Data recorded at the boundary between the warm and cold water in 

 the eastern half of the survey area are complex, and the isotherm pat- 

 terns shown in the analyses provide only a general configuration of the 

 boundary. Cold-water filaments were observed adjacent to. steep tempera- 

 ture gradients on several occasions but lacked sufficient continuity to 

 permit delineation in the analyses. An ART record of the sharp tempera- 

 ture gradient across the boundary between the warm and cold water on 6 

 October is shown in figure 8. The portion of the flight track shown is 

 indicated in figure 6 by the heavy line AA' , The location of the western 

 boundary between the warm water and the surrounding cooler water is shown 

 in figure 9 for 19, 20, and 21 September and for 6 and 7 October as 

 recorded by the NSRT system aboard the SANDS. 



Temperature and salinity sections taken on 6 October are represent- 

 ative of oceanographic conditions throughout the survey. The temperature 

 profile (figure 10) is characterized by (1) a seasonal thermocline which 

 impinges upon the shelf midway between Stations I and J, deepens with 

 increasing water depth until reaching a maximum depth of 55 meters between 

 Stations K and L, and finally shoals to 32 meters at the seaward terminus 

 of the section; (2) a warm core (T>23°C) in the near-surface layer in 

 the seaward half of the section; (3) a second warm core (T>'17°C) centered 

 at a depth of 85 meters at Station M; (4) a cold intrusion (T<110C) 

 between the near-surface warm core and the warm core at 85 meters; and (5) 

 a wedge of cold water (T<13°C) adjacent to the slope at a depth of 95 

 meters. The horizontal temperature gradient between the cold wedge adja- 

 cent to the slope and the warm core at 85 meters was 0.27°C/km. Although 

 current measurements were not made, density distribution implies anticy- 

 clonic circulation. 



The salinity profile for 6 October (figure 10) is similar to the 

 temperature profile in that (1) a core of relatively saline water (S> 

 35.50/00) coincided with the near-surface warm core, (2) a second core 

 (S>36.2°/oo) coincided with the warm core at 85 meters, (3) a wedge 

 of relatively low salinity water (S<33.5°/oo) coincided with the cold 

 intrusion at Station M, and (4) a horizontal salinity gradient coincided 

 with the horizontal temperature gradient. An isohaline surface layer was 

 observed only over the shelf. 



A composite T-S envelope (figure 11) was constructed using the data 

 from all 16 Nansen casts. Point A is the mean T-S relationship at the 

 Surface at Chesapeake Light Station as computed from data for 1956 to 

 196»+ (U.S. Department of Interior, 1957-1967). Point B represents the 

 mean T-S relationship of shelf water as defined by Ford and Miller (1952). 

 Point C represents Gulf Stream water using both observed data and the 

 criterion of Ford and Miller (T>25°C, S=36.0°/oo). Line DE indicates 

 North Atlantic Central Water as defined by Sverdrup (19^6). The distribution 

 of data points generally falls within three different oceanic regimes: (1) 

 a regime where temperature is inversely proportional to salinity as indi- 

 cated by the line AB, (2) a regime characterized by temperature directly 

 proportional to salinity as indicated by the line DE, and (3) a transition- 

 al area between the above two regimes. The three regimes will hereafter 



