Remote sensing methods for measuring the thickness of oil/oil product films on the sea surface

Abstract

Surfactant films on the sea surface are an indicator of the processes representing the environmental threat to water bodies and coastal areas. In particular, oil spilling from accidents with oil platforms, tankers and vessel bunkering operations is of great concern. For quantitative assessment of possible damage and development of measures to prevent a catastrophe, it is necessary to get information about the volume of pollutants. It can be estimated through the polluted area and the surface film thickness. Modern tools for the water surface remote sensing allow one to detect surface contaminants, to obtain information about the area of contamination, and to monitor surface pollutions. However, the film thickness estimation with sufficient accuracy is still a problem to be solved. This review describes in detail the capabilities of assessment of film thickness using remote sensing methods and instruments with an indication of their applicability limitations. Contemporary passive and active methods including optical, radio and acoustic ones, as well as their combinations are analyzed. In addition to traditional approaches to the film thicknesses estimation, such as visual observations, spectral reflectance, NIR and thermal imaging, laser fluorescence and laser-ultrasonic sensing, microwave radiometry and radar imaging, the review also provides information on developing new optoacoustic methods which are supposed to be very efficient.