UNCLASSIFIED 



Security Classification 



DOCUMENT CONTROL DATA - R&D 



(Security clagsitication ot titte. body of abstract and indexing annotation must be entered when tfie overall report ia classified) 



1. ORIGINATIN G ACTIVITY (Corporate author) 



U.S. Naval Oceanographic Office 



2a. REPORT SECURITY CLASSIFICATION 



Unclassified 



2b GROUP 



3. REPORT TITLE 



On the Interpretation of Fetch-Limited Wave Spectra as Measured by an Airborne Sea-Sweil 

 Recorder. 



4 DESCRIPTIVE NOTES (Type of report and inclusive dates) Jhjs peport mokeS Up O pOrtlOH of the principle 



author's Ph.D thesis ~ ^bmltted to Scrlpps Institution of Oceanography. 



5. AUTHORfS; (Last name, first name, initial) 



Bamett, T. P. and J. C. Wllkerswi 



6. REPO RT DATE 



May 1967 



7s. TOTAL NO. OF PAGES 



71 



76. NO. OF REFS 



27 



8a. CONTRACT OR GRANT NO. 



Not applicable 



b. PROJECT NO. 



Not applicable 



9a. ORIGINATOR'S REPORT NUMBERfSJ 



TR-191 



None 



10. AVAILABILITY/LIMITATION NOTICES 



GHiollfled users may obtain copies of this report from DDC. 



11. SUPPLEMENTARY NOTES 



None 



12. SPONSORING Ml LITAR Y ACT IVITY 



U.S. Naval Oceanographic Office 



13 ABSTRACT 



A section of sea surface that had been subjected to a constant^ offchore wind was 

 profiled using an airborne radar wave profiler. The profiles extended from the coast out a 

 distance of 190 nautical miles. From this data estimates of the spectrum of encounter of 

 the sea surface were obtained for a number of different fetch lengths. By solving a singular 

 Fredholm Integral equation of the first klnd^^ It was possible to retrieve the true wave spectrum 

 as a function of fetch length. Spectral growth curves were then obtained and analyzed In 

 light of recent theories of wave generation. The data lend support to the previous conclusions 

 of Snyder and Cox (1966) regarding two recent theories of wave generation. Specifically, the 

 data are consistent with the "resonance" theory of wave growth (Phillips, 1957), but at the 

 same time suggests that wave growth through an instability mechanism (Miles, 1957) is yet to 

 be understood. One of the most significant results of this study was that higher frequency 

 waves grow past or "overshoot" their eventual equilibrium energy value. After "overshooting" 

 they then rapidly decay bock to an equilibrium range. 



DD 



1473 



UNCLASSIRED 



Security Classification 



