On Radar Signatures of Upwelling

Abstract

In studies of upwelling, usually data from infrared and optical sensors is used which provides information on the sea surface temperature (SST) and the chlorophyll-a (Chl-a) concentration. In this paper, we show that also synthetic aperture radars (SAR) images can give valuable contribution to such studies. Upwelling regions become detectable by SAR because they are associated with a reduction of the radar backscatter due to ① the change of the stability of the air-sea interface or/and ② the presence of biogenic slicks. Furthermore, the boundary of upwelling regions consists of a line of increased radar backscatter due to the presence of convergent surface flow.

Keywords

• |upwelling|synthetic aperture radar|cyclonic eddies|agulhas return current|biogenic surface films|chlorophyll concentration|air-sea interface|sea surface temperature