Antarctic Slope Current controls warm ocean intrusions towards Totten Glacier

2021 ◽  
Author(s):  
Yoshihiro Nakayama ◽  
Chad Greene ◽  
Fernando Paolo ◽  
Vigan Mensah ◽  
Hong Zhang ◽  
...  
Keyword(s):  
Ocean Model ◽  
East Antarctica ◽  
Local Wind ◽  
Ice Shelf ◽  
Chain Reaction ◽  
Wind Stress Curl ◽  
A Chain ◽  
Antarctic Slope Current ◽  
The Antarctic ◽  
Ocean Boundary

<p><strong>The Totten Glacier in East Antarctica has received increasing attention in recent years for its ice loss and warm oceanographic conditions observed at the ice shelf front. Here, we developed satellite estimates of temporally varying Totten Ice Shelf (TIS) melt rates and a high-resolution ocean model. </strong><strong>We show that the Antarctic Slope Current (ASC) impedes ocean heat intrusions, and on-shelf intrusions enhance when the ASC weakens</strong><strong>. </strong><strong>The interannually varying strength of the ASC is primarily controlled by lateral ocean boundary conditions (and thus atmosphere and ocean circulations outside of the model domain) but also likely influenced by local wind stress curl and upstream decent of shelf water. We further </strong><strong>show that heat intrusions towards the TIS are enhanced with coastal freshening, suggesting that freshening from ice loss in West Antarcticacould start a chain reaction, leading to increased melt in East Antarctica, and further coastal freshening. </strong></p>

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.

First results from coupling the Parallel Ice Sheet Model with the Modular Ocean Model via an Antarctic ice-shelf cavity module

2021 ◽  
Author(s):  
Moritz Kreuzer ◽  
Ronja Reese ◽  
Willem Huiskamp ◽  
Stefan Petri ◽  
Torsten Albrecht ◽  
...  
Keyword(s):  
Time Scales ◽  
General Circulation ◽  
Ice Sheet ◽  
Circulation Model ◽  
Ocean Model ◽  
Global Ocean ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
First Results ◽  
The Antarctic

<p>The past and future evolution of the Antarctic Ice Sheet is largely controlled by interactions between the ocean and floating ice shelves. To investigate these interactions, coupled ocean and ice sheet model configurations are required. Previous modelling studies have mostly relied on high resolution configurations, limiting these studies to individual glaciers or regions over short time scales of decades to a few centuries. To study global and long term interactions, we developed a framework to couple the dynamic ice sheet model PISM with the global ocean general circulation model MOM5 via the ice-shelf cavity module PICO. Since ice-shelf cavities are not resolved by MOM5, but parameterized with the box model PICO, the framework allows the ice sheet and ocean model to be run at resolution of 16 km and 3 degrees, respectively. We present first results from our coupled setup and discuss stability, feedbacks, and interactions of the Antarctic Ice Sheet and the global ocean system on millennial time scales.</p>

Coupling the Parallel Ice Sheet Model with the Modular Ocean Model via an Antarctic ice-shelf cavity module

2020 ◽  
Author(s):  
Moritz Kreuzer ◽  
Ronja Reese ◽  
Willem Huiskamp ◽  
Stefan Petri ◽  
Ricarda Winkelmann
Keyword(s):  
Time Scales ◽  
Ice Sheet ◽  
Mass Conservation ◽  
Ocean Model ◽  
Computationally Efficient ◽  
Ice Shelf ◽  
Current Mass ◽  
Modular Ocean Model ◽  
Interactive Modelling ◽  
The Antarctic

