09.06.2021: Online Ocean Circulation and Climate Dynamics Colloquium

When?     Wednesday, 9 June 2021 at 11am
Where?    ZOOM meeting room: https://geomar-de.zoom.us/j/87973009382?pwd=RkhINnh2TTRBaWFiMDhMNDVmWGxaZz09
Meeting-ID: 879 7300 9382
Kenncode: 379011

Abstract:
The basal melt rate of Antarctica's ice shelves is largely controlled by heat delivered from the Southern Ocean to the Antarctic continental shelf. The Antarctic Slope Current (ASC) is an almost circumpolar feature that encircles Antarctica along the continental shelf break in an anti-clockwise direction. Because the circulation is to first order oriented along the topographic slope, it inhibits exchange of water masses between the Southern Ocean and the Antarctic continental shelf and thereby impacts cross-slope heat supply. Direct observations of the ASC system are sparse but indicate a highly variable flow field both in time and space. Given the importance of the circulation near the shelf break for cross-shelf exchange of heat, it is timely to further improve our knowledge of the ASC system. This study makes use of the global ocean-sea ice model ACCESS-OM2-01 with a 1/10-degree horizontal resolution and describes the spatial and temporal variability of the velocity field. We categorise the modelled ASC into three different regimes, similar to previous works for the associated Antarctic Slope Front: (i) A surface-intensified current found predominantly in East Antarctica, (ii) a bottom-intensified current found downstream of the dense shelf water formation sites in the Ross, Weddell, and Prydz Bay Seas, and (iii) a reversed current found in West Antarctica where the eastward flowing Antarctic Circumpolar Current impinges onto the continental shelf break. The temporal variability of the ASC varies between the regimes with only the surface-intensified ASC showing a clear seasonal signal in response to the variability in the wind field.

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