Eddy cancellation of the Ekman cell in subtropical gyres

• Published in: Journal of Physical Oceanography
• Main Authors: Doddridge, EW, Marshall, DP, McC Hogg, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Meteorological Soc 2016
• Subjects: Earth Sciences; Oceanography; Physical oceanography; Curl; Deacon; Southern Ocean
• Online Access: https://doi.org/10.1175/JPO-D-16-0097.1; http://ecite.utas.edu.au/150152

The presence of large-scale Ekman pumping associated with the climatological wind stress curl is the textbook explanation for low biological activity in the subtropical gyres. Using an idealized, eddy-resolving model, it is shown that Eulerian-mean Ekman pumping may be opposed by an eddy-driven circulation, analogous to the way in which the atmospheric Ferrel cell and the Southern Ocean Deacon cell are opposed by eddy-driven circulations. Lagrangian particle tracking, potential vorticity fluxes, and depthdensity streamfunctions are used to show that, in the model, the rectified effect of eddies acts to largely cancel the Eulerian-mean Ekman downwelling. To distinguish this effect from eddy compensation, it is proposed that the suppression of Eulerian-mean downwelling by eddies be called eddy cancellation.