Seasonal probability dispersion maps in the Mediterranean Sea obtained from the Mediterranean Forecasting System Eulerian velocity fields

Abstract

This paper presents a method to build seasonal probability dispersion maps from numerical Lagrangian trajectories as well as a user-friendly web site containing the results. The main aim is to provide useful tools for the description of dispersion properties at the Mediterranean Sea surface. Trajectories were obtained integrating with an off-line Lagrangian algorithm the Eulerian velocity fields, from January 2000 to December 2004, provided by the ocean general circulation model Modular Ocean Model used in the Mediterranean Forecasting System project. The statistics of dispersion properties over the entire surface of the Mediterranean Sea is calculated from the time evolution of "clusters" of numerical particles released in nonoverlapping grid boxes. Some examples of seasonal probability dispersion maps taken from the web site are shown and discussed. The results are checked against drifters of the Mediterranean Surface Drifter Database (1986-1999) by comparing the statistics of numerical and observed trajectories. The validation shows both deficiencies and skills of the methodology proposed for estimating Lagrangian dispersion variability. It also gives a starting point for discussion about future developments and improvements. Copyright 2007 by the American Geophysical Union.