The skewness and perhaps the kurtosis of surface elevations in very 

 shallow water can be expected to differ from the values for a normal- 

 ized Gaussian distribution. For the cnoidal wave profile in Figure 

 9, the skewness and kurtosis are equal to 2.0 and 5.8, respectively. 

 The figure also shows the distribution function, skewness, and kurtosis 

 for several idealized wave profiles. 



Wove Profile 



Distribution Function of 

 Seo-Surfoce Eievotions 



q,=-2.o 



Figure 9. Distribution function of sea- 

 surface elevations for several 

 idealized wave profiles. 



Both skewness and kurtosis for the normalized distribution function 

 of sea-surface elevations were computed for each record and are summa- 

 rized in the following section. For the accelerometer-buoy data, the 

 distribution functions represent doubly integrated vertical -surface 

 accelerations rather than directly measured sea-surface elevations. 

 For the pressure-gage data, the distribution functions represent sub- 

 surface pressure fluctuations. 



30 



