SOME FEATURES OF WIND WAVES IN LAKE MICHIGAN

Abstract

Sets of simultaneous data of wind profiles and surface waves recorded in Lake Michigan during fall 1965 facilitated a detailed study of generation and decay aspects of wind waves. A logarithmic wind profile, fitted to data measured simultaneously at 3 or 4 anemometer heights, appears to be satisfactory. From the parameters of frictional wind velocity and roughness element computed from the logarithmic wind profile, the spectral growth of waves according to recently developed theoretical models of wave generation was predicted. The energy spectra of measured waves indicate that wave energy growth rate is, as predicted, exponential with respect to time but is 8 times larger than the predicted rate. The decay of wave spectra at a single location was qualitatively examined. The peak frequency either increased or remained constant for decreasing spectral energy. The similarity in behavior of wave spectra was demonstrated through normalization which resulted in an empirical equation for wave spectra. The measured equilibrium range in the high‐frequency region of the spectra follows the f−5 rule.