Oil slick detectability along the range of large swath SAR images

The Normalized Radar Cross Section in SAR images depends on the incidence angle, on the wind intensity as well as on the angle between the radar beam and the wind direction; at incidence angles <; 20° the specular reflection is prevailing while at greater angles Bragg mechanism predominates. A surface slick damps short waves and its presence is revealed by dark spots on the image; the detectability of oil slicks is found not uniform along the range showing an increase in the center. The influence of the backscatter mechanisms due to specular reflection and Bragg mechanism on the oil slick detectability is discussed. We highlight the capability of SAR to detect oil slicks as a function of the position of the slick along the range, the dimension of the slick area as well as the wind vector deduced from SAR image itself.