Automated mapping of Antarctic supraglacial lakes and streams using machine learning

2020 ◽  
Author(s):  
Mariel Dirscherl ◽  
Andreas Dietz ◽  
Celia Baumhoer ◽  
Christof Kneisel ◽  
Claudia Kuenzer
Keyword(s):  
Machine Learning ◽  
Mass Balance ◽  
Antarctic Peninsula ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Ice Dynamics ◽  
Antarctic Ice Sheet ◽  
Supraglacial Lakes ◽  
The Antarctic ◽  
Sentinel 2

<p>Antarctica stores ~91 % of the global ice mass making it the biggest potential contributor to global sea-level-rise. With increased surface air temperatures during austral summer as well as in consequence of global climate change, the ice sheet is subject to surface melting resulting in the formation of supraglacial lakes in local surface depressions. Supraglacial meltwater features may impact Antarctic ice dynamics and mass balance through three main processes. First of all, it may cause enhanced ice thinning thus a potentially negative Antarctic Surface Mass Balance (SMB). Second, the temporary injection of meltwater to the glacier bed may cause transient ice speed accelerations and increased ice discharge. The last mechanism involves a process called hydrofracturing i.e. meltwater-induced ice shelf collapse caused by the downward propagation of surface meltwater into crevasses or fractures, as observed along large coastal sections of the northern Antarctic Peninsula. Despite the known impact of supraglacial meltwater features on ice dynamics and mass balance, the Antarctic surface hydrological network remains largely understudied with an automated method for supraglacial lake and stream detection still missing. Spaceborne remote sensing and data of the Sentinel missions in particular provide an excellent basis for the monitoring of the Antarctic surface hydrological network at unprecedented spatial and temporal coverage.</p><p>In this study, we employ state-of-the-art machine learning for automated supraglacial lake and stream mapping on basis of optical Sentinel-2 satellite data. With more detail, we use a total of 72 Sentinel-2 acquisitions distributed across the Antarctic Ice Sheet together with topographic information to train and test the selected machine learning algorithm. In general, our machine learning workflow is designed to discriminate between surface water, ice/snow, rock and shadow being further supported by several automated post-processing steps. In order to ensure the algorithm’s transferability in space and time, the acquisitions used for training the machine learning model are chosen to cover the full circle of the 2019 melt season and the data selected for testing the algorithm span the 2017 and 2018 melt seasons. Supraglacial lake predictions are presented for several regions of interest on the East and West Antarctic Ice Sheet as well as along the Antarctic Peninsula and are validated against randomly sampled points in the underlying Sentinel-2 RGB images. To highlight the performance of our model, we specifically focus on the example of the Amery Ice Shelf in East Antarctica, where we applied our algorithm on Sentinel-2 data in order to present the temporal evolution of maximum lake extent during three consecutive melt seasons (2017, 2018 and 2019).</p>

scholarly journals Changes in ice dynamics and mass balance of the Antarctic ice sheet

2006 ◽  
Vol 364 (1844) ◽  
pp. 1637-1655 ◽  
Author(s):  
Eric Rignot
Keyword(s):  
Mass Balance ◽  
Sea Level ◽  
Ice Sheet ◽  
East Antarctica ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Dynamics ◽  
Antarctic Ice Sheet ◽  
Ice Shelves ◽  
The Antarctic

The concept that the Antarctic ice sheet changes with eternal slowness has been challenged by recent observations from satellites. Pronounced regional warming in the Antarctic Peninsula triggered ice shelf collapse, which led to a 10-fold increase in glacier flow and rapid ice sheet retreat. This chain of events illustrated the vulnerability of ice shelves to climate warming and their buffering role on the mass balance of Antarctica. In West Antarctica, the Pine Island Bay sector is draining far more ice into the ocean than is stored upstream from snow accumulation. This sector could raise sea level by 1 m and trigger widespread retreat of ice in West Antarctica. Pine Island Glacier accelerated 38% since 1975, and most of the speed up took place over the last decade. Its neighbour Thwaites Glacier is widening up and may double its width when its weakened eastern ice shelf breaks up. Widespread acceleration in this sector may be caused by glacier ungrounding from ice shelf melting by an ocean that has recently warmed by 0.3 °C. In contrast, glaciers buffered from oceanic change by large ice shelves have only small contributions to sea level. In East Antarctica, many glaciers are close to a state of mass balance, but sectors grounded well below sea level, such as Cook Ice Shelf, Ninnis/Mertz, Frost and Totten glaciers, are thinning and losing mass. Hence, East Antarctica is not immune to changes.

