topography based on a grid of stations occupied 

 northeast of the Bahama Islands in April 1947 

 showed no general manifestations of the Antilles 

 Current in the upper 150 m, showing 

 southeastward flow instead. In a 330-nautical mile 

 (610-km) section from this grid off Great Abaco 

 Island (about lat. 27° to 28°N), a southeastward 

 flow of 2.8 X 10^ mVs was found in the upper 250 m, 

 and a weak northwestward flow of 0.7 x 10^ m Vs 

 was found in the 250- to 1,000-m layer, yielding a 

 net transport through the section of 2.1 x 10^ m^/s 

 southeastward. 



A similar conclusion can be drawn concerning a 

 much earlier investigation. Although Bigelow 

 (1917), in his pioneer analysis of the Bache data, 

 regarded the northward extension of warm water 

 in the surface layer east and north of the Bahama 

 Islands to be an expression of the Antilles Current, 

 his pertinent vertical section of temperature just 

 north of the Bahamas collected in March 1914 

 doesn't support that contention. The slope of the 

 temperature isopleths northeast of the Bahama 

 Islands indicated the presence of a southward 

 flowing surface current in the upper 200 m or so, 

 with a northward current at greater depth. Wiist 

 (1924) computed geostrophic current speeds and 

 volume transports from the Bache data including 

 the transect of eight stations, from Jupiter Inlet to 

 the Sargasso Sea (SW-NE) crossing just north of 

 the Bahamas. He found an 80-km band of north- 

 westward flow, which he called the Antilles 

 Current, contiguous with southeastward flowing 

 countercurrents on both sides. The transport of 

 the Antilles Current he computed, 12.0 x 10^ mVs, 

 was approximately balanced by the transport of 

 the two countercurrents, 12.4 x 10^ m^/s, yielding a 

 net transport through the portion of the section 

 seaward of the Gulf Stream (depths >800-900 m) of 

 0.4 X 10^ m Vs to the southeast. 



1000 FM 



GRAND B«HAM« 

 BUM ^ ,^/ 





During 1967-72, vessels of the U.S. Coast Guard 

 made nine occupations of Standard Section A-7, 

 each consisting of 16 oceanographic stations along 

 28°35'N from near Cape Canaveral at long. 

 80°10'W to a point about 520 nautical miles (960 

 km) offshore at long. 70° 15'W (Figure 2). 

 Temperature and salinity data were collected on 

 each station from casts of Nansen bottles located 

 at or near NODC (U.S. National Oceanographic 

 Data Center) standard depths or from lowerings 

 of STD (Salinity Temperature Depth) sensors 

 calibrated against data collected by Nansen bot- 

 tles and reversing thermometers. Contoured 

 profiles of temperature, salinity, and density are 

 to be published along with lists of the data in the 

 Coast Guard Oceanographic Report series (Robe in 

 press). This section transects the Antilles Current 

 where it is supposed to begin merging with the 

 Gulf Stream, thus providing a portrayal of its po- 

 tential contribution to the Gulf Stream system. 

 Unfortunately, the occupations are not distributed 

 uniformly throughout the seasons; five are in 

 winter, two in fall, and two in summer, so seasonal 

 variations cannot be discerned from the data. 



Geostrophic velocities were computed from the 

 temperature and salinity data utilizing a standard 

 computer program employed by the Coast Guard 

 Oceanographic Unit (Hislop^). The velocities were 

 computed relative to the 1,000-decibar surface 

 which was consistently reasonably level, as in- 

 dicated by the small variation of density at 1,000 m 

 (mean at = 27.547, standard deviation = 0.098, 

 sample size = 52). No attempt was made to carry 

 the computation into water shallower than about 

 800 m because of the considerable errors in- 

 troduced by extrapolation of water properties into 

 the bottom and by close approach to the Gulf 

 Stream. 



Vertical sections of geostrophic velocity were 

 hand drawn from lists of the computed values by 

 assigning the values to midpoints between sta- 

 tions at middepths between depths of temperature 

 and salinity observations. Interpolations neces- 

 sary for contouring were based on an assumption 

 of linear variation in properties horizontally and 

 vertically between data points. This procedure was 

 followed for six of the nine occupations of Stan- 

 dard Section A-7. Three occupations v^re rejected 

 because they contained too many short casts in 

 critical areas. 



Figure 2.-Location of stations occupied by U.S. Coast Guard 

 cutters along Standard Section A-7. The stations connected by 

 the solid line are those generally used in this study. 



'Hislop, A. S. 1973. Coast Guard Oceanographic Unit DDP-516 

 programs. Oceanogr. Unit Tech. Rep. 73-2, p. 16-17. Unpubl. 

 manuscr. 



628 



