Development of the CSOMIO Coupled Ocean-Oil-Sediment- Biology Model

Dmitry S Dukhovskoy,Linlin Cui,Robert Hetland,Victoria J Coles,Michael Stukel,Steven L Morey,Tian-Jian Hsu,Courtney K Harris,Andrew J Manning,Jiaze Wang,Eric P Chassignet,Kristen Thyng,Xu Chen

doi:10.3389/fmars.2021.629299

Abstract

The fate and dispersal of oil in the ocean is dependent upon ocean dynamics, as well as transformations resulting from the interaction with the microbial community and suspended particles. These interaction processes are parameterized in many models limiting their ability to accurately simulate the fate and dispersal of oil for subsurface oil spill events. This paper presents a coupled ocean-oil-biology-sediment modeling system developed by the Consortium for Simulation of Oil-Microbial Interactions in the Ocean (CSOMIO) project. A key objective of the CSOMIO project was to develop and evaluate a modeling framework for simulating oil in the marine environment, including its interaction with microbial food webs and sediments. The modeling system developed is based on the Coupled Ocean-Atmosphere-Wave-Sediment Transport model (COAWST). Central to CSOMIO’s coupled modeling system is an oil plume model coupled to the hydrodynamic model (Regional Ocean Modeling System, ROMS). The oil plume model is based on a Lagrangian approach that describes the oil plume dynamics including advection and diffusion of individual Lagrangian elements, each representing a cluster of oil droplets. The chemical composition of oil is described in terms of three classes of compounds: saturates, aromatics, and heavy oil (resins and asphaltenes). The oil plume model simulates the rise of oil droplets based on ambient ocean flow and density fields, as well as the density and size of the oil droplets. The oil model also includes surface evaporation and surface wind drift. A novel component of the CSOMIO model is two-way Lagrangian-Eulerian mapping of the oil characteristics. This mapping is necessary for implementing interactions between the ocean-oil module and the Eulerian sediment and biogeochemical modules. The sediment module is a modification of the Community Sediment Transport Modeling System. The module simulates formation of oil-particle aggregates in the water column. The biogeochemical module simulates microbial communities adapted to the local environment and to elevated concentrations of oil components in the water column. The sediment and biogeochemical modules both reduce water column oil components. This paper provides an overview of the CSOMIO coupled modeling system components and demonstrates the capabilities of the modeling system in the test experiments.

Highlights

The Deepwater Horizon (DWH) blowout at the Mississippi Canyon (MC252) Macondo well in the northern Gulf of Mexico released 4.9 million barrels (780,000 m3) of crude oil (Lubchenco et al, 2010)
This paper presents a coupled ocean-oil-biology-sediment modeling system developed by the Consortium for Simulation of Oil-Microbial Interactions in the Ocean (CSOMIO) project
The newly developed CSOMIO coupled modeling system presented here is designed to simulate three-dimensional movement of oil in the ocean and compositional changes of oil in the water column and at the surface, with explicitly modeled interactions with evolving sediment and biological components as opposed to prescribed parameterizations

Summary

INTRODUCTION

The Deepwater Horizon (DWH) blowout at the Mississippi Canyon (MC252) Macondo well in the northern Gulf of Mexico released 4.9 million barrels (780,000 m3) of crude oil (Lubchenco et al, 2010). Locations of Lagrangian floats and mean oil droplet size (Doil) in the model surface layer are shown for some time instance (Figure 6A). After the oil has been subject to biodegradation and sedimentation processes simulated in the biogeochemical and sediment-OPA modules, the modified oil fields (denoted with index k+1) need to be mapped back to the Lagrangian framework and updated by the OTWM In the model, both the biogeochemical and sedimentation processes modify concentrations of the oil compounds but do not explicitly modify the size of oil particles. Oil droplet density increases with time (Figure 8A), whereas both mass and size decrease as a result of oil consumption by microbes simulated in the biochemical model. Sediment, and biology interact and show the generally expected responses

SUMMARY AND CLOSING REMARKS

Findings

DATA AVAILABILITY STATEMENT