Chapter 12 



Tagged Water Masses for Studying the Oceans 



127 



locating gear, and careful crew training and 

 teamwork are necessary for subsurface radio- 

 logical surveys even at these moderate depths. 



Outline of tagging experiment in the thernio- 

 cline layer 



Figure 2 illustrates certain features which 

 must be considered in this region. The ship, A, 

 may lower a gamma sonde through an activated 

 pool and detect its presence by the receiving 

 of a signal like tliat shown on the right side of 

 the figure; the hydrographer may obtain a 

 water sample by triggering electrically a water 

 sampler at the moment the detector indicates 

 that the sampler is within the active layer. The 

 data in Table 3 make it clear that rapid response 

 is important during this sort of measurement; 

 a statistically significant signal must be accumu- 

 lated in the short period during which the 

 probe is passing through the active layer. 



Attention is called to the need for naviga- 

 tional and maneuvering aids here by including 

 schematically the parachute-drogue C. It is 

 difficult to maneuver a weighted detector hori- 

 zontally in order to study the lateral distribution 

 in detail. The use is suggested of towed gamma 

 detectors depressed to the desired level by 



hydrofoils controllable from the surface, more 

 or less as illustrated schematically at the left 

 of Figure 2. By means of a swivel-clamp, SC, 

 a pennant several meters long containing a row 

 of Geiger tubes or other gamma detectors, might 

 be suspended above the depressor so as to pre- 

 sent a vertical, linear array, thus giving a high 

 probability of intersecting wide lateral distri- 

 butions of activity. This sort of gear should not 

 be too awkward nor fragile for deck handling 

 at sea. Signals might be recorded partially, or 

 entirely inside the depressor, or reported to the 

 ship electronically or sonically. 



Ship A or a sister ship with similar gear 

 might stay in the pool during the whole experi- 

 ment, however, if the pool were lost after its 

 depth was established, then Ship B would likely 

 be the first to find it again with its towed 

 detector. 



Difficulties in sounding and exploring very deep 

 ivaters 



Bottom exploration so far has been confined 

 largely to sonic plotting and sounding by solid 

 cable; very deep wire casts are very time con- 

 suming and difficult; the ship generally is 

 moved laterally by surface currents before the 



OPERATlOM "poker CHIP" 



Figure 2 



