The Minerals Management Service (MMS) has made use of two kinds of oceanic drifters. One is the "Davis" or "CODE" type drifter, that tracks the top one meter (about three feet) of the surface ocean. The other is the "oil-following" or "oil-spill-simulating" drifter, which moves on the sea surface like an oil spill. Both kinds of drifters help MMS make better determinations of oil spill risk to natural resources from offshore oil and gas extraction and transportation, one of MMS's areas of responsibility.
Since 1993, MMS has deployed over 800 satellite-tracked CODE drifters to measure the surface ocean currents in areas of active or prospective oil and gas leasing, primarily in U. S. coastal waters in the Gulf of Mexico. This information enhances our collection of ocean current data, which we use to simulate oil spills in computer models.
In addition, many satellite-tracked oil-spill-simulating drifters have been deployed in accidental and intentional research spills to determine if they actually move like oil spills. MMS found two drifter shapes that moved on the water like many kinds of crude petroleum under low to moderate wind and sea conditions. A 12-inch diameter sphere and a 14-inch diameter disc have performed well as oil spill trackers/simulators. MMS is now using both these shapes in the Gulf of Mexico to compare against the oil spill computer models. The comparisons will help MMS improve its oil spill risk predictions.