Geometry, motion and mass balance of Dyer Plateau, Antarctica

AbstractGeodetic surveying and ground-based radar profiling were used to determine geometry and surface motion of the ice sheet on the Dyer Plateau, Antarctica, in the vicinity of an ice-core site on a local dome. Vertical strain measurements in the core hole constrain the depth profile of vertical velocity. These geophysical measurements are used to analyze the profiles of density and annual layer thickness measured on the ice core to estimate the current mass balance of the ice column and the past history of accumulation rate. Consideration of horizontal and vertical mass-flow divergence shows that the profiles of density and vertical velocity are not fully consistent with steady state. Mean density of the firn layer appears to be increasing, which leads to the deduction of a small rate of mass increase (≈ 0.02 m a− 1 ice-equivalent thickness). Over the last 200a there has been a gradual increase in accumulation rate from about 0.46 m a− 1 to 0.54 m a− 1 ice-equivalent thickness in recent time.

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1000 year ice-core records from Berkner Island, Antarctica

Annals of Glaciology ◽

10.3189/172756402781817176 ◽

2002 ◽

Vol 35 ◽

pp. 45-51 ◽

Cited By ~ 39

Author(s):

Robert Mulvaney ◽

Hans Oerter ◽

David A. Peel ◽

Wolfgang Graf ◽

Carol Arrowsmith ◽

...

Keyword(s):

Decadal Variability ◽

Ice Core ◽

Ice Cores ◽

Aerosol Deposition ◽

Climate History ◽

Joint Project ◽

The Past ◽

Annual Layer ◽

History Of ◽

Field Season

AbstractTwo medium-depth ice cores were retrieved from Berkner Island by a joint project between the Alfred-Wegener-Institut and the British Antarctic Survey in the 1994/95 field season. A 151m deep core from the northern dome (Reinwarthhöhe) of Berkner Island spans 700 years, while a 181 m deep core from the southern dome (Thyssenhöhe) spans approximately 1200 years. Both cores display clear seasonal cycles in electrical conductivity measurements, allowing dating by annual-layer counting and the calculation of accumulation profiles. Stable-isotope measurements (both δ18O and δD), together with the accumulation data, allow us to estimate changes in climate for most of the past millennium: the data show multi-decadal variability around a generally stable long-termmean. In addition, a full suite of major chemistry measurements is available to define the history of aerosol deposition at these sites: again, there is little evidence that the chemistry of the sites has changed over the past six centuries. Finally, we suggest that the southern dome, with an ice thickness of 950 m, is an ideal site from which to gain a climate history of the late stages of the last glacial and the deglaciation for comparison with the records from the deep Antarctic ice cores, and with other intermediate-depth cores such as Taylor Dome and Siple Dome.

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Inferring paleo-accumulation records from ice-core data by an adjoint method: application to James Ross Island's ice core

Climate of the Past Discussions ◽

10.5194/cpd-10-3821-2014 ◽

2014 ◽

Vol 10 (5) ◽

pp. 3821-3845 ◽

Cited By ~ 1

Author(s):

C. Martín ◽

R. Mulvaney ◽

G. H. Gudmundsson ◽

H. Corr

Keyword(s):

Vertical Velocity ◽

Adjoint Method ◽

Ice Core ◽

Synthetic Data ◽

Ice Cores ◽

Snow Accumulation ◽

Polar Regions ◽

History Of ◽

Climatic Record ◽

Accumulation History

Abstract. Ice cores contain a record of snow precipitation that includes information about past atmospheric circulation and mass imbalance in the polar regions. We present a novel adjoint method to reconstruct a climatic record by both optimally dating an ice-core and deriving from it a detailed accumulation history. The motivation of our work is the recent application of phase sensitive radar which measures the vertical velocity of an ice column. The velocity is dependent on the history of subsequent snow accumulation, compaction and compression; and in our inverse formulation of this problem, measured vertical velocity profiles can be utilized directly thereby reducing the uncertainty introduced by ice flow modelling. We first apply our method to synthetic data in order to study its capability and the effect of noise and gaps in the data on retrieved accumulation history. The method is then applied to the ice core retrieved from James Ross Island, Antarctica. We show that the method is robust and that the results depend on quality of the age-depth observations and the derived flow regime around the core site. The method facilitates the incorporation of increasing detail provided by ice-core analysis together with observed full-depth velocity in order to construct a complete climatic record of the polar regions.

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Snow accumulation rate on Qomolangma (Mount Everest), Himalaya: synchroneity with sites across the Tibetan Plateau on 50–100 year timescales

Journal of Glaciology ◽

10.3189/002214308784886126 ◽

2008 ◽

Vol 54 (185) ◽

pp. 343-352 ◽

Cited By ~ 53

Author(s):

Susan Kaspari ◽

Roger LeB. Hooke ◽

Paul Andrew Mayewski ◽

Shichang Kang ◽

Shugui Hou ◽

...

Keyword(s):

Tibetan Plateau ◽

Accumulation Rate ◽

Ice Core ◽

Snow Accumulation ◽

The Tibetan Plateau ◽

Mount Everest ◽

Mountain Meteorology ◽

Annual Layer ◽

Decadal Scale ◽

The Mean

AbstractAnnual-layer thickness data, spanning AD 1534–2001, from an ice core from East Rongbuk Col on Qomolangma (Mount Everest, Himalaya) yield an age–depth profile that deviates systematically from a constant accumulation-rate analytical model. The profile clearly shows that the mean accumulation rate has changed every 50–100 years. A numerical model was developed to determine the magnitude of these multi-decadal-scale rates. The model was used to obtain a time series of annual accumulation. The mean annual accumulation rate decreased from ∼0.8 m ice equivalent in the 1500s to ∼0.3 m in the mid-1800s. From ∼1880 to ∼1970 the rate increased. However, it has decreased since ∼1970. Comparison with six other records from the Himalaya and the Tibetan Plateau shows that the changes in accumulation in East Rongbuk Col are broadly consistent with a regional pattern over much of the Plateau. This suggests that there may be an overarching mechanism controlling precipitation and mass balance over this area. However, a record from Dasuopu, only 125 km northwest of Qomolangma and 700 m higher than East Rongbuk Col, shows a maximum in accumulation during the 1800s, a time during which the East Rongbuk Col and Tibetan Plateau ice-core and tree-ring records show a minimum. This asynchroneity may be due to altitudinal or seasonal differences in monsoon versus westerly moisture sources or complex mountain meteorology.

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Dating of a Dome Fuji (Antarctica) shallow ice core by volcanic signal synchronization with B32 and EDML1 chronologies

The Cryosphere Discussions ◽

10.5194/tcd-8-769-2014 ◽

2014 ◽

Vol 8 (1) ◽

pp. 769-804 ◽

Cited By ~ 9

Author(s):

Y. Motizuki ◽

Y. Nakai ◽

K. Takahashi ◽

M. Igarashi ◽

H. Motoyama ◽

...

Keyword(s):

