On the freshening of the northwestern Weddell Sea continental shelf

Abstract. We analyzed hydrographic data from the northwestern Weddell Sea continental shelf of the three austral winters 1989, 1997, and 2006 and two summers following the last winter cruise. During summer a thermal front exists at ~64° S separating cold southern waters from warm northern waters that have similar characteristics as the deep waters of the central basin of the Bransfield Strait. In winter, the whole continental shelf exhibits southern characteristics with high Neon (Ne) concentrations, indicating a significant input of glacial melt water. The comparison of the winter data from the shallow shelf off the tip of the Antarctic Peninsula, spanning a period of 17 yr, shows a salinity decrease of 0.09 for the whole water column, which has a residence time of <1 yr. We interpret this freshening as being caused by a combination of reduced salt input due to a southward sea ice retreat and higher precipitation during the late 20th century on the western Weddell Sea continental shelf. However, less salinification might also result from a delicate interplay between enhanced salt input due to sea ice formation in coastal areas formerly occupied by Larsen A and B ice shelves and increased Larsen C ice loss.

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On the freshening of the northwestern Weddell Sea continental shelf

Ocean Science Discussions ◽

10.5194/osd-7-2013-2010 ◽

2010 ◽

Vol 7 (6) ◽

pp. 2013-2042 ◽

Cited By ~ 2

Author(s):

H. H. Hellmer ◽

O. Huhn ◽

D. Gomis ◽

R. Timmermann

Keyword(s):

Sea Ice ◽

Continental Shelf ◽

Weddell Sea ◽

Central Basin ◽

Ice Shelf ◽

Thermal Front ◽

Ice Shelves ◽

Deep Waters ◽

Sea Ice Edge ◽

The Antarctic

Abstract. We analysed hydrographic data from the northwestern Weddell Sea continental shelf of three austral winters (1989, 1997 and 2006) and two summers following the last winter cruise. During summer a thermal front exists at ~64° S separating cold southern waters from warm northern waters that have similar characteristics as the deep waters of the central basin of the Bransfield Strait. In winter, the whole continental shelf exhibits southern characteristics with high Neon (Ne) concentrations, indicating a significant input of glacial melt water. The comparison of the winter data at the tip of the Antarctic Peninsula, spanning a period of 17 years, shows a salinity decrease of 0.09 for the whole water column. We interpret this freshening as a reduction in salt input to the water masses being advected northward on the western Weddell Sea continental shelf. Possible causes for the reduced winter salinification are a southward retreat of the summer sea ice edge together with more precipitation in this sector. However, the latter might have happened in conjunction with an increase in ice shelf mass loss, counteracting an enhanced salt input due to sea ice formation in coastal areas formerly occupied by Larsen A and B ice shelves.

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Explicit and parametrised representation of under ice shelf seas in a z* coordinate ocean model

10.5194/gmd-2017-37 ◽

2017 ◽

Cited By ~ 1

Author(s):

Pierre Mathiot ◽

Adrian Jenkins ◽

Christopher Harris ◽

Gurvan Madec

Keyword(s):

Sea Ice ◽

Continental Shelf ◽

Weddell Sea ◽

Depth Range ◽

Ice Shelf ◽

Ice Shelves ◽

Antarctic Continental Shelf ◽

Shelf Seas ◽

Ocean Properties ◽

The Antarctic

Abstract. Ice shelf/ocean interactions are a major source of fresh water on the Antarctic continental shelf and have a strong impact on ocean properties, ocean circulation and sea ice. However, climate models based on the ocean/sea ice model NEMO currently do not include these interactions in any detail. The capability of explicitly simulating the circulation beneath ice shelves is introduced in the non-linear free surface model NEMO. Its implementation into the NEMO framework and its assessment in an idealised and realistic circum-Antarctic configuration is described in this study. Compared with the current prescription of ice shelf melting (i.e. at the surface) inclusion of open sub-ice-shelf leads to a decrease sea ice thickness along the coast, a weakening of the ocean stratification on the shelf, a decrease in salinity of HSSW on the Ross and Weddell Sea shelves and an increase in the strength of the gyres that circulate within the over-deepened basins on the West Antarctic continental shelf. Mimicking the under ice shelf seas overturning circulation by introducing the meltwater over the depth range of the ice shelf base, rather than at the surface is also tested. It yields similar improvements in the simulated ocean properties and circulation over the Antarctic continental shelf than the explicit ice shelf cavity representation. With the ice shelf cavities opened, the widely-used “3 equations” ice shelf melting formulation enables an interactive computation of melting that has been assessed. Comparison with observational estimates of ice shelf melting indicates realistic results for most ice shelves. However, melting rates for Amery, Getz and George VI ice shelves are considerably overestimated.

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SEA ICE RETREAT ALTERS THE BIOGEOGRAPHY OF THE BERING SEA CONTINENTAL SHELF

Ecological Applications ◽

10.1890/07-0564.1 ◽

2008 ◽

Vol 18 (2) ◽

pp. 309-320 ◽

Cited By ~ 285

Author(s):

Franz J. Mueter ◽

Michael A. Litzow

Keyword(s):

Sea Ice ◽

Continental Shelf ◽

Bering Sea ◽

Ice Retreat ◽

Sea Ice Retreat ◽

The Bering Sea

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Explicit representation and parametrised impacts of under ice shelf seas in the z∗ coordinate ocean model NEMO 3.6

Geoscientific Model Development ◽

10.5194/gmd-10-2849-2017 ◽

2017 ◽

Vol 10 (7) ◽

pp. 2849-2874 ◽

Cited By ~ 30

Author(s):

Pierre Mathiot ◽

Adrian Jenkins ◽

Christopher Harris ◽

Gurvan Madec

Keyword(s):

