Gulf of Mexico dispersion calculations, technical report.

A short series of Lagrangian and Eulerian current measurements were taken within the boundaries of the Western Gulf of Mexico Waste Disposal Site (center at 27 degrees 20' N, 94 degree 36' W) on 25 and 26 July 1977. The measurements formed part of an ocean dumping acoustical investigation conducted by the NOAA Atlantic Oceanographic and Meteorological Laboratories (Miami) aboard the NOAA Researcher. Four 40m deep current profiles were obtained using a HydroProducts deck-readout current meter. The absolute currents obtained after allowing for the ship's drift were of the order of 0.5 kn or less. Eighteen drogues set variously for depths of 5, 10, and 20m were tracked by radar over a period of 19 hours. Analysis of the Plan Position Indicator photographs indicate a drift rate of 0.4 kn directed towards 115 degree. The calculated horizontal diffusion coefficient for the 5m drogues was of the order of 10 cubed cm. squared s. -1, two or three orders of magnitude less than usual. The horizontal diffusion coefficient for the 10m drogues (in the direction of drift) was of the order of 10 to the fifth power cm. squared s. -1.