As part of the Coastal Data Information Program sponsored by the U.S. 

 Army Corps of Engineers and the California Department of Boating and Water- 

 ways, SIO maintains a slope array wave gage in water approximately 26.9 ft 

 deep just offshore of Bolsa Chica (SIO reports the gage depth as 8.2 m) . This 

 wave gage has been in place since November 1980, and the longest period of 

 continuous data 27 months from February 1981 to May 1983. The next longest 

 continuous record contains 14 months of data (June 1986 to August 1987). 

 These two continuous records were combined to obtain a continuous 3 -year time 

 history of significant wave height, incident angle, and wave period at 6 -hour 

 intervals. The 3-year time history of wave conditions was compiled in a 

 manner that preserved the normal progression of the seasons. 



The next step in the examination of the wave data was to compare the 

 statistics of the available data sets at the stations of interest (MA hindcast 

 Station B, NMC hindcast Station 7, two LEO stations (Bolsa Chica and Hun- 

 tington Beach) , and the SIO wave gage at Sunset Beach) . Because the shoreline 

 change model uses a time- step procedure to calculate shoreline change, only 

 the LEO data and the gage data could be easily adapted. The gage data set was 

 the preferred data set because it provides a 17 -minute statistical and 

 objective summary at 6 -hour intervals (the time step typically used in the 

 shoreline change model). Alternatively, the more approximate and subjective 

 LEO data sets could have been used, but the observed wave conditions would 

 have been required to be assumed to persist for the entire day (4 time steps). 

 Therefore, the intent of the comparison was to verify the preferred data set 

 (the SIO gage data) in terms of representative wave statistics. 



The wave data for the five stations were transformed to a depth of 

 26.9 ft (the depth of the SIO gage) using linear wave theory refraction and 

 shoaling in order to compare the distribution of incident wave angles between 

 the data sets. Wave roses of incident angles were computed for each of the 

 stations. Comparison of the SIO gage data with the two LEO stations and MA 

 Station B hindcast revealed a distinct reduction in the variability of 

 incident wave angles in the gage data. In fact, the gage data show nearly 

 twice the percentage of waves occurring in the southwest (directly offshore 

 direction) angle band than any of the other stations. Additionally, the LEO 

 stations and MA Station B hindcast data sets have approximately 15 percent 



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