Modeling ice shelf water overflow and bottom water formation in the southern Weddell Sea

Abstract

Descent of Ice Shelf Water (ISW) overflowed from the Filchner Depression in the southern Weddell Sea and consequent Weddell Sea Bottom Water (WSBW) production is investigated through high resolution numerical experiments. The model reproduces the part of ISW which interacts with the submarine ridge near 36°W. The baroclinic instability wave developed near the exit of the Filchner Depression leads to intermittent outflow of ISW, and the intermittent passage of ISW-origin dense water induces 6-day period oscillation of velocity at the east side of the ridge which coincides well with mooring data. The existence of the ridge induces two different mechanisms for cross-isobath transport of the ISW-origin dense water: a strong downslope current at the east side of the ridge and offshore transport by eddies, which are generated when a gravity current makes a detour around the tip of the ridge, over a wide region to the west of the ridge. In a sensitivity experiment where thermobaricity is removed from the equation of state, there is almost no transport of the ISW-origin water below 3000 m depth. WSBW production rate as a result of descent of the ISW-origin dense water in the model domain is about ∼0.15 Sv. Copyright 2010 by the American Geophysical Union.