Upwelling characteristics derived from satellite sea surface temperature data in the Gulf of Finland, Baltic Sea

The seven-year (2000-2006) satellite sea surface temperature (SST) data were examined to determine characteristics of coastal upwellings during the warm period of the year (June-September) in the Gulf of Finland. A total of 20 sufficiently cloud-free SST images depicting well-expressed coastal upwelling were found. The area covered by upwelling water, the temperature difference between the upwelling and surrounding waters, and the location and area of filaments were estimated. The average area covered by the upwelling water was 4820 kM(2) and for the largest upwelling event 12 140 kM(2), i.e. 38% of the Gulf surface area. The average upwelling area along the Finnish coast (6120 km(2)) was larger than the upwelling area along the Estonian coast (4070 kM(2)) which likely results from a larger cumulative wind stress (the product of wind stress and its duration) of westerly winds during the observed upwellings. The detected upwelling filaments were predominantly related to an upwelling along the Finnish coast. The area of a single filament usually varied from 80 to 680 kM(2) while the total area of filaments reached the maximal value of 1420 kM(2) during the strongest upwelling event.