Deepwater Horizon Oil Spill Simulation from May 26 to July 31, 2010, Northern Gulf Institute, MSU, MS

The simulation is based on a Lagrangian particle tracker with random walk diffusion model. Input consists of latitude and longitude positions of parcels in the oil contaminated area, wind, current, and a large array of random numbers. In addition, new parcels are released at the location of the damaged Macondo rig. Twenty-five parcels are released at each position, and when combined with the diffusion coefficient (set to 10m2/s) results in a natural spread of the parcels with time. The parcel location is based on NASA MODIS satellite imagery, SAR imagery and NOAA oil trajectory maps. The parcels are advected at 80% of the ocean current speed and at 3% of the wind speed. Bilinear interpolation is applied at each timestep to determine the currents and winds at each parcel position. The pseudo-random numbers are uniformly distributed between 0 and 1 and generated by the efficient Mersenne Twister algorithm. The 10-m wind and near-surface ocean currents are provided from an operational, data assimilating forecast system run by the Naval Oceanographic Office called the Navy Coastal Ocean Model (NCOM) in the Intra-Americas Sea domain which covers the Gulf of Mexico and the Caribbean, interpolated to a 3-km Cartesian grid. NCOM assimilates water temperature, salinity analyses, and satellite altimeter data, and the Coupled Ocean-Atmosphere Prediction System (COAMPS) provides the atmospheric forcing. An examination of NCOM data and the oil spill simulation, as well as in-situ data from buoys, weather reanalysis maps, tide gauge data, scatterometer data, and HF radar show that two weather systems altered the currents and water levels such that oil was pushed into the western Mississippi Sound and the Rigolets. An easterly wind fetch from intensifying Hurricane Alex provided the first inland push, followed by a westward-drifting non-tropical low which had formed off the western edge of a Gulf cold front. In both cases, a generally weak pressure gradient was replaced by strong easterly winds which not only switched westerly coastal currents to an easterly direction, but also increased inland water levels by 0.6-0.8 m. These results show that cyclones located west of the oil spill can dramatically alter oil transport. We request that you acknowledge the Northern Gulf Institute as the source of this information.