The onshore-offshore components are computed by taking the sine of 

 the wind azimuth, with a 10° correction for the shoreline orientations, 

 multiplied by the wind velocity. Winds blowing onshore, or between 350° 

 and 170°, will result in positive sine values, while offshore winds be- 

 tween 170° and 350° will result in negative components. Ideally, where 

 wind velocity is constant, the highest positive or onshore value would 

 be for a wind azimuth of 80° (sine = 1) , whereas the highest offshore or 

 negative value would be for an azimuth of 260° (sine = -1). 



Alongshore wind components may be determined by taking the cosine of 

 the wind direction multiplied by the wind velocity. Wind-direction meas- 

 urements between 260° and 80° will have a positive sign or a northerly 

 alongshore component, whereas winds between 80 and 260 will have a 

 negative or southerly component. The maximum southerly alongshore com- 

 ponent will occur, with wind velocity held constant, at 170° (cosine 

 = -1), whereas the maximum northerly alongshore component will occur at 

 350° (cosine = +1) . The cosine function was chosen so that the signs 

 for alongshore wind components are consistent with those for breaker 

 angle and longshore current velocity. 



The percentage of the time different windspeeds were measured (in 

 5-mile per hour classes) is shown in the Table. The greater percentage 

 of winds in excess of 10 miles per hour recorded during the winter study 

 period is directly related to the frequent passage of polar high-pressure 

 systems during that period. Wind-direction readings averaged 218° for 

 the summer period and 223° for the winter period. 



Table. Summary of windsp 



^ed measurements, 1971- 



-72. 



Wind velocity (mi/h) 



Pet measured 



Summer 









0.1 to 5.0 



5.1 to 10.0 



10.1 to 20.0 



>20.0 



2.1 

 33.0 

 44.1 

 20.1 



0.7 



Mean velocity: 6.7 mi/h. 

 Maximum recorded: 21.5 mi/h. 



Winter 







0.1 to 5.0 



5.1 to 10.0 



10.1 to 20.0 



>20.0 



3.9 

 36.4 

 19.2 

 31.8 



8.7 



Mean velocity: 8.7 mi/h. 



Maximum recorded: 39.4 mi/h (gusts in excess of 55 mi 



/h). 



18 



