corresponding numbers from Figure 16 because A^g^j reduces the effect of 

 frequency- dependent broadening of the overall energy which is included in 



A^IDS • 



194. This condition is illustrated by Figure 18, which is a correlation 

 plot of the two directional spread parameters. Figure 18 shows that A^jpg 

 is almost always greater than or equal to A^gw • ^ likely mechanism is 

 refraction which varies from frequency to frequency in some wave fields (see 



Figure 18. Correlation of spectrally weighted directional 



spread parameter with spread parameter of integrated 



direction spectra 



Figure 7) and which smears the directional distribution of the integrated 

 direction spectrum along the direction axis. If the directional spread at 

 each frequency had a constant value, the spectrally weighted spread would have 

 that value since the contribution from each frequency would be the same. If 

 the distributions were offset slightly from frequency to frequency, as happens 

 under refraction, the summing of energy across all frequencies would make the 



78 



