PART 12 

 RECOMMENDATIONS AND CONCLUSIONS 



Conclusions 



The directional spectrum of a wind generated sea has been determined 

 from stereo data after correcting the data for differential shrinkage, column 

 noise, white noise and the presence of a swell. This spectrum shows a single 

 peak and the contributions from different wavelengths cover a wide range of 

 wavelengths and directions. When transfornaed to a frequency spectrum, 

 with directional effects eliminated, the results are remarkably close to the 

 theoretical spectrum derived by Neumann. The longer waves in the spec- 

 trum are concentrated over a narrower range of angles about the wind di- 

 rection than the shorter waves. 



The actual spectrum reflects some effects of sampling variation, wind 

 shear, and changing wind direction upwind which are difficult to isolate be- 

 cause of the nature of the wind data and the sampling variation. When these 

 are removed by simplifying assumptions, it is possible to obtain an analytic 

 representation for the spectrum which appears consistent with known pro- 

 perties of swell and sea surface slopes. 



The analytic representation which has been obtained rests upon some- 

 what shaky foundations as far as angular effects are concerned. However, for 

 forecasting it would appear advisable to incorporate these results into the 

 forecasting naethod without awaiting further verification. Certainly the re- 

 sults on which such a revision would be based are on firmer theoretical ground 



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