Remote sensing of sea surface temperature and chlorophyll during Lagrangian experiments at the Iberian margin

Satellite derived sea surface temperature (SST) and chlorophyll data are used to characterise the period of upwelling during a cruise on which two Lagrangian drift experiments were conducted off the Iberian Atlantic coast in August 1998. During the cruise there was a prolonged period of equator-ward winds which favour upwelling; three distinct maxima were observed in the meteorological data interspersed with periods of relaxation. The SST and chlorophyll imagery show upwelling to be active with distinct offshore filaments that are cooler and of higher chlorophyll concentration than the surrounding oceanic water; these filaments represent an important cross-shelf transport mechanism. A front detection methodology has been applied to satellite images and suggests that these filaments are distinct, long-lived features, characterised by enhanced primary production.