Remote Sensing of Oil Films in the Context of Global Changes

Abstract

Since the middle of the 20th century, during the global industrialization, crude oil has become a major source of energy, and the problem of oil spills in the sea has become a public concern. Spilled oil interacts with marine environments, causing damage to marine ecosystems and influencing the ocean-atmosphere interaction. The impact of accidental spills is catastrophic for coastal zones, and has far-reaching consequences, not realized or anticipated previously. Sea surface oil films play a significant role in important climate processes such as the exchange of momentum, heat and gas between the ocean and the atmosphere. However, nowadays there is no estimating method for determining how fully and how frequently the ocean is covered by oil films, even when slicks are imaged from space. Remote sensing is believed to offer an effective mean for accounting of the global impact of oil films, which could lead to an improvement of representing air-sea interactions in climate models. Among remote sensing techniques, spaceborne Synthetic Aperture Radar (SAR) is the primary remote sensor used for oil spill surveillance. Oil films floating on the sea surface are detectable by SARs, because they damp the short surface waves that are responsible for the radar backscattering. The European and Asian seas have been chosen as test basins to work out an oil spill mapping technology using SAR images, and these studies demonstrated the high potential of SAR-equipped satellites. An approach for oil spill mapping has been also developed. It is based on studies conducted within the analysis framework of a geographic information system (GIS). GIS-made oil spill maps can be a valuable source of information about oil spill distribution, statistics and sources. They allow scientists to identify the most polluted waters – an important step in development of monitoring scenario. Finally, a basis for the determination of volumes and extent of floating oil based on satellite remote sensing is provided. This paper reviews and discusses this problem in the context of global changes.