Volcanic Eruption ◽

Accumulation Rate ◽

Ice Core ◽

Volcanic Eruptions ◽

Annual Layer ◽

Signature Matching ◽

Dronning Maud Land ◽

Signal Synchronization ◽

The Mean ◽

Drilling Site

Abstract. We found extremely good synchronization of volcanic eruption signals between a shallow ice core drilled at Dome Fuji in 2001 (DF01 core) and the B32 shallow ice core from Dronning Maud Land, East Antarctica. We then applied volcanic signature matching to transfer the B32 chronology constructed by annual layer counting to a portion of the DF01 core for which annual layer counting was difficult because of the low precipitation rate. Matching was done by careful comparison of non-sea-salt sulfate (nssSO42−) data, which have a temporal resolution of about 1 yr, between the DF01 and B32 cores. The newly obtained chronology is called DFS1 (Dome Fuji Shallow ice core 1). In total, 31 volcanic eruptions were synchronized from AD 1900 back to AD 187, the earliest volcanic eruption date in the B32 core. The mean accumulation rate between synchronized volcanic horizons of the Dome Fuji core relative to rates at the B32 core drilling site did not differ significantly between these dates, increasing our confidence in this matching approach. We also used the B32-correlated EDML1/EDC3 chronology obtained from the top part of the EPICA Dronning Maud Land (DML) deep ice core to date a portion of the DF01 core. This new chronology, called DFS2 (Dome Fuji Shallow ice core 2), uses the correlations between B32 and EDML1/EDC3 ages to date the DF01 core from AD 1900 back to AD 199; moreover, four volcanic eruption dates from the EDML1/EDC3 chronology were used to date the interval from AD 199 back to AD 1. Because the EDML1/EDC3 ages were determined by adopting the B32 chronology back to AD 1170, DFS1 and DFS2 dates are identical between AD 1170 and 1900. These two methods enabled us to obtain a detailed chronology of the DF01 core, in particular the part before the last millennium, which has been difficult before this. We also present the absolute mean accumulation rates at Dome Fuji between AD 1 and 1900, based on the DFS1 and DFS2 chronologies.

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Annual-layer determinations and 167 year records of past climate of H72 ice core in east Dronning Maud Land, Antarctica

Annals of Glaciology ◽

10.3189/172756402781817086 ◽

2002 ◽

Vol 35 ◽

pp. 471-479 ◽

Cited By ~ 11

Author(s):

Fumihiko Nishio ◽

Teruo Furukawa ◽

Gen Hashida ◽

Makoto Igarashi ◽

Takao Kameda ◽

...

Keyword(s):

Mass Balance ◽

Ice Core ◽

Ice Cores ◽

Surface Mass Balance ◽

Tritium Content ◽

Surface Mass ◽

Annual Layer ◽

Dronning Maud Land ◽

Annual Resolution ◽

Continuous Accumulation

AbstractTo determine annual layers for reconstructing the past environment at annual resolution from ice cores, we employed snow-stake data back to 1972, tritium content, solid electrical conductivity measurements (ECM) and stratigraphic properties for the 73m ice core at the H72 site, east Dronning Maud Land, Antarctica. the average annual surface mass balance at H72 is 307 mma–1w.e. during the last 27 years from continuous accumulation data, 317 mma–1 w.e. according to the densification model and 311 mma–1 w.e. according to the average surface mass balance for 167 years based on annual-layer counting. the ECM age is closely coincident with tritium age, and corresponds with the snow-stake record back to AD 1972 from the surface to 15 m depth. the H72 ice core is dated as AD 1831by ECMat 73.16 mdepth.The time series of yearly surface mass balance at H72 shows an almost constant 311 mm a–1 w.e. for the last 167 years. the oxygen-isotope records indicate a significant trend to lower values, with negative gradient of 1.7% (100 years)–1.

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Secular Trends Of Accumulation Rate On Ice Cores From Dunde Ice Cap, China Over The Last 1000 Years

Annals of Glaciology ◽

10.3189/s0260305500009423 ◽

1990 ◽

Vol 14 ◽

pp. 363-363

Author(s):

Wu Xiaoling ◽

Li Zhongqin ◽

Xie Zichu

Keyword(s):

