25 



1 





1 



I 



1 1 1 1 1 

 SOUTH-NORTH / 



15 



- 







/ /" 



/ / 

 / / 

 X / 



y 



10 



- 





/ 



/ / 

 // 

 // 

 / 



/ 



NORTH-SOUTH 



5 

 n 



1 



/- 



^1 



/ 1 

 / / 



/ 



1 



1 



1 1 1 1 1 



4 8 12 16 20 24 28 32 36 

 HOURS 



Figure 10. Amplitude spectrum for the legs north - 

 south and south-north. 



ANALYSIS OF CHAIN DATA FROM SAN DIEGO TO HAWAII 



In August 1961, USS MARYSVILLE went from San Diego, California to 

 Honolulu, Hawaii (by the route shown in fig. 11) and recorded temperature dis- 

 tributions in the upper 230 meters with the thermistor chain. The ship's mean 

 direction was about 255°; mean speed was 6 knots. The data obtained during the 

 cruise were reported fully in reference 11, in which short-period waves of 

 encounter were analyzed for slope and power spectrum. Here, the longer internal 

 tide is given primary consideration. The record selected for the analysis covers 

 the period from 2000 hours on 4 August to 2000 on 17 August. 



The record was processed as follows: 



1. Data from one day's isotherms form one set. A 24-hour record corres- 

 ponds to about 150 nautical miles. 



2. The depths of the isotherms were read from the analog record every 

 10 minutes, taking mean values (by sight) for these points. 



.3- The Fourier analysis was carried out using three consecutive sets. 

 The combined sets are overlapping: 1-3, 2-4, 10-12, 11-13. It is assumed that the 

 spectra represent the situation in the centers of these areas. Fourier components 



38 



