The last three parameters in the table were added at CERC to the basic 

 parameter files provided by SIO. The number of major peaks in the short wave 

 spectrum was computed by a procedure similar to that of Thompson (1980). 

 Peaks were considered major if their energy density differed from that of the 

 intervening low point by at least 3 percent of the total energy. Amplification 

 factors for long and short waves were defined as 



( H <ln n „ ) 



am p J. 



sjong 'harbor gage 



( "s,long X 



long * array 



^ s 'harbor gage 



(l) 



Table 3 



Field Wave Parameters 



Description 



Symbol 



Year, month, day, hour, minute 





Significant wave height, long waves 



H sjcr, 



Peak wave period, long waves (greater than 29 sec) 



'pjong 



Significant wave height, short waves 



H s 



Peak wave period, short waves (3-25 sec) 



T, 



Incident wave direction, short waves 



6m 



Long-term average depth at Back Basin 





Mean depth over record length at Back Basin 



n 



Number of major peaks in short wave spectrum 



", 



Amplification factor, long waves 



AmpJ 



Amplification factor, short waves 



A 



n amp£ 



Estimation of T p 



The traditional procedure for estimating T p for wind waves and swell was 

 modified in this study to obtain better resolution in the swell periods. Peak 

 period is normally calculated as the reciprocal of the frequency at the midpoint of 

 the highest energy spectral band. This is a standard, widely accepted procedure. 

 The resolution with standard 0.01 -Hz spectral bands is sufficient to give a good 

 estimate of peak period over most of the possible frequency range, but it is rather 

 coarse for the longer swell periods. The standard procedure imposes some 

 limitations on the Kahului Harbor study for the following two reasons: 



a. Much of the wave energy at Kahului Harbor, including cases of greatest 

 interest, is long period, low frequency swell. 



16 



Chapter 2 Field Wave Measurements 



