SATELLITE DETECTION OF NATURAL FILMS ON THE OCEAN SURFACE

Natural films on the ocean surface influence air-sea fluxes of momentu m, heat and gas. It is therefore essential to be able to map the geogr aphical extent and variability of such films to determine the resultin g impact on the earth's climate system. Satellite based Synthetic Aper ture Radar (SAR) may prove very useful, and perhaps the only way, to q uantify global scale film distribution. In order to investigate the co mposition of natural film and its effect on radar return, in situ samp les of the surface microlayer were for the first time taken simultaneo usly with ERS-1 SAR coverage of the sea. Our results show that the fil m was enriched in organic composition and that the concentration of fa tty acids was generally one order of magnitude higher inside than outs ide natural film areas, resulting in a 6-17 dB decrease in radar backs catter.