ON WIND GENERATED OCEAN WAVES 

 WITH SPECIAL REFERENCE TO THE PROBLEM OF WAVE FORECASTING 



Introduction 



The most familiar cause of sea surface waves Is the wind, and 

 It Is on these wind generated waves that this report dwells. In re- 

 cent years, questions about the growth of waves under the action of 

 wind, and the dimensions of waves in the fully developed state have 

 been brought into the foreground of special oceanographic work. It 

 was due to necessity that this recent period of sea wave investiga- 

 tions was begun. Nobody who follows the sea or depends in any way 

 on the state of the sea can ignore the behavior of waves. Not only 

 navigators, sailors and fishermen, but naval personnel, naval engin- 

 eers and seaside dwellers who have to protect their coast against the 

 attacks of the sea, are deeply Interested in this problem. 



The state of the sea, or the sea surface roughness pattern, is 

 a complicated combination of many waves often including swell. The 

 rather steep breaking waves of irregular appearance result from local 

 winds, whereas the more regular undulating swell will in general have 

 been generated in an area far away from the region of observation. 

 For analyzing quantitatively the state of the sea at different wind 

 velocities, it is required to separate these two independent pheno- 

 mena. When describing or forecasting the state of the sea imder dif- 

 ferent conditions, independent forecasts of local wind generated waves 

 and of swell are necessary. After combination of the two separated 

 procedures we may get the actual state of the sea surface pattern. 



Many new ideas from recent progress on this subject have proven 

 to be useful for important practical work. Present methods of fore- 



