Lagrangian stochastic modelling for oil spills turbulent dispersion on ocean surface

Abstract

Releases of liquid petroleum hydrocarbon into the environment, especially into the ocean, are called {\em oil spills}. To correctly model dispersion on ocean surface both large and small scale processes must be considered. In fact, the motion of the centre of mass is driven by large scale meandering and spot enlarging is controlled by small scale turbulence. A Lagrangian stochastic model for turbulent dispersion of oil spills on ocean surface is here formulated: large scale meandering is analytically prescribed by the stream function proposed by Bower for meandering jet in the Gulf Stream; small scale turbulence has been modelled by a Lagrangian stochastic process for turbulent relative dispersion which is based on turbulent flow rotation. Numerical simulations are performed to highlight the effects on oil spills dispersion of differences in the velocity field intensity and those due to releases in the centre or in the boundary of a meandering jet.