Forecasting the Prestige oil spills

On November 13 th 2002 the tanker Prestige was off the coast of Galicia, Spain, when it suffered severe structural failure of the starboard cargo tanks. The ship was tugged away from the coast. On November 19 th , the vessel broke into two sections at about one hundred and thirty miles from the Galicia coast. The two parts of the wreck sank at a 3500 meters depth. More than 60,000 tons of heavy fuel were released into the marine environment. At sea containment and recovery, and aerial surveillance of the oil, were hampered by the weather and the oil remained at sea for a considerable period of time. Diffuse pollution was still reaching the coastline more than six months after the break. In France, a technical committee gathering experts of Cedre, Meteo-France, IFREMER and SHOM was implemented. The drifting committee was in charge to provide daily the Prefet Maritime with coherent and relevant elements on the drift of the oil, both observations and forecasts. Thus, the oil spill drift model MOTHY has been used routinely for several months. The paper presents the organization of the forecasts, the new implemented tools such as probabilistic forecasts and long range hindcasts, and an evaluation of the relative influence of the components of the current (wind, tide, wave, large scale).