Eddies in the Red Sea as seen by Satellite SAR Imagery

Abstract

We present the results of our observations of mesoscale and sub-mesoscale eddies in the Red Sea based on Synthetic Aperture Radar (SAR) imagery. The dataset used includes about 500 Envisat Advanced SAR (ASAR) images obtained in 2006–2011 over the Red Sea. We found more than 1,000 sub-mesoscale eddies, which manifest in the SAR imagery both due to surfactant films (“black” eddies) and wave/current interactions (“white” eddies), depending on the local wind speed. Sub-mesoscale eddies in the Red Sea seem to be more innumerous than in other inner seas, presumably due to a relatively deep upper mixed layer in this basin. Moreover, more than 50 meso- and basin-scale eddies were found, whose rotation was mostly anti-cyclonic and whose diameters ranged up to approximately 200 km. Most of the basin-scale eddies were found between 21 and 24°N, which is in agreement with earlier observations and with numerical modeling.