Sea Ice–Ocean Feedbacks in the Antarctic Shelf Seas

AbstractObserved changes in Antarctic sea ice are poorly understood, in part due to the complexity of its interactions with the atmosphere and ocean. A highly simplified, coupled sea ice–ocean mixed layer model has been developed to investigate the importance of sea ice–ocean feedbacks on the evolution of sea ice and the ocean mixed layer in two contrasting regions of the Antarctic continental shelf ocean: the Amundsen Sea, which has warm shelf waters, and the Weddell Sea, which has cold and saline shelf waters. Modeling studies where we deny the feedback response to surface air temperature perturbations show the importance of feedbacks on the mixed layer and ice cover in the Weddell Sea to be smaller than the sensitivity to surface atmospheric conditions. In the Amundsen Sea the effect of surface air temperature perturbations on the sea ice are opposed by changes in the entrainment of warm deep waters into the mixed layer. The net impact depends on the relative balance between changes in sea ice growth driven by surface perturbations and basal-driven melting. The changes in the entrainment of warm water in the Amundsen Sea were found to have a much larger impact on the ice volume than perturbations in the surface energy budget. This creates a net negative ice albedo feedback in the Amundsen Sea, reversing the sign of this typically positive feedback mechanism.

Download Full-text

Influence of the Southern Annular Mode on the sea ice-ocean system: the role of the thermal and mechanical forcing

Ocean Science ◽

10.5194/os-1-145-2005 ◽

2005 ◽

Vol 1 (3) ◽

pp. 145-157 ◽

Cited By ~ 37

Author(s):

W. Lefebvre ◽

H. Goosse

Keyword(s):

Sea Ice ◽

Air Temperature ◽

Wind Stress ◽

Southern Annular Mode ◽

Weddell Sea ◽

The Other ◽

Ice Thickness ◽

Sea Ice Thickness ◽

Annular Mode ◽

The Antarctic

Abstract. The global sea ice-ocean model ORCA2-LIM is used to investigate the impact of the thermal and mechanical forcing associated with the Southern Annular Mode (SAM) on the Antarctic sea ice-ocean system. The model is driven by idealized forcings based on regressions between the wind stress and the air temperature at one hand and the SAM index the other hand. The wind-stress component strongly affects the overall patterns of the ocean circulation with a northward surface drift, a downwelling at about 45° S and an upwelling in the vicinity of the Antarctic continent when the SAM is positive. On the other hand, the thermal forcing has a negligible effect on the ocean currents. For sea ice, both the wind-stress (mechanical) and the air temperature (thermal) components have a significant impact. The mechanical part induces a decrease of the sea ice thickness close to the continent and a sharp decrease of the mean sea ice thickness in the Weddell sector. In general, the sea ice area also diminishes, with a maximum decrease in the Weddell Sea. On the contrary, the thermal part tends to increase the ice concentration in all sectors except in the Weddell Sea, where the ice area shrinks. This thermal effect is the strongest in autumn and in winter due to the larger temperature differences associated with the SAM during these seasons. The sum of the thermal and mechaninal effects gives a dipole response of sea ice to the SAM, with a decrease of the ice area in the Weddell Sea and around the Antarctic Peninsula and an increase in the Ross and Amundsen Seas during high SAM years. This is in good agreement with the observed response of the ice cover to the SAM.

Download Full-text

Validation of reanalysis Southern Ocean atmosphere trends using sea ice data

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-14757-2020 ◽

2020 ◽

Vol 20 (23) ◽

pp. 14757-14768

Author(s):

William R. Hobbs ◽

Andrew R. Klekociuk ◽

Yuhang Pan

Keyword(s):

Southern Ocean ◽

Sea Ice ◽

Surface Temperature ◽

Air Temperature ◽

Surface Air Temperature ◽

Heat Fluxes ◽

Surface Energy Budget ◽

Close Coupling ◽

In Situ Data ◽

Temperature Trends

Abstract. Reanalysis products are an invaluable tool for representing variability and long-term trends in regions with limited in situ data, and especially the Antarctic. A comparison of eight different reanalysis products shows large differences in sea level pressure and surface air temperature trends over the high-latitude Southern Ocean, with implications for studies of the atmosphere's role in driving ocean–sea ice changes. In this study, we use the established close coupling between sea ice cover and surface temperature to evaluate these reanalysis trends using the independent, 30-year sea ice record from 1980 to 2010. We demonstrate that sea ice trends are a reliable validation tool for most months of the year, although the sea ice–surface temperature coupling is weakest in summer when the surface energy budget is dominated by atmosphere-to-ocean heat fluxes. Based on our analysis, we find that surface air temperature trends in JRA55 are most consistent with satellite-observed sea ice trends over the polar waters of the Southern Ocean.

