area (41°N,63°W) and produced strong northwest winds at 15 to 20 m/sec 

 and cool air temperatures near 12°C. On the following day, the wind 

 slowly decreased to 10 m/sec and shifted to the northeast; the tempera- 

 ture rose to 18°C. During the remainder of the survey the area was 

 dominated by weak weather systems. 



The direct effects of weather on the ocean are difficult to deter- 

 mine. The sea surface temperature pattern during phase I did not 

 represent the subsurface thermal structure. No major storms had influ- 

 enced the area for some time, thus the surface layer was not thoroughly 

 mixed, masking the major features. At 200 meters, however, below most 

 weather influences, the features are much more evident. During phase 

 II, the surface developed much clearer features due partially to the 

 two days of wind mixing by the storm of 30 and 31 October. 



Calculations were again made to predict vertical temperature changes 

 due to weather by use of the Gemmill and Nix model. The sea surface in 

 general would have cooled 0.5° to 1.5°C, if advection were not a factor. 

 However, it will be shown that the water both warmed and cooled to a 

 far greater extent, implying that advection is the more important mech- 

 anism for short-term temperature changes. 



B. DESCRIPTION OF ANALYSES AND CHANGES 



1. Horizontal Analyses 



To aid three-dimensional portrayal of the more important 

 features, they have been designated as follows: 



(A) Gulf Stream northern boundary 



(B) Warm eddy near 39.5°N,68°W 



(C) Cold ring near 36.5°N,67°W 



(D) Surface cold tongue at 40°N,67°W 



(E) Subsurface cold tongue at 40°N,67°W 



(F) Warm cell at 37°N,66°W 



(G) Sound channel region at 40°N,68°W 



The horizontal analyses (figures 8, 9, and 10) of phase I revealed 

 several major features. The northern boundary of the Gulf Stream (A) 

 is identified by a strong temperature gradient zone oriented east-west 

 across the center of the area. The gradient is weakest (3° to 5°C) at 

 the surface and strongest (10°C) at 450 meters. The boundary slopes 

 southward at a rate of 1:300. The center of the Gulf Stream on the 

 surface is warm (24°C) water. Evidence of a weak counter current is 

 located south of the Gulf Stream with slightly cooler water (<24°C). 

 The counter current is not evident at depth. 



Two isolated water masses were also detected during phase I: a 

 warm eddy (B) north of the Gulf Stream near 39°N,68°W and a cold ring 



