scholarly journals Transport of warm Upper Circumpolar Deep Water onto the western Antarctic Peninsula continental shelf

Ocean Science ◽  
2012 ◽  
Vol 8 (4) ◽  
pp. 433-442 ◽  
Author(s):  
D. G. Martinson ◽  
D. C. McKee
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: (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.

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

2011 ◽  
Vol 8 (6) ◽  
pp. 2479-2502 ◽  
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.

scholarly journals Sensitivity of Circumpolar Deep Water Transport and Ice Shelf Basal Melt along the West Antarctic Peninsula to Changes in the Winds

2012 ◽  
Vol 25 (14) ◽  
pp. 4799-4816 ◽  
Author(s):  
Michael S. Dinniman ◽  
John M. Klinck ◽  
Eileen E. Hofmann
Keyword(s):  
Continental Shelf ◽  
Antarctic Peninsula ◽  
Deep Water ◽  
Constant Factor ◽  
Ice Shelf ◽  
The West ◽  
Ice Shelves ◽  
Circumpolar Deep Water ◽  
West Antarctic ◽  
West Antarctic Peninsula

Abstract Circumpolar Deep Water (CDW) can be found near the continental shelf break around most of Antarctica. Advection of this relatively warm water (up to 2°C) across the continental shelf to the base of floating ice shelves is thought to be a critical source of heat for basal melting in some locations. A high-resolution (4 km) regional ocean–sea ice–ice shelf model of the west Antarctic Peninsula (WAP) coastal ocean was used to examine the effects of changes in the winds on across-shelf CDW transport and ice shelf basal melt. Increases and decreases in the strength of the wind fields were simulated by scaling the present-day winds by a constant factor. Additional simulations considered effects of increased Antarctic Circumpolar Current (ACC) transport. Increased wind strength and ACC transport increased the amount of CDW transported onto the WAP continental shelf but did not necessarily increase CDW flux underneath the nearby ice shelves. The basal melt underneath some of the deeper ice shelves actually decreased with increased wind strength. Increased mixing over the WAP shelf due to stronger winds removed more heat from the deeper shelf waters than the additional heat gained from increased CDW volume transport. The simulation results suggest that the effect on the WAP ice shelves of the projected strengthening of the polar westerlies is not a simple matter of increased winds causing increased (or decreased) basal melt. A simple budget calculation indicated that iron associated with increased vertical mixing of CDW could significantly affect biological productivity of this region.

Late Holocene advance of the Müller Ice Shelf, Antarctic Peninsula: sedimentological, geochemical and palaeontological evidence

1995 ◽  
Vol 7 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Eugene W. Domack ◽  
Scott E. Ishman ◽  
Andrew B. Stein ◽  
Charles E. McClennen ◽  
A.J. Timothy Jull
Keyword(s):  
Antarctic Peninsula ◽  
Deep Water ◽  
Sediment Cores ◽  
Austral Summer ◽  
Ice Age ◽  
Geochemical Data ◽  
Organic Carbon Content ◽  
Ice Shelf ◽  
Circumpolar Deep Water ◽  
The Antarctic

Marine sediment cores were obtained from in front of the Müller Ice Shelf in Lallemand Fjord, Antarctic Peninsula in the austral summer of 1990–91. Sedimentological and geochemical data from these cores document a warm period that preceded the advance of the Müller Ice Shelf into Lallemand Fjord. The advance of the ice shelf is inferred from a reduction in the total organic carbon content and an increase in well-sorted, aeolian, sand in cores proximal to the present calving line. This sedimentological change is paralleled by a change in the foraminiferal assemblages within the cores. Advance of the ice shelf is indicated by a shift from assemblages dominated by calcareous benthic and planktonic forms to those dominated by agglutinated forms. A 14C chronology for the cores indicates that the advance of the Müller Ice Shelf took place c. 400 years ago, coincident with glacier advances in other high southern latitude sites during the onset of the Little Ice Age. Ice core evidence, however, documents this period as one of warmer temperatures for the Antarctic Peninsula. We suggest that the ice shelf advance was linked to the exclusion of circumpolar deep water from the fjord. This contributed to increased mass balance of the ice shelf system by preventing the rapid undermelt that is today associated with warm circumpolar deep water within the fjord. We also document the recent retreat of the calving line of the Müller Ice Shelf that is apparently in response to a recent (four decade long) warming trend along the western side of the Antarctic Peninsula.

