213 



I have considered only a few limited examples of the general problem con- 

 cerning the exchange of energy and other properties across the air-sea boundary. 

 These have been chosen not because they are the most important, but because 

 they are the ones with which I am familiar. An excellent outline of the general 

 problem was given by Montgomery at M.I.T, only a year ago. 



DISCUSSION: R.O. Reid 



Solar radiation, with the major part of its energy concentrated at relative- 

 ly short wave lengths, including the visible part of the spectrum of electro- mag- 

 netic radiation, is essentially transmitted through the atmosphere or reflected 

 and scattered back to space by clouds and land-sea surfaces. Only a small por- 

 tion is actually absorbed by the atmosphere. However, the ocean absorbs, with- 

 in the upper 50 meters, virtually all of the short wave energy which reaches the 

 sea surface (excluding that which is reflected). The ocean, although being a 

 good absorber by virtue of its great mass and a good photosynthetic producer, is 

 a poor heat machine, being unable to develop within itself sufficient power to 

 sustain the circulation of the waters. Instead the ocean returns nearly all of the 

 radiative energy it receives, per unit time, to the sea surface, where it is liber- 

 ated to the atmosphere essentially as long wave radiation and latent heat -- 

 forms which the atmosphere is readily capable of absorbing and utilizing in its 

 comparatively efficient heat machine cycle. The thermal energy thus converted 

 to mechanical energy in the atmosphere is partially fed back to the ocean by mo- 

 mentum transfer across the sea surface. 



The amount of energy which is finally returned to the oceaji as mechanical 

 energy in this intricate feed back- counter feed back mechanism is actually but sin 

 insignificant portion of the original energy which is received by the ocean from 

 the sun (from 1/10, 000 to 1/1,000). Nevertheless this continual supply of ener- 

 gy in the form of "directed" kinetic energy is necessary and sufficient to account 

 for the generation and maintenance of surface waves and the quasi-permanent 

 circulation of the ocean in the presence of a continuous process of kinetic energy 

 degredation by turbulence and ultimately by viscosity. 



It is not difficult to see the need for adequate instrumentation capable of 

 procuring basic information on air-sea boundary processes, for the sea surface 

 is apparently the valve controlling the supply of energy for atmospheric storms 

 and in turn is a controlling link in the return of some of this energy utilized in 

 the generation and maintenance of ocean waves and currents. The theory of 

 generation and maintenance of waves and currents by wind is based in part upon 

 knowledge of mometum transfer from air to sea; while computations of the 

 supply of energy to atmospheric storms are in large measure dependent upon 

 latent heat transfer and back radiation. Consequently, ultimate improvement in 

 methods of prediction of waves, storm tides, currents, upwelling, and genesis 

 of storms in the atmosphere rests in no small measure on the validity of the fun- 

 damental concepts involved in the theories of boundary transfer processes. 



FORMS OF ENERGY TRANSFER 



In summary, there are presumably four important forms of energy trans- 

 fer which occur at the sea surface. These are, in order of their magnitude: 



(1) Radiative transfer 



Transmission, absorption and reflection of solar short wave radiation 

 Em^ission and absorption of long wave radiation 



(2) Latent heat transfer 

 Evaporation (upward flux of heat) 



