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tions may be revealed. This kind of evidence is essential to a description of the 

 fine structure of the transient state. In addition to evidence of the change in the 

 strength of currents, horizontal confluence and difluence of surface flow, there 

 may be a measurable change in the properties of the water parcel near each 

 buoy as it moves through the area. 



The drift of the buoys would only suggest the nature of the mean stream- 

 flow, for each buoy would tend to move in a random way with respect to the mean 

 motion vector. Since the mechanism of eddy diffusion, particularly on a large 

 scale, is not well understood, this might be studied separately by releasing a 

 group of buoys at one point for the purpose of observing their scatter and the 

 changes in water properties detected within the buoy field. It is also possible 

 that in some regions where the current pattern is not immediately evident, the 

 mean motion vector is small compared with the random component. Were the 

 mean motion vector subtracted and the currents plotted, in effect, with respect 

 to a reference frame moving at the mean motion rate, some intelligible system- 

 atic motions might appear. 



In view of these possible uses for surface buoys and their apparent prom- 

 ise of new and desirable kinds of data not easily obtained from shipboard, some 

 thought has also been given their use in obtaining subsurface data and the modi- 

 fications of design that may be required. 



Buoys which telemeter their position may be used, for example, to indi- 

 cate currents and trends of motion at depths below the surface if they are equip- 

 ped with large current crosses or other suitable drags to dominate their mo- 

 tions. With such equipment already below the surface it would be a relatively 

 simple matter to suspend the drag on an electric cable and measure temperature 

 or other scalars at that or lesser depths. It is also possible to suspend one or 

 more current meters below an otherwise undamped surface buoy to measure the 

 vertical shear. With the development of suitable inclinometers, a current 

 cross might be used to measure vertical shear adapting the technique of Pritch- 

 ard and Burt (1951). 



The problem of position detecting systems for drifting buoys has a num- 

 ber of solutions the simplest of which, theoretically, is to relay loran signals as 

 they are received at the buoy to a manned station where they can be compared 

 and plotted. But loran and other pulsed radio transmissions require large 

 bandwidths and the present areas of ground wave loran service are not very ex- 

 tensive. There are several phase difference methods for fixing and ranging on 

 buoys which may be used more freely and can be operated anywhere at sea on an 

 interrogation basis from a ship or shore point within the limits of ground wave 

 transmission. If it ever becomes a routine matter to anchor buoys in the deep 

 ocean, these might provide an independent reference system for either tempor- 

 ary hyperbolic navigation or ranging on buoys adrift. Outside the loran service 

 areas this type of system would permit ships of buoys to work with continuous 

 knowledge of the relative position of all points of observations, although the po- 

 sition with respect to the geographic coordinate system may be known with less 

 accuracy. 



In considering any such radio-location system, there is much to be 

 gained if the ship is free to move through the buoy field making observations of 

 other kinds. An anchored buoy reference system offers this possibility. If, 

 however, the ship is sailed on a regular gridwork of courses, advancing with the 

 buoys, it is possible for the position and rate of drift of the buoys to be dis- 

 cerned from the ship itself as the reference station. Ranges and bearings on 

 each of a group of buoys may be repeated at intervals and if the ship has sailed 



