include using high temporal-resolution simulations to further track the life cycle of individual updraft cores and study their characteristics.

  11. Sensitivity of Oxygen Isotopes of Sulfate in Ice Cores to Past Changes in Atmospheric Oxidant Concentrations

    Science.gov (United States)

    Sofen, E. D.; Alexander, B.; Kunasek, S. A.; Mickley, L.; Murray, L. T.; Kaplan, J. O.

    2009-12-01

    The oxygen isotopic composition (Δ17O) of sulfate from ice cores allows for a quantitative assessment of the past oxidative capacity of the atmosphere, which has implications for the lifetime of pollutants (e.g. CO) and greenhouse gases (e.g. CH4), and changes in the sulfur budget on various timescales. Using Δ17O of sulfate measurements from the WAIS-Divide, Antarctica and Site-A, Greenland ice cores as constraints, we use the GEOS-Chem global three-dimensional chemical transport model to study changes in the concentrations of OH, O3, and H2O2 and their impact on sulfate Δ17O between the preindustrial and present-day. The Greenland ice core sulfate oxygen isotope observations are insensitive to changes in oxidant concentrations on the preindustrial-industrial timescale due to the rising importance of metal catalyzed S(IV) oxidation in mid- to high-northern latitudes resulting from anthropogenic metal emissions. The small change in Antarctic ice core sulfate Δ17O observations on this timescale is consistent with simultaneous increases in boundary layer O3 (32%) and H2O2 (49%) concentrations in the Southern Hemisphere, which have opposing effects on the sulfate O-isotope anomaly. Sulfate Δ17O is insensitive to the relatively small (-12%) decrease in Southern Hemisphere OH concentrations on this timescale due to the dominance of in-cloud versus gas-phase formation of sulfate in the mid-to-high southern latitudes. We find that the fraction of sulfate formed globally through gas-phase oxidation has not changed substantially between preindustrial and present times, however the total amount of sulfate formed in the gas-phase has nearly quadrupled due to rising anthropogenic emissions of sulfur dioxide. Measurements over a glacial-interglacial cycle from the Vostok core indicate dramatic changes in the Δ17O of sulfate on this timescale, which provide a strong constraint for glacial-era atmospheric chemistry modeling efforts. We will present preliminary results of

  12. Improved stratigraphic dating at a low accumulation Alpine ice core through laser ablation trace element profiling at sub-mm depth resolution

    Science.gov (United States)

    Bohleber, Pascal; Spaulding, Nicole; Mayewski, Paul; Sneed, Sharon; Handley, Mike; Erhardt, Tobias; Wagenbach, Dietmar

    2015-04-01

    The small scale Colle Gnifetti glacier saddle (4450 m asl, Monte Rosa region) is the only ice core drilling site in the European Alps with a net accumulation low enough to offer multi-millennia climate records. However, a robust interpretation of such long term records (i.e. mineral dust, stable water isotopes) at the Colle Gnifetti (CG) multi core array is strongly challenged by depositional noise associated with a highly irregular annual layer stratigraphy. In combination with a relatively large vertical strain rate and rapid layer thinning, annual layer counting gets increasingly ambiguous as of approximately 100 years. In addition, this prevents clear attribution of likely volcanic horizons to historical eruption dates. To improve stratigraphic dating under such intricate conditions, we deployed laser ablation (LA) ICP-MS at sub-mm sample resolution. We present here the first LA impurity profiles from a new Colle Gnifetti ice core drilled 73 m to bedrock in 2013 at a site where the net snow accumulation is around 20 cm w.e. per year. We contrast the LA signal variability (including Ca, Fe, Na) to continuous flow analyses (CFA) records at cm-resolution (Ca, Na, melt water conductivity, micro- particle) recorded over the whole core length. Of special concern are the lower 28 m to bedrock, which have been continuously profiled in LA Ca, thus offering the direct comparison of Ca-signals between CFA and LA. By this means, we first validate at upper depths LA based annual layer identification through agreement with CFA based counting efforts before demonstrating the LA based counting still works at depths where CFA derived annual layers become spurious since embedded in strong, multi-year cycles. Finally, LA ice core profiling of our CG core has potential for not only dating improvement but also reveals benefits in resolving highly thinned basal ice sections including accounting for micro-structural features such as grain boundaries.

  13. High speed, high resolution, and continuous chemical analysis of ice cores using a melter and ion chromatography.

    Science.gov (United States)

    Cole-Dai, Jihong; Budner, Drew M; Ferris, Dave G

    2006-11-01

    Measurement of trace chemical impurities in ice cores contributes to the reconstruction of records of the atmospheric environment and of the climate system. Ion chromatography (IC) is an effective analytical technique for ionic species in ice cores but has been used on discretely prepared ice samples, resulting in extensive and slow sample preparation and potential for contamination. A new technique has been developed that utilizes IC as the online detection technique in a melter-based continuous flow system for quantitative determination of major ionic chemical impurities. The system, called CFA-IC for continuous flow analysis with ion chromatography detection, consists of an ice core melter, several ion chromatographs, and an interface that distributes meltwater to the IC instruments. The CFA-IC technique combines the accuracy, precision, and ease of use of IC measurement with the enhanced speed and depth resolution of continuous melting systems and is capable of virtually continuous, high-speed and high-resolution chemical analysis of long ice cores. The new technique and operating procedures have been tested and validated with the analysis of over 100 m of ice cores from Antarctica. The current CFA-IC system provides an all-major-ion analysis speed of up to 8 m a day at a depth resolution of approximately 2 cm.

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

    Science.gov (United States)

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

    2012-01-01

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

  15. Phylogenetic and physiological diversity of microorganisms isolated from a deep greenland glacier ice core

    Science.gov (United States)

    Miteva, V. I.; Sheridan, P. P.; Brenchley, J. E.

    2004-01-01

    We studied a sample from the GISP 2 (Greenland Ice Sheet Project) ice core to determine the diversity and survival of microorganisms trapped in the ice at least 120,000 years ago. Previously, we examined the phylogenetic relationships among 16S ribosomal DNA (rDNA) sequences in a clone library obtained by PCR amplification from genomic DNA extracted from anaerobic enrichments. Here we report the isolation of nearly 800 aerobic organisms that were grouped by morphology and amplified rDNA restriction analysis patterns to select isolates for further study. The phylogenetic analyses of 56 representative rDNA sequences showed that the isolates belonged to four major phylogenetic groups: the high-G+C gram-positives, low-G+C gram-positives, Proteobacteria, and the Cytophaga-Flavobacterium-Bacteroides group. The most abundant and diverse isolates were within the high-G+C gram-positive cluster that had not been represented in the clone library. The Jukes-Cantor evolutionary distance matrix results suggested that at least 7 isolates represent new species within characterized genera and that 49 are different strains of known species. The isolates were further categorized based on the isolation conditions, temperature range for growth, enzyme activity, antibiotic resistance, presence of plasmids, and strain-specific genomic variations. A significant observation with implications for the development of novel and more effective cultivation methods was that preliminary incubation in anaerobic and aerobic liquid prior to plating on agar media greatly increased the recovery of CFU from the ice core sample.

