Inflow of Warm Circumpolar Deep Water in the Central Amundsen Shelf

Abstract

The thinning and acceleration of the West Antarctic Ice Sheet has been attributed to basal melting induced by intrusions of relatively warm salty water across the continental shelf. A hydrographic section including lowered acoustic Doppler current profiler measurements showing such an inflow in the channel leading to the Getz and Dotson Ice Shelves is presented here. The flow rate was 0.3?0.4 Sv (1 Sv ≡ 106 m3 s?1), and the subsurface heat loss was estimated to be 1.2?1.6 TW. Assuming that the inflow persists throughout the year, it corresponds to an ice melt of 110?130 km3 yr?1, which exceeds recent estimates of the net ice glacier ice volume loss in the Amundsen Sea. The results also show a 100?150-m-thick intermediate water mass consisting of Circumpolar Deep Water that has been modified (cooled and freshened) by subsurface melting of ice shelves and/or icebergs. This water mass has not previously been reported in the region, possibly because of the paucity of historical data.