Along‐Slope Variability of Cross‐Slope Eddy Transport in East Antarctica.

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. Plain Language Summary: The transport of warm water from the open ocean to the Antarctic continental shelf has global significance, as it regulates the melt of ice shelves and dense water formation. We quantify the strength of eddy‐driven transport of relatively warm Circumpolar Deep Water (CDW) across the continental slope of East Antarctica from the observed cross‐slope density structure. We find that, in general, there is an eddy‐driven overturning: deeper CDW is transported onshore while shallower Antarctic Surface Water is transported offshore. Upon closer inspection, we find that regions with elevated temperature and salinity variability on density surfaces are associated with significantly stronger onshore transport of CDW by eddies. These hot spots of eddy transport produce warm and salty anomalies at the shelf break, impacting the reservoir of heat available to the shelf. Key Points: Cross‐slope eddy transport is inferred from observed density‐layer thickness gradients in East Antarctica between 0°E and 160°EEnhanced onshore transport (≈1.5 × East Antarctic mean) of warm, salty Circumpolar Deep Water occurs in regions of high isopycnal spice variabilityEddy‐induced overturning carries ≈0.8 m2/s of CDW poleward to produce warm, salty anomalies at the shelf break in eddying regions [ABSTRACT FROM AUTHOR]