Antarctic Peninsula mass trends from 2003 - 2016 using a Bayesian hierarchical model approach

2020 ◽  
Author(s):  
Stephen Chuter ◽  
Jonathan Rougier ◽  
Geoffrey Dawson ◽  
Jonathan Bamber
Keyword(s):  
Mass Balance ◽  
Spatial Resolution ◽  
Antarctic Peninsula ◽  
Ice Sheet ◽  
Stereo Image ◽  
Ice Dynamics ◽  
Antarctic Ice Sheet ◽  
Basin Scale ◽  
Grounding Line ◽  
The Antarctic

<p>Long-term continuous monitoring of Antarctic Ice Sheet mass balance is imperative to better understand its multi-decadal response to changes in climate and ocean forcing. Additionally, more accurate knowledge of contemporaneous mass balance is key for improved parameterisations in ice sheet models. The Antarctic Peninsula has undergone rapid changes in mass balance and ice dynamics over the last two decades, with satellite observations showing the presence of grounding line retreat and increases in ice sheet velocity. This is particularly the case after the collapse of the Larsen A and B ice shelves in 1995 and 2002, and more recently the glaciers draining the southern Antarctic Peninsula. As a result, this region provides analogues for future ice sheet response to ice shelf collapse in other regions of Antarctica. </p><p>Despite the region’s importance to understanding ice sheet dynamics, it is challenging to accurately assess mass balance due its geometry and mountainous topography. Conventional pulse-limited altimetry suffers from poor coverage and data loss over steep mountainous terrain, particularly before the launch of CryoSat-2 in 2010. In the case of gravimetry, the geometry of the region means the coarse spatial resolution of the GRACE mission (~300 km) cannot resolve small spatial scale glacier changes (particularly over northern Antarctic Peninsula) and suffers from signal leakage into the ocean. For the mass budget approach, the challenge of accurately modelling surface mass balance over the region’s mountainous topography coupled with the sparsity of ice thickness observations at the grounding line for many sectors can result in large uncertainties. As a result, it can be difficult to reconcile the results from different conventional approaches in this region. </p><p>To resolve this, we have developed and optimised the BHM framework used previously over the Antarctic Ice Sheet to specifically investigate the Antarctic Peninsula. This enables each latent process driving ice sheet mass change to be resolved at a higher spatial resolution compared to previous implementations across Antarctica as a whole. The new regional solution also incorporates more recent and higher resolution observations including: CryoSat-2 swath altimetry, stereo-image DEM differencing and NASA Operation Ice Bridge laser altimetry elevation rates. This is the first time such a range of observations of varying spatio-temporal resolutions will be combined into one assessment for the region. We will present results from the regionally optimised model from 2003 until present, including basin-scale mass trends and changes in spatial latent processes at an annual resolution. Additionally, we will discuss future opportunities, such as extending the record from this approach into the next decade and further understanding of the GIA response in this region. </p>

Recent glacial advance in the western Weddell Sea Sector driven by anomalous sea ice circulation

2020 ◽  
Author(s):  
Frazer Christie ◽  
Toby Benham ◽  
Julian Dowdeswell
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Ice Sheet ◽  
Weddell Sea ◽  
Landsat 8 ◽  
Ice Shelf ◽  
Total Contribution ◽  
Antarctic Ice Sheet ◽  
Ice Shelves ◽  
The Antarctic

<p>The Antarctic Peninsula is one of the most rapidly warming regions on Earth. There, the recent destabilization of the Larsen A and B ice shelves has been directly attributed to this warming, in concert with anomalous changes in ocean circulation. Having rapidly accelerated and retreated following the demise of Larsen A and B, the inland glaciers once feeding these ice shelves now form a significant proportion of Antarctica’s total contribution to global sea-level rise, and have become an exemplar for the fate of the wider Antarctic Ice Sheet under a changing climate. Together with other indicators of glaciological instability observable from satellites, abrupt pre-collapse changes in ice shelf terminus position are believed to have presaged the imminent disintegration of Larsen A and B, which necessitates the need for routine, close observation of this sector in order to accurately forecast the future stability of the Antarctic Peninsula Ice Sheet. To date, however, detailed records of ice terminus position along this region of Antarctica only span the observational period c.1950 to 2008, despite several significant changes to the coastline over the last decade, including the calving of giant iceberg A-68a from Larsen C Ice Shelf in 2017.</p><p>Here, we present high-resolution, annual records of ice terminus change along the entire western Weddell Sea Sector, extending southwards from the former Larsen A Ice Shelf on the eastern Antarctic Peninsula to the periphery of Filchner Ice Shelf. Terminus positions were recovered primarily from Sentinel-1a/b, TerraSAR-X and ALOS-PALSAR SAR imagery acquired over the period 2009-2019, and were supplemented with Sentinel-2a/b, Landsat 7 ETM+ and Landsat 8 OLI optical imagery across regions of complex terrain.</p><p>Confounding Antarctic Ice Sheet-wide trends of increased glacial recession and mass loss over the long-term satellite era, we detect glaciological advance along 83% of the ice shelves fringing the eastern Antarctic Peninsula between 2009 and 2019. With the exception of SCAR Inlet, where the advance of its terminus position is attributable to long-lasting ice dynamical processes following the disintegration of Larsen B, this phenomenon lies in close agreement with recent observations of unchanged or arrested rates of ice flow and thinning along the coastline. Global climate reanalysis and satellite passive-microwave records reveal that this spatially homogenous advance can be attributed to an enhanced buttressing effect imparted on the eastern Antarctic Peninsula’s ice shelves, governed primarily by regional-scale increases in the delivery and concentration of sea ice proximal to the coastline.</p>

