Abstract:

New parameterizations for physical processes that are related to the vertical transport of oil spills are implemented into the open source trajectory framework OpenDrift. These encompass the wave-entrainment of oil, two alternative formulations for the droplet size spectra, and turbulent mixing. The performance of the integrated oil spill model is evaluated by comparing model simulations with airborne observations of an oil slick. The results show that an accurate description of a chain of physical processes – in particular vertical mixing and oil weathering – is needed to represent the horizontal spreading of the oil spill. Using ensemble of simulations of a hypothetic oil spill, the general drift behavior of an oil spill is discussed. Vertical mixing of oil between the surface slick and entrained oil is identified as a crucial component for the horizontal transport of oil spills, and to explain the differences for drift of various oil types.

Suggested Citation:

Johannes Röhrs, Knut-Frode Dagestad, Helene Asbjørnsen, Tor Nordam and Jørgen Skancke. 2018. The effects of vertical mixing on the transport of oil spills using the OpenDrift ocean trajectory model with ROMS/NorKyst800 forcing from May 5-11, 2011. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7ZW1JHS

Purpose:

To test different model parameterizations.

Data Parameters and Units:

Time (seconds since 1970-01-01 00:00:00), Age (seconds), Diameter (m), Ocean vertical diffusivity (m^2/s), Interfacial area (m^2), Mass evaporated (kg), Water fraction (%), Y wind (m/s), Sea ice area fraction (%), Density (kg/m^3), Longitude (decimal degrees East), Oil film thickness (m), Sea surface wave period at variance spectral density maximum, Sea water salinity, X sea water velocity (m/s), Bulltime (s), X wind (m/s), Emulsion age (s), Sea surface wave stokes drift y velocity (m/s), Viscosity (N s/m^2 (Pa s)), Sea surface wave mean period from variance spectral density frequency moment (s), Entrainment length scale (m), Sea floor depth below sea level (m), Latitude (decimal degrees North), Mass dispersed (kg), Land binary mask, Sea surface wave significant height (m), Sea water temperature (K), Upward sea water velocity (m/s), Float mass oil (kg), Sea surface wave stokes drift x velocity (m/s), Y sea water velocity (m/s), Z vertical position (m), Wind drift factor (%), Fraction evaporated (%)

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