Impacts of Loop Current Frontal Cyclonic Eddies and Wind Forcing on the 2010 Gulf of Mexico Oil Spill

Nan D. Walker, Chet Pilley, Vandana V. Raghunathan, Eurico J. D'Sa, Robert R. Leben, Nicholas G. Hoffman, Peter J. Brickley, Patrice D. Coholan, Neha Sharma, Hans C. Graber, Raymond E. Turner

The 2010 Deepwater Horizon Gulf of Mexico oil spill, the largest in U.S. history, highlights the environmental risks inherent in deepwater drilling. These risks were mitigated by rapid access to real-time satellite measurements from passive (optical, infrared) and active (SAR, altimetry) sensors. This study employed satellite data, in tandem with in-situ current and wind measurements, to track surface oil and to better understand the causes for observed large-scale motions during the 84-day episode. The analysis revealed the merger of three cyclonic eddies along the Loop Current’s northern margin, ultimately forming a larger and more vigorous cyclonic eddy, measuring 280 x 130 km on 18 May. This larger cyclonic eddy, in tandem with a smaller anticyclonic eddy and a Loop Current (LC) meander, controlled the motion of the oil/dispersant mixture into deepwater (maximum current speed of 2.25 m/s), tripling the area of surface oiling from 9,623 to 33,575 km2. Two main events limited the flow of oil to the Florida Straits, the accumulation of oil within the merged eddy and the fact that this eddy did not move substantially for several months. The observed offshore entrainment of oil toward the LC was successfully hind-cast using a particle-tracking model based on geostrophic currents computed from satellite altimetry. This assessment of circulation processes may help to advance numerical circulation modeling efforts in this region of rapid current variability in support of safer deepwater drilling in the northern Gulf.

Ref: Geophysical Monograph Series, pp. 103-116, Jan. 1, 2011

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