The dispersion of passive tracers in marine environment: a case study of the Tyrrhenian Sea

The Tyrrhenian Sea is one of the most anthropized sub-basin of the Mediterranean Sea and this fact poses a challenge to authorities in charge of managing the marine environment. To cope with this question, the coupling of the ocean model POM (Princeton Ocean Model) with the Lagrangian dispersion model LASEMOD (LAgrangian SEa MODel) is addressed to investigate the temporal and spatial evolution of a passive pollutant released in the vicinity of the Latial coast. It is worth to note that the above LASEMOD has been developed by the authors. The POM is a three-dimensional, free surface, sigma coordinate, primitive equation ocean model which includes a turbulence sub-model. The LASEMOD is a first-order autoregressive model for the particle velocities. Such a model is based on the so called “well-mixed” condition (Thomson, 1987) and takes into account the integral time scale of the turbulence. This implies that dispersion is correctly resolved in the vicinity of the release and that, coherently with the theory, a full mixing is achieved at long travel times. The simulation shows with reasonably accuracy the time evolution of both the hydrodynamic and the concentration fields and provides a useful insight into the evaluation of the environmental impact of pollutant releases along the coast.