Ocean/ice shelf interaction in the southern Weddell Sea: results of a regional numerical helium/neon simulation |
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| Authors: | Christian B Rodehacke Hartmut H Hellmer Oliver Huhn Aike Beckmann |
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| Institution: | (1) University Bremen, Bremen, Germany;(2) Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven, Germany;(3) NASA Goddard Institute for Space Studies, New York, USA;(4) Present address: University of Helsinki, Helsinki, Finland |
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| Abstract: | 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 hydrostatic
pressure at the glacial base causes gases embedded in the ice to dissolve completely after being released by melting. Helium
and neon, with an extremely low solubility, are saturated in glacial meltwater by more than 1000%. At the continental slope
in front of the large Antarctic caverns, ISW mixes with ambient waters to form different precursors of Antarctic Bottom Water.
A regional ocean circulation model, 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, is presented. 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 show a “low-pass” filtering of the inflowing
signal due to cavern processes. On circumpolar scales, the simulated helium and neon distributions allow us to quantify the
ISW contribution to bottom water, which spreads with the coastal current connecting the major formation sites in Ross and
Weddell Seas.
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| Keywords: | Tracers Ice shelf water Antarctic bottom water Southern ocean Numerical model |
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