West and Galveston stations have enough information for the actual 

 computation of the tide. Therefore, at each station, only the mean 

 water level during the period considered, excluding the peak surge, 

 was removed from the raw data. Thus the recorded hydrographs which 

 are compared to those computed contain the tidal signal, but its 

 amplitude is small and does not unduly complicate the comparison. 



4. Simulation procedure 



The initial model wind and pressure fields were increased in 

 amplitude linearly from zero to their actual initial values over a 48 

 hour prototype time period. During this period Car la was kept 

 stationary at 19.04°N and 85.15 W which was its position at 1200 GMT 

 6 September. The simulation was carried out to 0000 GMT 13 

 September, approximately 28 h after landfall. 



The simulation for hurricane Allen starts at 0000 GMT 7 August 

 and ends at 0000 GMT 12 August. The initial position of the eye of 

 hurricane Allen during start up- was at 20.10 N and 81.90 W. 



At each time step the east and north component of wind stress 

 and the atmospheric pressure (the inverted barometric height) were 

 computed at each grid point. The sequence of wind and pressure 

 computations consisted of two linear interpolations. First, the 

 position of the eye and the other parameters at each time step were 

 linearly interpolated from two appropriate sets of values (6 h 

 apart) . The radial distance from the eye to each individual grid 

 point (I, J) was computed. The inverted barometric height was then 

 computed from (74). The angle between the line joining the eye to 



58 



