THE PROBLEM 



Investigate oceanographic factors pertinent to the behaviour of 

 underwater sound and to surface and subsurface navigation. 

 Specifically, study the thermal structure of the upper sea layers 

 by use of the towed thermistor chain. 



RESULTS 



1. The average slopes, autocorrelation, and power spectra of 

 the isotherms obtained with the NEL thermistor chain on the dif- 

 ferent "legs" of a deep-water cruise show that many internal 

 waves are of very long period. The spectra appear to be continu- 

 ous at very low frequencies and to possess minor peaks at higher 

 frequencies (1/20 to 1/3 cycle per minute). 



2. These studies further indicate a probable shoreward move- 

 ment of the dominant internal waves. 



3. The records of circular tows with the chain establish that the 

 thermal structure is complex. Although the circular paths fol- 

 lowed were too small to clearly demonstrate significant motion in 

 any particular direction, the data obtained do reveal that wave 

 crests and troughs of a generally similar type were crossed in all 

 directions of tow. 



RECOMMENDATIONS 



1. Continue development of the thermistor chain to improve the 

 quality, accuracy, and reliability of the data. 



2. Make detailed studies of the thermocline and its associated 

 internal waves by use of the chain. Include studies of the effects 

 on the thermocline of islands, shoals, coastal configurations, 



MBL/WHOI 



D 0301 OO^SM? fl 



