Oil pollution monitoring: An integrated approach

Oil pollution on the ocean has been highlighted in the past 40 years by several tanker accidents in Europe, like those of Exxon Valdez, Erika or Prestige. But these oil tanker accidents only account for a few percent of the total oil pollution worldwide and hide the regular pollution in important traffic zones like the Mediterranean and other oceans caused by oil drillings or illegal discharges. Due to very regular acquisitions from imaging radar on board satellites since the beginning of the 90's, statistical information about slicks is available all over the world oceans. From the first SAR satellites dedicated to research (ERS series, RadarSat-1) via European Envisat, TerraSAR-X, Cosmo Skymed or Canadian RadarSat-2 to the new European Sentinel series (namely Sentinel 1A, 1B and possibly 1C in the future) oriented towards services and applications, the expertise from the R&D community allows a much better oil spill monitoring nowadays. Oil spills appear as a dark patch on the SAR image. Nevertheless, detecting oil slicks and oil spills remains difficult, as other phenomena are also modifying the sea surface conditions: wind, sea state, currents, ... In order to go beyond oil spill detection and tracking and for setting an efficient prevention system, one must also detect and identify the ships responsible of the oil discharges. For that purpose, synergetic approaches have been used, mixing the radar imaging inputs with met information and mandatory ship identification systems (AIS - Automatic Identification System) mainly. This effort is quite important as the vast majority of these pollutions occur near the coastal zones where 80% of the world population lives.