Download Full-text

Influence of the Southern Annular Mode on the sea ice-ocean system: the role of the thermal and mechanical forcing

Ocean Science Discussions ◽

10.5194/osd-2-299-2005 ◽

2005 ◽

Vol 2 (3) ◽

pp. 299-329 ◽

Cited By ~ 7

Author(s):

W. Lefebvre ◽

H. Goosse

Keyword(s):

Sea Ice ◽

Air Temperature ◽

Wind Stress ◽

Southern Annular Mode ◽

Weddell Sea ◽

Ice Thickness ◽

Sea Ice Thickness ◽

Annular Mode ◽

Mechanical Forcing ◽

The Antarctic

Abstract. The global sea ice-ocean model ORCA2-LIM is used to investigate the impact of the thermal and mechanical forcing associated to the Southern Annular Mode (SAM) on the Antarctic sea ice-ocean system. To do so, the model is driven by idealized forcings based on regressions of the wind stress and the air temperature to SAM. The wind-stress component strongly affects the overall patterns of the ocean circulation with a northward surface drift, a downwelling at about 45° S and an upwelling in the vicinity of the Antarctic continent when SAM is positive. On the other hand, the thermal forcing has a negligible effect on the ocean currents. For sea ice, both the wind-stress (mechanical) and the air temperature (thermal) components have a significant impact. The mechanical part induces a decrease of the sea ice thickness close to the continent and a sharp decrease of the mean sea ice thickness in the Weddell sector. In general, the sea ice area also diminishes, with a maximum decrease in the Weddell Sea. On the contrary, the thermal part tends to increase the ice concentration in all sectors except in the Weddell Sea, where the ice area shrinks. This thermal effect is the strongest in autumn and in winter due to the larger temperature differences associated with SAM during these seasons. The sum of the thermal and mechaninal effects gives a dipole response of sea ice to the SAM, with a decrease of the ice area in the Weddell Sea and around the Antarctic Peninsula and an increase in the Ross and Amundsen Seas during high SAM years. This is in good agreement with the observed response of the ice cover to SAM.

Download Full-text

Sea ice trends in the Antarctic and their relationship to surface air temperature during 1979–2009

Climate Dynamics ◽

10.1007/s00382-011-1143-9 ◽

2011 ◽

Vol 38 (11-12) ◽

pp. 2355-2363 ◽

Cited By ~ 9

Author(s):

Qi Shu ◽

Fangli Qiao ◽

Zhenya Song ◽

Chunzai Wang

Keyword(s):

Sea Ice ◽

Air Temperature ◽

Surface Air Temperature ◽

The Antarctic

Download Full-text

The Early 1990s Change in ENSO–PSA–SAM Relationships and Its Impact on Southern Hemisphere Climate

Journal of Climate ◽

10.1175/jcli-d-15-0335.1 ◽

2015 ◽

Vol 28 (23) ◽

pp. 9393-9408 ◽

Cited By ~ 38

Author(s):

Jin-Yi Yu ◽

Houk Paek ◽

Eric S. Saltzman ◽

Tong Lee

Keyword(s):

