Abstract:

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. Use constraints: We request that you acknowledge the Northern Gulf Institute as the source of this information. Mississippi State University makes no warranty regarding these data, expressed or implied, nor does the distribution constitute such a warranty. Mississippi State University can not assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.

Suggested Citation:

Fitzpatrick, Patrick, and Yee Lau. 2014. Lagrangian particle tracker with random walk diffusion simulation: Oil concentration of the Deepwater Horizon oil spill from June 21 to July 11, 2010. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N76H4FDQ

Publications:

Zaron, E. D., Fitzpatrick, P. J., Cross, S. L., Harding, J. M., Bub, F. L., Wiggert, J. D., … Mooers, C. N. K. (2015). Initial evaluations of a Gulf of Mexico/Caribbean ocean forecast system in the context of the Deepwater Horizon disaster. Front. Earth Sci., 9(4), 605–636. doi:10.1007/s11707-014-0508-x

Purpose:

The Deepwater Horizon oil spill impacted the Mississippi River Delta, Barataria Bay, the barrier islands east of Louisiana, and the Alabama and Florida coast for an extended period of time from May through July. However, the Rigolets and western Mississippi coast were impacted for a briefer period from late June to early July. An important component to understanding the oil transport is to distinguish the influences behind this apex moment. A simulation was conducted for the period June 21 to July 11, 2010 to understand this inland transport.

Data Parameters and Units:

wmv movie of oil concentration in the Northern Gulf of Mexico. txt files with latitude (decimal degrees), longitude (decimal degrees), oil concentration in the water (percentage with values from 0 to 1). 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. NASA MODIS satellite imagery, SAR imagery from http://www.cstars.miami.edu (login now required, contact University of Miami for detail) ; Archived NOAA oil trajectory maps at http://www.noaa.gov/deepwaterhorizon/maps/index.html ; Current and archived NCOM AMSEAS data from http://edac-dap3.northerngulfinstitute.org/thredds/catalog/AmSeas/catalog.html

Individual Files: