Hl/3 -- average of the highest one- third wave heights using down- 

 DOWN crossing results (meters) 



Hl/10 -- average of the highest one- tenth wave heights using up- 

 UP crossing results (meters) 



Hl/10 -- average of the highest one- tenth wave heights using down- 

 DOWN crossing results (meters) 



Hmax -- maximum wave height using upcrossing results (meters) 

 UP 



Hmax -- maximum wave height using downcrossing results (meters) 

 DOWN 



41. The mean water surface elevation measurements (relative to NGVD) 

 include the effects of both tide and wave setup. The tidally induced mean 

 elevation is assumed to be constant across the surf zone; therefore, the 

 variation in the mean can be assumed to represent changes resulting from the 

 incident wave field. 



42 . The average breaking wave height during a particular run can be 

 determined from Table 4 as corresponding to the photopole having a maximum 

 wave height statistic, for example, the maximum root-mean- square wave height. 

 The location of the average breaking waves is then known to within an interval 

 of plus or minus half the nominal distance between photopoles (± 3 m) . During 

 the runs, visual estimates were also made of the average position of the 

 breakers; good agreement was found between the visual estimates and the 

 position inferred from the photopole record. 



31 



