Along-slope variability of cross-slope eddy transport in East Antarctica

Annie Foppert, Centre for Southern Hemisphere Oceans Research, CSIRO Oceans and Atmosphere, Hobart, Australia, Hobart, TAS, Australia, Stephen R Rintoul, Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC), Hobart, TAS, Australia and Matthew H England, Univ New South Wales, Sydney, NSW, Australia
Abstract:
Circumpolar Deep Water (CDW) transport across the Antarctic continental slope regulates the delivery of heat to the shelf and its availability to melt floating ice shelves. The cross-slope density field, calculated from profiles collected by conductivity-temperature-depth-tagged marine mammals on the East Antarctic slope (0–160°E, above 1,000- to 3,000-m isobaths), indicates eddy-driven overturning: onshore transport of CDW and offshore transport of shallower Antarctic Surface Water. Enhanced eddy activity, determined by a spice standard deviation threshold in the CDW layer, is present over about a third of the East Antarctic slope analyzed. Significantly stronger CDW transport in regions of elevated spice variability produces subsurface temperature anomalies of 0.2–0.25°C relative to the East Antarctic average. Estimating eddy diffusivity from the hydrography yields about 0.8 m2/s of warm CDW transport to the shelf break in high-variability regions. Variability of eddy-induced CDW transport influences the reservoir of heat available for transport across the shelf break.
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