Sea Ice ◽

Continental Shelf ◽

Weddell Sea ◽

Surface Model ◽

Depth Range ◽

Ice Shelf ◽

Ice Shelves ◽

Antarctic Continental Shelf ◽

Ocean Properties ◽

The Antarctic

Abstract. Ice-shelf–ocean interactions are a major source of freshwater on the Antarctic continental shelf and have a strong impact on ocean properties, ocean circulation and sea ice. However, climate models based on the ocean–sea ice model NEMO (Nucleus for European Modelling of the Ocean) currently do not include these interactions in any detail. The capability of explicitly simulating the circulation beneath ice shelves is introduced in the non-linear free surface model NEMO. Its implementation into the NEMO framework and its assessment in an idealised and realistic circum-Antarctic configuration is described in this study. Compared with the current prescription of ice shelf melting (i.e. at the surface), inclusion of open sub-ice-shelf cavities leads to a decrease in sea ice thickness along the coast, a weakening of the ocean stratification on the shelf, a decrease in salinity of high-salinity shelf water on the Ross and Weddell sea shelves and an increase in the strength of the gyres that circulate within the over-deepened basins on the West Antarctic continental shelf. Mimicking the overturning circulation under the ice shelves by introducing a prescribed meltwater flux over the depth range of the ice shelf base, rather than at the surface, is also assessed. It yields similar improvements in the simulated ocean properties and circulation over the Antarctic continental shelf to those from the explicit ice shelf cavity representation. With the ice shelf cavities opened, the widely used three equation ice shelf melting formulation, which enables an interactive computation of melting, is tested. Comparison with observational estimates of ice shelf melting indicates realistic results for most ice shelves. However, melting rates for the Amery, Getz and George VI ice shelves are considerably overestimated.

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On the factors controlling phytoplankton ice edge blooms in the marginal ice zone of the northwestern Weddell Sea during sea ice retreat 1988

Weddell Sea Ecology ◽

10.1007/978-3-642-77595-6_39 ◽

1993 ◽

pp. 333-333 ◽

Cited By ~ 1

Author(s):

Christiane Lancelot ◽

Sylvie Mathot ◽

Cornelis Veth ◽

Hein de Baar

Keyword(s):

Sea Ice ◽

Weddell Sea ◽

Marginal Ice Zone ◽

Ice Retreat ◽

Ice Edge ◽

Sea Ice Retreat

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Moisture transport and Antarctic sea ice: austral spring 2016 event

Earth System Dynamics ◽

10.5194/esd-9-939-2018 ◽

2018 ◽

Vol 9 (3) ◽

pp. 939-954 ◽

Cited By ~ 9

Author(s):

Monica Ionita ◽

Patrick Scholz ◽

Klaus Grosfeld ◽

Renate Treffeisen

Keyword(s):

Indian Ocean ◽

Sea Ice ◽

Ross Sea ◽

Weddell Sea ◽

Antarctic Region ◽

Austral Spring ◽

Ice Retreat ◽

The Indian Ocean ◽

Sea Ice Retreat ◽

The Antarctic

Abstract. In austral spring 2016 the Antarctic region experienced anomalous sea ice retreat in all sectors, with sea ice extent in October and November 2016 being the lowest in the Southern Hemisphere over the observational period (1979–present). The extreme sea ice retreat was accompanied by widespread warming along the coastal areas as well as in the interior of the Antarctic continent. This exceptional event occurred along with a strong negative phase of the Southern Annular Mode (SAM) and the moistest and warmest spring on record, over large areas covering the Indian Ocean, the Ross Sea and the Weddell Sea. In October 2016, the positive anomalies of the totally integrated water vapor (IWV) and 2 m air temperature (T2m) over the Indian Ocean, western Pacific, Bellingshausen Sea and southern part of Ross Sea were unprecedented in the last 39 years. In October and November 2016, when the largest magnitude of negative daily sea ice concentration anomalies was observed, repeated episodes of poleward advection of warm and moist air took place. These results suggest the importance of moist and warm air intrusions into the Antarctic region as one of the main contributors to this exceptional sea ice retreat event.

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Moisture transport and Antarctic sea ice: Austral spring 2016 event

10.5194/esd-2017-114 ◽

2017 ◽

Author(s):

Monica Ionita ◽

Patrick Scholz ◽

Klaus Grosfeld ◽

Renate Treffeisen

Keyword(s):

Indian Ocean ◽

Sea Ice ◽

Ross Sea ◽

Weddell Sea ◽

Antarctic Region ◽

Austral Spring ◽

Ice Retreat ◽

The Indian Ocean ◽

Sea Ice Retreat ◽

The Antarctic

Abstract. In austral spring 2016 the Antarctic region experienced anomalous sea ice retreat in all sectors, with sea ice extent in October and November 2016 being the lowest in the Southern Hemisphere over the observational record (1979–present). The extreme sea ice retreat was accompanied by widespread warming along the coastal areas as well as in the interior of the Antarctic continent. This exceptional event occurred along with a strong negative phase of the Southern Annular Mode (SAM) and the wettest and warmest spring on record, over large areas covering the Indian ocean, the Ross Sea and the Weddell Sea. In October 2016, the positive anomalies of the totally integrated water vapor (IWV) and 2 m air temperature (TT) over the Indian Ocean, Western Pacific, Bellingshausen Sea and southern part of Ross Sea were unprecedented in the last 39 years. In October and November 2016, when the lowest daily sea ice concentration anomalies were observed, repeated episodes of poleward advection of warm and moist air took place, with the most intense episode occurring at the end of November 2016. These results suggest the importance of moist and warm air intrusions into the Antarctic region as one of the main contributors to this exceptional sea ice retreat event.

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