scholarly journals ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21<sup>st</sup> century

2020 ◽  
Author(s):  
Helene Seroussi ◽  
Sophie Nowicki ◽  
Antony J. Payne ◽  
Heiko Goelzer ◽  
William H. Lipscomb ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Sea Level ◽  
Climate Model ◽  
Ice Sheet ◽  
East Antarctica ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Surface Mass ◽  
The Antarctic

Abstract. Ice flow models of the Antarctic ice sheet are commonly used to simulate its future evolution in response to different climate scenarios and inform on the mass loss that would contribute to future sea level rise. However, there is currently no consensus on estimated the future mass balance of the ice sheet, primarily because of differences in the representation of physical processes and the forcings employed. This study presents results from 18 simulations from 15 international groups focusing on the evolution of the Antarctic ice sheet during the period 2015–2100, forced with different scenarios from the Coupled Model Intercomparison Project Phase 5 (CMIP5) representative of the spread in climate model results. The contribution of the Antarctic ice sheet in response to increased warming during this period varies between −7.8 and 30.0 cm of Sea Level Equivalent (SLE). The evolution of the West Antarctic Ice Sheet varies widely among models, with an overall mass loss up to 21.0 cm SLE in response to changes in oceanic conditions. East Antarctica mass change varies between −6.5 and 16.5 cm SLE, with a significant increase in surface mass balance outweighing the increased ice discharge under most RCP 8.5 scenario forcings. The inclusion of ice shelf collapse, here assumed to be caused by large amounts of liquid water ponding at the surface of ice shelves, yields an additional mass loss of 8 mm compared to simulations without ice shelf collapse. The largest sources of uncertainty come from the ocean-induced melt rates, the calibration of these melt rates based on oceanic conditions taken outside of ice shelf cavities and the ice sheet dynamic response to these oceanic changes. Results under RCP 2.6 scenario based on two CMIP5 AOGCMs show an overall mass loss of 10 mm SLE compared to simulations done under present-day conditions, with limited mass gain in East Antarctica.

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.

Decreasing Antarctic surface mass balance due to runoff-dominated ablation by 2100

2020 ◽  
Author(s):  
Christoph Kittel ◽  
Charles Amory ◽  
Cécile Agosta ◽  
Nicolas Jourdain ◽  
Stefan Hofer ◽  
...  
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Surface Mass Balance ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Surface Mass ◽  
Ice Shelves ◽  
The Antarctic

&lt;p&gt;&lt;span&gt;The surface mass balance (SMB) of the Antarctic ice sheet is often considered as a negative contributor to the sea level rise as present snowfall accumulation largely compensate&lt;/span&gt;&lt;span&gt;s&lt;/span&gt;&lt;span&gt; for ablation through wind erosion, sublimation and runoff. The latter is even almost negligible since current Antarctic surface melting is limited to relatively scarce events over generally peripheral areas and refreezes almost entirely into the snowpack. However, melting can significantly affect the stability of ice shelves through hydrofracturing, potentially leading to their disintegration, acceleration of grounded ice and increased sea level rise. Although a large increase in snowfall is expected in a warmer climate, more numerous and stronger melting events could conversely lead to a larger risk of ice shelf collapse. In this study, we provide an estimation of the SMB of the Antarctic ice sheet for the end of the 21st&amp;#160;century by forcing the state-of-the-art regional climate model MAR with three different global climate models. We chose the models (from both the Coupled Model Intercomparison Project Phase 5 and 6 - CMIP5 and CMIP6) providing the best metrics for representing the current Antarctic climate. While the increase in snowfall largely compensates snow ablation through runoff in CMIP5-forced projections, CMIP6-forced simulations reveal that runoff cannot be neglected in the future as it accounts for a maximum of 50% of snowfall and becomes the main ablation component over the ice sheet. Furthermore, we identify a tipping point (ie., a warming of 4&amp;#176;C) at which the Antarctic SMB starts to decrease as a result of enhanced runoff particularly over ice shelves. Our results highlight the importance of taking into account meltwater production and runoff and indicate that previous model studies neglecting these processes yield overestimated SMB estimates, ultimately leading to underestimated Antarctic contribution to sea level rise. Finally, melt rates over each ice shelf are higher than those that led to the collapse of the Larsen A and B ice shelves, suggesting a high probability of ice shelf collapses all over peripheral Antarctica by 2100.&lt;/span&gt;&lt;/p&gt;