<p>Ocean-ice shelf interactions are the main drivers for the current mass loss from the Antarctic Ice Sheet. Recent studies have shown that increased continental meltwater input can enhance discharge through ice-ocean feedbacks. This raises the need for interactive modelling between ocean and ice-sheet systems to assess the consequences of additional freshwater input on the Antarctic region and beyond. While high-resolution simulations (1/4 degree or greater) can resolve detailed interactions between the ocean and ice shelf, the computational costs make them applicable only for regional studies or decadal to centennial time scales. In this study we present a framework for coupling a coarse resolution ocean model (MOM) to the Parallel Ice Sheet Model (PISM) via the Potsdam Ice-shelf Cavity mOdel (PICO). The intermediate model PICO approximates the overturning circulation in ice shelf cavities and includes ice-ocean boundary layer physics. We present this offline coupling approach and discuss the fluxes exchanged between the distinct model runs as well as energy and mass conservation. Using this flexible and computationally efficient framework, feedbacks between the ice and ocean can be analysed on a global spatial scale and paleoclimate time-scales.</p><p> </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.

scholarly journals Investigation of the impact of Antarctic ice-shelf melting in a global ice–ocean model (ORCA2-LIM)

2007 ◽  
Vol 46 ◽  
pp. 78-82 ◽  
Author(s):  
Caixin Wang ◽  
Aike Beckmann
Keyword(s):  
Climate Models ◽  
Water Mass ◽  
Ocean Model ◽  
Ice Shelf ◽  
Marginal Seas ◽  
Water Mass Formation ◽  
Complicated Process ◽  
The Antarctic ◽  
The Impact ◽  
Mass Formation

AbstractIce-shelf melting (ISM) removes heat from and injects fresh water into the adjacent ocean and contributes significantly to the freshwater balance and water mass formation in the Antarctic marginal seas. The thermodynamic interaction between ocean and ice shelf is a complicated process and usually not adequately included in the ocean–ice climate models. In this paper, the ISM from all major ice-shelf areas around Antarctica is added to a global coupled ice–ocean model ORCA2-LIM following the parameterization proposed by Beckmann and Goosse (2003). Using interannual forcing data from 1958 through 2000, the impact of ISM on Southern Ocean hydrography and sea-ice distribution is investigated. The model also shows global signatures of the Antarctic ISM.

scholarly journals FIELD OPERATIONS AND PROGRESS OF CHINESE AIRBORNE SURVEY IN EAST ANTARCTICA THROUGH THE “SNOW EAGLE 601”

2020 ◽  
Vol XLIII-B3-2020 ◽  
pp. 869-873
Author(s):  
X. Cui ◽  
J. Guo ◽  
L. Li ◽  
X. Tang ◽  
B. Sun
Keyword(s):  
Vital Role ◽  
East Antarctica ◽  
Base Stations ◽  
Ice Shelf ◽  
Laser Altimeter ◽  
The Past ◽  
Amery Ice Shelf ◽  
Data Gap ◽  
Airborne Survey ◽  
The Antarctic

Abstract. The Antarctic plays a vital role in the Earth system. However, our poor knowledge of the Antarctic limits predicting and projecting future climate changes and sea level rising due to rapid changing of the Antarctic. Airborne platforms can access most places of this hostile and remote continent and measure subice properties with high resolution and accuracy. China deployed the first fixed-wing airplane of “Snow Eagle 601” for Antarctic expeditions in 2015. Airborne scientific instruments, including radio-echo sounder, gravimeter, magnetometer, laser altimeter etc., were configured and integrated on the airplane. In the past four years, the airborne platform has been applied to survey the Princess Elizabeth Land, the largest data gap in Antarctica, Amery Ice Shelf and other critical areas in East Antarctica, and overall ∼150,000 km flight lines have been completed. Here, we introduced the “Snow Eagle 601” airborne platform and base stations, as well as field operations of airborne survey, including aviation supports, daily cycle of the scientific flight, data processing and quality control, and finally summarized progress of airborne survey in the past four years.

