the true wave spectrum. From the above lengths of record., one can 

 compute that each spectral estimate has 174 degrees of freedom so 

 that the dashed curves above and below" the solid curve show the upper 

 95 percent and the lower 5 percent confidence bands for portions of 

 the spectrum where it is not rapidl^r varying. The bounds are prob- 

 ably quite a bit broader at the point k = 10. Stated another way, 

 the true spectrum would lie between the bounds shov/n for nine points 

 out of ten, where it is not varying too rapidly, given that it could be 

 determined from a much larger record under which conditions were 

 stationary. 



Comparison with the Neumann Spectrum 

 This spectrum was compared with the theoretical spectrum de- 

 rived by Neumann [1954] in two different ways. The first was by 

 plotting the theoretical Neumann spectrum against the observed 

 spectrum, and the second was by computing the co-cumulative 

 spectrum. 



The comparison of the spectrum was obtained by evaluating 

 the Neumann spectrum with dimensions of ft -sec for a set of dif- 

 ferent wind speeds at the frequencies given by \i = 2Trk/96 and multi- 

 plying by 2it/96 with dimensions of sec"-^ to get an estimate of the 

 AE value with dimensions of ft between \i = 2T!-{k --j)/96 and 



jjL = 2iT(k +-^)/96. The quantities are thus directly comparable. 



136 