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

    Directory of Open Access Journals (Sweden)

    A. Ekaykin

    2015-12-01

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

  17. Melting and metallization of silica in the cores of gas giants, ice giants and super Earths

    CERN Document Server

    Mazevet, S; Taniuchi, T; Benuzzi-Mounaix, A; Guyot, F

    2014-01-01

    The physical state and properties of silicates at conditions encountered in the cores of gas giants, ice giants and of Earth like exoplanets now discovered with masses up to several times the mass of the Earth remains mostly unknown. Here, we report on theoretical predictions of the properties of silica, SiO$_2$, up to 4 TPa and about 20,000K using first principle molecular dynamics simulations based on density functional theory. For conditions found in the Super-Earths and in ice giants, we show that silica remains a poor electrical conductor up to 10 Mbar due to an increase in the Si-O coordination with pressure. For Jupiter and Saturn cores, we find that MgSiO$_3$ silicate has not only dissociated into MgO and SiO$_2$, as shown in previous studies, but that these two phases have likely differentiated to lead to a core made of liquid SiO$_2$ and solid (Mg,Fe)O.

  18. Variations of ion concentrations in the deep ice core and surface snow at NEEM, Greenland

    Science.gov (United States)

    Goto-Azuma, K.; Wegner, A.; Hansson, M.; Hirabayashi, M.; Kuramoto, T.; Miyake, T.; Motoyama, H.; NEEM Aerosol Consortium members

    2012-04-01

    Discrete samples were collected from the CFA (Continuous Flow Analysis) melt fractions during the field campaign carried out at NEEM, Greenland in 2009-2011, and were distributed to different laboratories. Ionic species were analyzed at National Institute of Polar Research (Japan) and Alfred Wegener Institute for Polar and Marine Research (Germany). Here we present and compare the ion concentration data obtained by both institutes. Most of the ions show good agreement between the two institutes. As is indicated with the CFA data (Bigler and the NEEM Aerosol Consortium members, EGU 2012), ion chromatograph data also display that calcium and sodium, mainly originated from terrestrial dust and sea-salt, respectively, show large variations associated with Dansgaard-Oeschger (DO) events. Chloride, fluoride, sulfate, sodium, potassium and magnesium also show such variations, as has been already reported for other Greenland ice cores. New ion data obtained from the NEEM deep core also show large variability of oxalate and phosphate concentrations during DO events. Acetate, which is thought to be mainly derived from biomass burning, as is oxalate, appears to show variability associated with DO events, but to a lesser extent. On the other hand, nitrate, ammonium and methanesulfonate do not show such variations. Together with ion data from the deep ice core, we present those from the pits dug during the NEEM field campaign to discuss seasonal variations of ionic species. The seasonal and millennial scale variations of ions are thought to be caused by changes in atmospheric circulation and source strength.

  19. A new method for high-resolution methane measurements on polar ice cores using continuous flow analysis.

    Science.gov (United States)

    Schüpbach, Simon; Federer, Urs; Kaufmann, Patrik R; Hutterli, Manuel A; Buiron, Daphné; Blunier, Thomas; Fischer, Hubertus; Stocker, Thomas F

    2009-07-15

    Methane (CH4) is the second most important anthropogenic greenhouse gas in the atmosphere. Rapid variations of the CH4 concentration, as frequently registered, for example, during the last ice age, have been used as reliable time markers for the definition of a common time scale of polar ice cores. In addition, these variations indicate changes in the sources of methane primarily associated with the presence of wetlands. In order to determine the exact time evolution of such fast concentration changes, CH4 measurements of the highest resolution in the ice core archive are required. Here, we present a new, semicontinuous and field-deployable CH4 detection method, which was incorporated in a continuous flow analysis (CFA) system. In CFA, samples cut along the axis of an ice core are melted at a melt speed of typically 3.5 cm/min. The air from bubbles in the ice core is extracted continuously from the meltwater and forwarded to a gas chromatograph (GC) for high-resolution CH4 measurements. The GC performs a measurement every 3.5 min, hence, a depth resolution of 15 cm is achieved atthe chosen melt rate. An even higher resolution is not necessary due to the low pass filtering of air in ice cores caused by the slow bubble enclosure process and the diffusion of air in firn. Reproducibility of the new method is 3%, thus, for a typical CH4 concentration of 500 ppb during an ice age, this corresponds to an absolute precision of 15 ppb, comparable to traditional analyses on discrete samples. Results of CFA-CH4 measurements on the ice core from Talos Dome (Antarctica) illustrate the much higher temporal resolution of our method compared with established melt-refreeze CH4 measurements and demonstrate the feasibility of the new method.

  20. Microparticles, soil, derived chemical components and sea salt in the Hans Tausen Ice Cap ice core from Peary Island, North Greenland

    DEFF Research Database (Denmark)

    Steffensen, J.P.; Andersen, M.L.S; Stampe, Mia

    2001-01-01

    to be a result of melt water run-off. Compared to Central Greenland ice cores the Hans Tausen ice is strongly enriched in soluble crustal material from local sources manifested by high concentrations of Ca2+ and nss Mg2+. In the bottom 100 m section our results indicate a loss of Ca2+ and Mg2+ relative to dust...... due to melt water run-off. Sea salt concentrations show little variation with depth, and our results indicate, that the sea salt in Hans Tausen ice is from remote sources. The North Polar Sea has not been a significant source of sea salt in the life time of the Hans Tausen ice cap. All our results...... are consistent with the hypothesis that the Hans Tausen ice cap was formed sometime during the Holocene: It started as a small ice cap of superimposed ice with heavy melting and strong influence of local dust sources. With time the ice cap grew, both horizontally and vertically, the surface got colder with less...

  1. Isotopic composition of ice cores and meltwater from upper fremont glacier and Galena Creek rock glacier, Wyoming

    Science.gov (United States)

    DeWayne, Cecil L.; Green, J.R.; Vogt, S.; Michel, R.; Cottrell, G.

    1998-01-01

    Meltwater runoff from glaciers can result from various sources, including recent precipitation and melted glacial ice. Determining the origin of the meltwater from glaciers through isotopic analysis can provide information about such things as the character and distribution of ablation on glaciers. A 9.4 m ice core and meltwater were collected in 1995 and 1996 at the glacigenic Galena Creek rock glacier in Wyoming's Absaroka Mountains. Measurements of chlorine-36 (36Cl), tritium (3H), sulphur-35 (35S), and delta oxygen-18 (??18O) were compared to similar measurements from an ice core taken from the Upper Fremont Glacier in the Wind River Range of Wyoming collected in 1991-95. Meltwater samples from three sites on the rock glacier yielded 36Cl concentrations that ranged from 2.1 ?? 1.0 X 106 to 5.8??0.3 X 106 atoms/l. The ice-core 36Cl concentrations from Galena Creek ranged from 3.4??0.3 X 105 to 1.0??0.1 X 106 atoms/l. Analysis of an ice core from the Upper Fremont Glacier yielded 36Cl concentrations of 1.2??0.2 X 106 and 5.2??0.2 X 106 atoms/l for pre- 1940 ice and between 2 X 106 and 3 X 106 atoms/l for post-1980 ice. Purdue's PRIME Lab analyzed the ice from the Upper Fremont Glacier. The highest concentration of 36Cl in the ice was 77 ?? 2 X 106 atoms/l and was deposited during the peak of atmospheric nuclear weapons testing in the late 1950s. This is an order of magnitude greater than the largest measured concentration from both the Upper Fremont Glacier ice core that was not affected by weapons testing fallout and the ice core collected from the Galena Creek rock glacier. Tritium concentrations from the rock glacier ranged from 9.2??0.6 to 13.2??0.8 tritium units (TU) in the meltwater to -1.3??1.3 TU in the ice core. Concentrations of 3H in the Upper Fremont Glacier ice core ranged from 0 TU in the ice older than 50 years to 6-12 TU in the ice deposited in the last 10 years. The maximum 3H concentration in ice from the Upper Fremont Glacier deposited in the

  2. Metagenomics Reveals Microbial Community Composition And Function With Depth In Arctic Permafrost Cores

    Science.gov (United States)

    Jansson, J.; Tas, N.; Wu, Y.; Ulrich, C.; Kneafsey, T. J.; Torn, M. S.; Hubbard, S. S.; Chakraborty, R.; Graham, D. E.; Wullschleger, S. D.

