Explaining the Weddell Polynya--a Large Ocean Eddy Shed at Maud Rise
D. M. Holland
Satellite observations have shown the occasional
occurrence of a large opening in the sea-ice cover of the Weddell Sea,
Antarctica, a phenomenon known as the Weddell Polynya. The transient
appearance, position, size, and shape of the polynya is explained here
by a mechanism by which modest variations in the large-scale oceanic flow past the Maud Rise seamount cause a horizontal cyclonic eddy to be
shed from its northeast flank. The shed eddy transmits a divergent
Ekman stress into the sea ice, leading to a crescent-shaped opening in
the pack. Atmospheric thermodynamical interaction further enhances the
opening by inducing oceanic convection. A sea-ice-ocean computer model simulation vividly demonstrates how this mechanism fully
accounts for the characteristics that mark Weddell Polynya events.
Center for Atmosphere-Ocean Science, Courant Institute of
Mathematical Sciences and Faculty of Arts and Science, New York
University, New York, NY 10012, USA. E-mail: holland{at}cims.nyu.edu
