Fetch Dependencies of the Spectral Parameters of the Wind-Waves in the Eastern Black Sea

Abstract

Fetch dependencies of spectral parameters have been studied since 1960s by a number of researchers in various parts of the world. Non-dimensional variables combining energy, frequency and fetch are used to represent fetch limited growth of waves under steady wind conditions. In the present study, in situ measurements carried out in the Eastern Black Sea at three locations (Sinop, