TM No„ 327 



ABSTEIACT 



The Uc S. Naval Underwater Ordnance Station (NUOS) is responsible for 

 the installation of a weapons range in AUTEC (Atlantic Undersea Test and 

 Evaluation Center). Since this work requires a knowledge of the environ- 

 mental factors affecting deep water tracking^ a program was established 

 to gather water current data in the Northeast Providence Channel and the 

 Tongue of the Ocean, Bahamas. Measurements were taken during February 

 and March 1963 by tracking a total of 27 parachute drogues placed at 

 various depths (lO to I5OO meters) along five transects in the areas 

 selected. Over 500 position fixes were taken using a Decca Hi-Fix navi- 

 gation system. 



Although water motion in the Tongue is of necessity related to water 

 motion in the Northeast Providence Channel, it is not apparent what 

 dynamic regime exists in the Tongue for a given dynamic regime in the 

 channel (and vice versa). This conclusion is based on the complex flow 

 patterns exhibited by deep drogues set along the entrance to the Tongue 

 (eddy motion was observed at depths of 6OO and 15OO meters). In other 

 words, if the ciorrent structure were well known in the Northeast Providence 

 Channel, it would still be most difficult to predict the current structure 

 in the Tongue of the Ocean. 



Current speed and vertical current gradients generally decreased in 

 magnitude from the Northeast Providence Channel to the Tongue, There was 

 a net in-channel flow along both transects located in the Northeast 

 Providence . Channel, although outflow could have occurred at depths where 

 no measurements were made. Variability in current speed exhibited by 

 individual drogues indicated a turbulent current structure. 



The circulation in the Tongue is also turbulent in nature^ i.e., 

 there is no well-defined mean motion such as that found in the Gulf Stream. 

 It is, therefore, extremely difficult to predict the current structure 

 over relatively short periods (two or three tidal cycles). 



Analysis of all current data indicates that it may be necessary to 

 monitor current information on the AUTEC weapons range prior to, during, 

 and after tracking experiments in order that the dynamic oceanographic 

 environment can be correlated with tracking data on the test vehicles. 



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