Remote Sensing of African CoastalWaters Using Active Microwaves Instrument

Abstract

Active microwave instruments flown on satellites to remotely sense the ocean are the radar altimeter, the scatterometer, and the Synthetic Aperture Radar (SAR). While radar altimeter data are mainly used as input for general ocean circulation models and for wind and global wave forecast, scatterometer and SAR data are well suited to investigate singular events in the marine boundary layer and in the ocean. Examples of atmospheric and oceanic phenomena observed by scatterometers and SARs over African coastal waters are presented. Concerning atmospheric phenomena, first near-surface wind fields derived from scatterometer data acquired over a cylone in the Mozambique Channel and over a wind front west of Morocco are presented. Then SAR images showing sea surface signatures of an atmospheric front, atmospheric gravity waves and a wind jet are presented. Quantitative information on the near-surface wind field is derived from two of the four SAR images shown. Concerning oceanic phenomena, three SAR images are presented. The first two SAR images show sea surface signatures of internal waves generated in the Strait of Gibraltar and at the Atlantic shelf west of Morocco and the third one shows sea surface signatures of biogenic surface films in the upwelling region off the coast of Senegal.