Sea Ice ◽

Southern Hemisphere ◽

Air Temperature ◽

Southern Oscillation ◽

Phase Relationship ◽

Surface Air Temperature ◽

Central Pacific ◽

Austral Spring ◽

Antarctic Sea Ice ◽

The Antarctic

Abstract This study uncovers an early 1990s change in the relationships between El Niño–Southern Oscillation (ENSO) and two leading modes of the Southern Hemisphere (SH) atmospheric variability: the southern annular mode (SAM) and the Pacific–South American (PSA) pattern. During austral spring, while the PSA maintained a strong correlation with ENSO throughout the period 1948–2014, the SAM–ENSO correlation changed from being weak before the early 1990s to being strong afterward. Through the ENSO connection, PSA and SAM became more in-phase correlated after the early 1990s. The early 1990s is also the time when ENSO changed from being dominated by the eastern Pacific (EP) type to being dominated by the central Pacific (CP) type. Analyses show that, while the EP ENSO can excite only the PSA, the CP ENSO can excite both the SAM and PSA through tropospheric and stratospheric pathway mechanisms. The more in-phase relationship between SAM and PSA impacted the post-1990s Antarctic climate in at least two aspects: 1) a stronger Antarctic sea ice dipole structure around the Amundsen–Bellingshausen Seas due to intensified geopotential height anomalies over the region and 2) a shift in the phase relationships of surface air temperature anomalies among East Antarctica, West Antarctica, and the Antarctic Peninsula. These findings imply that ENSO–Antarctic climate relations depend on the dominant ENSO type and that ENSO forcing has become more important to the Antarctic sea ice and surface air temperature variability in the past two decades and will in the coming decades if the dominance of CP ENSO persists.

Download Full-text

Validation of reanalysis Southern Ocean atmosphere trends using sea ice data

10.5194/acp-2020-580 ◽

2020 ◽

Author(s):

William R. Hobbs ◽

Andrew R. Klekociuk ◽

Yuhang Pan

Keyword(s):

Southern Ocean ◽

Sea Ice ◽

Surface Temperature ◽

Air Temperature ◽

Surface Air Temperature ◽

Heat Fluxes ◽

Surface Energy Budget ◽

Close Coupling ◽

In Situ Data ◽

Temperature Trends

Abstract. Reanalysis products are an invaluable tool for representing variability and long-term trends in regions with limited in-situ data, and especially the Antarctic. A comparison of 8 different reanalysis products shows large differences sea level pressure and surface air temperature trends over the high latitude Southern Ocean, with implications for studies of the atmosphere's role in driving ocean-sea ice changes. In this study, we use the established close coupling between sea ice cover and surface temperature to evaluate these reanalysis trends using the independent, 30-year sea ice record from 1980–2010. We demonstrate that sea ice trends are a reliable validation tool for most months of the year, although the sea ice-surface temperature coupling is weakest in summer when the surface energy budget is dominated by atmosphere-to-ocean heat fluxes. Based on our analysis, we find that surface air temperature trends in JRA55 are most consistent with satellite-observed sea ice trends over the polar waters of the Southern Ocean.

Download Full-text

Salinity effects on cultured Neogloboquadrina pachyderma (sinistral) from high latitudes: new paleoenvironmental insights

Geo-Marine Letters ◽

10.1007/s00367-020-00677-1 ◽

2021 ◽

Vol 41 (1) ◽

Author(s):

Jacqueline Bertlich ◽

Nikolaus Gussone ◽

Jasper Berndt ◽

Heinrich F. Arlinghaus ◽

Gerhard S. Dieckmann

Keyword(s):

Sea Ice ◽

Cold Water ◽

Weddell Sea ◽

Wall Thickening ◽

High Latitudes ◽

Neogloboquadrina Pachyderma ◽

Antarctic Sea Ice ◽

The Antarctic ◽

Water Species ◽

Cold Water Species

AbstractThis study presents culture experiments of the cold water species Neogloboquadrina pachyderma (sinistral) and provides new insights into the incorporation of elements in foraminiferal calcite of common and newly established proxies for paleoenvironmental applications (shell Mg/Ca, Sr/Ca and Na/Ca). Specimens were collected from sea ice during the austral winter in the Antarctic Weddell Sea and subsequently cultured at different salinities and a constant temperature. Incorporation of the fluorescent dye calcein showed new chamber formation in the culture at salinities of 30, 31, and 69. Cultured foraminifers at salinities of 46 to 83 only revealed chamber wall thickening, indicated by the fluorescence of the whole shell. Signs of reproduction and the associated gametogenic calcite were not observed in any of the culture experiments. Trace element analyses were performed using an electron microprobe, which revealed increased shell Mg/Ca, Sr/Ca, and Na/Ca values at higher salinities, with Mg/Ca showing the lowest sensitivity to salinity changes. This study enhances the knowledge about unusually high element concentrations in foraminifera shells from high latitudes. Neogloboquadrina pachyderma appears to be able to calcify in the Antarctic sea ice within brine channels, which have low temperatures and exceptionally high salinities due to ongoing sea ice formation.

