Coastal-ocean processes and their influence on the oil spilled off San Francisco by the M/V Puerto Rican

Abstract

The oil tanker M/V Puerto Rican exploded on 31 October 1984 and later broke apart to produce a major oil spill in the coastal waters off San Francisco, California, USA. Oil from this spill initially moved to the SSW until 5 November, when it abruptly reversed direction and began moving rapidly to the north and then to the NNW during the following week. The oceanic processes that most likely contributed to the displacement of the oil spilled by the Puerto Rican are examined within the framework of a simple, empirical-hindcasting model. A large-scale flow component, wind drift, and tidal currents are included in the model. Wind drift, inferred by using a simple linear formulation, was the single most important factor in determining the over-all displacement of the oil. Residuals from the model, however, indicate that the winds alone could not fully account for the sudden and dramatic reversal in oil movement that occurred on 5 November 1984. This reversal was surge-like and coincided with an increase in sea level along the central California coast. Finally, the close agreement between the local and advective changes in sea-surface temperature in the Gulf of the Farallones at the time of the Puerto Rican oil spill indicate, although not conclusively, that this reversal could have been related to the onset of the Davidson Current or other larger-scale flow phenomena.