Evidence of time-mean cyclonic cell southwest of Iberian Peninsula: The Mediterranean Outflow-driven β-plume?

Lamas L, Peliz A, Ambar I, Aguiar AB, Maximenko N, Teles-Machado A
Geophys.Res. Lett., 37, L12606, doi:10.1029/2010GL043339

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First observational evidence of time-mean cyclonic recirculation southwest of Iberia is presented. Data sets of hydrography, satellite altimetry and surface drifters velocities are analyzed jointly in order to obtain an accurate time-averaged circulation in the mid-latitude northeast Atlantic off the Gulf of Cadiz. A cyclonic recirculation cell with characteristics similar to those predicted by theoretical and modeling studies is detected in all computed velocity fields. The cell in the upper 1000-m layer exhibits transports of 3 to 4 Sv that are only slightly smaller than the model transports. The cell is centered at approximately 36N, 10W, is elongated zonally and extends to 15W westwards. Wind driven Sverdrup transport and β-plume dynamics are both suggested to play a role in the generation of the cyclonic cell, but the relative contribution of these effects is yet to be clarified. The core of the recirculation appears compact and the magnitude of the cell fades westwards much faster than predicted by the theoretical and modeling studies considered.