in 24 hours. The 10-day separation between the September and October 

 measurements, however, could be another matter, but anchor station 1 

 showed this dampening both times and anchor station 2 neither time. 

 The answer must be related to the station locations. Even though 

 the stations are only 19 miles apart, they do have the San Nicolas 

 Island ridge between them. The shallow depth of the ridge, about 

 55 meters, essentially isolates the two stations from each other. 

 With the stations separated as they are, a phenomenon such as internal 

 waves could affect one station and not the other. Defant (1950) 

 stated that repeated Nansen casts in a single location have shown 

 that vertical displacement of water masses does occur, and this has 

 been related to internal waves. He also has shown that internal 

 tide waves can exert a much greater influence on the thermohaline 

 structure of the oceans than do normal tides. According to Sverdrup, 

 et al (1942) , the period lengths of such waves in many cases correspond 

 to tidal periods. This could be the case at anchor station 1. Internal 

 waves may not be caused by tide-producing forces but rather by periodic 

 variations of actual tidal currents. Defant (1950) has concluded 

 that the effects of the earth's rotation and internal waves are 

 related and, together in varying combinations, may affect horizontal 

 distribution of temperature, salinity, and sound velocity. 



Further studies must be made of these interrelated parameters 

 before any definite conclusions can be drawn. An increase in sampling 

 frequency is needed as well. The use of a reliable and accurate 

 sound velocimeter system fulfills this requirement. 



E. Currents. 



1. General. Water movement within the survey area was investigated 

 in three ways: (1) parachute drogues, (2) self-recording current 

 meters, and (3) dynamic computations. 



2. Parachute Drogues . The drogue tracks at each of the five 

 launch sites are presented individually in Figures 17 through 21. 

 Also included in these figures are the tabular listings of drogue 

 distance, time, and velocity for each interval between navigational 

 fixes. The positions of navigational fixes are represented by circles 

 which are connected by straight lines. Because of this method, computed 

 speeds will be slightly less than the actual value. A few fixes 

 appeared inconsistent with the data and were not used. This elimination 

 of fixes also tends to give less drogue distance. Drag effect on 



the drogues, as discussed by Knauss (1963), was not taken into account 

 due to shallow drogue depths. 



Both average velocity and average interval velocity for each 

 drogue track are presented in Table I. Average velocities were obtained 

 by dividing the total distance covered by the drogue by the total 

 amount of time used to cover the distance. The average interval 

 velocity is the sum of the velocities for each interval between 



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