sea level and of the barometric pressure for Hurricanes Carla and 

 Camille. One method for representing the wind field is to digitize 

 the above charts for the hurricane in question. Usually the wind and 

 pressure data depicting the storm are sampled in time at particular 

 grid points and interpolated to provide the necessary input to the 

 surge model. However, such input data are tedious and laborious to 

 obtain and do not guarantee better quality of the input than can be 

 obtained by analytical representations of the forcing fields. It is 

 this latter approach which is used in this study. 



For a given hurricane, the following parameters are sampled in 

 time from the NWS charts: position, forward speed, central pressure, 

 radius vector (relative to the storm movement) to maximum winds, and 

 the maximum winds. With an analytical representation of the surface 

 wind and pressure fields the above parameters need only to be inter- 

 polated in time. 



The wind field representation prior to consideration of the land 

 influence as given by Jelesnianski (1965) is employed in this study. 

 The x,y-wind components for a stationary storm are: 



and 



V r 



V = 



y 



[ - (x-Xj^ sin <f> - (y-y h ) cos <j> ] 



= — [ + (x-x,D cos <j> - (y-y h ) sin <j> ] 

 h 



r F(r h ) , (82) 



where 



r h = [(x-x h ) 2 + (y-y h ) 2 ] 



• (83) 



V is the maximum wind, cj> is the ingress angle, and F(r, ) is 



V2 1/2 



(r h /R h ) ' if r h < 1^ or (\/\) if \ ^R h> Distance from 



the storm center (x, , y, ) to the region of maximum winds is R, . 



The translation of the storm provides an alteration in the wind field 

 which is carried out following the method of Jelesnianski (1965). 

 This involves the vector addition to the above field of a supplemen- 

 tal velocity whose direction is parallel to that of the storm and 

 whose magnitude depends only upon it . The resulting modified 



values of V and V are used to compute the wind-stress 



x y 

 components : 



74 



