in 1962 (Table 1). This increase was probably due to 

 greater public awareness of the program in 1963 than in 

 1962. 



The technique used to depict surface currents was the 

 same as used by Day (1958). Recovered bottles were 

 grouped into two time periods of 15 days each, i.e., 0-15 

 days and 16-30 days. The 0-15 day recoveries were first 

 plotted as straight lines connecting points of release and 

 recovery. These lines were resolved into directional ar- 

 rows, and over these arrows we then plotted, as straight 

 lines, the 16-30 day recoveries. The final step was to 

 reduce the 16-30 day straight lines to flow arrows con- 

 forming with the 0-15 directional arrows, thus depicting 

 residual drift, not the actual path traversed by a bottle. 

 The reason for the selected groupings and the exclusion 

 of bottles recovered after 30 days was the existence of the 

 sand or sand-shell beaches throughout the northwestern 

 Gulf of Mexico, and the possibility of bottles drifting 

 ashore, remaining intact, but not being found until some 

 later date. 



Rates of drift, killometers per day, were determined 

 from recoveries made within 15 days after release. In in- 

 stances where several bottles were returned from a single 

 station, the bottle or bottles adrift for the shortest time 

 period were used to determine rate of drift. Also, if two or 



more bottles, recovered from the same release, were 

 adrift for the same period of time but had traveled dif- 

 ferent distances, these distances were averaged before 

 determination of drift rate. Consequently, one direc- 

 tional arrow may represent the recovery of several bot- 

 tles, and the speed an average speed. 



Daily wind data from the climatological records pub- 

 lished monthly by the U.S. Weather Bureau, now the 

 National Weather Service, were used to depict prevailing 

 wind conditions over the study area during each cruise 

 (U.S. Department of Commerce 1962-1963a, 1962-1963b, 

 1962-1963c). This information was recorded at weather 

 stations in Brownsville and Galveston, Tex., and New 

 Orleans, La. Since the time required to complete each 

 cruise varied, it was arbitrarily decided to construct 

 resultant wind vectors for the time period between the 

 first and last days of each cruise plus an additional 15 

 consecutive days. These data were converted to Beau- 

 fort units and incorporated into progressive vector anal- 

 ysis, the lengths of which measured in Beaufort units 

 were divided by the total number of days to give a vector 

 average for each period under consideration. 



All drift bottle release and recovery data used in this 

 report are on file in the National Oceanographic Data 

 Center, Department of Commerce, Washington, D.C. 

 20235, under Ref. 78-0035. 



Table 1 Numbers of drift bottles released and recovered In the Gulf of 



Mexico within 0-15 and 16-30 days, by cruises, 1962 and 1963. 





Inclusive 





Total 



Recoveries 



Z Recovered 



Cruise 





Dates 





Deposited 



0-15 



16-30 



Within 30 days 



1-62 



Feb. 



17-Feb. 



27 



651 



25 



12 



6 



2-62 



Mar. 



20-Mar. 



27 



697 



27 



53 



11 



3-62 



Apr. 



18-Apr. 



26 



690 



33 



39 



10 



4-62 



May 



18-May 



22 



525 



26 



11 



7 



5-62 



June 



18- July 



1 



691 



32 



25 



8 



6-62 



July 



18-Aug. 



1 



276 



21 



10 



11 



7-62 



Sep . 



7-Sep. 



25 



663 



45 



26 



11 



8-62 



Oct. 



16-Oct. 



30 



594 



13 



8 



4 



9-62 



Nov. 



14-Dec. 



5 



697 



74 



19 



13 



10-62 



Dec. 



4-Dec. 



19 



583 



30 



1 



5 



1962 Totals 









6,067 



326 



204 



9 



1-63 



Jan. 



22-Feb. 



5 



305 



13 



5 



6 



2-63 



Feb. 



19-Mar. 



9 



203 



14 



20 



17 



3-63 



Mar. 



27-Apr. 



6 



254 



21 



61 



32 



4-63 



Apr. 



21-May 



7 



180 



46 



24 



39 



5-63 



May 



13-May 



23 



209 



57 



21 



37 



6-63 



June 



19-June 



27 



192 



25 



31 



29 



7-63 



July 



10- July 



16 



50 



1 



1 



4 



8-63 



Aug. 



17-Aug. 



31 



118 



9 



6 



13 



9-63 



Sep. 



22-Oct. 



4 



86 



10 



35 



42 



10-63 



Oct. 



20-Nov 



4 



111 







13 



12 



11-63 



Nov. 



20-Dec. 



1 



88 



1 



9 



11 



1963 Totals 









1,796 



197 



226 



24 



