An operational model for oil spill and Search and Rescue Operations is presented. The model constructs a daily database of velocity predictions provided by an Operational Forecasting System and integrates the Eulerian velocities to obtain the trajectory forward in time adding a random walk term to simulate the diffusion.
The model computes the probability density function from a set of particles giving the areas of accumulated probability. Several tests are performed in order to determine the optimal numerical scheme as well as the internal computational time step. Diffusion is assessed by computing the distance between the trajectories of particles computed from model forecast and model reanalysis velocities. A total of 8 months of daily diffusion fields are averaged to get a constant in time and variable in space diffusion in the Western Mediterranean. The model is tested against the trajectory of three SVP drifters deployed in the Balearic Sea. For these experiments, the position of the drifters laid within the curve of the 50% of accumulated probability for the 24h forecast. For a 72h forecast the drifters fall, in the worse cases, within the contour of 90% of accumulated probability. The areas corresponding to 70% and 90% of accumulated probability are similar in shape and magnitude.
An operational system for oil spill tracking in the probability domain. Application to the Western Mediterranean SeaDownload
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