Surface Drift Predictions of the Deepwater Horizon Spill: The Lagrangian Perspective

One of the key challenges for oil spill response is forecasting the movement of the oil plume. This is a classic Lagrangian transport problem, with a few added layers of complication, since the oil does not behave as a conservative tracer in the ocean water. The comprehensive mobilization of resources, both observational and modeling, around the Deepwater Horizon oil spill from April 20 until July 15, 2010, has yielded a unique opportunity to investigate the accuracy of Lagrangian predictions. Here we focus on the surface dynamics. A variety of different forecasting methods, based on state-of-the-art numerical circulation models and in situ drifter observations, are evaluated against satellite image data taken during the early weeks of the Deepwater Horizon oil spill. The role of wind forcing versus ocean current forcing is explored. Regions of low and high uncertainty in the forecast are identified using Lagrangian tools such as direct Lyapunov exponent maps and verified against the observations.