Accumulation Rate ◽

Ice Core ◽

Ice Cores ◽

Surface Strain ◽

Entire Length ◽

Ice Age ◽

Cooperative Research ◽

Ice Cap ◽

Annual Layer ◽

Lanzhou Institute

Cooperative research programs were conducted on the Dunde Ice Cap (38°06′N, 96°26′E), China, in 1984, 1986, 1987, by the Lanzhou Institute of Glaciology and Geocryology (LIGG), China and the Byrd Polar Research Center (BPRC), U.S.A. This paper gives the preliminary results of the analysis on accumulation rate of the ice cap over the last 1000 years. Three ice cores were recovered to bedrock from the ice-cap summit (5324 m a.s.l.). Core D-1 (139.8 m long) was divided in the field along the entire length and was shared equally between LIGG and BPRC. Core D-2 (136.6 m long) was returned frozen complete to the LIGG for ice-core measurements. In Core D-3 (138.4 m long) the upper sectors were melted and bottled in the field and the lower sectors were returned frozen to the BPRC, U.S.A. Core D-1 was analyzed in China along the entire length for oxygen isotope, liquid conductivity and pH. A year-by-year dating of the ice cores has been made with Dansgaard-Johnsen’s flow pattern by using the data of surface strain-rate (August 1986 to August 1987) and tritium measurements. The resulting time-scales of the ice cores in Dunde Ice Cap yield an age of 4600 yr B.P. The annual layer thicknesses of core D-1 were measured mainly by δ18O analysis and liquid conductivity. The lower δ18O is generally associated with higher electrical conductivity. Annual layer thickness was converted to accumulation rates and compared with meteorological records from Delingxa Meteorological Station. The mean accumulation rate is 518 mm in ice-equivalent. Particular attention is given to the possible impact of the Little Ice Age. Based on spectral analysis of time series for the accumulation variation with depth, short-term (30, 33 year at 0.01 level) and intermediate-term variation (120 year) were discussed. The ice-core research program has been supported by the Chinese National Foundation of Natural Science under Grant DO125-4860011.

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Interpolation methods for Antarctic ice-core timescales: application to Byrd, Siple Dome and Law Dome ice cores

Climate of the Past ◽

10.5194/cp-10-1195-2014 ◽

2014 ◽

Vol 10 (3) ◽

pp. 1195-1209 ◽

Cited By ~ 11

Author(s):

T. J. Fudge ◽

E. D. Waddington ◽

H. Conway ◽

J. M. D. Lundin ◽

K. Taylor

Keyword(s):

Accumulation Rate ◽

Ice Core ◽

Ice Cores ◽

Linear Interpolation ◽

Atmospheric Methane ◽

Interpolation Methods ◽

The Past ◽

Annual Layer ◽

Siple Dome ◽

Abrupt Changes

Abstract. Antarctic ice cores have often been dated by matching distinctive features of atmospheric methane to those detected in annually dated ice cores from Greenland. Establishing the timescale between these tie-point ages requires interpolation. While the uncertainty at tie points is relatively well described, uncertainty of the interpolation is not. Here we assess the accuracy of three interpolation schemes using data from the WAIS Divide ice core in West Antarctica; we compare the interpolation methods with the annually resolved timescale for the past 30 kyr. Linear interpolation yields large age errors (up to 380 years) between tie points, abrupt changes in duration of climate events at tie points, and an age bias. Interpolations based on the smoothest accumulation rate (ACCUM) or the smoothest annual-layer thickness (ALT) yield timescales that more closely agree with the annually resolved timescale and do not have abrupt changes in duration at tie points. We use ALT to assess the uncertainty in existing timescales for the past 30 kyr from Byrd, Siple Dome, and Law Dome. These ice-core timescales were developed with methods similar to linear interpolation. Maximum age differences exceed 1000 years for Byrd and Siple Dome, and 500 years for Law Dome. For the glacial–interglacial transition (21 to 12 kyr), the existing timescales are, on average, older than ALT by 40 years for Byrd, 240 years for Siple Dome, and 150 years for Law Dome. Because interpolation uncertainty is often not considered, age uncertainties for ice-core records are often underestimated.

