GENERAL CHARACTER OF THE DATA 



Figure 3 is an example of raw chain data taken off the 

 southern tip of Baja California during the USNEL Boundary Ex- 

 pedition. The thermal structure shown is typical of that region 

 of the ocean and is from Sample Area 8. The record is a two- 

 dimensional picture or cross section of the temperature structure 

 in the upper 750 feet of the ocean. The depth scale is not linear 

 because the catenary- like configuration of the chain under tow 

 results in the thermistors being closer together at the top than at 

 the bottom of the chain. In the analog output record the vertical 

 scale is magnified about 100 times (97 times at normal towing 

 depth of 750 feet) over the horizontal. 



Three points need to be made with respect to the validity of 

 these temperature structure data. First, if the vertical fluctua- 

 tions in isotherm depth are related to internal waves (a periodic 

 phenomenon) , a Doppler frequency shift may be introduced into 

 the data measured by moving sensors. The extent of this shift is 



SURFACE 



100- 

 200- 

 300 - 



Si 40 ° 



500- 

 600 - 



700 - 

 750 - 







SAMPLE AREA 

 20° C 



V, s f , „y-' » 





15"C 





12°C 



-6 MILES- 



Figure 3. NEL Thermistor Chain data from Sample Area 8, off the southern tip of 

 Baja California. Section set off by vertical lines selected for detailed analysis. 



11 



