Seasonal and interannual studies of vortices in sea surface temperature data

An algorithm for calculating feature displacement velocities and for detecting vortices has been applied to 13 years of sea surface temperature data derived from Advanced Very High Resolution Radiometer (AVHRR) data. A unique global event database for seasonal and interannual studies of the spatial distribution of oceanic vortices was created for the years 1986-1998. The results indicate that (1) the number of vortices in each season is fairly constant from year to year in each hemisphere - however, their preferred locations change on seasonal to interannual time-scales; (2) the maximum number of vortices were detected in the summer and in the winter in all oceans and the minimum number were detected in the autumn; and ( 3) the distribution of the spatial density function shows preferred localizations such as 40degreesS, the tropical instability region, marginal seas, western boundary and eastern boundary current regimes.