Circulation Beneath Fimbulisen: Measurements and Modeling

Antarctic ice shelves are the floating extensions of the Antarctic Ice Sheet, covering around 40% of the continental shelf. The cavities beneath the ice shelves are important to the climate system through their contribution to the production of the globally important Antarctic Bottom Water. However, they remain some of the most difficult areas of the world ocean to access. Many of the processes that take place under larger ice shelves can be observed more conveniently beneath smaller ice shelves such as Fimbulisen, an ice shelf in the eastern Weddell Sea. In February 2005 an Autonomous Underwater Vehicle (AUV), Autosub-2, was the first AUV successfully to perform measurements beneath an ice shelf when it was sent under Fimbulisen, yielding temperature, salinity, and current data, as well as an acoustic image of the underside of the ice. The data from Autosub show that (relatively) warm water can access the base of the ice shelf; this inflow is probably controlled by winds near the ice front. We will compare features in these data with other measurements in the area, and with recent model results using the POLAIR coupled ocean/ice shelf modeling framework.