Favre and Coantia 



One of the essential steps in the solution of the air- sea inter- 

 action problem lies in the understanding of small-scale processes 

 in the air and water layers adjacent to the interface, where the 

 various forms of energy are either transferred or converted, while 

 going from one medium to the other. The experimental study of 

 these phenomena involves a detailed and delicate exploration of a 

 region whose thickness is of the order of the wave height. Now, 

 experiments performed at sea are subjected to such environmental 

 constraints that the accuracy and repeatability of measurements 

 seems necessarily limited. It has therefore appeared useful to 

 complement field studies by laboratory experiments, where an ex- 

 tensive investigation is feasible under exactly repeatable conditions 

 and with the possibility to control independently each of the govern- 

 ing parameters. 



This is the program which has been undertaken at I. M. S. T. , 

 and which is described in the present paper. The preliminary steps 

 of this program have included: collection of information about cur- 

 rent research; attempt of a critical survey of existing knowledge, 

 in order to find out definite research objectives; and a first theoreti- 

 cal study of the physical mechanisms of air- sea interactions, and 

 of their governing parameters. These studies have led to the con- 

 clusion that it would be feasible to obtain, in the laboratory, a partial 

 simulation of the atmospheric-oceanic energy exchange processes, 

 provided that a sufficiently large facility could be realized. 



The following steps of the program have then comprised: 

 the preliminary design of this facility, combining a micrometeorolo- 

 gical wind tunnel with a 40 meters long wave tank; the realization of 

 a one-fifth scale model, and its use for various preliminary tests 

 and experiments; the detailed design and the building of the large 

 wind- wave facility; and, last but not least, the development of various 

 theoretical and Instrumental researches. 



The purpose of the present paper Is to introduce the various 

 objectives and results of our research program, and to describe the 

 facilities which have been, or are being, realized. Due to space 

 limitation, that presentation will be limited to a rather short account 

 referring to previous publications for more details, when possible. 

 The plan adopted is logical rather than chronological: 



- Theoretical studies; 



- Setting up the characteristics and design of the large air- 

 sea facility; 



- Model tests; 



- Building of the air- sea facility; 



- Studies of measuring Instruments and methods. 



At last, we shall try to draw some preliminary conclusions 

 about this program, the prospects It opens, and Its possible appli- 

 cations. We shall also have the pleasure to express our thanks to 

 the many Individuals and organizations who have contributed to Its 

 realization. 



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