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Snow algae in a Himalayan ice core: new environmental markers for ice-core analyses and their correlation with summer mass balance

Annals of Glaciology ◽

10.3189/172756406781812276 ◽

2006 ◽

Vol 43 ◽

pp. 148-153 ◽

Cited By ~ 10

Author(s):

Yoshitaka Yoshimura ◽

Shiro Kohshima ◽

Nozomu Takeuchi ◽

Katsumoto Seko ◽

Koji Fujita

Keyword(s):

Mass Balance ◽

Snow Cover ◽

Air Temperature ◽

Algal Biomass ◽

Ice Core ◽

Algal Growth ◽

Environmental Indices ◽

Snow Algae ◽

Annual Layer ◽

Cover Thickness

AbstractSnow algae in a shallow ice core (6.98 m long) from Yala glacier in the Langtang region of Nepal were examined for potential use as environmental markers in ice-core analysis. The ice core, taken at 5350m a.s.l. in 1994, was estimated to contain 11 annual layers from 1984 to 1994 from the profile of algal biomass. Algal biomass in each annual layer was noted to be correlated with air temperature, and the following two environmental indices which were calculated from air temperature and precipitation at Kyangjing (3920m a.s.l.), the village nearest to Yala glacier: estimated mean snow-cover thickness (MST) and estimated summer mass balance (SMB). Both parameters reflect snow-cover thickness on algal layers, which would be a major determinant of the light available for algal growth on the glacier. Snow algal biomass in the ice core appears to be a good environmental marker for indicating air temperature and accumulation during summer, which is important for understanding the mass balance of summer-accumulation-type glaciers in this region.

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Secular Trends Of Accumulation Rate On Ice Cores From Dunde Ice Cap, China Over The Last 1000 Years

Annals of Glaciology ◽

10.1017/s0260305500009423 ◽

1990 ◽

Vol 14 ◽

pp. 363

Author(s):

Wu Xiaoling ◽

Li Zhongqin ◽

Xie Zichu

Keyword(s):

Accumulation Rate ◽

Ice Core ◽

Ice Cores ◽

Surface Strain ◽

Entire Length ◽

Ice Age ◽

Cooperative Research ◽

Ice Cap ◽

Annual Layer ◽

Lanzhou Institute

Cooperative research programs were conducted on the Dunde Ice Cap (38°06′N, 96°26′E), China, in 1984, 1986, 1987, by the Lanzhou Institute of Glaciology and Geocryology (LIGG), China and the Byrd Polar Research Center (BPRC), U.S.A. This paper gives the preliminary results of the analysis on accumulation rate of the ice cap over the last 1000 years. Three ice cores were recovered to bedrock from the ice-cap summit (5324 m a.s.l.). Core D-1 (139.8 m long) was divided in the field along the entire length and was shared equally between LIGG and BPRC. Core D-2 (136.6 m long) was returned frozen complete to the LIGG for ice-core measurements. In Core D-3 (138.4 m long) the upper sectors were melted and bottled in the field and the lower sectors were returned frozen to the BPRC, U.S.A. Core D-1 was analyzed in China along the entire length for oxygen isotope, liquid conductivity and pH. A year-by-year dating of the ice cores has been made with Dansgaard-Johnsen’s flow pattern by using the data of surface strain-rate (August 1986 to August 1987) and tritium measurements. The resulting time-scales of the ice cores in Dunde Ice Cap yield an age of 4600 yr B.P. The annual layer thicknesses of core D-1 were measured mainly by δ18O analysis and liquid conductivity. The lower δ18O is generally associated with higher electrical conductivity. Annual layer thickness was converted to accumulation rates and compared with meteorological records from Delingxa Meteorological Station. The mean accumulation rate is 518 mm in ice-equivalent. Particular attention is given to the possible impact of the Little Ice Age. Based on spectral analysis of time series for the accumulation variation with depth, short-term (30, 33 year at 0.01 level) and intermediate-term variation (120 year) were discussed. The ice-core research program has been supported by the Chinese National Foundation of Natural Science under Grant DO125-4860011.

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