    2013-12-01

    The Arctic is one of the most climatically sensitive regions on Earth and current surveys show that permafrost degradation is widespread in arctic soils. Biogeochemical feedbacks of permafrost thaw are expected to be dominated by the release of currently stored carbon back into the atmosphere as CO2 and CH4. Understanding the dynamics of C release from permafrost requires assessment of microbial functions from different soil compartments. To this end, as part of the Next Generation Ecosystem Experiment in the Arctic, we collected two replicate permafrost cores (1m and 3m deep) from a transitional polygon near Barrow, AK. At this location, permafrost starts from 0.5m in depth and is characterized by variable ice content and higher pH than surface soils. Prior to sectioning, the cores were CT-scanned to determine the physical heterogeneity throughout the cores. In addition to detailed geochemical characterization, we used Illumina MiSeq technology to sequence 16SrRNA genes throughout the depths of the cores at 1 cm intervals. Selected depths were also chosen for metagenome sequencing of total DNA (including phylogenetic and functional genes) using the Illumina HiSeq platform. The 16S rRNA gene sequence data revealed that the microbial community composition and diversity changed dramatically with depth. The microbial diversity decreased sharply below the first few centimeters of the permafrost and then gradually increased in deeper layers. Based on the metagenome sequence data, the permafrost microbial communities were found to contain members with a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. The surface active layers had more representatives of Verrucomicrobia (potential methane oxidizers) whereas the deep permafrost layers were dominated by several different species of Actinobacteria. The latter are known to have a diverse metabolic capability and are able to adapt to stress by entering a dormant yet

  3. Oxygen isotopic composition of micrometer-sized quartz grains in EPICA-Dome C ice core

    Science.gov (United States)

    Delmonte, B.; Hoppe, P.; Hellebrand, E.; Huth, J.; Petit, J.; Maggi, V.

    2006-12-01

    Depicting the geographic provenance of aeolian dust reaching the interior of the East Antarctic plateau is of primary importance for a thorough underst94anding of paleo-atmospheric circulation patterns. A geochemical approach based on the 87Sr/86Sr versus 143Nd/144Nd isotopic signature of mineral particles extracted from Antarctic ice cores and comparison with samples from the Potential Source Areas (PSA) of the Southern Hemisphere has been classically used. This allowed pointing out a dominant Southern South American provenance for dust in the EPICA-Dome C and Vostok ice cores during late Quaternary glacial stages. However, the Sr-Nd isotopic fields from other potential source regions did show a partial overlap with the South American and glacial dust fields, and complementary arguments had to be invoked to infer that their possible contribution is negligible. In this study, we propose a new approach for dust fingerprinting based on the 18O/16O ratios of micrometer- sized quartz grains (1 to 2 μm in size) entrapped in Antarctic ice. Micrometric quartz grains were first identified through SEM/EDX in a sample from the EPICA-Dome C ice core dating back the last glacial maximum. O-isotopic measurements on 25 single grains were performed with the NanoSIMS ion microprobe at the Max-Plank-Institute for Chemistry in Mainz. 18OSMOW values are between 2 and 43 per mil; however most 18OSMOW values fall within a gaussian distribution with a mean 18OSMOW of 25.5 per mil and standard deviation of 2.6 per mil (1^3). These results suggest that a significant contribution from Australian and New Zealand sources seems very unlikely during glacial stage 2, but unfortunately 18OSMOW values for small quartz grains from the Southern Hemisphere PSAs are very scarce. NanoSIMS O-isotopic measurements on Aeolian quartz grains entrapped in Antarctic ice by is a promising tool for investigating the geographic provenance of mineral dust in Quaternary times.

  4. Gas records from the West Greenland ice margin covering the Last Glacial termination: a horizontal ice core

    DEFF Research Database (Denmark)

    Petrenko, V.; Severinghaus, J.P.; Brook, E.J.

    2006-01-01

    Certain sites along ice sheet margins provide an easily accessible and almost unlimited supply of ancient ice at the surface. Measurements of gases in trapped air from ice outcropping at Pakitsoq, West Greenland, demonstrate that ancient air is mostly well preserved. No alterations in delta O-18......-uniformly thinned, with many cross-cutting bands of bubble-free ice and dust. The cross-cutting features are associated with anomalies in both the gas and the ice records. With careful sampling to avoid these, the ice at Pakitsoq is suitable for recovery of large-volume samples of the ancient atmosphere...

  5. INTegrating Ice core, MArine, and TErrestrial records (COST Action ES0907)

    Science.gov (United States)

    Hoek, Wim; Rasmussen, Sune; Renssen, Hans; Hajdas, Irka; Brauer, Achim; Blockley, Simon; Svensson, Anders; Moreno, Ana; Roche, Didier; Valdes, Paul; Birks, Hilary; Solveig Seidenkrantz, Marit; Evelpidou, Niki

    2013-04-01

    The objective of INTIMATE is to reconstruct past abrupt and extreme climate changes over the period 60,000 to 8000 years ago, by facilitating INTegration of Ice core, MArine, and TErrestrial palaeoclimate records and using the combined data in climate models to better understand the mechanisms and impact of change, thereby reducing the uncertainty of future prediction. The project is organized in four working groups: WG-1 Dating and Chronological Modelling A reliable chronological framework is the basis of all studies of the past climate. WG1 is dedicated to developing and improving dating methods over the last 60,000 years and bringing scientists together to develop a coherent dating framework in which records can be compared at unprecedented detail. WG-2 Quantification of Past Climate The aim of WG-2 is to collect and quantify information of past climate from e.g. ice cores, tree rings, corals, stalagmites, and marine and lake sediments in order to draw a detailed picture of the highly variable climate evolution in the North Atlantic region. WG-3 Modelling Mechanisms of Past Change Our ability to forecast the rates and magnitudes of future change depends on numerical models. By using combined ice core, terrestrial, and marine data sets as targets, WG-3 will optimize methodologies to evaluate model simulations and make data-model comparisons. WG-4 Climate Impacts The aim of WG-4 is to gain insights into the impacts of past climatic changes on animal and human populations and the ecosystems of which they are part. WG-4 will quantify the magnitudes and rates of population, species, and ecosystem responses to climate events of different magnitudes in space and through time. The INTIMATE network and the workshops and meetings are open to all interested scientists. INTIMATE also supports research exchange visits. More information can be found at http://cost-es0907.geoenvi.org/

  6. Recent temperature increase recorded in an ice core in the source region of Yangtze River

    Institute of Scientific and Technical Information of China (English)

