Surface heat and salt flux estimates over the western Antarctic Peninsula shelf from isobaric floats


W. Owens, R. Limeburner and R. Beardsley



During February 2003 four isobaric floats were deployed over the western Antarctic Peninsula (WAP) shelf near Marguerite Bay to characterize the Lagrangian currents and repeatedly profile the local hydrographic structure. These isobaric floats passively drifted at a depth of 250 m; profiled pressure, temperature and conductivity every 5 days; and transmitted their surface position and hydrographic data via satellite at the end of each profile. The tracks of the floats at 250-m depth indicate cross-shelf flow of about 130 km towards the shelf break over time scales of 250 to 350 days. The floats’ data transmissions were sporadic during winter but continued to function properly when the extensive sea ice over the shelf melted the following spring. One float returned to near its deployment position after 198 days, thus completing a closed anticyclonic path about 80 km in diameter over the WAP shelf. The 20-30 profiles of pressure, temperature and conductivity made during February through September 2003 by each float were used to estimate changes in heat and salt content over the WAP shelf during austral fall. The mid-shelf region had a surface mixed layer about 80-m deep above a deeper stratified region.




Received title, author list, and abstract on 07/18/05.