Eddy cancellation of the Ekman cell in subtropical gyres

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 circ...

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Bibliographic Details
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
Description
Summary: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.

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