During winter the sea ice extent around Antarctica's coastline is approximately 19 million square kilometres - an area nearly three times the size of Australia. Sea ice has a significant influence on the mean state and variability of regional and global climates. The extent to which a cover of sea ice modifies ocean-atmosphere interaction is determined primarily by the thickness and concentration of the ice and by the thickness and density of its snow cover.
Salt rejection during the autumn ice formation, followed by ice advection and subsequent summer melt further north, results in a net freshwater flux and change in ocean buoyancy. The ice thickness, ice drift and snow cover on the ice are themselves determined by ocean-atmosphere interactions.
Deep and bottom water formation south of the Antarctic Circumpolar Current occurs mostly through dense water formation, by cooling and brine release, on the Antarctic continental shelves. Sea ice formation counteracts freshwater gain by precipitation, minus evaporation and melting of ice shelves and icebergs.
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