Gulf of Mexico historic (1955-1987) surface drifter data analysis

Analysis of historic (1955-1987) surface drifters (mostly cards and bottles ) released in the Gulf of Mexico reflect two meteorological seasons of the Gulf, winter and nonwinter. Five clusters of high drifter recoveries eviden t in both seasons were identified: 1) south Texas; 2) Louisiana-Texas borde r; 3) Mississippi River Delta to Cape San Bias, Florida; 4) Tampa, west Flo rida; and 5) southern to eastern Florida. A chi-squared test revealed that the distributions of drifter landings and human population, represented by human marine activities, are different at the 95% confidence level. Current s and winds are the dominant factors controlling the geographical distribut ion of drifter landings, while population density in coastal areas plays a minor role. The drifters' geographical distribution and the distributions o f marine mammal and turtle strandings have correlations (statistically not significant) of 0.25 and 0.31, respectively. Recovered drifters in selected segments in the eastern Gulf received drifters released primarily in the e astern Gulf, whereas western areas received drifters from everywhere. This distribution is probably the result of the westward surface drift driven by prevailing westward winds in the Gulf. Landing probabilities from drifters when compared with results from the Oil Spill Risk Analysis (OSRA) model w ere within an order of magnitude and their spatial distributions have corre lation coefficients of 0.44 to 0.49 (significant at 80% level) for the tota l, winter, and nonwinter seasons.