Ocean/ice interaction at the base of deep drafted Antarctic ice shelves modifies the physical properties of inflowing shelf waters to become Ice Shelf Water (ISW).In contrast to the conditions at the atmosphere/ocean interface, the increased hydrostaticpressure at the glacial base causes gases embedded in the ice to solve completely after being released by melting. Helium and neon with an extremely low solubility are supersatured in glacial meltwater by more than 1000%. At the continentalslope in front of the large Antarctic caverns ISW mixes with ambient waters toform different precursors of Antarctic Bottom Water. A regional ocean circulation model is presented which uses an explicit formulation of the ocean/ice shelf interaction to describe for the first time the input of noble gases to the Southern Ocean. The results reveal a long-term variability of the basal mass loss solely controlled by the interaction between waters of the continental shelf and the ice shelf cavern. Modeled helium and neon supersaturations from the Filchner-Ronne Ice Shelf front reveal a "low-pass" filtering of the inflowing signal due to cavern processes. On circumpolar scales the helium and neon distributions in the Southern Ocean quantify the ISW contribution to bottom water which spreads with the coastal current connecting the major formation sites in Ross and Weddell Seas.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > POL1-Processes and interactions in the polar climate system