Download Full-text

Seasonally changing contribution of sea ice and snow cover to uncertainty in multi-decadal Eurasian surface air temperature trends based on CESM simulations

Climate Dynamics ◽

10.1007/s00382-021-05746-4 ◽

2021 ◽

Author(s):

Zhaomin Ding ◽

Renguang Wu

Keyword(s):

Sea Ice ◽

Air Temperature ◽

Western Siberia ◽

Russian Far East ◽

Far East ◽

Surface Air Temperature ◽

The Caspian Sea ◽

Sea Ice Concentration ◽

Northern Siberia ◽

The Impact

AbstractThis study investigates the impact of sea ice and snow changes on surface air temperature (SAT) trends on the multidecadal time scale over the mid- and high-latitudes of Eurasia during boreal autumn, winter and spring based on a 30-member ensemble simulations of the Community Earth System Model (CESM). A dynamical adjustment method is used to remove the internal component of circulation-induced SAT trends. The leading mode of dynamically adjusted SAT trends is featured by same-sign anomalies extending from northern Europe to central Siberia and to the Russian Far East, respectively, during boreal spring and autumn, and confined to western Siberia during winter. The internally generated component of sea ice concentration trends over the Barents-Kara Seas contributes to the differences in the thermodynamic component of internal SAT trends across the ensemble over adjacent northern Siberia during all the three seasons. The sea ice effect is largest in autumn and smallest in winter. Eurasian snow changes contribute to the spread in dynamically adjusted SAT trends as well around the periphery of snow covered region by modulating surface heat flux changes. The snow effect is identified over northeast Europe-western Siberia in autumn, north of the Caspian Sea in winter, and over eastern Europe-northern Siberia in spring. The effects of sea ice and snow on the SAT trends are realized mainly by modulating upward shortwave and longwave radiation fluxes.

Download Full-text

General circulation model CO2 sensitivity experiments: Snow-sea ice albedo parameterizations and globally averaged surface air temperature

Climatic Change ◽

10.1007/bf00161596 ◽

1986 ◽

Vol 8 (3) ◽

pp. 231-241 ◽

Cited By ~ 49

Author(s):

Warren M. Washington ◽

Gerald A. Meehl

Keyword(s):

Sea Ice ◽

General Circulation Model ◽

Air Temperature ◽

General Circulation ◽

Surface Air Temperature ◽

Circulation Model ◽

Co2 Sensitivity ◽

Sensitivity Experiments

Download Full-text

Remote sensing of multiyear ice in the Antarctic

10.5194/dach2022-284 ◽

2021 ◽

Author(s):

Christian Melsheimer ◽

Gunnar Spreen

Keyword(s):

Time Series ◽

Sea Ice ◽

Global Climate ◽

Ice Cover ◽

Cold Season ◽

Arctic Sea Ice ◽

Weddell Sea ◽

Detailed Knowledge ◽

The Antarctic ◽

Multiyear Ice

The changing sea ice cover of polar seas is of key importance for the exchange of heat and moisture between atmosphere and ocean and hence for weather and climate, and in addition, the sea ice and its long-term changes are &#160;an indicator for global change. &#160;In order to properly understand and model the evolution of the sea ice cover and its interaction with the global climate system, we need detailed knowledge about sea ice, i.e., not only its extent, but also, e.g., its thickness and its type. We can broadly distinguish a few different sea ice types that have different dynamic and thermodynamic properties, namely: young ice (YI, thin/smooth new ice), first-year ice (FYI, formed during one cold season), and multiyear ice (MYI, which has survived at least one melt season). The&#160; latter is of particular interest as it is usually thicker than other ice types (thus, takes more time to melt), much less saline, and may accommodate a unique ecosystem. Sea ice types in the Antarctic, until recently, have not been monitored much because of the lack of appropriate remote&#160; sensing methods. While the Antarctic sea ice is greatly dominated by FYI, there are, nevertheless, considerable amounts of MYI, in particular in the Weddell Sea. We have recently adapted an algorithm for the detection of Arctic sea ice types for application in the Antarctic. The algorithm uses data from space-borne microwave radiometers and scatterometers as input. So far we have compiled a time series of daily Antarctic MYI data (and also an estimate of YI and FYI) data at a spatial resolution of 12.5 km, starting in 2013, but excluding the melt seasons when the algorithm does not work. Here give an overview of the data, showing, e.g., the quite large interannual variability of MYI and its evolution in the Weddell Sea, and discuss shortcomings of the algorithm and possible ways forward. The time series of daily Antarctic MYI data can in principle be extended backwards to the year 2000, when the used satellite data first became available, and with planned future satellite missions, it can be continued for years to come.

Download Full-text