A Reanalysis of the Spectra Observed in JONSWAP

Abstract

The frequency spectra of wind-driven waves observed during JONSWAP are reanalyzed to establish whether the Toba formulation for the high-frequency tail (∼f⁻⁴) fits the data better the Phillips formulation (∼f⁻⁵) used originally in the JONSWAP project. The results indicate that the f⁻⁴ tail provides a statistically better fit to the observed spectra. The proportionality factor in Toba's spectrum, which is theoretically expected to be a universal constant, is found to be uncorrelated with the growth stage of the waves. There is a relatively large scatter in the observed values, which can partly be ascribed to the influence of tidal currents.