Stream, we found four crossings of the North Wall in May, 

 June, and November (Figs. 7-10). 



In mid-May (Fig. 7), the North Wall was indicated just to 

 the east of station 13 (approximately lat. 37°00'N, long. 

 69°00'W). Unfortunately, there are not enough observations 

 to completely describe the crossing. 



In June (Fig. 8), just the opposite occurred. Observa- 

 tions were made from the east right up to the North Wall, 

 discontinued for about 130 nautical miles, then recommenc- 

 ed. A crossing of the North Wall is detectable, but not well 

 defined, between stations 19 and 18 (approximately lat. 

 37°15'N, long.69°30'W). The November section (Fig. 9) 

 shows the North Wall of the Gulf Stream between stations 

 15 and 16 (lat. 37°30'N, long.71°00'W). In the transect made 

 4 days later (Fig. 10) the North Wall of the Gulf Stream 

 showed up at station 10 (lat. 38°00'N, long.71°00'W). 



Cold Cell.— The cold cell, sometimes referred to as 

 winter water (water less than 8°C), has been described by 

 Ketchum and Corwin (1964) and Whitcomb (1970). This 

 feature was transected on four occasions (Figs. 7, 8, 9, 10). 

 These four crossings show how the cold cell degenerates 

 throughout the summer. The first crossing in May (Fig. 7) 

 shows a cold cell with a temperature range of 6°-8°C until 

 finally in the last of November (Fig. 10) the cell structure is 

 barely detectable and has warmed to 14°C. 



In May (Fig. 7), a cell of bottom water extended 80 

 nautical miles offshore to a maximum depth of 75 m, with a 

 temperature range of 6°-8°C. In June (Fig. 8), the cold cell 

 of bottom water was still evident, although by this time the 

 cell had begun to warm and extend out to the shelf break. 



The November section (Fig. 9) shows still a further 

 warming and decay of the cold cell. The extent of the cold 

 cell had decreased to less than 60 nautical miles and warmed 

 to a range of 12°-14°C. 



The second November section (Fig. 10) showed the cold 

 cell had eroded to less than 30 nautical miles extent and 

 warmed to 14°C. 



Shelf Water-Slope Water Front. -The Shelf Water- 

 Slope Water front was transected in May just to the east of 

 station 5 (Fig. 7), indicated by a thermal change from 10° to 

 17°C in about 18 nautical miles. Low sea surface salinities 

 and temperatures out to station 5 also indicated the extent 

 of the shelf water. 



In June (Fig. 8), the front appeared between stations 25 

 and 24. At this time there was less sea surface temperature 

 change to indicate the front, instead the most pronounced 

 surface signature of the front was in the form of the strong 

 surface salinity gradient changing slope and sign at station 23. 



The November section (Fig. 9), shows that the Shelf 

 Water- Slope Water front had no expression in either surface 

 temperature or salinity, but a weak temperature gradient 

 between stations 7 and 8, at about 50- m depth, suggests that 

 the front might have been present there. 



In the transect made 4 days later (Fig. 10), a definite 

 surface signature of the shelf water was apparent in both sea 

 surface salinity and temperature. The Shelf Water- Slope 

 Water front did not show up in the subsurface data on this 

 transect, but surface salinities of less than 34°/oo readily 

 identify the shelf water region. 



ACKNOWLEDGMENTS 



Appreciation is extended to the Maritime Academy 

 Training representatives in New York and New Orleans, M. 

 Chicurel and D. Thompson, respectively. Their diligent 

 efforts to place midshipmen on board ships that were 

 scheduled to traverse preselected oceanic areas were 

 instrumental to the success of this program. In addition, 

 thanks are extended to the Moore McCormack Lines and 

 Grace Prudential Lines of New York and the Delta 

 Steamship Company and Lykes Brothers of New Orleans. 



LITERATURE CITED 



BOISVERT, W. E. 



1967. Major currents in the North and South Atlantic Oceans 

 between 64°N and 60°S. U.S. Nav. Oceanogr. Off., Tech. Rep. 

 TR-193, 92 p. 

 KETCHUM, B. H., and N. CORWIN. 



1964. The persistence of "winter" water on the continental shelf 

 south of Long Island, New York. Limnol. Oceanogr. 9:467-475. 

 LEIPPER, D. F. 



1970. A sequence of current patterns in the Gulf of Mexico. J. 

 Geophys. Res. 75:637-657. 

 NOWLIN, W. D., JR., and H. J. McLELLAN. 



1967. A characterization of the Gulf of Mexico waters in winter. 

 J. Mar. Res. 25:29-59. 

 WHITCOMB. V. L. 



1970. Oceanography of the Mid-Atlantic Bight in support of 

 ICNAF. September-December 1967. U.S. Coast Guard Oceano- 

 graphic Report No. 35, CG 373-35, 157 p. 

 WORTHINGTON, L. V. 



1964. Anomalous conditions in the Slope Water area in 1959. J. 

 Fish. Res. Board Can. 21:327-333. 



FIGURES 



The figures are grouped by geographical location and 

 time. They consist of two vertical sections of temperature, a 

 plot of surface temperature and salinity versus distance 

 along the transect, and a locator chart. 



GULF OF MEXICO TRANSECTS 



Figures 



Vessels 



Date 



1 

 2 

 3 



4 

 5 

 6 



Delta Argentina 

 Gulf Shipper 

 Gulf Shipper 

 Gulf Trader 

 Gulf Trader 

 Delta Norte 



1- 2 Jan. 1973 

 12-15 Feb. 1973 

 20-24 Apr. 1973 

 1- 2 Aug. 1973 

 14-15 Oct. 1973 

 3- 5 Nov. 1973 



WESTERN ATLANTIC TRANSECTS 



7 



Mormac Argo 



12-13 May 1973 



8 



Mormac Argo 



17-18 Jun. 1973 



9 



Mormac Rigel 



1 Nov. 1973 



10 



Mormac Argo 



5 Nov. 1973 



