The Marysville data for one such traverse are presented graphically in Figure 

 B-3 with the isotherms plotted at integral Celsius degrees. The figure shows 

 that the depth of the thermocline varied over the course by about 30 feet and 

 that the temperature structure was quite irregular below the thermocline . No 

 measurements were shown above the top of the thermocline (200 feet) and the 

 velocity at the surface was not given. Thus it is impossible to determine the 

 velocity gradient in the surface duct from this data. However, the text of ref- 

 erence (1) contains the statement that there was a temperature inversion of less 

 than 1°C in the channel. It is not possible to use the data to establish the de- 

 pendence of the temperature field below the thermocline either on space or time , 



2 . 2 The Transition Water Region . The Transition Water Region lies to 

 the east of the Boundary Region . The Marysville carried out a single transit in 

 this region and recommended to the Rexburg, a location at 30° 22.0' N, 122° 

 54.0' W. This site was selected because of the existence of a layer of constant 

 depth over a distance of about 20 miles . The Marysville data in Figure B-4 

 show that the temperature structure below the layer was more regular than in 

 the Boundary Region. It is not possible to determine if the temperature field 

 was time dependent since there was only one transit. There are no measure- 

 ments in the surface layer but in the text of Reference (1) it is stated that there 

 were no inversions in the surface channel at this site . 



The Rexburg and Davis began their experiments 18 hours after the Marysville 

 survey. 



3. BATHYTHERMOGRAPH DATA OBTAINED BY USS REXBURG 

 AND USNS CHARLES H . DAVIS " ~ 



During the acoustical experiments bathythermograph casts were made at one- 

 hour intervals from both the Rexburg and the Davis . The measurements were 

 made both in the surface duct and below the thermocline . In both regions the 

 agreement between the data from the two ships confirms the existence of a well 

 defined surface duct along the track between them . 



The data included measurements of surface temperature and thus provided 

 records of temperature versus depth and the depth of the surface duct . In both 

 areas the surface layers were practically isothermal, the total change in tem- 

 perature with depth in each case being nearly within the accepted error for 

 bathythermographs, i.e., about ±0.2°C. The bathythermograph casts showed 

 that in both areas the depth of the thermocline varied during the acoustical ex- 

 periments by approximately 50 feet. Since the ships were moving apart it is not 

 possible to separate the spatial and temporal dependence of this variation. In 

 the Boundary Region the depth of the duct varied from 225 to 175 feet and in the 

 Transition Water Region from about 260 to 210 feet. 



B-4 



Arthur ZB.IUttleJnr. 



