50 THE HEAT BUDGET OF THE OCEANS 



than one thousandth part of the radiation received at the surface and 

 can be neglected when deaUng with the heat budget of the oceans. In 

 a few basins where the deep water is nearly stagnant and where conduc- 

 tion of heat from above or from the sides is negligible, the amount of 

 heat conducted through the bottom may conceivably play a part in 

 determining the distribution of temperature, but so far no such case is 

 known with certainty. 



The kinetic energy transmitted to the sea by the stress of the wind 

 on the surface and part of the tidal energy are dissipated by friction and 

 transformed into heat. The energy transmitted by the wind can be 

 estimated at about one ten-thousandth part of the radiation received at 

 the surface and can be neglected. In shallow coastal waters with strong 

 tidal currents the dissipation of tidal energy may be so great, however, 

 that it may become of some local importance. Thus, in the Irish 

 Channel, according to Taylor, the dissipation amounts to about 0.002 

 g cal/cmVmin, or 1050 g cal/cmVyear. The average depth can be 

 taken as about 50 m, or 5000 cm, and, if the same water remained in 

 the Irish Channel a full year, the increase in temperature would be about 

 0.2° C, oh an average. Such an effect, however, has not been established, 

 and, as it can be expected in shallow coastal waters only, it is of no 

 significance to the general heat budget of the oceans. 



It is estimated that in ocean regions of abundant plant life, up to 

 0.8 per cent of the incoming radiation may be utilized by the plants for 

 photosynthesis, but over all ocean areas the average amount is probably 

 less than one tenth of the maximum values and can be neglected as 

 unimportant. 



The only processes to be considered, therefore, are the radiation 

 processes and the exchange of heat and water vapor with the atmosphere, 

 so that for the oceans as a whole the average annual heat budget can be 

 written in the form 



Qs-Qi>-Qh-Qe = 0. (IV, 1) 



If specific regions and time intervals are considered, it must be taken 

 into account that heat may be brought into or out of a region by ocean 

 currents or by processes of mixing, and that during short time intervals 

 a certain amount of heat may be used for changing the temperature of 

 the water. The complete equation for the heat balance of any part of 

 the ocean in a given time interval is, therefore, 



Qs- Qb-Qh-Qe-Qv-Q6 = 0, (IV, 2) 



where Qv represents the net amount that is brought into or out of the 

 region by currents or processes of mixing, and where Q^ represents the 

 amount of heat used locally for changing the temperature of the sea 

 water. 



