The impact of Southern Ocean Bathymetry on the ocean circulation and overlying atmosphere

• Main Authors: De Boer, A., Hutchinson, D., Roquet, F., Sime, L., Burls, N., Heuze, C.
• Format: Conference Object
• Language: English
• Published: 2023
• Subjects: Antarctic; Campbell Plateau; Curl; Drake Passage; Kerguelen; Mid-Atlantic Ridge; Ross Sea; Southern Ocean; The Antarctic; Antarc*
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016649

The presentation will focus around the impact that major topographic features in the Southern Ocean have on the path of the Antarctic Circumpolar Current (ACC), and their relatively unknown role in the coupled ocean-atmosphere system. We investigate their influence by respectively flattening the bathymetry around the Kerguelen Plateau, Campbell Plateau, Mid-Atlantic Ridge, and Drake Passage in four simulations in a coupled climate model. The barriers lead to an increase in the ACC transport of between 3% and 14% in the four simulations. The removal of Kerguelen Plateau bathymetry increases convection south of the plateau and the removal of Drake Passage bathymetry reduces convection upstream in the Ross Sea, affecting the deep overturning cell. When the barriers are removed, zonal flattening of the currents leads to SST anomalies upstream and downstream of their locations. Interestingly, these SST anomalies strongly correlate to precipitation in the overlying atmosphere, with correlation coefficients ranging between r=0.92 and r=0.97 in the four experiments. Windspeed anomalies are also positively correlated to SST anomalies in some locations but other forcing factors obscure this correlation in general. Meridional variability in the wind stress curl contours over the Mid-Atlantic Ridge, the Kerguelen Plateau and the Campbell Plateau disappears when these barriers are removed, confirming the impact of bathymetry on overlying winds.