separation, and periodic regrowth of the layer was 

 calculated by the approximate momentum technique. 

 Resistance and damping coefficients calculated on 

 this basis show generally excellent agreement with 

 experiment. 



NO. 118 - August 1959 



" Wave Variability and Wave Spectra for Wind-Generated 

 Gravity Waves " by C. L. Bretschneider 



Wave records from a wide variety of locations have been 

 utilized in a statistical analysis of the probability 

 distributions of wave heights and wave periods; and a 

 family of wave spectra which allows for an arbitrary 

 linear correlation between wave height and wave period 

 squared is suggested. It is proposed that in early 

 stages of wave generation the correlation is nearly 

 unity, but as the generation proceeds the correlation 

 decreases, ultimately approaching zero for a fully 

 developed sea. 



NO. 119 - August 1960 



"Sand Movement by Wind Action (on the Characteristics of 

 Sand Traps) " by K. Horikawa, and H. W. Shen 



Results by other investigators for wind pattern and 

 velocity profile and their relation to sand movement 

 are reviewed and discussed. Movement of sand by wind 

 is studied in a laboratory wind tunnel to verify these 

 relationships, separating that moved by processes of 

 surface creep and saltation. Several types of sand 

 traps are calibrated and their efficiency studied, and 

 characteristics discussed. 



NO. 120 - August 1960 



" The Prediction of Hurricane Storm - Tides in New York 

 Bay " by B. W. Wilson 



This report is concerned with the solution of the 

 problem of correlating on a two-dimensional basis the 

 meteorological parameters of severe offshore storms 

 with the known surge induced by them in New York Bay, 

 and with the application of the results to the predic- 

 tion of likely effects in New York Bay from a design- 

 hurricane of given strength traversing a given path 

 at a given speed. Using an empirical method with 



108 



