Source Regions, Abyssal Pathways, and Bottom Flow Channels (for Waters of the Antarctic Origin)

The Antarctic margin is surrounded by two westward flowing currents: the Antarctic Slope Current and the Antarctic Coastal Current. The former influences key processes near the Antarctic margin by regulating the flow of heat and nutrients onto and off the continental shelf, while together they advect nutrients, biological organisms, and temperature and salinity anomalies around the coastline, providing a connective link between different shelf regions. However, the extent to which these currents transport water from one sector of the continental shelf to another, and the timescales over which this occurs, remain poorly understood. Concern that crucial water formation sites around the Antarctic coastline could respond to non-local freshwater forcing from ice shelf meltwater motivates a more thorough understanding of zonal connectivity around Antarctica. In this study, we use daily velocity fields from a global high-resolution ocean-sea ice model, combined with the Lagrangian tracking software Parcels, to investigate the pathways and timescales connecting different regions of the Antarctic continental shelf with a view to understanding the timescales of meltwater transport around the continent. Virtual particles are released over the continental shelf, poleward of the 1000 metre isobath, and are tracked for 20 years. Our results show a strong seasonal cycle connecting different sectors of the Antarctic continent, with more particles arriving further downstream during winter than during summer months. Strong advective links exist between West Antarctica and the Ross Sea while shelf geometry in some other regions acts as barriers to transport. We also highlight the varying importance of the Antarctic Slope Current and Antarctic Coastal Current in connecting different sectors of the coastline. Our results help to improve our understanding of circum-Antarctic connectivity and the timescales of meltwater transport from source regions to downstream shelf locations. Furthermore, the timescales and pathways we present provide a baseline from which to assess long-term changes in Antarctic coastal circulation due to local and remote forcing.

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Exchange Between the Argentine and Brazil Basins; Abyssal Pathways and Bottom Flow Channels (for Waters of the Antarctic Origin)

Abyssal Channels in the Atlantic Ocean ◽

10.1007/978-90-481-9358-5_4 ◽

2010 ◽

pp. 99-177

Author(s):

Eugene G. Morozov ◽

Alexander N. Demidov ◽

Roman Y. Tarakanov ◽

Walter Zenk

Keyword(s):

Flow Channels ◽

The Antarctic

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Late Cretaceous palaeoenvironments and biotas: an Antarctic perspective

Antarctic Science ◽

10.1017/s0954102092000555 ◽

1992 ◽

Vol 4 (4) ◽

pp. 371-382 ◽

Cited By ~ 9

Author(s):

J. A. Crame

Keyword(s):

Late Cretaceous ◽

High Latitude ◽

Evolutionary Significance ◽

Source Regions ◽

Palynological Assemblages ◽

James Ross Island ◽

Extinction Events ◽

The Antarctic ◽

Cretaceous Period ◽

Mass Extinction Events

The Cretaceous period is often regarded as one of "greenhouse" warmth, with perhaps its acme occurring in the late Albian stage (100 Ma ago). However, it is now apparent that, even at this time, there were significant meridional temperature gradients and distinct temperate biotas in the highest latitude regions. This is particularly so in the Southern Hemisphere, where an extensive Albian fossil record from Antarctica, Australia and New Zealand has revealed the presence of austral floras and faunas. With the recent improvements in stratigraphical correlations, it has become possible to trace the later Cretaceous palaeoenvironmental record in the Antarctic Peninsula region. Unfortunately, resolution of the early Late Cretaceous (Cenomanian–Coniacian stages) is still imprecise; there are some indications of strongly differentiated palynological assemblages, but studies of both macrofaunas and palaeotemperature estimates are incomplete. By the Santonian–Campanian, high-latitude biotas are well developed in the James Ross Island region and their enhancement through the final stages of the Cretaceous can be linked to a phase of global cooling. The persistence of low diversity temperate communities in high latitude regions may be of considerable ecological and evolutionary significance. For example, there is evidence to suggest that these communities may have been more resistant to mass extinction events; they may also have been important source regions for replacement taxa that arose after such events.

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Influence of sea-ice anomalies on Antarctic precipitation using source attribution in the Community Earth System Model

The Cryosphere ◽

10.5194/tc-14-429-2020 ◽

2020 ◽

Vol 14 (2) ◽

pp. 429-444

Author(s):

Hailong Wang ◽

Jeremy G. Fyke ◽

Jan T. M. Lenaerts ◽

Jesse M. Nusbaumer ◽

Hansi Singh ◽

...