    KANG ShiChang; ZHANG YongJun; QIN DaHe; REN JiaWen; ZHANG QiangGong; Bjorn GRIGHOLM; Paul A. MAYEWSKI

    2007-01-01

    Interests on climate change in the source region of Yangtze River have been raised since it is a region with the greatest warming over the Tibetan Plateau (TP). A 70-year history of precipitation δ18O has been recovered using an ice core record retrieved in a plat portion of the firn area in the Guoqu Glacier (33°34′37.8″N, 91°10′35.32″E, 5720 m a.s.l.), Mt. Geladaindong (the source region of Yangtze River), in November, 2005. By using a significant positive relationship between ice core δ18O record and summer air temperature (July to September) from the nearby meteorological stations, a history of summer air temperature has been reconstructed for the last 70 years. Summer temperature was relatively low in 1940s and high in 1950s to the middle of 1960s. The lowest temperature occurred in the middle of 1970s.Temperature was low in 1980s and dramatically increased since 1990s, keeping the trend to the beginning of the 21st century. The warming rate recorded in the ice core with 0.5°C/10 a since 1970s is much higher that that in the central TP and the Northern Hemisphere (NH), and it becomes 1.1°C/10 a since 1990s which is also higher than these from the central TP and the NH, reflecting an accelerated warming and a more sensitive response to global warming in the high elevation region.

  7. Duration of Greenland Stadial 22 and ice-gas Δage from counting of annual layers in Greenland NGRIP ice core

    Directory of Open Access Journals (Sweden)

    M. Bigler

    2012-11-01

    Full Text Available High-resolution measurements of chemical impurities and methane concentrations in Greenland ice core samples from the early glacial period allow the extension of annual-layer counted chronologies and the improvement of gas age-ice age difference (Δage essential to the synchronization of ice core records. We report high-resolution measurements of a 50 m section of the NorthGRIP ice core and corresponding annual layer thicknesses in order to constrain the duration of the Greenland Stadial 22 (GS-22 between Greenland Interstadials (GIs 21 and 22, for which inconsistent durations and ages have been reported from Greenland and Antarctic ice core records as well as European speleothems. Depending on the chronology used, GS-22 occurred between approximately 89 (end of GI-22 and 83 kyr b2k (onset of GI-21. From annual layer counting, we find that GS-22 lasted between 2696 and 3092 years and was followed by a GI-21 pre-cursor event lasting between 331 and 369 yr. Our layer-based counting agrees with the duration of stadial 22 as determined from the NALPS speleothem record (3250 ± 526 yr but not with that of the GICC05modelext chronology (2620 yr or an alternative chronology based on gas-marker synchronization to EPICA Dronning Maud Land ice core. These results show that GICC05modelext overestimates accumulation and/or underestimates thinning in this early part of the last glacial period. We also revise the possible ranges of NorthGRIP Δdepth (5.49 to 5.85 m and Δage (498 to 601 yr at the warming onset of GI-21 as well as the Δage range at the onset of the GI-21 precursor warming (523 to 654 yr, observing that temperature (represented by the δ15N proxy increases before CH4 concentration by no more than a few decades.

  8. Unexpected increase in elemental carbon values over the last 30 years observed in a Svalbard ice core

    Directory of Open Access Journals (Sweden)

    M. M. Ruppel

    2014-05-01

    Full Text Available Black carbon (BC is a light-absorbing particle that warms the atmosphere–Earth system. The climate effects of BC are amplified in the Arctic where its deposition on light surfaces decreases the albedo and causes earlier melt of snow and ice. Despite its suggested significant role in Arctic climate warming there is little information on BC concentrations and deposition in the past. Here we present results on BC (here operationally defined as elemental carbon (EC concentrations and deposition on a Svalbard glacier between 1700 and 2004. The inner part of a 125 m deep ice core from Holtedahlfonna glacier (79°8' N, 13°16' E, 1150 m a.s.l. was melted, filtered through a quartz fibre filter and analysed for EC using a thermal optical method. The EC values started to increase after 1850 and peaked around 1910, similar to ice core records from Greenland. Strikingly, the EC values again increase rapidly between 1970 and 2004. This rise is not seen in Greenland ice cores and it seems to contradict atmospheric BC measurements indicating generally decreasing atmospheric BC concentrations since 1989 in the Arctic. Several hypotheses, such as changes in scavenging efficiencies, post-depositional processes and differences in the vertical distribution of BC in the atmosphere, are discussed for the differences between the Svalbard and Greenland ice core records, and the ice core and atmospheric measurements in Svalbard. In addition, the divergent BC trends between Greenland and Svalbard ice cores may be caused by differences in the analytical methods used, including the operational definitions of quantified particles, and detection efficiencies of different-sized BC particles. Regardless of the cause of the increasing EC values in the recent decades, the results have significant implications for the past radiative energy balance at the coring site.

  9. Anomalously-dense firn in an ice-shelf channel revealed by wide-angle radar

    Directory of Open Access Journals (Sweden)

    R. Drews

    2015-10-01

    Full Text Available The thickness of ice shelves, a basic parameter for mass balance estimates, is typically inferred using hydrostatic equilibrium for which knowledge of the depth-averaged density is essential. The densification from snow to ice depends on a number of local factors (e.g. temperature and surface mass balance causing spatial and temporal variations in density–depth profiles. However, direct measurements of firn density are sparse, requiring substantial logistical effort. Here, we infer density from radio-wave propagation speed using ground-based wide-angle radar datasets (10 MHz collected at five sites on Roi Baudouin Ice Shelf (RBIS, Dronning Maud Land, Antarctica. Using a novel algorithm including traveltime inversion and raytracing with a prescribed shape of the depth–density relationship, we show that the depth to internal reflectors, the local ice thickness and depth-averaged densities can reliably be reconstructed. For the particular case of an ice-shelf channel, where ice thickness and surface slope change substantially over a few kilometers, the radar data suggests that firn inside the channel is about 5 % denser than outside the channel. Although this density difference is at the detection limit of the radar, it is consistent with a similar density anomaly reconstructed from optical televiewing, which reveals 10 % denser firn inside compared to outside the channel. The denser firn in the ice-shelf channel should be accounted for when using the hydrostatic ice thickness for determining basal melt rates. The radar method presented here is robust and can easily be adapted to different radar frequencies and data-acquisition geometries.

  10. The 4700 aB.P. volcanic signal detected in Vostok BH8 ice core, Antarctica

    Institute of Scientific and Technical Information of China (English)

    LIU Leibao; KANG Jiancheng; Jean R. Petit; Jefferson C. Sim(o)es; Martine De Angelis

    2005-01-01

    The detailed electrical conductivity measurement (ECM), trace chemical compositions and microparticles concentration analysis are performed for BH8 ice core from the depth of 126.0m to 130.0m at Vostok Station. At depth 128.7m, a volcanic signal 4726 a B.P. is detected. The volcanic sulphate flux is 95.8 kg·km-2, sulphate peak concentration 1352.8 ng·g-1, duration time about 10.1 years, comparable with some well-known volcanic events. The results indicate that it seems to be a relatively large scale, long lasting volcanic signal with farther volcanic origin.

  11. High-frequency paleoclimatic variability: a spectral analysis of the Vostok ice-core isotopic record

    Energy Technology Data Exchange (ETDEWEB)

    Yiou, P.; Genthon, C.; Jouzel, J.; Le Treut, H.; Lorius, C.; Ghil, M.; Korotkevich, Y.S.

