Modeling Ocean–Cryosphere Interactions off Adélie and George V Land, East Antarctica

Abstract

Ocean–cryosphere interactions along the Adélie and George V Land (AGVL) coast are investigated using a coupled ocean–sea ice–ice shelf model. The dominant feature of the Mertz Glacier Tongue (MGT), located at approximately 145°E, was a highly productive winter coastal polynya system, until its calving in February 2010 dramatically changed the regional “icescape.” This study examines the annual mean, seasonal, and interannual variabilities of sea ice production; basal melting of the MGT; ice shelves, large icebergs, and fast ice; Dense Shelf Water (DSW) export; and bottom water properties on the continental slope and rise, and assesses the impacts of the calving event. The interannual variability of the winter coastal polynya regime is dominated by the regional offshore winds and air temperature, which are linked to activity of the Amundsen Sea low pressure system. This is the main driver of the interannual variability of DSW exported from the AGVL region. The calving event led to a decrease in sea ice production that resulted in a decrease in the density of DSW export. Subsequently, there is extensive freshening downstream over the continental shelf and slope regions. In addition, it is found that the calving event causes a significant decrease in the mean melt rate of the MGT, resulting from a decrease in ocean heat flux into the cavity due to ocean circulation changes.