Abstract:

The dataset contains the numerical results of alternative scenarios of oil spills similar to the Deepwater Horizon (DWH) in 2010. Two scenarios of alternative locations - the east (27.0N, 85.168W) and the west (26.66N, 93.19W) Gulf of Mexico - were run 2010-04-20 to 2010-07-17. The third scenario is run at the DWH location for 2010-09-01 to 2010-11-28. Oil dispersal and concentrations were simulated using the updated oil application of the Connectivity Modeling System (oil-CMS). Post-processing analysis yielded 4-D spatiotemporal data on a 0.02-degree regular horizontal grid. Daily-averaged oil concentrations are provided for a 1-m deep surface layer and 125 20-m thick layers extending to 2500m; the summed oil mass within a layer is provided for 125 20-m thick layers extending to 2500m on a two-hour interval. CMS has a Lagrangian, particle-tracking framework, computing particle evolution and transport in the ocean interior. 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 parameterization used surface winds and wind stressed from the 0.5-degree Navy Operational Global Atmospheric Prediction System (NOGAPS). 3000 particles were released every 2 hours for 87 days, for a total of 3,132,000 oil particles. The depth of release was 1222 m or 300m above the oil well. Initial particle sizes were determined at random by the CMS in the range of 1-500 micron, with a model peak between 50-70 microns, consistent with oil left untreated by dispersants. Each particle contained three (3) pseudo-components accounting for the differential oil density as follows: 10% light oil of density of 800kg/m^3, 75% oil with a density of 840 kg/m^3, and 15% heavy oil of 950 kg/m^3 density. The half-life decay rates of oil fractions were 30 days, 40 days, and 180 days, respectively. The surface evaporation half-life was set to 250 hours; horizontal diffusion was set to 10 m^2/s in the present case. The transport and evolution of the oil particles were tracked by the oil-CMS model during the 90 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. A hindcast of the DWH spill can be downloaded in the related dataset available under GRIIDC Unique Dataset Identifier (UDI): R4.x267.000:0084 (DOI: 10.7266/N7KD1WDB).

Suggested Citation:

Claire B. Paris, Natalie Perlin. 2020. Daily hindcast of oil concentrations estimates from the far-field modeling of deep water spill scenarios in the east and the west Gulf of Mexico, and a spill occurring during the Fall using the oil application of Connectivity Modeling System (oil-CMS).. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/HDC8HS51

Purpose:

Simulation of the effects of alternative locations and seasonal forcing on the Deepwater Horizon blowout.

Data Parameters and Units:

0-1 m cases: Time (days after the blowout, [days]), Latitude (center of grid cell, [degrees north]), Longitude (center of grid cell, [degrees east]), zlevs_bnd (vertical layer boundaries, [m]), zlevs (mid-depth of the vertical layers, [m]), depth (Bathymetric depth, [m]), oil_conc (oil concentration, [ppb]). 2500 m cases: Time (days after the blowout, [days]), Latitude (center of grid cell, [degrees north]), Longitude (center of grid cell, [degrees east]), zbound (vertical layer boundaries, [m]), depth (Bathymetric depth, [m]), oil_conc (oil concentration, [ppb]). Oil mass cases: Time (seconds elapsed after blowout, [s]), Latlim (latitudinal extent of area, [degrees N]), Lonlim (longitudinal extent of area, [degrees E]), zlevs_bnd (vertical layer boundaries, [m]), zlevs (mid-depth of the vertical layers, [m]), oil_mass (area-cumulative mass of oil in a vertical layer [kg]).

Methods:

Many of the files are compressed with the option “DeflateLevel=9” (maximum compression), for space-storage reasons, and may need the NetCDF version higher than 4.2.1.1 to view it. Python or Matlab could be used to read these files.

Individual Files: