Radar remote sensing of the Earth surface is a relatively new and promising technology that can be used for continuous monitoring of oil spills in sea waters. Images made by using special radars installed on satellite platforms can cover areas of up to 500 km in swath and have resolution that allows to localize oil spills on the water surface.

Radar remote sensing of the Earth surface is a relatively new and promising technology that can be used for continuous monitoring of oil spills in sea waters. Images made by using special radars installed on satellite platforms can cover areas of up to 500 km in swath and have resolution that allows to localize oil spills on the water surface.

Radar data images appear to be highly suitable for monitoring oil spills in sea waters because the technology does not really depend on the weather or light conditions. It is known that an oil spill on the water surface forms a thin film, which due to oil properties looks on a radar image like a darker spot on brighter water surface.

At low wind speeds, between 0 and 2-3 m/s, the water surface looks quite dark on radar images. In this case, oil spills, which are also dark, cannot be effectively detected. Moderate wind speeds, between 3 and 9-11 m/s, are ideal for oil spills detection – spills can be seen as dark spots on light background. When the wind is stronger it becomes more difficult to detect spills as the sea is very unstable and oil is mixing with the water surface layer.

Usually the process of oil spills detection on a radar image begins with localization of “suspicious” areas. After that it is necessary to classify the detected areas. These can be oil spills, some spots of natural biological origin (like substances produced by living organisms, plankton etc) or just unpolluted water surface that looked somehow different from normal during sounding.

For the detection of an oil spill on a radar image it is important to take into account their typical characteristics:

• form – an oil spill usually has simple shape;
• edges – oil spills have smooth edges with higher gradient than for slicks of natural origin;
• size – usually very big slicks are of natural origin e.g. algae or plankton colonies;
• geographical location – obviously oil spills can be found mainly in areas of oil production or around oil transportation routes.

Using radar images it is possible to detect the following types of oil spills:

• crude oil;
• black oil, diesel etc;
• oil spills brought by river waters;
• technological waste waters from ships;
• oil leakages for gryphons on the sea bed.

More details about technologies of detecting oil spills can be found here.