THE EFFECT OF WINDSPEED ON SEA-SURFACE TEMPERATURE RETRIEVAL FROM SPACE

The effect of windspeed on water emissivity, whilst being negligible around normal incidence, becomes significant above angles of about 50-degrees. We calculate the effect of windspeed On retrieved sea surface temperature and show that errors become significant for the potentially very accurate Along Track Scanning Radiometer (ATSR, carried on board ESA's first remote sensing satellite, ERS-1) since brightness temperatures measured at almost-equal-to 56-degrees, as well as those measured at nadir, are used to provide improved atmospheric correction. We show that when an SST retrieval algorithm generated assuming zero windspeed is applied to brightness temperatures calculated for windspeeds of 5, 10 and 15 m/s, a potential error of up to 0.4 K is introduced. Since coincident windspeed data can be obtained from the ERS-1 radar altimeter, accurate correction can be made for this effect and we Provide a Preliminary algorithm for the correction of ATSR SST data.