TM No. 327 



Average subsurface currents are less accurate than the surface 

 current measurements^ and may be accurate to within 15 percent of the 

 surface current. 



Maximum or peak current speeds presented in the tables are at 

 best only a first approximation to the actual current, with the ex- 

 ception of the surface current measurements at T5' 



Precise measurements of peak current speeds, especially near the 

 bottom, can best be made using the self-recording Richards on -type 

 current meter. 



Apparently, two separate dynamic regimes exist -- the Northeast 

 Providence Channel area, which in itself is quite complex, and the Tongue 

 of the Ocean. Both areas are turbulent in nature. They are related to 

 the extent that the energy required for driving the circulation in the 

 Tongue can come only from the Sargasso Sea via the Northeast Providence 

 Channel, and from the Florida Straits via the Northwest Providence 

 Channel (sill depth of 660 meters). Assuming that the current structure 

 in the Northeast Providence Channel were known, it would still be most 

 difficult to predict the current structure in the Tongue of the Ocean. 

 This is due to the effect of the physiographic structure of the channel 

 and Tongue on the water motion. 



Although wind data taken during the cruise are not complete and 

 In many cases were estimated, the wind effect on the surface floats 

 was apparently considerable at certain previously noted times (see 

 appendix B). Persistent northeast winds may explain in part the fact 

 that nearly all drogues moved southerly into the channel along Tl. 

 Wind effects were also quite noticeable on the surface floats of the 

 drogues along T3 and T5 during the latter period of tracking. 



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