On the Nature and Significance of the Antarctic Slope Front

The region near the edge of the continental shelf around Antarctica is the primary site for renewal of Antarctic surface waters and the deepest layers of the World Ocean. Here the Circumpolar Deep Water (CDW) reservoir approaches the sea surface and is transformed into a variety of surface, slope and shelf waters. It is the locus of enhanced exchange of heat, salt, gases and freshwater between the ocean, atmosphere, sea ice and glacial ice, and of nutrient and particulate material transport on and off the continental shelf. Rejuvenated near-surface waters here mix back into the deep ocean to modify the CDW and form Antarctic Bottom Water. The Antarctic Slope Front is a common oceanographic feature near the shelf break and has a major bearing on these processes. This topographically controlled front is marked by strong subsurface gradients in ocean temperature and chemistry, and by stronger alongshore currents than most of the adjacent continental shelf. It is one of the preferred routes for icebergs moving westward along the continental margin, and is characterized by regionally lower winter sea ice cover. There is significant evidence for regionally higher biological productivity along the Antarctic Slope Front.