INTERANNUAL VARIABILITY IN SUMMER SEA ICE MINIMUM, COASTAL POLYNYAS AND BOTTOM WATER FORMATION IN THE WEDDELL SEA

As sea ice formation plays a key role in driving Antarctic Bottom Water (AABW) production through brine rejection and the associated production of High Salinity freezing point Shelf Water 0tSSW), a possible link between interannual variability of the ice cover and changes in AABW production is expected. Analysis of satellite data indicates that the summer minimum extents (and area) in the Weddell Sea were highly variable from 1979 through 1995, but the correlations of summer ice characteristics to those of subsequent winter are generally weak. We observed, instead, that unusually low summer minimum extents which occurred in 1981, 1985, 1988, and 1993 were preceded by high winter maximum extents (with effects in 1985 not as large as other years). During years of high winter maximum extents, the meridional winds were observed to be relatively strong and coastal polynya areas were greater than average. Wind effects appear to be an important factor in causing the large variability observed in the ice cover while the effects of air temperature variations are not apparent. Temporal variability of AABW in the western Weddell Sea from 1963 through 1993 also is observed, with the bottom water salinity being significantly lower in 1992 and 1993 than those in earlier decades. A strong direct connection of the ice data with AABW is not apparent from available data but our results suggest the intriguing possibility that AABW formation is affected by the passage of the Antarctic Circumpolar Wave.