scholarly journals Accumulation variability and mass budgets of the Lambert Glacier-Amery Ice Shelf system, East Antarctica, at high elevations

2006 ◽  
Vol 43 ◽  
pp. 351-360 ◽  
Author(s):  
Jiahong Wen ◽  
Kenneth C. Jezek ◽  
Andrew J. Monaghan ◽  
Bo Sun ◽  
Jiawen Ren ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Accumulation Rate ◽  
Temporal Variations ◽  
High Elevation ◽  
East Antarctica ◽  
Ice Shelf ◽  
Surface Mass ◽  
Amery Ice Shelf ◽  
High Elevations ◽  
Lambert Glacier

AbstractThe temporal and spatial variability of the annual accumulation rate and the mass budgets of five sub-basins of the Lambert Glacier-Amery Ice Shelf system (LAS), East Antarctica, at high elevations are assessed using a variety of datasets derived from field measurements and modeling. The annual temporal variations of the accumulation rate for four cores from the west and east sides of the LAS are around ±34%. Decadal fluctuation of the accumulation from the DT001 firn core drops to ±10%, and the 30 year fluctuation to ±5%, which is assumed to contain the information about the regional and long-term trend in accumulation. The 15-point running mean of the annual accumulation rate derived from stake measurements can remove most of the high-frequency spatial variation so as to better represent the local accumulation. Model simulations show that the spatial variability of erosion/ deposition of snow by the wind has a noticeable impact on the surface mass balance at the higher parts of the LAS. Mass-budget estimates at high-elevation sub-basins of the LAS suggest drainage 9 has a negative imbalance of −0.7 ± 0.4 Gta-1, Lambert and Mellor Glaciers have a positive imbalance of 3.9 ± 2.1 and 2.1 ±2.4 Gta-1 respectively, and Fisher Glacier and drainage 11 are approximately in balance. The higher-elevation region as a whole has a positive mass imbalance of 4.4 ± 6.3 Gta-1, which is consistent with the most recent radar altimetry assessment that shows an overall thickening over this region.

scholarly journals Ice thickness over the southern limit of the Amery Ice Shelf, East Antarctica, and reassessment of the mass balance of the central portion of the Lambert Glacier-Amery Ice Shelf system

2014 ◽  
Vol 55 (66) ◽  
pp. 81-86 ◽  
Author(s):  
Jiahong Wen ◽  
Long Huang ◽  
Weili Wang ◽  
T.H. Jacka ◽  
V. Damm ◽  
...  
Keyword(s):  
Mass Balance ◽  
Atmospheric Modeling ◽  
East Antarctica ◽  
Central Portion ◽  
Ice Thickness ◽  
Ice Shelf ◽  
Southern Limit ◽  
Surface Mass ◽  
Amery Ice Shelf ◽  
Lambert Glacier

AbstractWe combine radio-echo sounding ice thickness data from the BEDMAP Project database and the PCMEGA (Prince Charles Mountains Expedition of Germany and Australia) dataset to generate a new ice thickness grid for the southern limit region of the Amery Ice Shelf, East Antarctica. We then reassess the mass balance of the central portion of the Lambert-Amery system, incorporating flow information derived from synthetic aperture radar interferometry (InSAR) and a modeled surface mass-balance dataset based on regional atmospheric modeling. Our analysis reveals that Mellor and Fisher Glaciers are approximately in balance to the level of our measurement uncertainty, while Lambert Glacier has a positive imbalance of 4.2 ±2.3 Gta1. The mass budget for the whole Lambert Glacier basin is approximately in balance, and the average basal melt rate in the downstream section of the ice shelf is 5.1 ± 3.0 m a-1. Our results differ substantially from other recent estimates using hydrostatically derived ice thickness data.

scholarly journals Modelling the response of the Lambert Glacier–Amery Ice Shelf system, East Antarctica, to uncertain climate forcing over the 21st and 22nd centuries

2014 ◽  
Vol 8 (3) ◽  
pp. 1057-1068 ◽  
Author(s):  
Y. Gong ◽  
S. L. Cornford ◽  
A. J. Payne
Keyword(s):  
Climate Model ◽  
Global Environmental Change ◽  
Ice Sheet ◽  
Adaptive Mesh ◽  
Ocean Model ◽  
East Antarctica ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Grounding Line ◽  
Lambert Glacier

Abstract. The interaction between the climate system and the large polar ice sheet regions is a key process in global environmental change. We carried out dynamic ice simulations of one of the largest drainage systems in East Antarctica: the Lambert Glacier–Amery Ice Shelf system, with an adaptive mesh ice sheet model. The ice sheet model is driven by surface accumulation and basal melt rates computed by the FESOM (Finite-Element Sea-Ice Ocean Model) ocean model and the RACMO2 (Regional Atmospheric Climate Model) and LMDZ4 (Laboratoire de Météorologie Dynamique Zoom) atmosphere models. The change of ice thickness and velocity in the ice shelf is mainly influenced by the basal melt distribution, but, although the ice shelf thins in most of the simulations, there is little grounding line retreat. We find that the Lambert Glacier grounding line can retreat as much as 40 km if there is sufficient thinning of the ice shelf south of Clemence Massif, but the ocean model does not provide sufficiently high melt rates in that region. Overall, the increased accumulation computed by the atmosphere models outweighs ice stream acceleration so that the net contribution to sea level rise is negative.

