SEA SURFACE 



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12°C 



~100 FT 

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3 Ml. 



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Figure 9(A). A thermal ridge or dome, indicative of divergence (Position 4, fig. 5). 



A detailed examination of recorded thermal structure fur- 

 nished information on other oceanographic processes (figs. 9 A 

 and 9B). 



The detail of long waves of encounter (fig. 9A) averaging 

 0.44 mile in length can reflect a natural geographical phenomenon 

 or a Doppler effect. The smooth, 20-foot-high waves may be 

 shorter than recorded if traveling in the same direction as the 

 ship. If surface waves were influencing the depth of the sensors, 

 the internal waves would appear as irregular marks, since each 

 recorded scan would give an irregular outline to the curve (the 

 scan would fall at all phases of the surface wave). Surface waves, 

 because of ship stability and bead lagging, have little or no effect 

 on the recording of smooth, sine-shaped internal waves. 



In a second enlargement (fig. 9B), the recorded isotherms 

 are much different from those of only 1-1/2 hours earlier al- 

 though the speed and direction of towing were the same. The 

 fluctuation and rough appearance of the isotherms are attributed 

 to short -length internal waves, or waves propagating in an opposite 

 direction to the ship. The waves of encounter are so short that 



14 



