Oceanographic processes near the Filchner Sill - plans for fieldwork in 2007

• Main Authors: Makinson, K., Nicholls, K.W., Abrahamsen, E.P.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Bjerknes Centre for Climate Research 2007
• Subjects: Marine Sciences; Hydrology; Antarctic; Brunt Ice Shelf; Helmert Bank; Stancomb-Wills Ice Stream; The Antarctic; Weddell; Weddell Sea; Antarc*; Ice Shelf; Ice Shelves
• Online Access: http://nora.nerc.ac.uk/id/eprint/10112/; http://folk.uib.no/ngfso/FRISP/Rep17/makinson06.pdf

Introduction Over the Antarctic continental shelves, the focus of attention has been on the export of cold dense shelf waters to the world’s deep ocean and their contribution to Antarctic Bottom Water (AABW) production. Far less attention has been given to the import, onto the continental shelves, of surface and warm deep waters, which are key components of the heat, salt and mass budgets for the shelf seas. In order to quantify these budgets, mechanisms that control the rate of cross-shelf exchange need to be identified if we are to better understand the interactions between the Antarctic shelf seas and adjacent oceans. In the southeastern Weddell Sea, east of 26°W, the water masses over the narrow continental shelf are separated from the deep ocean by a series of fronts and associated currents. During winter, cooling leads to the formation of Winter Water (WW), while over the continental shelf water masses are freshened by glacial melt from the ice shelves that fringe the region [Fahrbach et al., 1994]. This cross-shelf density gradient supports a westward slope front current. In addition, the prevailing easterly winds produce a surface Ekman transport, leading to an increase in sea surface elevation toward the coast and a downwelling of the isopycnals that both deepens the interface between the WW and the underlying Weddell Deep Water (WDW) and supports a westward coastal current. In the southeastern Weddell Sea where the open shelf is very narrow, these currents effectively merge and are referred to as the Antarctic Coastal Current [Fahrbach et al., 1992]. Once the coastal current passes the Stancomb-Wills Ice Stream, which overhangs the shelf break, the continental shelf broadens and the current separates into coastal and slope components [Foster and Carmack, 1976]. The coastal component heads south towards Brunt Ice Shelf while the slope component flows west towards the Filchner Sill. North of Helmert Bank, WDW is found below the depth of both the shelf break and the troughs that cut some 200 m deeper into ...