scholarly journals ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

2020 ◽  
Author(s):  
Helene Seroussi ◽  
Heiko Goelzer ◽  
Mathieu Morlighem ◽  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Sea Level ◽  
Climate Model ◽  
Ice Sheet ◽  
East Antarctica ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Surface Mass ◽  
The Antarctic

&lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;p&gt;Ice flow models of the Antarctic ice sheet are commonly used to simulate its future evolution in response to differ- ent climate scenarios and inform on the mass loss that would contribute to future sea level rise. However, there is currently no consensus on estimated the future mass balance of the ice sheet, primarily because of differences in the representation of physical processes and the forcings employed. This study presents results from 18 simulations from 15 international groups focusing on the evolution of the Antarctic ice sheet during the period 2015-2100, forced with different scenarios from the Coupled Model Intercomparison Project Phase 5 (CMIP5) representative of the spread in climate model results. The contribution of the Antarctic ice sheet in response to increased warming during this period varies between -7.8 and 30.0 cm of Sea Level Equivalent (SLE). The evolution of the West Antarctic Ice Sheet varies widely among models, with an overall mass loss up to 21.0 cm SLE in response to changes in oceanic conditions. East Antarctica mass change varies between -6.5 and 16.5 cm SLE, with a significant increase in surface mass balance outweighing the increased ice discharge under most RCP 8.5 scenario forcings. The inclusion of ice shelf collapse, here assumed to be caused by large amounts of liquid water ponding at the surface of ice shelves, yields an additional mass loss of 8 mm compared to simulations without ice shelf collapse. The largest sources of uncertainty come from the ocean-induced melt rates, the calibration of these melt rates based on oceanic conditions taken outside of ice shelf cavities and the ice sheet dynamic response to these oceanic changes. Results under RCP 2.6 scenario based on two CMIP5 AOGCMs show an overall mass loss of 10 mm SLE compared to simulations done under present-day conditions, with limited mass gain in East Antarctica.&lt;/p&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt;

scholarly journals Remote Sensing of Antarctic Glacier and Ice-Shelf Front Dynamics—A Review

2018 ◽  
Vol 10 (9) ◽  
pp. 1445 ◽  
Author(s):  
Celia Baumhoer ◽  
Andreas Dietz ◽  
Stefan Dech ◽  
Claudia Kuenzer
Keyword(s):  
Remote Sensing ◽  
Antarctic Peninsula ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Clear Trend ◽  
Antarctic Ice Sheet ◽  
Victoria Land ◽  
The Antarctic ◽  
Front Dynamics

The contribution of Antarctica’s ice sheet to global sea-level rise depends on the very dynamic behavior of glaciers and ice shelves. One important parameter of ice-sheet dynamics is the location of glacier and ice-shelf fronts. Numerous remote sensing studies on Antarctic glacier and ice-shelf front positions exist, but no long-term record on circum-Antarctic front dynamics has been established so far. The article outlines the potential of remote sensing to map, extract, and measure calving front dynamics. Furthermore, this review provides an overview of the spatial and temporal availability of Antarctic calving front observations for the first time. Single measurements are compiled to a circum-Antarctic record of glacier and ice shelf retreat/advance. We find sufficient frontal records for the Antarctic Peninsula and Victoria Land, whereas on the West Antarctic Ice Sheet (WAIS), measurements only concentrate on specific glaciers and ice sheets. Frontal records for the East Antarctic Ice Sheet exist since the 1970s. Studies agree on the general retreat of calving fronts along the Antarctic Peninsula. East Antarctic calving fronts also showed retreating tendencies between 1970s until the early 1990s, but have advanced since the 2000s. Exceptions of this general trend are Victoria Land, Wilkes Land, and the northernmost Dronning Maud Land. For the WAIS, no clear trend in long-term front fluctuations could be identified, as observations of different studies vary in space and time, and fronts highly fluctuate. For further calving front analysis, regular mapping intervals as well as glacier morphology should be included. We propose to exploit current and future developments in Earth observations to create frequent standardized measurements for circum-Antarctic assessments of glacier and ice-shelf front dynamics in regard to ice-sheet mass balance and climate forcing.

