ABSTRACT 



Analysis of nearly 900 bathythermograms taken at half- 

 hourly intervals at Ocean Weather Station ECHO between 

 2 and 21 September 1959 reveals that convective mixing, 

 the most easily identified physical process involved in the 

 daily heating and cooling cycle, extended to a depth of 60 

 feet near sunrise. Measurement of radiational heating was 

 complicated by apparent internal wave action on a weak 

 thermocline at 60 feet. Estimation of the coefficient of 

 thermal conductivity from the data yielded a value much 

 lower than expected because of simultaneous turbulent 

 heat transfer. After elimination of known sources of tem- 

 perature variations (instrumental or human errors), advec- 

 tive heat exchange was revealed to be the major source of 

 remaining variations. The energy involved in advection was 

 much greater than that involved in the vertical processes 

 of heating, cooling, and convective mixing. 



