Atmospheric moisture transport across the Southern Ocean via satellite observations

Meridional moisture transport across the Southern Ocean was measured using a combination of TIROS operational vertical sounder and special sensor microwave/imager satellite data from 1988. Satellite and radiosonde estimates of moisture flux compare favorably near Macquarie Island (54.5°S, 158.9°). The zonally averaged, vertically integrated, moisture flux values across 50°S and 60°S are −31.8 and −15.2 kg m−1 s−1, respectively. Resulting moisture convergence for the 50°–60°S latitude band is 636±50 kg m−2 yr−1, about 50% larger than indicated by contemporary studies using radiosondes or atmospheric analyses. Within this latitude band the poleward moisture transport peaks in the South Pacific sector near 135°E, with a secondary maximum in the Amundsen Sea sector close to 135°W. There is a dramatic moisture flux discontinuity across the Antarctic peninsula and the tip of South America near 45°W, with equatorward moisture transport at all latitudes in the Weddell Sea sector. A regional study of West Antarctica indicates large poleward moisture flux is accomplished through the Bellingshausen and Amundsen Seas only.