Chemical and oil spill rapid response modelling in the Strait of Gibraltar–Alborán Sea

A numerical model that simulates the dispersion of contaminants, including oil spills, in the Strait of Gibraltar–Alborán Sea region has been developed. The hydrodynamic is solved in advance and includes a barotropic model for calculating tides and a reduced gravity model for the average circulation. Dispersion is calculated using particle-tracking methods. Turbulent diffusion and specific processes for contaminants (for instance decay, biodegradation or oil evaporation) are simulated by Monte Carlo techniques. Computed tide elevations and currents are in agreement with observations. Also, the reduced gravity model reproduces the main characteristics of the residual circulation in the area (namely the western Alborán gyre, WAG, and the coastal circulation mode). Some examples of dispersion calculations are given. The calculated transit time of contaminants over the Alborán Sea is in agreement with that obtained from float experiments. The model may be used to support the decision-making process after a pollutant release in the area.