Large-scale processes governing the seasonal variability of the Antarctic sea ice

The seasonal variability of sea-ice cover in the Southern Ocean is examined using daily sea-ice concentration and ice velocity products for 2003-2009, derived from Advanced Microwave Scanning Radiometer for EOS (AMSR-E) data. This study quantitatively shows the contribution of (1) ice production/reduction within the sea ice, (2) ice production/reduction at the sea-ice edge and (3) zonal ice transport to the seasonal change of sea-ice area. Area of greatest ice production occurs along the coast of Ross Sea and East Antarctica from March to September. The contribution of zonal transport to the seasonal change of ice area is one order magnitude smaller than local ice production/reduction. Clear regional and seasonal differences are found in the large-scale processes named above. Generally, ice area increases due to ice production, both at the ice edge and within the pack in the autumn and winter. The most significant ice production at the ice edge occurred in the Weddell Sea; the ice production provides 56% of total increase of ice cover in this area. In contrast, moderate ice melting occurs at the ice edge through almost all months in the Indian Ocean sector.