Residence time and transformation of warm Circumpolar Deep Water on the Antarctic continental shelf

Abstract. Five thermistor moorings were placed on the continental shelf of the western Antarctic Peninsula (between 2007 and 2010) in an effort to identify the mechanism(s) responsible for delivering warm Upper Circumpolar Deep Water (UCDW) onto the broad continental shelf from the Antarctic Circumpolar Current (ACC) flowing over the adjacent continental slope. Historically, four mechanisms have been suggested: (1) eddies shed from the ACC, (2) flow into the cross-shelf-cutting canyons with overflow onto the nominal shelf, (3) general upwelling, and (4) episodic advective diversions of the ACC onto the shelf. The mooring array showed that for the years of deployment, the dominant mechanism is eddies; upwelling may also contribute but to an unknown extent. Mechanism 2 played no role, though the canyons have been shown previously to channel UCDW across the shelf into Marguerite Bay. Mechanism 4 played no role independently, though eddies may be advected within a greater intrusion of the background flow.

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Transport of warm upper circumpolar deep water onto the Western Antarctic Peninsula Continental Shelf

Ocean Science Discussions ◽

10.5194/osd-8-2479-2011 ◽

2011 ◽

Vol 8 (6) ◽

pp. 2479-2502 ◽

Cited By ~ 2

Author(s):

D. G. Martinson

Keyword(s):

Continental Shelf ◽

Antarctic Peninsula ◽

Deep Water ◽

Antarctic Circumpolar Current ◽

Western Antarctic Peninsula ◽

Dominant Mechanism ◽

Circumpolar Deep Water ◽

Marguerite Bay ◽

Circumpolar Current ◽

The Antarctic

Abstract. Five thermistor-moorings were placed on the continental shelf of the Western Antarctic Peninsula (between 2007 and 2010) in an effort to identify the mechanism(s) responsible for delivering warm Upper Circumpolar Deep Water (UCDW) onto the broad continental shelf from the Antarctic Circumpolar Current (ACC) flowing over the adjacent continental slope. Historically, four mechanisms have been suggested (or assumed): (1) eddies shed from the ACC, (2) flow into the cross-shelf-cutting canyons with overflow onto the nominal shelf, (3) general upwelling, and (4) episodic sweeping of ACC meanders over the shelf. The mooring array showed that for the years of deployment, the dominant mechanism is eddies; upwelling may also contribute but to an unknown extent. Mechanisms 2 and 4 played no role, though the canyons have been shown previously to channel UCDW across the shelf into Marguerite Bay.

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Reproductive biology of two species of holothurian from the deep-sea order Elasipoda, on the Antarctic continental shelf

Deep Sea Research Part II Topical Studies in Oceanography ◽

10.1016/j.dsr2.2008.07.002 ◽

2008 ◽

Vol 55 (22-23) ◽

pp. 2515-2526 ◽

Cited By ~ 21

Author(s):

E.A. Galley ◽

P.A. Tyler ◽

C.R. Smith ◽

A. Clarke

Keyword(s):

Continental Shelf ◽

Reproductive Biology ◽

Deep Sea ◽

Antarctic Continental Shelf ◽

The Antarctic

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Pathways and timescales of connectivity around the Antarctic continental shelf

10.5194/egusphere-egu21-14011 ◽

2021 ◽

Author(s):

Hannah Dawson ◽

Adele Morrison ◽

Veronica Tamsitt ◽

Matthew England

Keyword(s):

Continental Shelf ◽

Ross Sea ◽

Coastal Current ◽

West Antarctica ◽

Source Regions ◽

Freshwater Forcing ◽

Antarctic Continental Shelf ◽

Antarctic Continent ◽

Antarctic Slope Current ◽

The Antarctic

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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Upper ocean salinity variabilities in the Southern Ocean responding to the recent surface salting in perspective of climate changes

10.5194/egusphere-egu21-4727 ◽

2021 ◽

Author(s):

Ling Du ◽

Xubin Ni

Keyword(s):

Southern Ocean ◽

Deep Water ◽

Water Mass ◽

Water Cycle ◽

Upper Ocean ◽

Tropical Ocean ◽

Circumpolar Deep Water ◽

Salinity Changes ◽

Ocean Salinity ◽

The Antarctic

Water cycle have prevailed on upper ocean salinity acting as the climate change fingerprint in the numerous observation and simulation works. Water mass in the Southern Ocean accounted for the increasing importance associated with the heat and salt exchanges between Subantarctic basins and tropical oceans. The circumpolar deep water (CDW), the most extensive water mass in the Southern Ocean, plays an indispensable role in the formation of Antarctic Bottom Water. In our study, the observed CTDs and reanalysis datasets are examined to figure out the recent salinity changes in the three basins around the Antarctica. Significant surface salinity anomalies occurred in the South Indian/Pacific sectors south of 60&#186;S since 2008, which are connected with the enhanced CDW incursion onto the Antarctic continental shelf. Saltier shelf water was found to expand northward from the Antarctica coast. Meanwhile, the freshening of Upper Circumpolar Deep Water(UCDW), salting and submergence of Subantarctic Mode Water(SAMW) were also clearly observed. The modified vertical salinity structures contributed to the deepen mixed layer and enhanced intermediate stratification between SAMW and UCDW. Their transport of salinity flux attributed to the upper ocean processes responding to the recent atmospheric circulation anomalies, such as the Antarctic Oscillation and Indian Ocean Dipole. The phenomena of SAMW and UCDW salinity anomalies illustrated the contemporaneous changes of the subtropical and polar oceans, which reflected the meridional circulation fluctuation. Salinity changes in upper southern ocean (< 2000m) revealed the influence of global water cycle changes, from the Antarctic to the tropical ocean, by delivering anomalies from high- and middle-latitudes to low-latitudes oceans.

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