35 



Primarily, there are four ways in which energy can be exchanged between 

 the oceans and the atmosphere : 



(1) by the transfer of momentum, 



(2) by the radiative interaction, 



(3) tiy conduction and convection of sensible heat, and 



(k) by molecular and turbulent transport of latent heat in the 

 form of water vapor. 



I would like to deal with these different kinds of energy exchange in 

 the order indicated above . When doing so I should emphasize that a complete 

 review cannot be expected, because here in Tallahassee I do not have at 

 hand my extensive and detailed file of references which, of course, I could 

 not bring with me. Therefore, my presentation is certainly biased by a fair 

 amount of randomness as far as the literature reported is concerned. 



THE TRANSFER OF MOMENTUM 



With a view to the well-known irregularity of motion near and at the 

 sea surface our final aim must be to get a complete time record of the 

 field of motion both in air and in water as well as of the distribution of 

 pressure and stress in the marine boundary layer. These time records must 

 show as high an amount of temporal resolution and must also be as long as 

 would be necessary in order to allow (l) a spectral analysis of all fluctua- 

 tions which may contribute to the transfer of momentum and (2) a reliable 

 estimate of the vertical momentum flux. Further, a time record taken at 

 only one point would certainly not be sufficient but must be supplemented 

 by others taken nearby or by some suitable device which provides informa- 

 tion about the spatial properties of the flow. On the base of such empirical 

 information and using sound physical principles, theory must try to develop 

 suitable models which can be applied for predicting purposes . 



Looking first at some empirical evidence on the instantaneous wind 

 field around moving ocean waves we can hardly see anything at all. The 

 only measurements, which came to my knowledge and which at least supply a 

 certain part of the information wanted, are those published by Pond, Stewart, 

 and Burling (1963) and the - still unpublished - results obtained by Brocks 

 and Hasse (I963) . 



Pond, Stewart, and Burling measured turbulence spectra of the 

 "downstream" component of the wind over waves of approximately 30 cm height 

 using a hot-wire anemometer. The probe was mounted at 1 to 2 m above the 

 water level, at which height the mean wind speed was about 3 m/sec. No 

 indication is given as to whether the measuring site was close to the shore 

 or well on the open sea. But the smallness of the wave heights mentioned 



