| Abstract: | The paper concentrates on the evolution of a spectrum of short wind waves (SW) along the profile of a long surface wave (LW).
Short wave spectral variations are considered in the relaxation approximation. The SW spectrum is modulated by the orbital
velocities of long waves and by the variations of wind stress along the LW profile. The latter effect occurs due to wind flux
perturbations induced by both the long wave proper and variations of the sea surface roughness induced by the SW modulations.
To describe this effect, a feedback mechanism is introduces—the growth of energy of short waves results in the larger roughness
of the sea surface, thereby contributing to the local wind stress, which facilitates, in turn, the growth of short waves.
With moderate and strong winds being involved, this effect (aerodynamic feedback) is shown to be dominant in the short wave
spectrum modulation. The mechanism becomes more efficient with intensification of the wind and decreasing of the long waves'
frequency. Results of model calculations are in agreement with the known experimental data.
Translated by Vladimir A. Puchkin. |
