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

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 36°N, 10°W, is elongated zonally and extends to 15°W 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.

[1]  D. Chambers,et al.  Mean Dynamic Topography of the Ocean Derived from Satellite and Drifting Buoy Data Using Three Different Techniques , 2009 .

[2]  P. Marchesiello,et al.  Surface circulation in the Gulf of Cadiz: 2. Inflow‐outflow coupling and the Gulf of Cadiz slope current , 2009 .

[3]  J. Price,et al.  The Upper-Oceanic Response to Overflows: A Mechanism for the Azores Current , 2008 .

[4]  P. Marchesiello,et al.  Surface circulation in the Gulf of Cadiz: Model and mean flow structure , 2007 .

[5]  S. Kida Overflows and upper ocean interaction : a mechanism for the Azores Current , 2006 .

[6]  R. Pingree,et al.  Ocean structure and climate (Eastern North Atlantic): in situ measurement and remote sensing (altimeter) , 2002, Journal of the Marine Biological Association of the United Kingdom.

[7]  E. Chassignet,et al.  On the Connection between the Mediterranean Outflow and the Azores Current , 2001 .

[8]  Yanli Jia Formation of an Azores Current Due to Mediterranean Overflow in a Modeling Study of the North Atlantic , 2000 .

[9]  H. Hurlburt,et al.  Modeled Sverdrup flow in the North Atlantic from 11 different wind stress climatologies , 2000 .

[10]  M. Iorga,et al.  Signatures of the Mediterranean outflow from a North Atlantic climatology 1. Salinity and density fields , 1999 .

[11]  Bablu Sinha,et al.  Position and structure of the Subtropical/Azores Front region from combined Lagrangian and remote sensing (IR/altimeter/SeaWiFS) measurements , 1999, Journal of the Marine Biological Association of the United Kingdom.

[12]  R. Pingree The Eastern Subtropical Gyre (North Atlantic): Flow Rings Recirculations Structure and Subduction , 1997, Journal of the Marine Biological Association of the United Kingdom.

[13]  M. Arhan,et al.  The Eastern Boundary of the Subtropical North Atlantic , 1994 .

[14]  R. Pingree,et al.  A shallow meddy (a smeddy) from the secondary Mediterranean salinity maximum , 1993 .

[15]  T. Müller,et al.  Some observations of the Azores Current and the North Equatorial Current , 1989 .

[16]  P. Richardson,et al.  A quasi‐synoptic survey of the thermocline circulation and water mass distribution within the Canary Basin , 1986 .

[17]  P. Marchesiello,et al.  Filament generation off the Strait of Gibraltar in response to Gap winds , 2009 .

[18]  Fabienne Gaillard,et al.  Circulation patterns and transport of the Azores Front-Current system , 2002 .