    1988-01-01

    This paper uses a recently analysed isotopic record from an ice core drilled at the Soviet Antartic Station VOSTOK, representing a total time span of about 160,000 years. Results obtained show the existence of a significative climatic variability at the time scale of 10,000 years and below. The many spectral peaks appear to be approximate linear combination of a little number among them, a clear indication of the non linear nature of climate fluctuations at these ''short'' time scales.

  12. The ice-core record - Climate sensitivity and future greenhouse warming

    Science.gov (United States)

    Lorius, C.; Raynaud, D.; Jouzel, J.; Hansen, J.; Le Treut, H.

    1990-01-01

    The prediction of future greenhouse-gas-warming depends critically on the sensitivity of earth's climate to increasing atmospheric concentrations of these gases. Data from cores drilled in polar ice sheets show a remarkable correlation between past glacial-interglacial temperature changes and the inferred atmospheric concentration of gases such as carbon dioxide and methane. These and other palaeoclimate data are used to assess the role of greenhouse gases in explaining past global climate change, and the validity of models predicting the effect of increasing concentrations of such gases in the atmosphere.

  13. Continuous ice core melter system with discrete sampling for major ion, trace element and stable isotope analyses.

    Science.gov (United States)

    Osterberg, Erich C; Handley, Michael J; Sneed, Sharon B; Mayewski, Paul A; Kreutz, Karl J

    2006-05-15

    We present a novel ice/firn core melter system that uses fraction collectors to collect discrete, high-resolution (32 trace elements by inductively coupled plasma sectorfield mass spectrometry (ICP-SMS), and stable oxygen and hydrogen isotopes by isotope ratio mass spectrometry (IRMS). The new continuous melting with discrete sampling (CMDS) system preserves an archive of each sample, reduces the problem of incomplete particle dissolution in ICP-SMS samples, and provides more precise trace element data than previous ice melter models by using longer ICP-SMS scan times and washing the instrument between samples. CMDS detection limits are similar to or lower than those published for ice melter systems coupled directly to analytical instruments and are suitable for analyses of polar and mid-low-latitude ice cores. Analysis of total calcium and sulfur by ICP-SMS and calcium ion, sulfate, and methanesulfonate by IC from the Mt. Logan Prospector-Russell Col ice core confirms data accuracy and coregistration of the split fractions from each sample. The reproducibility of all data acquired by the CMDS system is confirmed by replicate analyses of parallel sections of the GISP2 D ice core.

  14. Ice core measurements of the isotopic composition of nitrate: new results and interpretation

    Science.gov (United States)

    Steig, E. J.; Hastings, M. G.; Alexander, B.; Jarvis, J. C.; Kunasek, S. C.

    2006-12-01

    Several fundamental questions about the magnitude of natural variability in the global nitrogen cycle, and the impact of human activities in the last century, remain open. For example, lakes around the world show significant declines in organic nitrogen isotope ratios but it remains unclear to what extent this reflects changed nitrate sources or in situ changes in lake biogeochemistry. It also remains unknown whether atmospheric NOx mixing ratios were significantly different during the last glacial period; because atmospheric NOx abundances influence methane oxidation chemistry, this may have implications for closure of the global methane budget. While ice core measurements of nitrate concentration demonstrate that human activity has at least doubled the concentration of nitrogen oxides in the atmosphere in the last century, more quantitative use of such data has proven difficult due to the variety of possible nitrate sources, the complex atmospheric chemistry, and the potential for post-depositional change. The utility of ice cores in elucidating past changes in the global nitrogen cycle may be greatly enhanced through the analysis of nitrate isotope ratios. Our work on ice cores is coupled with direct atmospheric measurements of gas-phase HNO3 and its precursors, and global modeling of isotope variations in reactive nitrogen species, reported elsewhere at this meeting. Here, we report on our ongoing analyses of nitrogen and oxygen isotope ratios from ice cores at South Pole, the WAIS Divide (site of the new US drilling effort in West Antarctica), GISP2, and a new 100-meter core from Summit, Greenland. Snow pit data demonstrate that changes in oxygen isotope ratios (δ18O and Δ17O [= δ17O -0.52*δ18O]) in nitrate can be related directly to changes in the ratio of gas phase ("daytime") vs. aqueous phase ("nighttime") chemistry in the production of nitrate in the atmosphere. Nitrogen isotope ratios (δ15N) are also affected by photochemistry, but variations in

  15. Atmospheric Mercury Depositional Chronology Reconstructed from Lake Sediments and Ice Core in the Himalayas and Tibetan Plateau.

    Science.gov (United States)

    Kang, Shichang; Huang, Jie; Wang, Feiyue; Zhang, Qianggong; Zhang, Yulan; Li, Chaoliu; Wang, Long; Chen, Pengfei; Sharma, Chhatra Mani; Li, Qing; Sillanpää, Mika; Hou, Juzhi; Xu, Baiqing; Guo, Junming

    2016-03-15

    Alpine lake sediments and glacier ice cores retrieved from high mountain regions can provide long-term records of atmospheric deposition of anthropogenic contaminants such as mercury (Hg). In this study, eight lake sediment cores and one glacier ice core were collected from high elevations across the Himalaya-Tibet region to investigate the chronology of atmospheric Hg deposition. Consistent with modeling results, the sediment core records showed higher Hg accumulation rates in the southern slopes of the Himalayas than those in the northern slopes in the recent decades (post-World War II). Despite much lower Hg accumulation rates obtained from the glacier ice core, the temporal trend in the Hg accumulation rates matched very well with that observed from the sediment cores. The combination of the lake sediments and glacier ice core allowed us to reconstruct the longest, high-resolution atmospheric Hg deposition chronology in High Asia. The chronology showed that the Hg deposition rate was low between the 1500s and early 1800, rising at the onset of the Industrial Revolution, followed by a dramatic increase after World War II. The increasing trend continues to the present-day in most of the records, reflecting the continuous increase in anthropogenic Hg emissions from South Asia.

  16. Photobiology of sea ice algae during initial spring growth in Kangerlussuaq, West Greenland: insights from imaging variable chlorophyll fluorescence of ice cores.

    Science.gov (United States)

    Hawes, Ian; Lund-Hansen, Lars Chresten; Sorrell, Brian K; Nielsen, Morten Holtegaard; Borzák, Réka; Buss, Inge

    2012-06-01

    We undertook a series of measurements of photophysiological parameters of sea ice algae over 12 days of early spring growth in a West Greenland Fjord, by variable chlorophyll fluorescence imaging. Imaging of the ice-water interface showed the development of ice algae in 0.3-0.4 mm wide brine channels between laminar ice crystals in the lower 4-6 mm of the ice, with a several-fold spatial variation in inferred biomass on cm scales. The maximum quantum yield of photosynthesis, F(v) /F(m), was initially low (~0.1), though this increased rapidly to ~0.5 by day 6. Day 6 also saw the onset of biomass increase, the cessation of ice growth and the time at which brine had reached -2 °C. We interpret this as indicating that the establishment of stable brine channels at close to ambient salinity was required to trigger photosynthetically active populations. Maximum relative electron transport rate (rETR(max)), saturation irradiance (E(k)) and photosynthetic efficiency (α) had also stabilised by day 6 at 5-6 relative units, ~30 μmol photons m⁻² s⁻¹ and 0.4-0.5 μmol photons m⁻²s⁻¹, respectively. E(k) was consistent with under-ice irradiance, which peaked at a similar value, confirming that daytime irradiance was adequate to facilitate photosynthetic activity throughout the study period. Photosynthetic parameters showed no substantial differences with depth within the ice, nor variation between cores or brine channels suggesting that during this early phase of ice algal growth cells were unaffected by gradients of environmental conditions within the ice. Variable chlorophyll fluorescence imaging offers a tool to determine how this situation may change over time and as brine channels and algal populations evolve.

