Physical Oceanography of Oil Spills

MURRAY, STEPHEN P., Louisiana State University, Baton Rouge, LA

The introduction of petroleum products and crude oil from ship accidents and damaged platforms into the ocean remains a significant problem. Weather systems of nearly all sizes and time scales may have strong effects on oil slick movement and dispersal. Thunderstorms, local weather systems, mid-latitude high- and low-pressure systems, tropical cyclones, and the trade winds and prevailing westerlies of the planetary wind system are all potentially important agents in the movement and dispersal of oil slicks. Currents driven by these wind systems are influenced by the rotation of the earth, which causes them to veer to the right of the wind in the northern hemisphere. Wind shifts or sudden decreases in wind stress induce circular or inertial oscillations whose period varies with latitud . Near the shore these effects are severely damped by the blocking action of the coast, causing the flow to run more or less parallel to the coastal boundary. All these effects will in turn exert significant control over the movement of entrained oil slicks. In the near-field region of an oil spill tidal currents can also be of considerable importance. Rotary currents, characteristic of open-shelf waters and effective dispersal agents of oil, arise from the influence of the rotation of the earth on the tidal current. Another such interaction between rotation of the earth and the tide produces Kelvin waves, which result in unusually high tidal ranges along the coast to the right of the tidal wave propagation. Both effects have been important in recent oil spills. All these oceanographic p ocesses, reviewed in this talk, have played key roles in major spills over the last 15 years from the Torrey Canyon to the Mega-Borg.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)