The control of the Southern Hemisphere Westerlies on the position of the Subtropical Front
| Type | Article | ||||||||
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| Date | 2013-10 | ||||||||
| Language | English | ||||||||
| Author(s) | de Boer Agatha M.1, 2, Graham Robert M.1, 2, Thomas Matthew3, Kohfeld Karen E.4 | ||||||||
| Affiliation(s) | 1 : Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden. 2 : Stockholm Univ, Bolin Ctr Climate Res, SE-10691 Stockholm, Sweden. 3 : IFREMER, Lab Phys Oceans, Plouzane, France. 4 : Simon Frasier Univ, Sch Resource & Environm Management, Burnaby, BC, Canada. |
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| Source | Journal Of Geophysical Research-oceans (0148-0027) (Amer Geophysical Union), 2013-10 , Vol. 118 , N. 10 , P. 5669-5675 | ||||||||
| DOI | 10.1002/jgrc.20407 | ||||||||
| WOS© Times Cited | 34 | ||||||||
| Keyword(s) | Subtropical Front, wind stress curl, Southern Ocean, satellite data, fronts, Dynamical Subtropical Front | ||||||||
| Abstract | In recent years the latitudinal position of the Subtropical Front (STF) has emerged as a key parameter in the global climate. A poleward positioned front is thought to allow a greater salt flux from the Indian to the Atlantic Ocean and so drive a stronger Atlantic Meridional Overturning Circulation. Here the common view that the STF aligns with the zero wind stress curl (WSC) is challenged. Based on the STF climatologies of Orsi et al. (1995), Belkin and Gordon (1996), Graham and De Boer (2013), and on satellite scatterometry winds, we find that the zero WSC contour lies on average approximate to 10 degrees, approximate to 8 degrees, and approximate to 5 degrees poleward of the front for the three climatologies, respectively. The circulation in the region between the Subtropical Gyres and the zero WSC contour is not forced by the WSC but rather by the strong bottom pressure torque that is a result of the interaction of the Antarctic Circumpolar Current with the ocean floor topography. The actual control of the position of the STF is crucially dependent on whether the front is regarded as simply a surface water mass boundary or a dynamical front. For the Agulhas Leakage problem, the southern boundary of the so-called Super Gyre may be the most relevant property but this cannot easily be identified in observations. | ||||||||
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