scholarly journals Air Content Of The Byrd Core And Past Changes In The West Antarctic Ice Sheet

1982 ◽  
Vol 3 ◽  
pp. 269-273 ◽  
Author(s):  
D. Raynaud ◽  
I. M. Whillans
Keyword(s):  
Stable Isotope ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ice Sheet ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Ice Age ◽  
Gas Content ◽  
Stable Isotope Ratios ◽  
Antarctic Ice Sheet

Analyses of ice cores taken from the Antarctic ice sheet can provide information on the environmental conditions under which the ice was formed. New results from measurements of gas content and stable isotope ratios in the Byrd station ice core are discussed and interpreted in terms of past iceflow changes.165 selected ice samples from 32 different depth levels along the core were processed for total gas content V and stable isotope ratios. This large dataset is used to discuss the variability and significance of the values of V at different depths. The short term variations of V are mainly explained by heterogeneities of the pore volume when the firn pores close off.The general trends in the values of V with depth are then used to investigate the possibility of past changes in the ice sheet. They suggest near-steady flow during the past few tens of thousands of years and that a thickening of about 200 to 250 m occurred in this area of the ice sheet at the end of the last ice age. This thickening could be due to a change in the accumulation rate.

scholarly journals Air Content Of The Byrd Core And Past Changes In The West Antarctic Ice Sheet

1982 ◽  
Vol 3 ◽  
pp. 269-273 ◽  
Author(s):  
D. Raynaud ◽  
I. M. Whillans
Keyword(s):  
Stable Isotope ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ice Sheet ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Ice Age ◽  
Gas Content ◽  
Stable Isotope Ratios ◽  
Antarctic Ice Sheet

Analyses of ice cores taken from the Antarctic ice sheet can provide information on the environmental conditions under which the ice was formed. New results from measurements of gas content and stable isotope ratios in the Byrd station ice core are discussed and interpreted in terms of past iceflow changes.165 selected ice samples from 32 different depth levels along the core were processed for total gas content V and stable isotope ratios. This large dataset is used to discuss the variability and significance of the values of V at different depths. The short term variations of V are mainly explained by heterogeneities of the pore volume when the firn pores close off.The general trends in the values of V with depth are then used to investigate the possibility of past changes in the ice sheet. They suggest near-steady flow during the past few tens of thousands of years and that a thickening of about 200 to 250 m occurred in this area of the ice sheet at the end of the last ice age. This thickening could be due to a change in the accumulation rate.

scholarly journals Precipitation regime and stable oxygen isotopes at Dome C, East Antarctica – a comparison of two extreme years 2009 and 2010

2015 ◽  
Vol 15 (21) ◽  
pp. 30473-30509
Author(s):  
E. Schlosser ◽  
B. Stenni ◽  
M. Valt ◽  
A. Cagnati ◽  
J. G. Powers ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Ice Core ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Atmospheric Model ◽  
Stable Isotope Ratios ◽  
Stable Water Isotopes ◽  
Precipitation Regime ◽  
Meridional Transport ◽  
Measuring Period

Abstract. At the East Antarctic deep ice core drilling site Dome C, daily precipitation measurements have been initiated in 2006 and are being continued until today. The amounts and stable isotope ratios of the precipitation samples as well as crystal types are determined. Within the measuring period, the two years 2009 and 2010 showed striking contrasting temperature and precipitation anomalies, particularly in the winter seasons. The reasons for these anomalies and their relation to stable isotope ratios are analysed using data from the mesoscale atmospheric model WRF (Weather Research and Forecasting Model) run under the Antarctic Mesoscale Prediction System (AMPS). 2009 was relatively warm and moist due to frequent warm air intrusions connected to amplification of Rossby waves in the circumpolar westerlies, whereas the winter of 2010 was extremely dry and cold. It is shown that while in 2010 a strong zonal atmospheric flow was dominant, in 2009 an enhanced meridional flow prevailed, which increased the meridional transport of heat and moisture onto the East Antarctic plateau and led to a number of high-precipitation/warming events at Dome C. This was also evident in a positive (negative) SAM index and a negative (positive) ZW3 index during the winter months of 2010 (2009). Changes in the frequency or seasonality of such event-type precipitation can lead to a strong bias in the air temperature derived from stable water isotopes in ice cores.

scholarly journals The Chemical Stratigraphy of Polar Ice Sheets — A Method of Dating Ice Cores

1981 ◽  
Vol 27 (95) ◽  
pp. 3-9
Author(s):  
A. T. Wilson ◽  
C. H. Hendy
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Ice Sheet ◽  
Ice Cores ◽  
Antarctic Ice Sheet ◽  
The Core ◽  
Similar Work ◽  
Polar Ice Sheets ◽  
Vostok Station ◽  
East Antarctic Ice Sheet

