Satellite observations of mesoscale ocean features and copropagating atmospheric surface fields in the tropical belt

Recent studies of air-sea interaction using satellite data have shown a high positive correlation between wind speed and sea surface temperature (SST) over mesoscale ocean features in certain frontal regions. The aim of this study is to determine to what extent mesoscale ocean dynamics modifies the surface wind speed over the global tropics between 40degreesS and 40degreesN. Cross-spectral and linear regression methods are used to identify robust relationships between ocean and atmospheric variables. The ocean dynamical features, measured by their sea surface height anomaly (SSHA), affect SST in a manner consistent with advection of the mean temperature gradient by anomalous currents. The response varies from 0.2 degreesC of SST per cm of SSHA near the equator to 0.05 degreesC cm(-1) at higher latitudes. A remarkably consistent in-phase relationship between SST and wind speed is found over the complete domain. Wind speed response varied from 0.5 to 1.5 ms(-1) per degreesC of SST change. This in-phase response of wind speed is consistent with previous studies suggesting that the SST variations cause changes in the vertical exchange of momentum and in the pressure gradient, which alter the wind speed.