Water properties on the west Antarctic Peninsula continental shelf: a model study of effects of surface fluxes and sea ice

2002 ◽  
Vol 49 (21) ◽  
pp. 4863-4886 ◽  
Author(s):  
David A Smith ◽  
John M Klinck
Keyword(s):  
Sea Ice ◽  
Continental Shelf ◽  
Antarctic Peninsula ◽  
Surface Fluxes ◽  
The West ◽  
Water Properties ◽  
West Antarctic ◽  
Model Study ◽  
West Antarctic Peninsula

scholarly journals Changes in the upper ocean mixed layer and phytoplankton productivity along the West Antarctic Peninsula

2018 ◽  
Vol 376 (2122) ◽  
pp. 20170173 ◽  
Author(s):  
Oscar Schofield ◽  
Michael Brown ◽  
Josh Kohut ◽  
Schuyler Nardelli ◽  
Grace Saba ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Mixed Layer ◽  
Carbon Fixation ◽  
Upper Ocean ◽  
The West ◽  
Phytoplankton Productivity ◽  
West Antarctic ◽  
West Antarctic Peninsula

The West Antarctic Peninsula (WAP) has experienced significant change over the last 50 years. Using a 24 year spatial time series collected by the Palmer Long Term Ecological Research programme, we assessed long-term patterns in the sea ice, upper mixed layer depth (MLD) and phytoplankton productivity. The number of sea ice days steadily declined from the 1980s until a recent reversal that began in 2008. Results show regional differences between the northern and southern regions sampled during regional ship surveys conducted each austral summer. In the southern WAP, upper ocean MLD has shallowed by a factor of 2. Associated with the shallower mixed layer is enhanced phytoplankton carbon fixation. In the north, significant interannual variability resulted in the mixed layer showing no trended change over time and there was no significant increase in the phytoplankton productivity. Associated with the recent increases in sea ice there has been an increase in the photosynthetic efficiency (chlorophyll a -normalized carbon fixation) in the northern and southern regions of the WAP. We hypothesize the increase in sea ice results in increased micronutrient delivery to the continental shelf which in turn leads to enhanced photosynthetic performance. This article is part of the theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

Water-mass properties and circulation on the west Antarctic Peninsula Continental Shelf in Austral Fall and Winter 2001

2004 ◽  
Vol 51 (17-19) ◽  
pp. 1925-1946 ◽  
Author(s):  
John M. Klinck ◽  
Eileen E. Hofmann ◽  
Robert C. Beardsley ◽  
Baris Salihoglu ◽  
Susan Howard
Keyword(s):  
Continental Shelf ◽  
Antarctic Peninsula ◽  
Water Mass ◽  
The West ◽  
West Antarctic ◽  
Mass Properties ◽  
West Antarctic Peninsula

Extreme Anomalous Atmospheric Circulation in the West Antarctic Peninsula Region in Austral Spring and Summer 2001/02, and Its Profound Impact on Sea Ice and Biota*

2006 ◽  
Vol 19 (15) ◽  
pp. 3544-3571 ◽  
Author(s):  
Robert A. Massom ◽  
Sharon E. Stammerjohn ◽  
Raymond C. Smith ◽  
Michael J. Pook ◽  
Richard A. Iannuzzi ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Phytoplankton Bloom ◽  
Wide Field ◽  
The West ◽  
Austral Spring ◽  
Sea Ice Extent ◽  
Ice Dynamics ◽  
West Antarctic ◽  
West Antarctic Peninsula

Abstract Exceptional sea ice conditions occurred in the West Antarctic Peninsula (WAP) region from September 2001 to February 2002, resulting from a strongly positive atmospheric pressure anomaly in the South Atlantic coupled with strong negative anomalies in the Bellingshausen–Amundsen and southwest Weddell Seas. This created a strong and persistent north-northwesterly flow of mild and moist air across the WAP. In situ, satellite, and NCEP–NCAR Reanalysis (NNR) data are used to examine the profound and complex impact on regional sea ice, oceanography, and biota. Extensive sea ice melt, leading to an ocean mixed layer freshening and widespread ice surface flooding, snow–ice formation, and phytoplankton growth, coincided with extreme ice deformation and dynamic thickening. Sea ice dynamics were crucial to the development of an unusually early and rapid (short) retreat season (negative ice extent anomaly). Strong winds with a dominant northerly component created an unusually compact marginal ice zone and a major increase in ice thickness by deformation and over-rafting. This led to the atypical persistence of highly compact coastal ice through summer. Ecological effects were both positive and negative, the latter including an impact on the growth rate of larval Antarctic krill and the largest recorded between-season breeding population decrease and lowest reproductive success in a 30-yr Adélie penguin demographic time series. The unusual sea ice and snow cover conditions also contributed to the formation of a major phytoplankton bloom. Unexpectedly, the initial bloom occurred within compact sea ice and could not be detected in Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) ocean color data. This analysis demonstrates that sea ice extent alone is an inadequate descriptor of the regional sea ice state/conditions, from both a climatic and ecological perspective; further information is required on thickness and dynamics/deformation.

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.

scholarly journals Marine pelagic ecosystems: the West Antarctic Peninsula

2006 ◽  
Vol 362 (1477) ◽  
pp. 67-94 ◽  
Author(s):  
Hugh W Ducklow ◽  
Karen Baker ◽  
Douglas G Martinson ◽  
Langdon B Quetin ◽  
Robin M Ross ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Marine Ecosystem ◽  
Ocean Dynamics ◽  
The West ◽  
Sea Ice Extent ◽  
The Past ◽  
West Antarctic ◽  
West Antarctic Peninsula ◽  
The Antarctic

The marine ecosystem of the West Antarctic Peninsula (WAP) extends from the Bellingshausen Sea to the northern tip of the peninsula and from the mostly glaciated coast across the continental shelf to the shelf break in the west. The glacially sculpted coastline along the peninsula is highly convoluted and characterized by deep embayments that are often interconnected by channels that facilitate transport of heat and nutrients into the shelf domain. The ecosystem is divided into three subregions, the continental slope, shelf and coastal regions, each with unique ocean dynamics, water mass and biological distributions. The WAP shelf lies within the Antarctic Sea Ice Zone (SIZ) and like other SIZs, the WAP system is very productive, supporting large stocks of marine mammals, birds and the Antarctic krill, Euphausia superba . Ecosystem dynamics is dominated by the seasonal and interannual variation in sea ice extent and retreat. The Antarctic Peninsula is one among the most rapidly warming regions on Earth, having experienced a 2°C increase in the annual mean temperature and a 6°C rise in the mean winter temperature since 1950. Delivery of heat from the Antarctic Circumpolar Current has increased significantly in the past decade, sufficient to drive to a 0.6°C warming of the upper 300 m of shelf water. In the past 50 years and continuing in the twenty-first century, the warm, moist maritime climate of the northern WAP has been migrating south, displacing the once dominant cold, dry continental Antarctic climate and causing multi-level responses in the marine ecosystem. Ecosystem responses to the regional warming include increased heat transport, decreased sea ice extent and duration, local declines in ice-dependent Adélie penguins, increase in ice-tolerant gentoo and chinstrap penguins, alterations in phytoplankton and zooplankton community composition and changes in krill recruitment, abundance and availability to predators. The climate/ecological gradients extending along the WAP and the presence of monitoring systems, field stations and long-term research programmes make the region an invaluable observatory of climate change and marine ecosystem response.

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