Extended Abstract (584K)J1.3
Sea ice response to wind forcing from AMIP models (INVITED)
Cecilia M. Bitz, University of Washington, Seattle, WA; and J. C. Fyfe, G. M. Flato, and R. E. Moritz
The arctic surface circulation simulated by atmospheric general circulation models (GCMs) is assessed in the context of driving sea ice motion. The mean sea level pressure simulated by the GCMs is generally too high over the Arctic Ocean, except in the Beaufort and Chukchi Seas, where it is too low. This pattern creates anomalous winds that tend to transport too much ice away from the coast of Greenland and the Canadian Archipalego, and into the East Siberian Sea, producing a pattern of ice thickness in the Arctic that is rotated by roughly 180 degrees relative to what is expected based on observations. GCM winds also drive too little ice transport through Fram Strait and too much transport east of Svalbard by way of the Barents Sea. These errors in ice thickness and transport influence ice growth and melt rates and hence the freshwater flux into the ocean. Sensitivity experiments show the ice response depends primarily on the climatological mean annual cycle of the geostrophic winds. Daily wind variability is necessary to create sufficient ice deformation and open water, but the sea ice response is rather insensitive to the details of the daily variations. Sensitivity experiments with the NCAR CCM3.6 are carried out to test the influence of resolution, boundary conditions, and model physics on the arctic surface circulation.
Joint Session 1, Air-Sea Interactions in High Latitudes (Joint with the Sixth Conference on Polar Meteorology and Oceanography and the 11th Conference on Interaction of the Sea and Atmosphere)
Wednesday, 16 May 2001, 8:00 AM-10:00 AM
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