Ocean Circulation and Dynamics on the West Antarctic Peninsula Continental Shelf

Carlos Moffat-Varas, Ph.D., 2007
Robert Beardsley, W. Brechner Owens, Advisors

Observations of current velocity, temperature, salinity and pressure from a 2-year moored array deployment and four hydrographic cruises conducted by the United States Southern Ocean GLOBEC program on the western Antarctic Peninsula continental shelf are used to characterize the ocean circulation and its connection to fresh water and heat fluxes on the shelf. Marguerite Trough, a large bathymetric feature connecting the shelf-break to Marguerite Bay, plays a critical role in determining the circulation. At time-scales of 5 to 20 days, the observations reveal the presence of bottom-trapped topographic Rossby waves in Marguerite Trough. The subtidal circulation in the trough has a significant wind-driven component, with downwelling-favorable winds forcing cross-shelf flow on the northern side of Marguerite Trough and along the shore on the outer shelf. Upwelling-favorable winds force roughly the opposite circulation. The cyclonic circulation on the trough helps advect blobs of salty, warm and nutrient-rich water across the shelf. Finally, the first description of the Antarctic Peninsula Coastal Current (APCC) is provided. The APCC is a seasonal and forced by freshwater fluxes associated with large glacier melt and precipitation rates in the region.