Eddy-induced cross-shelf export of high Chl-a coastal waters in the SE Bay of Biscay

Anna Rubio, Ainhoa Caballero, Alejandro Orfila, Ismael Hernández-Carrasco, Luis Ferrer, Manuel González, Lohitzune Solabarrieta, Julien Mader

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Different remote sensing data were combined to characterise a winter anticyclonic eddy in the southeastern Bay of Biscay and to infer its effects on cross-shelf exchanges, in a period when typical along shelf-slope currents depict a cyclonic pattern. While the joint analysis of available satellite data (infrared, visible and altimetry) permitted the characterisation and tracking of the anticyclone properties and path, data from a coastal high-frequency radar system enabled a quantitative analysis of the surface cross-shelf transports associated with this anticyclone. The warm core anticyclone had a diameter of around 50km, maximum azimuthal velocities near 50cms−1 and a relative vorticity of up to −0.45f. The eddy generation occurred after the relaxation of a cyclonic wind-driven current regime over the shelf-slope; then, the eddy remained stationary for several weeks until it started to drift northwards along the shelf break. The surface signature of this eddy was observed by means of high-frequency radar data for 20 consecutive days, providing a unique opportunity to characterise and quantify, from a Lagrangian perspective, the associated transport and its effect on the Chl-a surface distribution. We observed the presence of mesoscale structures with similar characteristics in the area during different winters within the period 2011–2014. Our results suggest that the eddy-induced recurrent cross-shelf export is an effective mechanism for the expansion of coastal productive waters into the adjacent oligotrophic ocean basin.
Original languageEnglish (US)
Pages (from-to)290-304
Number of pages15
JournalRemote Sensing of Environment
Volume205
DOIs
StatePublished - Dec 8 2017

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