  New parameterizations for the spectra dissipation of wind-generated waves are
proposed. The rates of dissipation have no predetermined spectral shapes and
are functions of the wave spectrum and wind speed and direction, in a way
consistent with observation of wave breaking and swell dissipation properties.
Namely, the swell dissipation is nonlinear and proportional to the swell
steepness, and dissipation due to wave breaking is non-zero only when a
non-dimensional spectrum exceeds the threshold at which waves are observed to
start breaking. An additional source of short wave dissipation due to long wave
breaking is introduced to represent the dissipation of short waves due to
longer breaking waves. Several degrees of freedom are introduced in the wave
breaking and the wind-wave generation term of Janssen (J. Phys. Oceanogr.
1991). These parameterizations are combined and calibrated with the Discrete
Interaction Approximation of Hasselmann et al. (J. Phys. Oceangr. 1985) for the
nonlinear interactions. Parameters are adjusted to reproduce observed shapes of
directional wave spectra, and the variability of spectral moments with wind
speed and wave height. The wave energy balance is verified in a wide range of
conditions and scales, from gentle swells to major hurricanes, from the global
ocean to coastal settings. Wave height, peak and mean periods, and spectral
data are validated using in situ and remote sensing data. Some systematic
defects are still present, but the parameterizations yield the best overall
results to date. Perspectives for further improvement are also given.
