MOTHY (Modèle Océanique de Transport d'Hydrocarbures) is a pollutant drift model, developed and operated by Météo-France. MOTHY includes hydrodynamic coastal ocean modelling and real time atmospheric forcing from a global meteorological model. Pollutants can be oil or floating objects. To improve forecasts on the Mediterranean Sea, several methods were tested to inject large scale currents (permanent part) into the MOTHY system. The best results were obtained with monthly means of currents at 5 meters (from Mercator system). The addition of altimetric corrections improved the results. In addition the impact of wave (or swell) current, which is usually neglected in such models, is investigated. The literature has surprisingly little to say on the topic of wave-driven surface oil slicks. Earlier review on oil spill transport modelling includes wave driven transport among potential advection mechanisms. The discussion of wave-induced advection (mass transport) adopts a Lagrangian framework, focusing on the analyses of Stokes and Longuet-Higgins for the vertical profile of the Lagrangian velocity beneath waves. In our work, the action of a vertical shear due to waves is accounted for by including the Stokes drift due to weakly non linear waves. We evaluate this term and compare with observations of Erika pollution incident.

This content is only available as a PDF.