39 



So far this is all that has come to my notice about measurements of 

 the instantaneous wind field around ocean waves. The spectral analysis 

 seems to be a suitable method of representing and studying such very ir- 

 regular motions . However, I would wish that it may not only be applied 

 to the wind field over the sea but also to the wave motion at and - if 

 possible - below the sea surface. Simultaneously taken records of this 

 sort would yield highly useful information on the mechanical interaction 

 between air and sea, in particular if the measurements of the motion in 

 both media were supplemented by records of the pressure distribution and 

 its fluctuations . Apparently, plans and preparations for such an approach 

 as well as preliminary field tests are being made at the University of 

 British Columbia, Vancouver (Stewart and Burling, 196h) . 



Certainly the whole problem is easier to tackle by laboratory 

 measurements , although the result obtained there may not always be meaningful 

 with respect to open-sea conditions. One interesting paper of this kind 

 has recently been published by Schooley (1963) who tried to measure the 

 wind field above wind- gene rated water waves in a short tunnel by photograph- 

 ing the tracks of neutrally buoyant soap bubbles . The data could be sum- 

 marized in form of vertical wind profiles (Figure k) above certain points 



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 DISTANCE ALONG WAVE (em) 



Figure k. Vertical wind profiles above four different points along a 

 water wave in a wind- water tunnel (from Schooley, 1963). 



along the wave profile and show the expected strong increase of wind speed 

 with height above the crest region as well as the less steep gradient above 

 the trough. I said "expected" because a similar result haii-ia^^'obtained "^/ee. 

 decade^ ago by Motzfeld (1937) who investigated the air flow over a wavy 



