Reference h demonstrated that mean temperatures calciolated from 

 BT measurements made at relatively short-time intervals for periods 

 of several days or a few weeks are sufficiently accurate to be used 

 for heat budget calculations, even though individual BT's may contain 



HEAT BUDGET CALCULATIONS 



The generalized heat budget may be characterized by the relation- 

 ship 



Qs - Qb - Qe - Qh + Qv + Qg ■ ° 



where Qg = incoming solar radiation 



Q-^j z back radiation from the sea surface 



Qg = evaporative heat exchange 



Qj^ = sensible heat exchange 



Q^ m heat change due to currents and mixing 



Qfl = local heat change or heat expended in warming or cooling 

 the water. 



In past practice, the Oceanographic Prediction Division rearranged this 

 equation to isolate the local heat change as the right-hand term of the 

 equation, thus: Qs - Qb - Qe " Qh + "^v ■ '^B' "^^^ te-rra was isolated, 

 because the time of year when this term changes from positive to nega- 

 tive is extremely important in making long-range ice predictions. Thus, 

 whem the theory of ice potential was developed in 1952 (reference 3) t 

 this term was used in determining when oceanographic observations were 

 to be made for predicting winter growth of sea ice. 



At the time of the present cruise, Q^ can be considered to be 

 essentially zero. OWS ECHO is located in an area of relatively homoge- 

 nous water, and thus Qy.is expected to be small but not necessarily zero. 



Radiation data were obtained in September 1959 to supplement the 

 BT data. Albedos of sea and sky deduced from analysis of the radiation 

 and BT data permitted estimation of heat exchange processes of the ver- 

 tical water column from surface to 100 feet. The details of this cal- 

 culation form the basis of this report. 



RADIATION DATA 



Continuous radiation data were obtained with two Eppley pyrheli- 

 ometers mounted together over the ship's bow. An upright instrument 

 measured total incoming radiation from sun and sky, and an inverted 