  17. Measuring stable isotopes of hydrogen and oxygen in ice by means of laser spectrometry : The Bolling transition in the Dye-3 (south Greenland) ice core

    NARCIS (Netherlands)

    Trigt, R. van; Meijer, H.A.J.; Sveinbjornsdottir, A.E.; Johnsen, S.J.; Kerstel, E.R.Th.

    2002-01-01

    We report on the first application of a new technique in ice-core research, based on direct absorption infrared laser spectrometry (LS), for measuring H-2 O-17 and O-18 isotope ratios. The data are used to calculate the deuterium excess d (defined as delta(2)H - 8delta(18)O) for a section of the

  18. Ice core evidence for a 20th century increase in surface mass balance in coastal Dronning Maud Land, East Antarctica

    Science.gov (United States)

    Philippe, Morgane; Tison, Jean-Louis; Fjøsne, Karen; Hubbard, Bryn; Kjær, Helle A.; Lenaerts, Jan T. M.; Drews, Reinhard; Sheldon, Simon G.; De Bondt, Kevin; Claeys, Philippe; Pattyn, Frank

    2016-10-01

    Ice cores provide temporal records of surface mass balance (SMB). Coastal areas of Antarctica have relatively high and variable SMB, but are under-represented in records spanning more than 100 years. Here we present SMB reconstruction from a 120 m-long ice core drilled in 2012 on the Derwael Ice Rise, coastal Dronning Maud Land, East Antarctica. Water stable isotope (δ18O and δD) stratigraphy is supplemented by discontinuous major ion profiles and continuous electrical conductivity measurements. The base of the ice core is dated to AD 1759 ± 16, providing a climate proxy for the past ˜ 250 years. The core's annual layer thickness history is combined with its gravimetric density profile to reconstruct the site's SMB history, corrected for the influence of ice deformation. The mean SMB for the core's entire history is 0.47 ± 0.02 m water equivalent (w.e.) a-1. The time series of reconstructed annual SMB shows high variability, but a general increase beginning in the 20th century. This increase is particularly marked during the last 50 years (1962-2011), which yields mean SMB of 0.61 ± 0.01 m w.e. a-1. This trend is compared with other reported SMB data in Antarctica, generally showing a high spatial variability. Output of the fully coupled Community Earth System Model (CESM) suggests that, although atmospheric circulation is the main factor influencing SMB, variability in sea surface temperatures and sea ice cover in the precipitation source region also explain part of the variability in SMB. Local snow redistribution can also influence interannual variability but is unlikely to influence long-term trends significantly. This is the first record from a coastal ice core in East Antarctica to show an increase in SMB beginning in the early 20th century and particularly marked during the last 50 years.

  19. Continuous flow analysis method for determination of soluble iron and aluminium in ice cores.

    Science.gov (United States)

    Spolaor, A; Vallelonga, P; Gabrieli, J; Roman, M; Barbante, C

    2013-01-01

    Iron and aluminium are the two most abundant metals on the Earth's crust, but they display quite different biogeochemical properties. While iron is essential to many biological processes, aluminium has not been found to have any biological function at all. In environmental studies, iron has been studied in detail for its limiting role in the bioproductivity of high nutrient, low carbon oceanic zones, while aluminium is routinely used as a reference of crustal contributions to atmospheric deposition archives including peat bogs, lacustrine and marine sediments and ice sheets and glaciers. We report here the development of a flow injection analysis technique, which has been optimised for the simultaneous determination of soluble iron and aluminium in polar ice cores. Iron was determined by its catalytic role in the reduction of N,N-dimethyl-p-phenylenediamene (DPD) to a semiquinonic form (DPDQ) and subsequent absorption spectroscopy at 514 nm. Aluminium was determined by spectroscopic analysis of an aluminium-lumogallion complex that exhibits fluorescence at 560 nm. These techniques have been applied to a section of Greenland ice dated to 1729-1733 AD and indicate that volcanism is a source of highly soluble aluminium and iron.

  20. Synchronisation of the EDML and EDC ice cores for the last 52 kyr by volcanic signature matching

    DEFF Research Database (Denmark)

    Severi, M.; Becagli, S.; Castellano, E.

    2007-01-01

    A common time scale for the EPICA ice cores from Dome C (EDC) and Dronning Maud Land (EDML) has been established. Since the EDML core was not drilled on a dome, the development of the EDML1 time scale for the EPICA ice core drilled in Dronning Maud Land was based on the creation of a detailed...... stratigraphic link between EDML and EDC, which was dated by a simpler 1D ice-flow model. The synchronisation between the two EPICA ice cores was done through the identification of several common volcanic signatures. This paper describes the rigorous method, using the signature of volcanic sulfate, which.......2 corresponding to an uncertainty of up to 20% in the estimate of the time duration in at least one of the two ice cores. Significant deviations of R up to 1.4-1.5 are observed between 18 and 28 kyr before present (BP), where present is defined as 1950. At this stage our approach does not allow us unequivocally...

  1. Atmospheric depositions of black carbon, inorganic pollutants and mineral dust from the Ortles, Eastern European Alps ice cores during the last 3000 years

    Science.gov (United States)

    Bertò, Michele; Barbante, Carlo; Gabrielli, Paolo; Gabrieli, Jacopo; Spolaor, Andrea; Dreossi, Giuliano; Laj, Paolo; Zanatta, Marco; Stenni, Barbara

    2017-04-01

    Reconstructions of the atmospheric content of black carbon, heavy metals and mineral dust covering millennial time scales are rare, particularly in the European region. Evaluating the human impact on the environment through mining and industrial activities, road traffic, biomass and coal burning, and the naturally emitted aerosols atmospheric load, is important to know the degree of contaminations and the quality of melting water, the radiative effect on the glacier's radiative balance, the atmospheric aerosols' climatic impacts and the recent decades pollutions emissions policies' efficiencies. Four ice cores were drilled in 2011 from the "Alto dell'Ortles" (3859 m), the highest glacier of the Mt. Ortles massif (South Tirol, Italy). Three 74 m long ice cores were dated by mean of 210Pb, tritium, beta emissions and 14C analyses following also the new dating technique based on filtering the ice for extracting the carbonaceous component of the deposited aerosols. The depth-age curve was obtained by using a Monte Carlo based empirical fitting model (COPRA). The basal ice of core#2 and #3 was dated back to about 7000 years b.p., whereas that of core#1, about one meter shorter, to 3000 years before present. Below the firn-ice transition, at a depth of about 24 m, the borehole temperature revealed the presence of well-preserved cold ice (Gabrielli et al, 2012). The O and H stable isotopes profiles describe well the atmospheric warming as well as the low temperatures recorded during the Little Ice Age (LIA). The proximity of the "Alto dell'Ortles" to densely industrialized areas (Po Valley) makes these ice cores specifically suited for reconstructing the anthropogenic impacts in the Eastern European Alpine region over the last 3 millennia. The ice core#1 was analyzed with a "Continuous Flow Analysis" system (CFA). The separation between internal and external parts of the core prevents any kind of contamination. The core was melted at about 2.5 cm min-1 and simultaneous

  2. Ice and Dust in the Quiescent Medium of Isolated Dense Cores

    Science.gov (United States)

    Boogert, A. C. A.; Huard, T. L.; Cook, A. M.; Chiar, J. E.; Knez, C.; Decin, L.; Blake, G. A.; Tielens, A. G. G. M.; van Dishoeck, E. F.