AbstractStudies of the chemical stratigraphy in the snow near Vostok station, which is near the centre of the East Antarctic ice sheet, show that sodium exhibits annual concentration differences of up to a factor of ten. Similar work on the 952 m Vostok ice core enabled accumulation rates along selected parts of the core to be determined. This in turn enables the core to be dated. The accumulation rate in this central region of the East Antarctic ice sheet for the last 50000 years has been determined and is presented. An interesting result is that the accumulation rate during the last glacial period is only half that in post-glacial times. Results from the bottom of the core provide some evidence of a past surge in the East Antarctic ice sheet.

scholarly journals The Chemical Stratigraphy of Polar Ice Sheets — A Method of Dating Ice Cores

1981 ◽  
Vol 27 (95) ◽  
pp. 3-9 ◽  
Author(s):  
A. T. Wilson ◽  
C. H. Hendy
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Ice Sheet ◽  
Ice Cores ◽  
Antarctic Ice Sheet ◽  
The Core ◽  
Similar Work ◽  
Polar Ice Sheets ◽  
Vostok Station ◽  
East Antarctic Ice Sheet

Abstract Studies of the chemical stratigraphy in the snow near Vostok station, which is near the centre of the East Antarctic ice sheet, show that sodium exhibits annual concentration differences of up to a factor of ten. Similar work on the 952 m Vostok ice core enabled accumulation rates along selected parts of the core to be determined. This in turn enables the core to be dated. The accumulation rate in this central region of the East Antarctic ice sheet for the last 50000 years has been determined and is presented. An interesting result is that the accumulation rate during the last glacial period is only half that in post-glacial times. Results from the bottom of the core provide some evidence of a past surge in the East Antarctic ice sheet.

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

2016 ◽  
Vol 30 (9) ◽  
pp. 1324-1347 ◽  
Author(s):  
C. M. Zdanowicz ◽  
E. M. Krümmel ◽  
A. J. Poulain ◽  
E. Yumvihoze ◽  
J. Chen ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Stable Isotope Ratios ◽  
Arctic Glacier

scholarly journals Primary results of glaciological studies along an 1100 km transect from Zhongshan station to Dome A, East Antarctic ice sheet

2000 ◽  
Vol 31 ◽  
pp. 198-204 ◽  
Author(s):  
Qin Dahe ◽  
Ren Jiawen ◽  
Kang Jiancheng ◽  
Xiao Cunde ◽  
Li Zhongqin ◽  
...  
Keyword(s):  
Mass Balance ◽  
Accumulation Rate ◽  
Ice Sheet ◽  
Ice Cores ◽  
Spatial And Temporal Variability ◽  
Dome A ◽  
Antarctic Ice Sheet ◽  
Zhongshan Station ◽  
Inaccessible Area ◽  
East Antarctic Ice Sheet

AbstractThe Chinese National Antarctic Research Expedition (GHINARE) carried out three traverses from Zhongshan station to Dome A, Princess Elizabeth Land and Inaccessible Area, East Antarctic ice sheet, during the 1996/97 to 1998/99 Antarctic field seasons. The expeditions are part of the Chinese International Trans-Antarctic Scientific Expedition program. In this project, glaciological investigations of mass balance, ice temperature, ice flow, stratigraphy in snow pits and snow/firn ice cores, as well as the glaciochemical study of surface snow and shallow ice cores, have been carried out. In the 1998/99 field season, CHINARE extended the traverse route to 1128 km inland from Zhongshan station. The density profiles show that firnification over Princess Elizabeth Land and Inaccessible Area (290–1100 km along the route) is fairly slow, and the accumulation rate recovered from snow pits along the initial 460 km of the route is 4.6–21 cm (46–210 kg m–2a–1 ) water equivalent. The initial 460 km of the route can be divided into four sections based on the differences of accumulation rate. This pattern approximately coincides with the study on the Lambert Glacier basin (LGB) by Australian scientists. During the past 50 years, the trends of both air temperature and accumulation rate show a slight increase in this area, in contrast to the west side of the LGB. Data on surface accumulation rates and their spatial and temporal variability over ice-drainage areas such as the LGB are essential for precise mass-balance calculation of the whole ice sheet, and are important for driving ice-sheet models and testing atmospheric models.

scholarly journals Reconstructing seasonality through stable isotope and trace element analysis of the Proserpine stalagmite, Han-sur-Lesse Cave, Belgium: indications for climate-driven changes during the last 400 years

2019 ◽  
Author(s):  
Stef Vansteenberge ◽  
Niels de Winter ◽  
Matthias Sinnesael ◽  
Sophie Verheyden ◽  
Steven Goderis ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Trace Element ◽  
Seasonal Variations ◽  
Seasonal Variability ◽  
Water Discharge ◽  
Growth Period ◽  
Isotope Ratios ◽  
17Th Century ◽  
Ice Age ◽  
Stable Isotope Ratios

