Marine surface conditions and atmospheric forcing over Marguerite Bay and adjacent shelf, western Antarctica Peninsula, 2001-2003

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

As part of the 2001-2003 U.S. GLOBEC Southern Ocean field program, high-quality surface meteorological measurements were made during eleven research vessel cruises in the Marguerite Bay and adjacent shelf region, western Antarctic Peninsula. These measurements included surface wind, air and sea surface temperature, relative humidity, barometric pressure, incident short- and long-wave radiation, and sea-ice conditions. Two automatic weather stations (AWSs) deployed on low islands in the mouth of Marguerite Bay returned complete time series measurements of wind, air temperature, relative humidity and pressure for the two-year field study. These in-situ measurements, plus weather measurements collected at the British Antarctic Survey station Rothera near the head of Marguerite Bay, output from the Antarctic Mesoscale Prediction System (AMPS) weather model, and QuikScat scatterometer data provide an excellent basis to describe the surface conditions and atmospheric forcing fields during the SO GLOBEC study. The AWS and Rothera air temperature records were highly correlated and showed that the early onset of sea ice in 2002 austral winter was due in part to record low air temperatures in May and June. Winds over Marguerite Bay exhibited strong synoptic and season variability, with monthly mean winds directed southward. Several explanations are presented for the observed episodic strong relatively warm winds towards the southwest out of Marguerite Bay. Estimates of wind stress and heat flux were made using the shipboard data and the COARE2.6 bulk formulation for ice-free conditions. These show significant variability in both forcing fields on synoptic time scales, with the diurnal importance of insolation reduced during austral winter.

STATUS UPDATE:

Title, abstract, and author list received on 06/22/05.