    2011-03-01

    The relation between ices in the envelopes and disks surrounding young stellar objects (YSOs) and those in the quiescent interstellar medium (ISM) is investigated. For a sample of 31 stars behind isolated dense cores, ground-based and Spitzer spectra and photometry in the 1-25 μm wavelength range are combined. The baseline for the broad and overlapping ice features is modeled, using calculated spectra of giants, H2O ice and silicates. The adopted extinction curve is derived empirically. Its high resolution allows for the separation of continuum and feature extinction. The extinction between 13 and 25 μm is ~50% relative to that at 2.2 μm. The strengths of the 6.0 and 6.85 μm absorption bands are in line with those of YSOs. Thus, their carriers, which, besides H2O and CH3OH, may include NH+ 4, HCOOH, H2CO, and NH3, are readily formed in the dense core phase, before stars form. The 3.53 μm C-H stretching mode of solid CH3OH was discovered. The CH3OH/H2O abundance ratios of 5%-12% are larger than upper limits in the Taurus molecular cloud. The initial ice composition, before star formation occurs, therefore depends on the environment. Signs of thermal and energetic processing that were found toward some YSOs are absent in the ices toward background stars. Finally, the peak optical depth of the 9.7 μm band of silicates relative to the continuum extinction at 2.2 μm is significantly shallower than in the diffuse ISM. This extends the results of Chiar et al. to a larger sample and higher extinctions. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  3. Possible recent warming hiatus on the northwestern Tibetan Plateau derived from ice core records

    Science.gov (United States)

    An, Wenling; Hou, Shugui; Zhang, Wangbin; Wu, Shuangye; Xu, Hao; Pang, Hongxi; Wang, Yetang; Liu, Yaping

    2016-09-01

    Many studies have reported enhanced warming trend on the Tibetan Plateau (TP), even during the warming hiatus period. However, most of these studies are based on instrumental data largely collected from the eastern TP, whereas the temperature trend over the extensive northwestern TP remains uncertain due to few meteorological stations. Here we combined the stable isotopic δ18O record of an ice core recovered in 2012 from the Chongce glacier with the δ18O records of two other ice cores (i.e., Muztagata and Zangser Kangri) in the same region to establish a regional temperature series for the northwestern TP. The reconstruction shows a significant warming trend with a rate of 0.74 ± 0.12 °C/decade for the period 1970-2000, but a decreasing trend from 2001 to 2012. This is consistent with the reduction of warming rates during the recent decade observed at the only two meteorological stations on the northwestern TP, even though most stations on the eastern TP have shown persistent warming during the same period. Our results suggest a possible recent warming hiatus on the northwestern TP. This could have contributed to the relatively stable status of glaciers in this region.

  4. Ice Core Perspective on Mercury Pollution during the Past 600 Years.

    Science.gov (United States)

    Beal, Samuel A; Osterberg, Erich C; Zdanowicz, Christian M; Fisher, David A

    2015-07-07

    Past emissions of the toxic metal mercury (Hg) persist in the global environment, yet these emissions remain poorly constrained by existing data. Ice cores are high-resolution archives of atmospheric deposition that may provide crucial insight into past atmospheric Hg levels during recent and historical time. Here we present a record of total Hg (HgT) in an ice core from the pristine summit plateau (5340 m asl) of Mount Logan, Yukon, Canada, representing atmospheric deposition from AD 1410 to 1998. The Colonial Period (∼1603-1850) and North American "Gold Rush" (1850-1900) represent minor fractions (8% and 14%, respectively) of total anthropogenic Hg deposition in the record, with the majority (78%) occurring during the 20th Century. A period of maximum HgT fluxes from 1940 to 1975 coincides with estimates of enhanced anthropogenic Hg emissions from commercial sources, as well as with industrial emissions of other toxic metals. Rapid declines in HgT fluxes following peaks during the Gold Rush and the mid-20th Century indicate that atmospheric Hg deposition responds quickly to reductions in emissions. Increasing HgT fluxes from 1993 until the youngest samples in 1998 may reflect the resurgence of Hg emissions from unregulated coal burning and small-scale gold mining.

  5. The Laschamp geomagnetic excursion featured in nitrate record from EPICA-Dome C ice core

    Science.gov (United States)

    Traversi, R.; Becagli, S.; Poluianov, S.; Severi, M.; Solanki, S. K.; Usoskin, I. G.; Udisti, R.

    2016-01-01

    Here we present the first direct comparison of cosmogenic 10Be and chemical species in the period of 38–45.5 kyr BP spanning the Laschamp geomagnetic excursion from the EPICA-Dome C ice core. A principal component analysis (PCA) allowed to group different components as a function of the main sources, transport and deposition processes affecting the atmospheric aerosol at Dome C. Moreover, a wavelet analysis highlighted the high coherence and in-phase relationship between 10Be and nitrate at this time. The evident preferential association of 10Be with nitrate rather than with other chemical species was ascribed to the presence of a distinct source, here labelled as “cosmogenic”. Both the PCA and wavelet analyses ruled out a significant role of calcium in driving the 10Be and nitrate relationship, which is particularly relevant for a plateau site such as Dome C, especially in the glacial period during which the Laschamp excursion took place. The evidence that the nitrate record from the EDC ice core is able to capture the Laschamp event hints toward the possibility of using this marker for studying galactic cosmic ray flux variations and thus also major geomagnetic field excursions at pluri-centennial-millennial time scales, thus opening up new perspectives in paleoclimatic studies. PMID:26819064

  6. Ice core based Pb pollution from gasoline in South America in the context of a 2000 year metallurgical history

    Science.gov (United States)

    Eichler, Anja; Gramlich, Gabriela; Kellerhals, Thomas; Tobler, Leonhard; Schwikowski, Margit

    2015-04-01

    Lead (Pb) is highly neurotoxic and, in contrast to many other heavy metals including cobalt, copper, and zinc, it has no beneficial effects to humans even at low concentrations. The introduction of leaded gasoline in the 1920s initiated a period of unabated growth in the global emissions of Pb. Prior to the onset of leaded gasoline phase-out in the 1970s, atmospheric Pb levels increased dramatically. Long-term histories of Pb pollution in Eastern and Western Europe, Asia, and North America suggest that emissions from leaded gasoline within the Northern Hemisphere are dominant compared to that from metallurgy and coal combustion during the second half of the 20th century. However, there is no equivalent data for Southern America. Although exploitation of the extensive polymetallic deposits of the Andean Altiplano in South America since pre-colonial times has caused substantial emissions of neurotoxic Pb into the atmosphere, its historical significance compared to recent Pb pollution from leaded gasoline is not yet resolved. Here we present the first comprehensive, high-resolution two millennia Pb emission history for South America, based on ice core records of Pb concentrations, Pb enrichment factors (EFs), and Pb isotope ratios from Illimani glacier in Bolivia. Complementary to local air pollution recorded in lake sediments, ice cores from mid latitude glaciers provide information about more extended source areas. Illimani is the highest mountain of the eastern Bolivian Andes and is located at the northeastern margin of the Bolivian Altiplano. The ice core Pb deposition history revealed enhanced Pb EFs due to metallurgical processing for silver production during periods of the Tiwanaku/Wari culture (AD 450-950), the Inca empires (AD 1450-1532), colonial times (AD 1532-1900), and tin production at the beginning of the 20th century. After the 1960s 208Pb/207Pb ratios decreased significantly, whereas Pb EFs increased by a factor of three compared to the emission level

