Distribution of oil concentrations in the Gulf of Mexico estimated from the Connectivity Modeling System simulation of the Deepwater Horizon 2010 oil spill; with wind drift

The dataset contains the post-processed results of the 2010 Deepwater Horizon oil spill incident at Macondo well in the Gulf of Mexico, as estimated from the simulations using the latest updated version of the oil application of the Connectivity Modeling System (CMS) or oil-CMS. In this version, the specified hydrocarbon pseudo-components are in the same droplet. The post-processing analysis yielded 4-D spatiotemporal data of the daily oil concentrations on a regular horizontal and vertical grid for the 167-day simulation period. CMS has a Lagrangian, particle-tracking framework, computing particle evolution and transport in the ocean interior. CMS simulation start date: April 20, 2010, 0000 UTC, and particles were tracked for 167 days. Oil particles release location: 28.736N, 88.365W, depth is 1222m or 300m above the oil well. 3000 particles were released every 2 hours, for 87 days, equivalent to total of 3132000 oil particles released during the simulation. Initial particle sizes were determined at random by the CMS in the range of 1-500 micron. Each particle contained three (3) pseudo-components accounting for the differential oil density as follows: 10% of light oil with the density of 800kg/m^3, 75% of the oil with 840 kg/m^3, and 15% of a heavy oil with 950 kg/m^3 density. The half-life decay rates of oil fractions were 30 days, 40 days, and 180 days, respectively. Ocean hydrodynamic forcing for the CMS model was used from the HYbrid Coordinate Ocean Model (HYCOM) for the Gulf of Mexico region on a 0.04-deg. horizontal grid and 40 vertical levels from the surface to 5500m. It provided daily average 3-D momentum, temperature and salinity forcing fields to the CMS model. The surface wind drift was also accounted for as follows. Wind stress components were used from the 0.5-degree Navy Operational Global Atmospheric Prediction System (NOGAPS), and 3% of their values were added to the top level ocean velocity components, considering the wind stress rotation. The transport and evolution of the oil particles were tracked by the oil-CMS model during the 167 days of the simulation, recording each particle’s horizontal position, depth, diameter, and density into the model output every 2 hours. Model data need to be post-processed to obtain oil concentrations estimates. The post-processing algorithm took into the account the total amount of oil spilled during the 87-day incident as estimated from the reports (730000 tons), and the assumptions about the oil particle size distribution at the time of the release as estimated in the prior studies. The current dataset assumes the oil was not treated with the chemical dispersants, and the modal peak in initial particle distribution is between 50-70 micron. The data for the oil concentrations are daily average values in ppb units. Horizontal 0.01-degree grid covers the Gulf of Mexico (25N-30.75N, 84W-93W), and vertical grid extends from the surface to the depth of 2400m at 20m increments. Daily oil concentrations are also estimated for the following vertical layers: 0-1m, 1-20m, 20-50m, 50-200m, and 200-200m; a separate file is for the layer of 0-1m and for the 0-20m layer; a separate file for the 0-1m surface layer concentrations is also provided for a greater region extending east of the Florida Peninsula (79W). Post-processed NetCDF files were created using Matlab software package, v. R2014b, and used compression to keep file size small. Maximum compression, or ‘DeflateLevel’ = 9 was used in most of the files. Numerical simulations and post-processing were performed using a Pegasus supercomputer at the Center of Computational Science, University of Miami, during the period of 2016-2017.