Goodknight and Russell (1963) give a tabulation of the significant height 

 and period for waves recorded on an oil drilling platform in approximately 10 

 meters (33 feet) of water, 2.5 kilometers (1.5 miles) from shore near Burr- 

 wood, Louisiana during Hurricanes Audrey (1957) and Ella (1950) and Tropical 

 Storms Bertha (1957) and Esther (1957). These wave records were used to 

 evaluate the applicability of the Rayleigh distribution function (Chapter 3, 

 Section 11,2 Wave Height Variability) to hurricane statistics for wave heights 

 and periods. They concluded that the Rayleigh distribution function is 

 adequate for deriving the ratios between H , H,„ , H , etc., with 

 sufficient accuracy for engineering design, but that its acceptance as a basic 

 law for wave height distributions is questionable. 



2. Model Wind and Pressure Fields for Hurricanes . 



Many mathematical models have been proposed for use in studying hurri- 

 canes. Each is designed to simulate some aspect of the storm as accurately as 

 possible without making excessively large errors in describing other aspects 

 of the storm. Each model leads to a slightly different specification of the 

 surface wind field. Available wind data are sufficient to show that some 

 models duplicate certain aspects of the wind field better than certain other 

 models; but there are not enough data for a determination of a best model for 

 all purposes. 



One of the simplest and earliest models for the hurricane wind field is the 

 Rankin vortex. For this model, it is assumed that 



U = Kr for r < R 



(3-55) 



U = .!^ for r > R 



r 



where K is a constant, R the radial distance from the storm center to the 

 region of maximum windspeed, and r the radial distance from the storm center 

 to any specified point in the storm system. 



This model can be improved by adding a translational component to account 

 for storm movement and a term producing cross-isobar flow toward the storm 

 center. 



Extensions of this model are still being used in some engineering studies 

 (Collins and Viehman, 1971). This model gives an artificial discontinuity in 

 the horizontal gradient of the windspeed at the radius of maximum winds and 

 does not reproduce the well-known area of calm winds near the storm center. 



A more widely used model was given by Myers (1954). A concise mathematical 

 description of this model is given by Harris (1958) as follows: 



R 

 p-— ^ = e ^ (3-56) 



3-81 



