Impact of Shelf and Sea Ice on Water Mass Modifications and Large-Scale Oceanic Circulation in the Weddell Sea

Abstract

The thermohaline circulation of the global ocean is driven to a large extent by water mass modifications that take place in the northern and southern Atlantic Ocean and its adjacent seas. In the Arctic and northern Atlantic Oceans, lateral and vertical mixing leads to the formation of North Atlantic Deep Water, a layer whose characteristics can be traced throughout the deep layers of most of the world ocean. South of the Antarctic Circumpolar Current, however, density layers influenced by the North Atlantic are shallow and they consequently lose large quantities of heat to the atmosphere. This occurs both through direct contact of the upper ocean/sea ice layer with the atmosphere or indirectly by conduction through the quasi-permanent ice shelves. Such heat losses initiate processes that produce cold and dense water masses, with the most important being formed in the Weddell Sea which in turn recirculate back toward the north at abyssal depths as various forms of Antarctic Bottom Water.