scholarly journals Revisiting Ice Flux and Mass Balance of the Lambert Glacier–Amery Ice Shelf System Using Multi-Remote-Sensing Datasets, East Antarctica

2022 ◽  
Vol 14 (2) ◽  
pp. 391
Author(s):  
Derui Xu ◽  
Xueyuan Tang ◽  
Shuhu Yang ◽  
Yun Zhang ◽  
Lijuan Wang ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Mass Balance ◽  
Ice Sheet ◽  
East Antarctica ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Amery Ice Shelf ◽  
Grounding Line ◽  
Lambert Glacier ◽  
The Antarctic

Due to rapid global warming, the relationship between the mass loss of the Antarctic ice sheet and rising sea levels are attracting widespread attention. The Lambert–Amery glacial system is the largest drainage system in East Antarctica, and its mass balance has an important influence on the stability of the Antarctic ice sheet. In this paper, the recent ice flux in the Lambert Glacier of the Lambert–Amery system was systematically analyzed based on recently updated remote sensing data. According to Landsat-8 ice velocity data from 2018 to April 2019 and the updated Bedmachine v2 ice thickness dataset in 2021, the contribution of ice flux approximately 140 km downstream from Dome A in the Lambert Glacier area to downstream from the glacier is 8.5 ± 1.9, and the ice flux in the middle of the convergence region is 18.9 ± 2.9. The ice mass input into the Amery ice shelf through the grounding line of the whole glacier is 19.9 ± 1.3. The ice flux output from the mainstream area of the grounding line is 19.3 ± 1.0. Using the annual SMB data of the regional atmospheric climate model (RACMO v2.3) as the quality input, the mass balance of the upper, middle, and lower reaches of the Lambert Glacier was analyzed. The results show that recent positive accumulation appears in the middle region of the glacier (about 74–78°S, 67–85°E) and the net accumulation of the whole glacier is 2.4 ± 3.5. Although the mass balance of the Lambert Glacier continues to show a positive accumulation, and the positive value in the region is decreasing compared with values obtained in early 2000.

scholarly journals Basal melting and freezing under the Amery Ice Shelf, East Antarctica

2010 ◽  
Vol 56 (195) ◽  
pp. 81-90 ◽  
Author(s):  
Jiahong Wen ◽  
Yafeng Wang ◽  
Weili Wang ◽  
K.C. Jezek ◽  
Hongxing Liu ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Melting Rate ◽  
Scientific Basis ◽  
East Antarctica ◽  
Northwestern Part ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Velocity Surface ◽  
Ice Velocity ◽  
Basal Melting

AbstractThe basal melting and freezing rates under the Amery Ice Shelf, East Antarctica, are evaluated, and their spatial distributions mapped. Ice velocity, surface elevation and accumulation rate datasets are employed in the analysis, along with a column-averaged ice density model. Our analysis shows that the total area of basal melting is 34 700 km2, with a total annual melt of 62.5 ± 9.3 Gt and an average melting rate of 1.8 ± 0.3 m a−1. Basal freezing mainly occurs in the northwestern part of the ice shelf, over a total area of 26 100 km2 and with a maximum freezing rate of 2.4 ± 0.4 m a−1. The total marine ice that accretes to the ice-shelf base is estimated to be 16.2 ± 2.4 Gt a−1. Using a redefined grounding line and geometry of the Amery Ice Shelf, we estimate the net melt over the ice-shelf base is about 46.4 ± 6.9 G ta−1, which is higher than previous modeling and oceanographic estimates. Net basal melting accounts for about half of the total ice-shelf mass loss, with the rest being from iceberg discharge. Our basal melting and freezing distribution map provides a scientific basis for quantitative analysis of ice–ocean interaction at the ice-shelf–ocean interface.

scholarly journals Surface meltstreams on the Amery Ice Shelf, East Antarctica

1998 ◽  
Vol 27 ◽  
pp. 177-181 ◽  
Author(s):  
Helen A. Phillips
Keyword(s):  
Synthetic Aperture Radar Image ◽  
East Antarctica ◽  
Altimeter Data ◽  
Topographic Map ◽  
Ice Shelf ◽  
Brightness Temperatures ◽  
Amery Ice Shelf ◽  
Microwave Imager ◽  
Shelf Region ◽  
Lambert Glacier