Keyword(s):

Southern Ocean ◽

Sea Ice ◽

Interannual Variability ◽

Moisture Transport ◽

Lower Latitude ◽

Source Attribution ◽

Source Regions ◽

Antarctic Precipitation ◽

The Antarctic ◽

The Impact

Abstract. We conduct sensitivity experiments using a general circulation model that has an explicit water source tagging capability forced by prescribed composites of pre-industrial sea-ice concentrations (SICs) and corresponding sea surface temperatures (SSTs) to understand the impact of sea-ice anomalies on regional evaporation, moisture transport and source–receptor relationships for Antarctic precipitation in the absence of anthropogenic forcing. Surface sensible heat fluxes, evaporation and column-integrated water vapor are larger over Southern Ocean (SO) areas with lower SICs. Changes in Antarctic precipitation and its source attribution with SICs have a strong spatial variability. Among the tagged source regions, the Southern Ocean (south of 50∘ S) contributes the most (40 %) to the Antarctic total precipitation, followed by more northerly ocean basins, most notably the South Pacific Ocean (27%), southern Indian Ocean (16 %) and South Atlantic Ocean (11 %). Comparing two experiments prescribed with high and low pre-industrial SICs, respectively, the annual mean Antarctic precipitation is about 150 Gt yr−1 (or 6 %) more in the lower SIC case than in the higher SIC case. This difference is larger than the model-simulated interannual variability in Antarctic precipitation (99 Gt yr−1). The contrast in contribution from the Southern Ocean, 102 Gt yr−1, is even more significant compared to the interannual variability of 35 Gt yr−1 in Antarctic precipitation that originates from the Southern Ocean. The horizontal transport pathways from individual vapor source regions to Antarctica are largely determined by large-scale atmospheric circulation patterns. Vapor from lower-latitude source regions takes elevated pathways to Antarctica. In contrast, vapor from the Southern Ocean moves southward within the lower troposphere to the Antarctic continent along moist isentropes that are largely shaped by local ambient conditions and coastal topography. This study also highlights the importance of atmospheric dynamics in affecting the thermodynamic impact of sea-ice anomalies associated with natural variability on Antarctic precipitation. Our analyses of the seasonal contrast in changes of basin-scale evaporation, moisture flux and precipitation suggest that the impact of SIC anomalies on regional Antarctic precipitation depends on dynamic changes that arise from SIC–SST perturbations along with internal variability. The latter appears to have a more significant effect on the moisture transport in austral winter than in summer.

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Exchange Between the Argentine and Brazil Basins; Abyssal Pathways and Bottom Flow Channels (for Waters of the Antarctic Origin)

Bottom Gravity Currents and Overflows in Deep Channels of the Atlantic Ocean ◽

10.1007/978-3-030-83074-8_4 ◽

2021 ◽

pp. 141-244

Author(s):

Eugene G. Morozov ◽

Roman Y. Tarakanov ◽

Dmitry I. Frey

Keyword(s):

Flow Channels ◽

The Antarctic

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Influence of Sea Ice Anomalies on Antarctic Precipitation Using Source Attribution

10.5194/tc-2019-69 ◽

2019 ◽

Cited By ~ 1

Author(s):

Hailong Wang ◽

Jeremy Fyke ◽

Jan Lenaerts ◽

Jesse Nusbaumer ◽

Hansi Singh ◽

...

Keyword(s):

Southern Ocean ◽

Sea Ice ◽

Interannual Variability ◽

Atmospheric Circulation ◽

Lower Latitude ◽

Source Attribution ◽

Source Regions ◽

Antarctic Precipitation ◽

The Antarctic ◽

The Impact

Abstract. We conduct sensitivity experiments using a climate model that has an explicit water source tagging capability forced by prescribed composites of sea ice concentrations (SIC) and corresponding SSTs to understand the impact of sea ice anomalies on regional evaporation, moisture transport, and source–receptor relationships for precipitation over Antarctica. Surface sensible heat fluxes, evaporation, and column-integrated water vapor are larger over Southern Ocean (SO) areas with lower SIC, but changes in Antarctic precipitation and its source attribution with SICs reflect a strong spatial variability. Among the tagged source regions, the Southern Ocean (south of 50° S) contributes the most (40 %) to the Antarctic total precipitation, followed by more northerly ocean basins, most notably the S. Pacific Ocean (27 %), S. Indian Ocean (16 %) and S. Atlantic Ocean (11 %). The annual mean Antarctic precipitation is about 150 Gt/year more in the “low” SIC case than in the “high” SIC case. This difference is larger than the model-simulated interannual variability of Antarctic precipitation (99 Gt/year). The contrast in contribution from the S. Ocean, 102 Gt/year, is even more significant, compared to the interannual variability of 35 Gt/year in Antarctic precipitation that originates from the S. Ocean. The horizontal transport pathways from individual vapor source regions to Antarctica are largely determined by large-scale atmospheric circulation patterns. Vapor from lower latitude source regions takes elevated pathways to Antarctica. In contrast, vapor from the Southern Ocean moves southward within the lower troposphere to the Antarctic continent, so the contribution of nearby sources also depends on regional coastal topography. The impact of sea ice anomalies on regional Antarctic precipitation also depends on atmospheric circulation changes that result from the prescribed composite SIC/SST perturbations. In particular, regional wind anomalies along with surface evaporation changes determine regional shifts in the zonal and meridional moisture fluxes that can explain some of the resultant precipitation changes.

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