(h) The parameters *λ*j control the shape and the sharpness of the spectral peak of the Ochi-Hubble

spectral model if in either spectral component (i.e., sea or swell) the values of *H*sj and *ω*0j are held constant.

Therefore, *λ*1 and *λ*2 are called the *spectral shape parameters*. On the assumption of a narrow-bandedness

of the entire Ochi-Hubble spectrum, an equivalent significant wave height may be calculated by

2

2

(II-1-158)

Note that for *λ*1 = 1 and *λ*2 = 0, the *PM *spectra may be recovered from this equation.

(i) In shallow water, the wave spectrum deviates from the standard spectra forms presented so far, and

at frequencies above the peak, the spectrum no longer decays as *f*-5. Kitaigorodoskii et al. (1975) showed that

the equilibrium range is proportional to *-3 *power of the wave number, and thus, the form of the spectrum is

of *f*-3 in the high-frequency range. This change is attributed to the effect of water depth on wave spectrum

and to the interaction between spectral components. Bouws et al. (1984) proposed a variation to the

the product of *JONSWAP *and the *Kitaigorodoskii depth function *accounting for the influence of the water

depth, is called the *TMA spectrum *after the names of three sources of data used in its development (Texel,

Marsen, and Arsloe).

Water Wave Mechanics

II-1-91

Integrated Publishing, Inc. |