Microwave radiometer system for the detection of oil slicks

A major problem of radiometric sensors in the detection of oil spills on the sea is differentiating the oil spill from other objects on the water surface such as rough areas, areas with warm and cold streams, oil-water emulsions, areas with seaweed, etc. A procedure to convert antenna temperatures to brightness temperatures and then to the oil thickness is described. Generally, a calibration procedure at the start of each experiment is needed. In order to develop and test these procedures, a polarization method has been designed for remotely detecting an oil slick. This required building three radiometers operating in the millimeter-wave bands (W, W_a, k_u) as well as associated laboratory test equipment. Experimental results, obtained in the laboratory and in an outdoor test facility, conform well with theoretical computations using an air-oil-water stratified layer model. This new method of microwave radiometry by measuring its polarization contrasts at two orthogonal polarizations is a next step in the development of microwave sensors for detecting oil spills.