DISCUSSION 



The most interesting feature in the analyses is the presence of warm 

 water in the eastern segment of the survey area. The thermal structure 

 in the boundary between the warm water and the surrounding cooler water 

 is similar to that of the northern edge of the Gulf Stream but less intense. 

 Minimum observed SST occurred in a filament at the cold-water side of the 

 boundary. Maximum observed salinity in the warm water (36.2°/oo) compared 

 with salinity values associated with the Gulf Stream (>36.0°/oo). Because 

 only two observations exceeded 34.7''/oo, the warm water must be classified 

 as intermediate wa;ter rather than Gulf Stream water. Temperature sections 

 show no direct influence of the warm water below 60 meters. However, the 

 configuration of underlying temperature inversions in the area of the warm 

 water is considerably more complex than the configuration of the inversion 

 at 37''N, suggesting that the influence of the warm water extends through 

 the seasonal thermocline. 



The area of warm water corresponds to warm water observed by Ichiye 

 (1966, 1967) approximately 150 kilometers northeast of Cape Hatteras. A 

 small cold core in the center of this eddy is believed to be caused by 

 entrainment of cold surface water from the northeast. A similar process 

 would account for the cold tongue extending northeastward to the south of 

 the warm water observed by SANDS. 



A transient zone of intermediate SST was reported between the coastal 

 water and the Gulf Stream (Mazeika, 1968). This intermediate zone is 

 characterized by (1) an initial temperature change of approximately S'C 

 in less than 2 kilometers, (2) an area of varied SST as much as 111 kilo- 

 meters in width, and (3) a second, steeper temperature gradient at the 

 northern edge of the Gulf Stream. The zone was observed to vary in width 

 during a 24-hour period from being almost nonexistent to 28 kilometers. 

 Alternating cold-water belts and warm cores were observed within the zone. 

 Similarity between Mazeika 's data and features observed by Ichiye and the 

 present survey suggests that Mazeika may have also traversed the warm eddy. 

 Warm water observed during a survey seaward of the Virginia Capes in 

 February and March 1967 suggests that intrusion of warm water into coastal 

 areas occurs throughout the year. The mean temperature gradient across the 

 boundary (0.9°C/km) observed during the present survey compares favorably 

 with the gradient of O.S'C/km observed during the winter survey. 



Little displacement of the western boundary of the warm water was 

 observed during Phase I. During the interval between phases, however, 

 both counterclockwise rotation of the boundary and dissipation of the 

 warm core were observed. With the exception of a 3-day period between 

 30 September and 3 October when northt;rly winds occurred, wind-drift 

 currents were toward the east. It is unlikely that the northerly winds 

 could have overcome momentum imparted by the Gulf Stream to the extent 

 observed. A decrease in SST of nearly 2.5°C was observed in the gyre between 

 the flight of 21 September and the flight of 6 October, whereas little or 