scholarly journals Mass evolution of the Antarctic Peninsula over the last two decades from a joint Bayesian inversion

2021 ◽  
Author(s):  
Stephen J. Chuter ◽  
Andrew Zammit-Mangion ◽  
Jonathan Rougier ◽  
Geoffrey Dawson ◽  
Jonathan L Bamber
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
Joint Inversion ◽  
Ice Sheet ◽  
Surface Processes ◽  
Ice Dynamics ◽  
Bayesian Hierarchical ◽  
Relative Contribution ◽  
Mass Losses ◽  
The Antarctic

Abstract. The Antarctic Peninsula has been an increasingly significant contributor to Antarctic Ice Sheet mass losses over the last two decades. However, due to the challenges presented by the topography and geometry of the region, there remain large variations in mass balance estimates from conventional approaches and in assessing the relative contribution of individual ice sheet processes. Here, we use a regionally optimised Bayesian Hierarchical Model joint inversion approach, that combines data from multiple altimetry studies (ENVISAT, ICESat-1, CryoSat-2 swath), gravimetry (GRACE and GRACE-FO) and localised DEM differencing observations, to solve for annual mass trends and their attribution to individual driving processes for the period 2003–2019. The region experienced a mass imbalance rate of −19 ± 1.1 Gt yr−1 between 2003 and 2019, predominantly driven by accelerations in ice dynamic mass losses in the first decade and sustained thereafter. Inter-annual variability is driven by surface processes, particularly in 2016 due to increased precipitation driven by an extreme El Niño, which temporarily returned the sector back to a state of positive mass balance. In the West Palmer Land and the English Coast regions, surface processes are a greater contributor to mass loss than ice dynamics in the early part of the 2010s, although both processes are acting simultaneously. Our results show good agreement with conventional and other combination approaches, improving confidence in the robustness of mass trend estimates, and in turn, understanding of the region’s response to changes in external forcing.

scholarly journals A Joint Inversion Estimate of Antarctic Ice Sheet Mass Balance Using Multi-Geodetic Data Sets

2019 ◽  
Vol 11 (6) ◽  
pp. 653 ◽  
Author(s):  
Chunchun Gao ◽  
Yang Lu ◽  
Zizhan Zhang ◽  
Hongling Shi
Keyword(s):  
Mass Balance ◽  
Joint Inversion ◽  
Ice Sheet ◽  
Mass Change ◽  
West Antarctica ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
Forward Models ◽  
Uplift Rates ◽  
The Antarctic

Many recent mass balance estimates using the Gravity Recovery and Climate Experiment (GRACE) and satellite altimetry (including two kinds of sensors of radar and laser) show that the ice mass of the Antarctic ice sheet (AIS) is in overall decline. However, there are still large differences among previously published estimates of the total mass change, even in the same observed periods. The considerable error sources mainly arise from the forward models (e.g., glacial isostatic adjustment [GIA] and firn compaction) that may be uncertain but indispensable to simulate some processes not directly measured or obtained by these observations. To minimize the use of these forward models, we estimate the mass change of ice sheet and present-day GIA using multi-geodetic observations, including GRACE and Ice, Cloud and land Elevation Satellite (ICESat), as well as Global Positioning System (GPS), by an improved method of joint inversion estimate (JIE), which enables us to solve simultaneously for the Antarctic GIA and ice mass trends. The GIA uplift rates generated from our JIE method show a good agreement with the elastic-corrected GPS uplift rates, and the total GIA-induced mass change estimate for the AIS is 54 ± 27 Gt/yr, which is in line with many recent GPS calibrated GIA estimates. Our GIA result displays the presence of significant uplift rates in the Amundsen Sea Embayment of West Antarctica, where strong uplift has been observed by GPS. Over the period February 2003 to October 2009, the entire AIS changed in mass by −84 ± 31 Gt/yr (West Antarctica: −69 ± 24, East Antarctica: 12 ± 16 and the Antarctic Peninsula: −27 ± 8), greater than the GRACE-only estimates obtained from three Mascon solutions (CSR: −50 ± 30, JPL: −71 ± 30, and GSFC: −51 ± 33 Gt/yr) for the same period. This may imply that single GRACE data tend to underestimate ice mass loss due to the signal leakage and attenuation errors of ice discharge are often worse than that of surface mass balance over the AIS.

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