obtaining shallcw water wave data at a point between 

 stations by interpolation and refraction analysis is 

 worked out for Long Branch, N. J. 



NO. 56 - October 1954 



II-A "An Ele ctro nic Wave Spectrum Analyzer and Its Use in 



F Engineering Problems" by Willard J. Pierson, Jr. 



The theory of a wave spectrum analyzer designed and 

 constructed by S. S. Chang (see BEB Tech. Memo No. 58) 

 is described and the operation of the filters in the 

 analyzer explained theoretically. Methods for computing 

 information on the free surface wave spectrum, the 

 energy flux in the surf beats and in the waves, and 

 the average "period" are developed. These methods 

 are simplified to make them practical, and techniques 

 for rapid evaluation of data are developed. A detailed 

 example is carried out. Several other possible appli- 

 cations to engineering usage are shewn. 



NO. 57 - February 1955 



II-A "North Atlantic Coast Wave Statistics Hindcast by the Wave 



Spectrum Method" by G. Neumann and R. W. James 



Detailed statistical wave data for deep water off the 

 North Atlantic Coast based on hindcasts from synoptic 

 weather charts for the 3-year period 1947-1949, are 

 derived by the relatively new wave spectrumi method as 

 developed by Neumann, Pierson and James, for the same 

 offshore stations for which data was developed in 

 Technical Memorandum No. 55. The wave statistics are 

 presented in comparable parameters to those previously 

 derived by the Sverdrup-Munk method and given in 

 Technical Memorandum No. 55. 



NO. 58 - July 1955 



II-A "A Magnetic Tape Wave Recorder and Energy Spectrum Analyzer 



F for the Analysis of Ocean Wave Records" by Sheldon S. Chang 



An instrument which produces a wave record on magnetic 

 tape and from this tape produces a power (energy) density 

 spectrum as a function of frequency is described. Photo- 

 graphs and detailed drawings are included. The instrument 

 analyzes a 20-minute wave record in approximately three 

 minutes and records the resulting power spectrum on chart 

 paper . 



96 



