plots of each field data time series analyzed with the MRS program and the 

 synthesized time series obtained by recombining the constituents are included 

 in Appendix B. Each field record with the corresponding synthesized record is 

 shown together on a single page for a visual comparison. The vertical eleva- 

 tion scale is meaningful for relative elevations in a record but not in an 

 absolute or mean sense. 



2. Wave Groups . 



The LVTS (eq. 26), described previously, was computed and processed for 

 records from the three sites. The record lengths used are 1,024 seconds for 

 Columbia Light and 1,200 seconds for South Haven and South Pass. Major peaks 

 and valleys from the LVTS are plotted versus time in Appendix E. The magni- 

 tude of the peaks and the time between peaks are erratic. The modulation 

 period 



mod 



1 



ef. 



(35) 



and the variance of the original time series, a^, are shown to scale on each 

 plot for reference. 



The grouping parameter, G (eq. 29) is listed with each plot in Appendix 

 E. The range of grouping parameters is comparable at all three sites. Group- 

 ing parameters are also given in Table 4, including G values from a larger 

 sample of data from Columbia Light and South Pass. 



Individual wave heights were estimated by the procedures described in the 

 previous section for all three sites, using 1,024-second records for Columbia 

 Light and 1,200-second records for South Haven and South Pass. The autocor- 

 relation between heights (eq. 30) is given in Table 5 for up to three lags. 

 Autocorrelations are generally greater than zero at the first lag and are 

 in most cases highest for South Haven. Very few of the records show any evi- 

 dence of positive autocorrelation beyond the first lag. The autocorrelations 

 between periods (eq. 31) and between amplitudes (eq. 32) are given in Tables 

 6 and 7 for the three sites. There is little evidence of autocorrelation 

 between wave periods. 



The height of the highest single wave in each Columbia Light record is 

 plotted in Figure 31 as a function of grouping parameter, G (see eq. 29). 

 Each height is scaled by the significant height for the record, estimated as 

 4a . The largest height, about twice the significant height, coincides with a 

 high value of G. To provide perspective in the figure, the ratio of highest 

 wave height to significant wave height was calculated from the Rayleigh dis- 

 tribution for the exceedance probability 1/N, where N is the number of 

 waves in the record. N was estimated in two ways for each record: (a) the 

 number of individual waves identified, and (b) the record length divided by 

 peak spectral period . The highest and lowest values of N from all records 

 by either of the two estimates are used in the figure to indicate the range of 

 ratios expected from the Rayleigh distribution. Similar plots for the second 

 and third highest wave heights in each record are given in Figures 32 and 33. 



51 



