On the detectability of marine oil pollution in European marginal waters by means of ERS SAR imagery

We have analyzed more than 700 ERS SAR images of European marginal waters (acquired between December 1996 and November 1998 over the Baltic Sea, the North Sea, and the northwestern Mediterranean Sea) with respect to the detectability of marine oil pollution. By taking into account mean surface winds we define the "normalized visibility" of marine oil pollution, i.e., the dependence of the oil spill detectability on wind speed. The normalized visibility, therefore, is a quantitative estimate of the usefulness of satellite-borne SAR techniques for oil spill monitoring, and it enables us to show that the Baltic Proper, even though less pollution has been detected by the ERS SAR, is likely to be as polluted as the northwestern Mediterranean Sea. Finally, we compare the results of the analysis of SAR images from the Baltic Sea with pollution data provided by local oil surveillance authorities. We use surveillance data from oil spills detected by both satellite-borne and airborne sensors to get more information on the life time of such oil spills. Again, this comparison helps to better describe the efficiency of the ERS SAR for oil spill monitoring.