Oil spill detection with Synthetic Aperture Radar (SAR)

November 25, 2019 -- Marine pollution is a great and very troublesome problem and can be directly or indirectly by man made source giving energy or substance to the marine environment. The biggest source of this effect is oil, which penetrates the marine environment by several inputs. This phenomenon must be urgently detected, identified and solved. Remote sensing is a scientific domain that can give solutions for this crucial problem. More precisely SAR is a remarkable sensor of remote sensing that seems to be a compulsory and effective choice. A couple of other sensors can complement to SAR observation and make it more reliable. However a coin has two sides and SAR has limitations and challenges in oil spill monitoring that must be brought to completion.

Vessels are commonly used if they are equipped with specialized radars, which can detect oil at sea but they can cover a very limited area. However vessels are quite necessary in case oil sampling is required. Moreover the main systems to monitor sea’s oil pollution are the airplanes and satellites equipped with remote sensing devices. Remote sensing devices that are available for oil spill detection include infrared video and photography, thermal infrared imaging, airborne laser fluorosensors, airborne and spaceborne optical sensors and airborne and spaceborne Synthetic Aperture Radar (SAR). Generally remote sensing sensors can help to identify minor spills before they cause widespread damage. In different cases and size of accidents different systems-sensors are used. For example in larger accidents, satellite remote sensing is an excellent way to get an overview of the oil spill expansion and follow its development.

Thus there are crucial factors that must be taken seriously into consideration as mentioned above, such as size of accident, different weather conditions and cost. Sensors should be operational both in day and night in order to constitute an effective surveillance system. Oil spill monitoring is necessary at any time so sensors should have the capability to operate the night. Optical i.e. UV (ultraviolet) sensors for example, cannot work during the night and the effect of the weather conditions such, as rain, fog and clouds should be limited. Radar sensors are the best sensors for oil spill surveillance in adverse weather conditions. Also airborne surveillance is limited by the high costs and is less efficient for wide area surveillance due to its limited coverage.

While spaceborne SAR can be used for a first warning and aircrafts are suitable to be brought into action to identify the polluter, the extent and the type of spill[3]. In this regard, the main systems to detect and identify sea-based oil pollution are the use of airplanes and satellites equipped with Synthetic Aperture Radar (SAR) sensors, which have proven from several surveys to be the most effective and valuable tools and that renders them as a compulsory choice.