Gulf Stream thermal fronts detected by synthetic aperture radar

Abstract

Our purpose is to detect ocean surface features, specifically oceanic thermal fronts, through analysis of SAR (synthetic aperture radar)‐derived wind stress fields. Fine‐resolution measurements of near‐surface wind speeds over the Gulf Stream region of the Northwest Atlantic were made using SAR images collected by RADARSAT‐2. Linear statistical relationships between the wind stress curl and divergence to the crosswind and downwind components of the SST gradient field were used to derive a new method for detecting Gulf Stream thermal fronts from Synthetic Aperture Radar (SAR) imagery. In particular, sea surface temperature front features, as suggested by corresponding AVHRR and MODIS images, are evident in both of the wind stress curl and divergence fields. The importance of this methodology is that clouds are often present in the Northwest Atlantic in autumn and winter months and they obscure AVHRR and MODIS images, whereas SAR can penetrate clouds.