Atlantic Equatorial Countercurrent 
The Atlantic Equatorial Countereurrent flows eastward between 
the west-setting Atlantic North and South Equatorial Currents. The 
approximate boundaries and monthly variations in extent are shown in 
Figure 3. The surface countercurrent is best defined during August 
and September, when it extends from about 52° to 10°W and joins the 
Guinea Current. In October it narrows and separates into two parts 
at about 7°N, 35°W. ‘The western part, which appears to be a region 
where the countercurrent probably sinks and flows eastward beneath 
the equatorial currents, gradually diminishes in size to the west-~ 
northwest, while the eastern part diminishes to the east-southeast 
as shown in the lower half of Figure 3. The greatest separation 
oceurs during March; during April the western part of the countercurrent 
disappears, but in May it reappears in the vicinity of 0°, 4O°W. The 
two segments progress west-northwest without too much change in size. 
They merge at about 6°N, 43°W during August and continue their flow 
eastward uninterrupted through September. 
Table 3 indicates frequencies of speeds by prevailing direction 
during the northern summer, when the countercurrent is most pronounced. 
Speeds are stronger but less persistent in the western part of the 
countercurrent, as shown by the decreasing frequency of observations 
to the east in the higher speed groups of 1.3 to 2.5 knots and 
increasing frequency to the east in the lower speed groups of 0.1 to 
1.2 knots. Speeds have been observed to exceed 3.0 knots at times. 
