TM NOo 327 



transect 2 -which indicated a net flov out of the channel, but their motions 

 were so erratic that one fix plus or minus the last fix on the surface float 

 could have appreciably altered the value found for the resultant net motion 

 (eddy motion) This is not to imply that there is no outflow from the Tongue; 

 it simply means that for depths at which currents were measured, there was 

 no definitive outflow from the Tongue at transects 1 and 2. Certainly, if 

 there is a flow of water into the Tongue, there must be an outflow at some 

 depth (possibly a depth at which no current measurements were taken) „ 



Two drogues. Tango II and SR-II, were set at 1000 meters in the eastern 

 and western parts of the Tongue, respectively. Both drogues indicated a net 

 flow into the Tongue. (See figure 11.) Drogue SR-II followed the l600-meter 

 isobath, whereas drogue Tango II showed a very erratic course with a net 

 motion toward the southwest. The average speed for both drogues was nearly 

 the same. (See table k . ) 



Current measurements taken the previous year (reference 3) in approx- 

 imately the same area indicated a net northerly motion at 50 and 200 meters, 

 but a net southerly motion at 500 meters « The 50 meter drogue track was 

 remarkably similar to that of drogues Romeo II and 3-III] i.e., the drogue 

 coursed southward during the first 11 hours of tracking, gradually veered to 

 the east, then moved northward during the remaining tracking period. 



Transects 3 and k were run simultaneously, and both T3 and Th were run 

 during a portion of transect 5o 



Vertical current gradients were computed the same as before, except that 

 the bearing of the lopgltudinal axis of the Tongue (3i<-0°T-l60°T) was used in 

 place of the axis of the Northeast Providence Channel. 



Drogues set along T3 were located in the eastern half of the Tongue, with 

 the exception of drogue SR-II (lOOO meters), which was located in the western 

 part of the Tongue. 



Figure 12 is a diagram of the current gradients for transect 3- There 

 was a net flow of water out of the Tongue at 200 and 500 meters, and a net 

 flow of water into the Tongue at 1000 meters. This was indicated by both 

 1000 meter drogues. Negative gradients were shown from 200 to 1000 meters. 



Transect k 



A series of special drogue measurements was made U-5 kilometers east of 

 Middle Bight in an attempt to learn more about the character of the surface 

 currents and how closely these currents are related to the tidal motion on 

 the banks. Of particular interest was the degree of mixing of bank water 

 with Tongue water. Table 5 is a summary of drogue data obtained along T4. 



11 