  7. Human and climate impacts on Holocene fire activity recorded in polar and mountain ice cores

    Science.gov (United States)

    Kehrwald, Natalie; Zennaro, Piero; Kirchgeorg, Torben; Li, Quanlian; Wang, Ninglian; Power, Mitchell; Zangrando, Roberta; Gabrielli, Paolo; Thompson, Lonnie; Gambaro, Andrea; Barbante, Carlo

    2014-05-01

    Fire is one of the major influences of biogeochemical change on local to hemispheric scales through emitting greenhouse gases, altering atmospheric chemistry, and changing primary productivity. Levoglucosan (1,6-anhydro-β-D-glucopyranose) is a specific molecular that can only be produced by cellulose burning at temperatures > 300°C, comprises a major component of smoke plumes, and can be transported across > 1000 km distances. Levoglucosan is deposited on and archived in glaciers over glacial interglacial cycles resulting in pyrochemical evidence for exploring interactions between fire, climate and human activity. Ice core records provide records of past biomass burning from regions of the world with limited paleofire data including polar and low-latitude, high-altitude regions. Here, we present Holocene fire activity records from the NEEM, Greenland (77° 27'N; 51° 3'W; 2454 masl), EPICA Dome C, Antarctica (75° 06'S; 123° 21'E; 3233 masl), Kilimanjaro, Tanzania (3° 05'S, 21.2° E, 5893 masl) and the Muztagh, China (87.17° E; 36.35° N; 5780 masl ice cores. The NEEM ice core reflects boreal fire activity from both North American and Eurasian sources. Temperature is the dominant control of NEEM levoglucosan flux over decadal to millennial time scales, while droughts influence fire activity over sub-decadal timescales. Our results demonstrate the prominence of Siberian fire sources during intense multiannual droughts. Unlike the NEEM core, which incorporates the largest land masses in the world as potential fire sources, EPICA Dome C is located far from any possible fire source. However, EPICA Dome C levoglucosan concentrations are consistently above detection limits and demonstrate a substantial 1000-fold increase in fire activity beginning approximately 800 years ago. This significant and sustained increase coincides with Maori arrival and dispersal in New Zealand augmented by later European arrival in Australia. The EPICA Dome C levoglucosan profile is

  8. Ice core reconstruction of sea ice change in the Amundsen-Ross Seas since 1702 A.D.

    Science.gov (United States)

    Thomas, Elizabeth R.; Abram, Nerilie J.

    2016-05-01

    Antarctic sea ice has been increasing in recent decades, but with strong regional differences in the expression of sea ice change. Declining sea ice in the Bellingshausen Sea since 1979 (the satellite era) has been linked to the observed warming on the Antarctic Peninsula, while the Ross Sea sector has seen a marked increase in sea ice during this period. Here we present a 308 year record of methansulphonic acid from coastal West Antarctica, representing sea ice conditions in the Amundsen-Ross Sea. We demonstrate that the recent increase in sea ice in this region is part of a longer trend, with an estimated ~1° northward expansion in winter sea ice extent (SIE) during the twentieth century and a total expansion of ~1.3° since 1702. The greatest reconstructed SIE occurred during the mid-1990s, with five of the past 30 years considered exceptional in the context of the past three centuries.

  9. Core to Atmosphere Exploration of Ice Giants: A Uranus Mission Concept Study

    Science.gov (United States)

    Jensema, R. J.; Arias-Young, T. M.; Wilkins, A. N.; Ermakov, A.; Bennett, C.; Dietrich, A.; Hemingway, D.; Klein, V.; Mane, P.; Marr, K. D.; Masterson, J.; Siegel, V.; Stober, K. J.; Talpe, M.; Vines, S. K.; Wetteland, C. J.

    2014-12-01

    Ice giants remain largely unexplored, as their large distance from the Sun limits both Earth-based observations and spacecraft visits. The significant occurrence of ice giant-sized planets among detected exoplanets presents an impetus to study Uranus to understand planetary formation, dynamics, and evolution. In addition, Uranus is also uniquely interesting, given the large inclination of its rotation axis and magnetospheric configuration. In this work, we design a mission concept that aims to maximize scientific return by measuring Uranus' chemical composition, internal structure, and magnetosphere, the first two being primary indicators of ice giant formation mechanisms. For this study, we analyze the trade space for a Uranus mission constrained by a cost cap of $1B. We discuss the decision making processes behind our choices of the science priorities, instrument suite and orbital configuration. Trade space decisions include a strong onboard instrument suite in lieu of a descent probe, an orbiter instead of a flyby mission, and design constraints on the power and propulsion systems. The mission, CAELUS (Core and Atmospheric Evolution Laboratory for Uranus Science), is designed for an August 2023 launch. Following a 14-year cruise with multiple planetary gravity assists, the spacecraft would begin its science mission, which consists of a series of ten 30-day near-polar orbits around Uranus. The instrument suite would consist of a microwave radiometer, Doppler seismometer, magnetometer, and UV spectrometer. These four instruments, along with a high-gain antenna capable of gravity science, would provide a comprehensive science return that meets the bulk of the scientific objectives of the 2013 NRC Planetary Science Decadal Survey for ice giants, most notably those regarding the chemical composition, interior structure, and dynamo of Uranus. This mission concept was created as part of an educational exercise for the 2014 Planetary Science Summer School at the Jet

  10. Anomalously high arsenic concentration in a West Antarctic ice core and its relationship to copper mining in Chile

    Science.gov (United States)

    Schwanck, Franciele; Simões, Jefferson C.; Handley, Michael; Mayewski, Paul A.; Bernardo, Ronaldo T.; Aquino, Francisco E.

    2016-01-01

    Arsenic variability records are preserved in snow and ice cores and can be utilized to reconstruct air pollution history. The Mount Johns ice core (79°55‧S; 94°23‧W and 91.2 m depth) was collected from the West Antarctic Ice Sheet in the 2008/09 austral summer. Here, we report the As concentration variability as determined by 2137 samples from the upper 45 m of this core using ICP-SFMS (CCI, University of Maine, USA). The record covers approximately 125 years (1883-2008) showing a mean concentration of 4.32 pg g-1. The arsenic concentration in the core follows global copper mining evolution, particularly in Chile (the largest producer of Cu). From 1940 to 1990, copper-mining production increased along with arsenic concentrations in the MJ core, from 1.92 pg g-1 (before 1900) to 7.94 pg g-1 (1950). In the last two decades, environmental regulations for As emissions have been implemented, forcin