On the movement of Deepwater Horizon Oil to northern Gulf beaches

- Ocean currents and Stokes drift transported DWH oil to northern Florida beaches.
- Stokes drift relative effect increased nearshore due to circulation anisotropy.
- Circulation brought oil to the nearshore vicinity and waves deposited oil on the beach.

Surface oil of Deepwater Horizon origin sullied the northern Gulf of Mexico marshes and beaches from Louisiana to Florida. The Mississippi to Florida beaches were particularly impacted during the month of June 2010. We review the evolution of the surface oil as it approached the beach and then consider the mechanisms of transport. Both the ocean circulation and ocean waves are found to be important. The circulation appears to control the transport of surface oil in deep waters and over most of the continental shelf. But as oil approaches shallow water the wave orientation may become more conducive than the circulation orientation for transporting oil to the beach. In essence it is found that the circulation gets the oil to the vicinity of the beach, whereas the waves, via Stokes drift, are responsible for the actual beaching of oil. A combination of observations and numerical model simulations are used to demonstrate this.