REPORT DOCUMENTATION PAGE 



Form Approved 

 OMB No. 0704-0188 



Public reporting burden for thii collection of information le estimated to average 1 hour per response, including the 

 gathering and maintaining the data needed, end completing and reviewing the collection of information. Send 

 collection of information, including suggestion! for reducing this burden to Washington Headquarters Services. C 

 Davis Highway. Suite 1204. Arlington. VA 22202-4302. and to the Office of Management and Budget. Pape 



reviewing instructions, searching existing data sources. 



tgarding this burden esbmate or any other aspect of this 

 rate for information Operations and Reports. 1 21 6 Jeffersor 

 Reduction Project (0704-01881. Washington. DC 20E03. 



1. AGENCY USE ONLY (Leave blank) 



2. REPORT DATE 



February 1994 



3. REPORT TYPE AND DATES COVERED 



Final Report 



4. TITLE AND SUBTITLE 



Storm Evolution of Directional Seas in Shallow 

 Water 



6. AUTHOR(S) 

 Charles E. 



Long 



5. FUNDING NUMBERS 



7. PERFORMING ORGANIZATION NAMEIS) AND ADDRESS(ES) 



U.S. Army Engineer Waterways Experiment Station 

 Coastal Engineering Research Center 

 3909 Halls Ferry Road 

 Vicksburg, MS 39180-6199 



8. PERFORMING ORGANIZATION 

 REPORT NUMBER 



Technical Report 

 CERC-94-2 



9. SPONSORING/MONITORING AGENCY NAMEIS) AND ADDRESS(ES) 



U.S. Army Corps of Engineers 

 Washington, DC 20314-1000 



10. SPONSORING/MONITORING 

 AGENCY REPORT NUMBER 



1 1 . SUPPLEMENTARY NOTES 



Available from National Technical Information Service, 5285 Port Royal Road, 

 Springfield, VA 22161 



12a. DISTRIBUTION/AVAILABILITY STATEMENT 



Approved for public release; distribution is unlimited 



12b. DISTRIBUTION CODE 



13. ABSTRACT (Maximum 200 words) 



Measured storm wave frequency-direction spectra are presented to illus- 

 trate the evolution of wind wave energy distributions near times of high 

 energy. Twenty-nine storm events, extracted from a 5-year database, are 

 identified and described. Instrumentation consists of a nine-element linear 

 array of bottom-mounted pressure gauges distributed along the 8-m isobath 

 about 900 m offshore of Duck, NC, site of the Field Research Facility (FRF) 

 of the UlS. Army Engineer Waterways Experiment Station, Coastal Engineering 

 Research Center. Iterative Maximum Likelihood Estimation is used to deter- 

 mine directional distributions of wave energy. Events, identified by 

 elevation and duration of wave energy, are due to both localized storms and 

 long-period swell radiating from major weather events in the distant, deep 

 Atlantic Ocean. Frequency-direction spectra associated with storms known as 

 "northeasters" have a curiously recurrent pattern of broad directional 

 distributions at low frequencies near the spectral peaks and distinct 

 bimodal distributions over a broad range of high frequencies. Reasons for 

 this behavior are not obvious but require clarification because such wave 

 patterns do not conform to conventional models used in engineering design. 

 The differences may lead to substantial variations in design results. 



14. SUBJECT TERMS 

 Frequency-direction spectra 

 Storms 



Wave climate 

 Wind Waves 



15. NUMBER OF PAGES 

 131 



16. PRICE CODE 



17. SECURITY CLASSIFICATION 

 OF REPORT 



UNCLASSIFIED 



18. SECURITY CLASSIFICATION 

 OF THIS PAGE 



UNCLASSIFIED 



19. SECURITY CLASSIFICATION 

 OF ABSTRACT 



20.LIMITATIONOFABSTRACT 



NSN 7540-01-280-5500 



Standard Form 298 (Rev 2-89) 



Prescribed by Or Deth 230-18 

 286 102 



