GEOSTROPHIC SURFACE CURRENTS AS DERIVED FROM SATELLITE SST IMAGES AND MEASURED BY A LAND-BASED HF RADAR

Sea-surface temperatures (SST), as observed from a space-borne radiometer (AVHRR), are related to surface currents as measured by the high-frequency coastal radar (CODAR) in Norwegian coastal waters. Both systems yield about the same spatial resolution of the order of 1km. Introducing a number of simplifying assumptions, the geostrophic portion of surface currents is derived from the SST distribution and compared with the CODAR measurements. In areas, characterised by strong temperature gradients, good agreement is found for current velocity and also for relative vorticity.