RAPID: Evaluation of the near term impact of the Deepwater Horizon blowout to the South Florida coast

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Intellectual merit: This RAPID project aims to assess how, where, and when the oil products entrained in the Loop Current might impact the South Florida coast. The oil spill from deep waters of the northern Gulf of Mexico is threatening coastal areas in south Florida due to entrainment in the large-scale current system. Assessment of the transport and the fate of the oil require processes extending across oceanic scales and scales relevant to coastal ecosystems to be taken into account simultaneously. To this end, the integrated use of a series of nested ocean and coastal circulation models as a single application is critical in order to be able to identify pathways of the oil mixture from the deeper part of the Gulf of Mexico to the shallow areas of Florida Bay and the Florida coral reef track. Past work in nesting a high-resolution Florida Key model with the Gulf of Mexico real-time Hybrid Coordinate Ocean Model (HYCOM)-based Ocean Predictions System using a multi-scale numerical modeling framework, the Connectivity Modeling System (CMS) provides the framework for this study. This modeling framework, originally developed for larval transport and connectivity studies, is well suited for rapid assessment of the impact of the Deepwater Horizon blowout on south Florida coast. The CMS has a hierarchy of embedded Lagrangian Stochastic Particle Models allowing probabilistic dispersion of particles with individual attributes and behaviors and has the capability of tracking the three-dimensional movement of the particles across nested domains. First, the formation of surface slicks, subsurface layers, and deep plumes and their pathways to the Loop Current will be simulated by conducting probabilistic runs of CMS with the highest resolution operational products available yet for the region (i.e., 1-4 km HYCOM-based Ocean Predictions System). In order to do this, we will adapt CMS to oil-gas mixture behavior (i.e., flow rate, density, viscosity, terminal velocity) and add processes of wind forcing, evaporation and weathering. The investigators will use an envelop of oil mixture behavior, varying the size of particles in the model and improve the 'oil module' through systematic comparisons of model results with time series of Eulerian observations. Second, the effect of hurricanes on the redistribution of the oil in the water column will be simulated. Given the large uncertainties inherent in the oil prediction problem, the proposed research will generate statistical estimates of the near-term impact of the oil-dispersant mixture to the South Florida coast.Broader Impacts: This project will provide a new understanding of transport pathways and accumulating areas resulting from the interactions of the circulation with the oil mixed with huge quantities of dispersant. Further, it will help guiding other RAPID efforts on field detection of oil products. In the longer term, the proposed work will constitute a baseline for studying the impact of the oil and its weathered states on the marine meroplankton and on fisheries. Results will also be useful to develop operational efforts in agencies and academia that will help preparedness for any future extreme events. The investigators on this project will collaborate with other scientists working in the Gulf of Mexico.Current website links on the Academic Task Force Rosenstiel School of Marine and Atmospheric Science website (http://www.rsmas.miami.edu/oil-spill) having updates of HYCOM water parcel trajectories will be expanded using the CMS adapted to the oil with its capability to go from the Gulf of Mexico regional model to the high resolution Florida Keys model. Finally, the multi-scale CMS framework is designed to be a community model and has been undergoing rigorous testing. We are planning to use the proposed effort to insure a public release of an open source code and user's guide later in the fall (http:// www.rsmas.miami.edu/personal/cparis/cms/description.html).