극지해양의 기후변화 시그널: 온난해류의 침입효과

초록

Climate change is a consequence of interactions between oceanic and atmospheric forcings. In Polar Oceans, the warm water mass intrusion is considered as an important driving force to affect rapid sea ice reduction and ice shelf melting through changes in the horizontal and vertical flux of heat, salt and momentum. In the Arctic, after passing through the Bering Strait, the Pacific-origin summer water (PSW) can be highly transformed by air-sea interactions dependent on sea ice cover and redistributed in the vicinity of the Chukchi Borderland/Mendeleev Ridge by the rectification of oceanic current in the presence of large amplitude of seafloor topography and localized freshwater pool in the large scale gyre. Recent IBRV Araon cruises reveal that the thickness of PSW in the Chukchi Borderland during 2011 summer is 1.5 times greater than that during 2008 summer. This suggests that volume of delivered PSW substantially increased, which might be in association with the changes in upper ocean circulation. The warmest water mass exists in the eastern flank of Chukchi Plateau, and the signal of warm temperature gradually diminishes toward the west direction. In the Antarctic, 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 shelves) 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.