The wake of the Canary Islands viewed by SAR

Abstract

The mountainous islands of the Canaries archipelago represent obstacles to both the Trade winds and the Canary Current flowing equatorward past them. Oceanic eddies, cyclonic and anticyclonic, have been observed frequently downstream of the islands, and the existence of a lee region of weak winds behind the islands is well known. On occasion, recirculating trapped wind eddies appear to be formed downflow of Gran Canaria in particular. In situ observations of hydrographic properties and surface winds downstream of the island, together with AVHRR imagery and SAR frames during a period of two weeks in summer 1995 are analysed. A clear signal is evident in the SAR data coincident with the zone of strongest wind shear on either side of the lee region. The relation to the characteristic stratified, war surface layer region in the lee and the cooler, well-mixed surface layer in the area exposed to the Trades is discussed.