A topographic map of a 120 km by 20 km section of the Amery Ice Shelf, East Antarctica, mapped with the global positioning system (GPS) in the spring of 1995, revealed two long, shallow troughs in the ice-shelf surface. Smooth features coinciding with these troughs appeared in a synthetic aperture radar image acquired 18 months earlier. ERS-1 altimeter waveform sequences and backscatter measurements along repeat satellite ground tracks across the same section of the Amery Ice Shelf, for the 1993-94 summer, exhibited a dramatic change over a 2 km sector between 30 January and 2 February 1994. The change is consistent with the presence of liquid water on the ice-shelf surface, located in the deeper of the two troughs. A time series of special sensor microwave/ imager brightness temperatures over the Lambert Glacier-Amery Ice Shelf region for the same period has sharp maxima on 5 January and 21 January 1994. These maxima are interpreted as the melting events leading to the meltstream observed in the altimeter data 25 days later.

scholarly journals Late Quaternary dynamics of the Lambert Glacier-Amery Ice Shelf system, East Antarctica

2021 ◽  
Vol 252 ◽  
pp. 106738
Author(s):  
Li Wu ◽  
David J. Wilson ◽  
Rujian Wang ◽  
Sandra Passchier ◽  
Wout Krijgsman ◽  
...  
Keyword(s):  
Late Quaternary ◽  
East Antarctica ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Lambert Glacier

scholarly journals Geostatistical estimation from radar altimeter data with respect to morphological units outlined by SAR data: application to Lambert Glacier/Amery Ice Shelf, East Antarctica

2004 ◽  
Vol 39 ◽  
pp. 251-255 ◽  
Author(s):  
Ralf Stosius ◽  
Ute C. Herzfeld
Keyword(s):  
Surface Characteristics ◽  
East Antarctica ◽  
Morphological Properties ◽  
Altimeter Data ◽  
Shelf Area ◽  
Radar Altimeter ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Sar Data ◽  
Lambert Glacier

AbstractThe objective of this paper is the comparison of two kriging methods, ordinary kriging and kriging within strata, for calculation of digital elevation models (DEMs) from radar altimeter data, and application to the Lambert Glacier/Amery Ice Shelf system, East Antarctica. Two new DEMs are presented. First, a DEM of the Lambert Glacier/Amery Ice Shelf system is calculated from 1997 European Remote-sensing Satellite-2 (ERS-2) radar altimeter (RA) data using geostatistical interpolation. RA data have high along-track density, but gaps between tracks are several kilometers, depending on the observation mode; this requires interpolation. Because the ice-stream/ice-shelf system is of primary interest in glaciological investigations, in the first approach a variogram characteristic of the Lambert Glacier ice surface is used. The resultant map has low errors for the glacier and the ice shelf. To match the surface characteristics of different morphological units that constitute the Lambert Glacier/Amery Ice Shelf region, a second DEM is constructed as follows: We utilize RADARSAT synthetic aperture radar (SAR) data that were collected in 1997 during the first Antarctic Imaging Campaign and composed into a 125m backscatter-data mosaic by Jezek (1999) and we co-reference the 125m mosaic with the altimetry-derived DEM. The Lambert Glacier/Amery Ice Shelf area is then subdivided into several regions which are homogeneous with respect to characteristic surface-morphological properties identified in the SAR mosaic. For those regions, a problem-oriented complex kriging method known as kriging within strata is performed, and the resulting DEM is compared to the DEM that was derived from kriging without regional subdivision.

scholarly journals Climatic signals from 76 shallow firn cores in Dronning Maud Land, East Antarctica

2015 ◽  
Vol 9 (3) ◽  
pp. 925-944 ◽  
Author(s):  
S. Altnau ◽  
E. Schlosser ◽  
E. Isaksson ◽  
D. Divine
Keyword(s):  
Meteorological Data ◽  
Southern Annular Mode ◽  
Temporal Variations ◽  
East Antarctica ◽  
Positive Trend ◽  
Ice Shelf ◽  
Data Set ◽  
Surface Mass ◽  
Dronning Maud Land ◽  
Climatic Signals

Abstract. The spatial and temporal distribution of surface mass balance (SMB) and δ18O were investigated in the first comprehensive study of a set of 76 firn cores retrieved by various expeditions during the past 3 decades in Dronning Maud Land, East Antarctica. The large number of cores was used to calculate stacked records of SMB and δ18O, which considerably increased the signal-to-noise ratio compared to earlier studies and facilitated the detection of climatic signals. Considerable differences between cores from the interior plateau and the coastal cores were found. The δ18O of both the plateau and the ice shelf cores exhibit a slight positive trend over the second half of the 20th century. In the corresponding period, the SMB has a negative trend in the ice shelf cores, but increases on the plateau. Comparison with meteorological data from Neumayer Station revealed that for the ice shelf regions, atmospheric dynamic effects are more important than thermodynamics while on the plateau; the temporal variations of SMB and δ18O occur mostly in parallel, and thus can be explained by thermodynamic effects. The Southern Annular Mode (SAM) has exhibited a positive trend since the mid-1960s, which is assumed to lead to a cooling of East Antarctica. This is not confirmed by the firn core data in our data set. Changes in the atmospheric circulation that result in a changed seasonal distribution of precipitation/accumulation could partly explain the observed features in the ice shelf cores.

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