KASILINGAM, D., and O. SHEMDIN, Ocean Research & Engineering, Pasadena, CA

ABSTRACT: Use of Polarimetric Radar Measurements to Estimate the Thickness of Oil Slicks

Since oil slicks damp out the short-scale roughness of the ocean surface, radar measurements of these areas can be used to detect and monitor oil spills. However, obtaining quantitative information about these spills have been very difficult. In the past, investigators have used an absolute measure of the damping to try and quantify the oil thickness. This scheme has had only limited success.

In the LOGAN:CLT experiment, radar measurements of oil slicks are made at different radar frequencies and polarizations. Measurements are made at P-band, L-band, C-band, and X-band. At these different frequencies, the radar signatures of the slicks are measured for both horizontal and vertical polarization. The relative magnitudes of the H-pol and V-pol signatures for the oil slick are found to be different from the relative magnitudes of the respective signatures in the uncontaminated area. Even though the damping effect is the same in both polarizations, the presence of the slick has varying effects on the scattering coefficients for H-pol and V-pol. This results in the difference in the relative magnitudes of their signatures. The change in the relative magnitudes is a function of he dielectric properties of the slick and the slick thickness. Hence, if the dielectric properties are known, then the ratio of H-pol to V-pol can be used to estimate the thickness of the slicks. Measurements from the LOGAN:CLT experiment at all four radar frequencies were used to estimate the thickness of sample oil slicks. As expected, the X-band measurements are more sensitive to the thickness than are the lower frequencies. Depending on the dielectric properties of the oil, thickness down to 1 mm can be measured using X-band radar measurements.

AAPG Search and Discovery Article #90992©1993 AAPG Pacific Section Meeting, Long Beach, California, May 5-7, 1993.