Circumpolar Deep Water (CDW) intrusion over the continental shelf in the Amundsen Sea.

Abstract

The Amundsen Sea sector is the most rapidly changing region of the Antarctic ice sheets. It has been claimed that the rapid retreat of the glaciers (or ice sheets) is primarily related to the intrusion of warm Circumpolar Deep Water (CDW) which acts as an oceanic heat source. The Amundsen shelf troughs were suspected to be main conduits supplying warm CDW onto the continental shelf, eroding the underside of the ice sheets and glaciers. Despite the critical role of CDW in the continental shelf of the Amundsen Sea, vital information is still absent from the existing body of knowledge pertaining to spatial-temporal variability of CDW. This is mainly because the Amundsen Sea is remotely located and the extremely harsh weather and sea conditions limited the access to its inner shelf. Lack of data hindered our evaluation and prediction of physical processes and associated biogeochemical processes in the Amundsen Sea. Using the icebreaker R/V Araon, a multi-disciplinary scientific cruise was conducted between December, 2010 and January, 2011 to timely address these processes. During the expedition, total 30 CTD stations were visited. It was observed that the warm CDW occupied a large volume off the continental slope. As it was transported onto the continental shelf, it was modified (i.e., cooled and freshened) to be modified CDW (MCDW) by interacting with Antarctic Surface Water. Two crosW) which acts as an oceanic heat source. The Amundsen shelf troughs were suspected to be main conduits supplying warm CDW onto the continental shelf, eroding the underside of the ice sheets and glaciers. Despite the critical role of CDW in the continental shelf of the Amundsen Sea, vital information is still absent from the existing body of knowledge pertaining to spatial-temporal variability of CDW. This is mainly because the Amundsen Sea is remotely located and the extremely harsh weather and sea conditions limited the access to its in