Surface Forcing over the West Antarctic Peninsula Shelf During

Austral Summer-Fall 2001

R. Beardsley, R. Limeburner, M. Caruso, J. Hyatt

Woods Hole Oceanographic Institution

As part of the U.S. Southern Ocean GLOBEC program, meteorological measurements were made aboard the R/V Gould and R/VIB Palmer during cruises in and near Marguerite Bay on the West Antarctic Peninsula shelf from April through May 2001. These measurements included wind speed and direction, air temperature, relative humidity, barometric pressure, sea-surface temperature, and downward short- and long-wave radiation. The surface wind stress and heat flux were then computed using bulk formula.

This region of the West Antarctic Peninsula shelf experiences large seasonal changes in surface forcing. Passing low pressure systems become more frequent and stronger from summer into winter, when gale-force winds occur on average every ~2.5-3 days. Cloud cover becomes much more persistent, further reducing the shortwave heat flux as the sun approaches winter solstice. Air temperatures drop to below freezing and sea-surface temperatures reach freezing and ice formation occurs. Despite increased winds from summer into winter, sensible and latent heat losses become less important in the net surface heat flux as longwave cooling becomes the dominant component over open water before ice formation.