Systematic forcing of large-scale geophysical flows by eddy-topography interaction

1987 ◽  
Vol 184 ◽  
pp. 463-476 ◽  
Author(s):  
Greg Holloway
Keyword(s):  
Wave Propagation ◽  
Continental Shelf ◽  
Numerical Experiments ◽  
Antarctic Circumpolar Current ◽  
Large Scale ◽  
Geophysical Flows ◽  
Dominant Mechanism ◽  
Coastal Oceans ◽  
Circumpolar Current ◽  
Closure Theory

The interaction of eddies with variations in topography, together with a tendency for large-scale wave propagation, generates a systematic stress which acts upon large-scale mean flows. This stress resists the midlatitude tropospheric westerlies, resists the oceanic Antarctic Circumpolar Current, and may be a dominant mechanism in driving coastal undercurrents. Associated secondary circulation provides a systematic upwelling in coastal oceans, pumping deeper water onto continental shelf areas. The derivation rests in turbulence closure theory and is supported by numerical experiments.

scholarly journals Baroclinic Transport Time Series of the Antarctic Circumpolar Current Measured in Drake Passage

2014 ◽  
Vol 44 (7) ◽  
pp. 1829-1853 ◽  
Author(s):  
María Paz Chidichimo ◽  
Kathleen A. Donohue ◽  
D. Randolph Watts ◽  
Karen L. Tracey
Keyword(s):  
Time Series ◽  
Standard Deviation ◽  
Deep Water ◽  
Antarctic Circumpolar Current ◽  
Drake Passage ◽  
Polar Front ◽  
Intermediate Water ◽  
Circumpolar Deep Water ◽  
Circumpolar Current ◽  
Baroclinic Transport

Abstract The first multiyear continuous time series of Antarctic Circumpolar Current (ACC) baroclinic transport through Drake Passage measured by moored observations is presented. From 2007 to 2011, 19 current- and pressure-recording inverted echo sounders and 3 current-meter moorings were deployed in Drake Passage to monitor the transport during the cDrake experiment. Full-depth ACC baroclinic transport relative to the bottom has a mean strength of 127.7 ± 1.0 Sverdrups (Sv; 1 Sv ≡ 106 m3 s−1) with a standard deviation of 8.1 Sv. Mean annual baroclinic transport is remarkably steady. About 65% of the baroclinic transport variance is associated with time periods shorter than 60 days with peaks at 20 and 55 days. Nearly 28% of apparent energy in the spectrum computed from transport subsampled at the 10-day repeat cycle of the Jason altimeter results from aliasing of high-frequency signals. Approximately 80% of the total baroclinic transport is carried by the Subantarctic Front and the Polar Front. Partitioning the baroclinic transport among neutral density γn layers gives 39.2 Sv for Subantarctic Surface Water and Antarctic Intermediate Water (γn < 27.5 kg m−3), 57.5 Sv for Upper Circumpolar Deep Water (27.5 < γn < 28.0 kg m−3), 27.7 Sv for Lower Circumpolar Deep Water (28.0 < γn < 28.2 kg m−3), and 3.3 Sv for Antarctic Bottom Water (γn > 28.2 kg m−3). The transport standard deviation in these layers decreases with depth (4.0, 3.1, 2.1, and 1.1 Sv, respectively). The transport associated with each of these water masses is statistically steady. The ACC baroclinic transport exhibits considerable variability and is a major contributor to total ACC transport variability.

scholarly journals ENSO and variability of the Antarctic Peninsula pelagic marine ecosystem

2008 ◽  
Vol 21 (2) ◽  
pp. 135-148 ◽  
Author(s):  
Valerie J. Loeb ◽  
Eileen E. Hofmann ◽  
John M. Klinck ◽  
Osmund Holm-Hansen ◽  
Warren B. White
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Antarctic Circumpolar Current ◽  
Southern Oscillation ◽  
Marine Ecosystem ◽  
Weddell Sea ◽  
Enso Variability ◽  
Decadal Scale ◽  
Circumpolar Current ◽  
The Antarctic

AbstractThe West Antarctic Peninsula region is an important source of Antarctic krill (Euphausia superba) in the Southern Ocean. From 1980–2004 abundance and concentration of phytoplankton and zooplankton, krill reproductive and recruitment success and seasonal sea ice extent here were significantly correlated with the atmospheric Southern Oscillation Index and exhibited three- to five-year frequencies characteristic of El Niño–Southern Oscillation (ENSO) variability. This linkage was associated with movements of the Southern Antarctic Circumpolar Current Front and Boundary, a changing influence of Antarctic Circumpolar Current and Weddell Sea waters, and eastward versus westward flow and mixing processes that are consistent with forcing by the Antarctic Dipole high-latitude climate mode. Identification of hydrographic processes underlying ecosystem variability presented here were derived primarily from multi-disciplinary data collected during 1990–2004, a period with relatively stable year-to-year sea ice conditions. These results differ from the overwhelming importance of seasonal sea ice development previously established using 1980–1996 data, a period marked by a major decrease in sea ice from the Antarctic Peninsula region in the late 1980s. These newer results reveal the more subtle consequences of ENSO variability on biological responses. They highlight the necessity of internally consistent long-term multidisciplinary datasets for understanding ecosystem variability and ultimately for establishing well-founded ecosystem management. Furthermore, natural environmental variability associated with interannual- and decadal-scale changes in ENSO forcing must be considered when assessing impacts of climate warming in the Antarctic Peninsula–Weddell Sea region.

Sign in / Sign up

Export Citation Format

Share Document