DISPERSION OF PASSIVE TRACERS IN MODEL FLOWS - EFFECTS OF THE PARAMETRIZATION OF SMALL-SCALE PROCESSES

A set of numerical experiments is presented, in which we study the dyn amics of passive particles advected by given two-dimensional velocity fields and perturbed by a non-white noise with a characteristic time t au. Data and model results have shown that this kind of random perturb ation is able to represent subgridscale processes for upper ocean meso scale turbulence for regions of the world ocean where turbulence can b e assumed to be homogeneous. Extensive computations in different field s characterized by cell-like structure, both stationary and time-depen dent, representing very idealized geophysical flow situations, show th at the presence of a finite correlation time scale does lead to enhanc ed or arrested dispersion, depending on the considered flow; however, it does not seem to affect the gross qualitative behaviour of the disp ersion processes, which is primarily affected by the large-scale veloc ity field.