Abstract. Annually laminated speleothems allow the reconstruction of paleoclimate down to a seasonal scale. In this study, an annually laminated stalagmite from the Han-sur-Lesse Cave (Belgium) is used to study the expression of the seasonal cycle in northwestern Europe during the Little Ice Age. More specifically, two historical 12-year-long growth periods (ca. 1593–1605 CE and 1635–1646 CE) and one modern growth period (1960–2010 CE) are analysed on a sub-annual scale for their stable isotope ratios (δ13C and δ18O) and trace element (Mg, Sr, Ba, Zn, Y, Pb, U) content. Seasonal variability in the proxies is confirmed with frequency analysis. Zn, Y and Pb show distinct annual peaks in all three investigated periods related to annual flushing of the soil during winter. A strong seasonal in phase relationship between Mg, Sr and Ba in the modern growth period reflects a substantial influence of prior calcite precipitation (PCP). In particular, PCP occurs during summers when recharge of the epikarst is low. This is also evidenced by earlier observations of increased δ13C values during summer. In the 17th century intervals, there is a distinct antiphase relationship between Mg, Sr and Ba, suggesting that varying degrees of incongruent dissolution of dolomite control the observed seasonal variations. The processes controlling seasonal variations in Mg, Sr and Ba in the speleothem appear to change between the 17th century and 1960–2010 CE. The Zn, Y, Pb and U concentration profiles, stable isotope ratios and morphology of the speleothem laminae all point towards increased seasonal amplitude in cave hydrology and higher drip water discharge during the 17th century. These observations reflect an increase in water excess above the cave and recharge of the epikarst, due to a combination of lower summer temperatures and increased winter precipitation during the 17th century. This study indicates that the transfer function controlling Mg, Sr and Ba seasonal variability varies over time. Which process is dominant, either PCP or dolomite dissolution, is clearly climate-driven and can thus be used as a paleoclimate proxy itself.

scholarly journals A first chronology for the NEEM ice core

2013 ◽  
Vol 9 (3) ◽  
pp. 2967-3013 ◽  
Author(s):  
S. O. Rasmussen ◽  
P. Abbott ◽  
T. Blunier ◽  
A. Bourne ◽  
E. Brook ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Conductivity Measurement ◽  
Ice Cores ◽  
Monte Carlo Analysis ◽  
Heat Diffusion ◽  
Ice Age ◽  
Age Difference ◽  
Electrical Conductivity Measurement ◽  
Volcanic Origin

Abstract. 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.

scholarly journals Thinning of the Ice Sheet Estimated from Total Gas Content of Ice Cores in Mizuho Plateau, East Antarctica

1990 ◽  
Vol 14 ◽  
pp. 131-135 ◽  
Author(s):  
Takao Kameda ◽  
Masayoshi Nakawo ◽  
Shinji Mae ◽  
Okitsugu Watanabe ◽  
Renji Naruse
Keyword(s):  
Linear Relation ◽  
Vertical Profile ◽  
General Trend ◽  
Gradual Increase ◽  
Ice Core ◽  
Ice Sheet ◽  
Ice Cores ◽  
Gas Content ◽  
Ice Formation ◽  
Slope Flow

A linear relation between total gas content in ice and the elevation of ice formation (i.e. pore close-off) was obtained from seven shallow ice cores in Mizuho Plateau, Antarctica. The derived relation was applied to the vertical profile of total gas content in a 700 m long ice core at Mizuho Station. A general trend of gradual increase in total gas content was observed from 600 to 200 m in depth, from which toward the upper layer it showed a steep increase. After eliminating the effect of down-slope flow of ice around Mizuho Station, it was estimated that the thickness of the ice sheet decreased by about 350 m at maximum during the last 2000 years. This tendency also appears in the δ18O profile of the same ice core.

scholarly journals Stable Isotope Analysis of a Submarine Ice Cliff at Explorers Cove, McMurdo Sound, Antarctica

1984 ◽  
Vol 30 (104) ◽  
pp. 112-115 ◽  
Author(s):  
William L. Stockton ◽  
Ted E. DeLaca ◽  
Michael J. Deniro
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Sea Water ◽  
Isotope Analysis ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Stable Isotope Ratios ◽  
Mcmurdo Sound

AbstractStable isotope ratios and salinities of ice samples obtained from a submarine ice cliff at Explorers Cove demonstrate that the upper parts of the ice cliff have frozen directly from sea-water and are an underwater expression of permafrost, whereas the lower parts appear to be partially glacial in origin. These results indicate that there may be ice cores in the moraines of Explorers Cove, in which case the coastline of McMurdo Sound is more extensively ice-cored than previously known.

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