Thermohaline structure and mixing in the region of Prydz Bay, Antarctica

Abstract

Temperature and salinity data, collected during successive summer expeditions to the region of Prydz Bay, Antarctica between 1981 and 1985, indicate that the mixing processes responsible for the thermohaline circulation are similar to those in the Weddell Sea. In particular, Circumpolar Deep Water intrudes over the continental shelf break, aided by periodic upwelling processes associated with the tides and continental shelf waves, and mixes with the colder Shelf Water associated with the formation of sea ice over the continental shelf. Mixing of these intrusive water masses is enhanced by shear, and the resultant cold and salty mixture, termed here Prydz Bay Bottom Water, flows westward and downslope under the influence of the Coriolis force and Antarctic coastal winds. Prydz Bay Bottom Water is insufficiently dense to reach abyssal depths, and probably interleaves with the Circumpolar Deep Water at intermediate depths. The mixing processes are likely to be responsible for active bottom water formation in Prydz Bay for most of the year, except perhaps in the summer months when the mixture is insufficiently dense to flow down the continental slope.