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.

scholarly journals Modeling intensive ocean–cryosphere interactions in Lützow-Holm Bay, East Antarctica

2020 ◽  
Author(s):  
Kazuya Kusahara ◽  
Daisuke Hirano ◽  
Masakazu Fujii ◽  
Alexander D. Fraser ◽  
Takeshi Tamura
Keyword(s):  
Sea Ice ◽  
Bottom Topography ◽  
East Antarctica ◽  
Ice Shelf ◽  
Atlantic Sector ◽  
Ice Shelves ◽  
Water Intrusion ◽  
Fast Ice ◽  
Basal Melting ◽  
The Antarctic

Abstract. Basal melting of Antarctic ice shelves accounts for more than half of the mass loss from the Antarctic Ice Sheet. Many studies have focused on active basal melting at ice shelves in the Amundsen-Bellingshausen Seas and the Totten Ice shelf, East Antarctica. In these regions, the intrusion of Circumpolar Deep Water (CDW) onto the continental shelf is a key component for the localized intensive basal melting. Both regions have a common oceanographic feature: southward deflection of the Antarctic Circumpolar Current on the eastern flank of ocean gyres brings CDW onto the continental shelves. The physical setting of Shirase Glacier Tongue (SGT) in Lützow-Holm Bay corresponds to a similar configuration for the Weddell Gyre in the Atlantic sector. Here, we conduct a 2–3 km resolution simulation of an ocean-sea ice-ice shelf model using a newly-compiled bottom topography dataset in the bay. The model can reproduce the observed CDW intrusion along the deep trough. The modeled SGT basal melting reaches a peak in summer and minimum in autumn and winter, consistent with the wind-driven seasonality of the CDW thickness in the bay. The model results suggest the existence of eastward-flowing undercurrent on the upper continental slope in summer, and the undercurrent contributes to the seasonal-to-interannual variability of the warm water intrusion into the bay. Furthermore, numerical experiments with and without fast-ice cover in the bay demonstrate that fast ice plays a role as an effective thermal insulator and reduces local sea-ice formation, resulting in much warmer water intrusion into the SGT cavity.

scholarly journals Modeling intensive ocean–cryosphere interactions in Lützow-Holm Bay, East Antarctica

2021 ◽  
Vol 15 (4) ◽  
pp. 1697-1717
Author(s):  
Kazuya Kusahara ◽  
Daisuke Hirano ◽  
Masakazu Fujii ◽  
Alexander D. Fraser ◽  
Takeshi Tamura
Keyword(s):  
Sea Ice ◽  
Bottom Topography ◽  
East Antarctica ◽  
Ice Shelf ◽  
Atlantic Sector ◽  
Ice Shelves ◽  
Water Intrusion ◽  
Fast Ice ◽  
Basal Melting ◽  
The Antarctic

Abstract. Basal melting of Antarctic ice shelves accounts for more than half of the mass loss from the Antarctic ice sheet. Many studies have focused on active basal melting at ice shelves in the Amundsen–Bellingshausen seas and the Totten ice shelf, East Antarctica. In these regions, the intrusion of Circumpolar Deep Water (CDW) onto the continental shelf is a key component for the localized intensive basal melting. Both regions have a common oceanographic feature: southward deflection of the Antarctic Circumpolar Current brings CDW toward the continental shelves. The physical setting of the Shirase Glacier tongue (SGT) in Lützow-Holm Bay corresponds to a similar configuration on the southeastern side of the Weddell Gyre in the Atlantic sector. Here, we conduct a 2–3 km resolution simulation of an ocean–sea ice–ice shelf model using a recently compiled bottom-topography dataset in the bay. The model can reproduce the observed CDW intrusion along the deep trough. The modeled SGT basal melting reaches a peak in summer and a minimum in autumn and winter, consistent with the wind-driven seasonality of the CDW thickness in the bay. The model results suggest the existence of an eastward-flowing undercurrent on the upper continental slope in summer, and the undercurrent contributes to the seasonal-to-interannual variability in the warm water intrusion into the bay. Furthermore, numerical experiments with and without fast-ice cover in the bay demonstrate that fast ice plays a role as an effective thermal insulator and reduces local sea ice formation, resulting in much warmer water intrusion into the SGT cavity.

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