computed from (72). 



Attempts were made to obtain a simple expression for both k and 

 Wjjj as a function of the azimuthal angle (measured from the north) 

 such that these two parameters could be internally computed. 

 However, no simple relationship could be established due to the 

 complexities of the patterns of azimuthal variation of k and Vl^ 

 which, in addition, varied irregularly for each map time. Therefore, 

 these parameters have to be specified serially. Furthermore, linear 

 interpolation in time to obtain these parameters for intermediate 

 time step computations constrained the values to the same set of 

 azimuths (relative to heading) throughout the simulation period. As 

 a result, an a priori linear interpolation in space was employed to 

 get k and Wj^ as continuous functions of azimuth. A standard set of 

 azimuths was then selected. 



Finally, the surface wind fields for each map time were 

 constructed using the interpolational routine employed in the model. 

 Comparison between the computed and observed wind fields was made and 

 final adjustments of k, if necessary, were decided. Figures 10 and 

 11 are examples of the computed wind fields at 0000 GMT 7 September 

 and 1200 GMT 9 September, respectively. The solid circles indicate 

 the observed wind speed from the surface charts. 



b) Surface wind for hurricane Allen 



The inadequate coverage in both space and time of surface wind 

 charts for hurricane Allen aborted attempts to fully analyze these 

 charts as practiced in hurricane Car la. Therefore, NWS-23 was used 



46 



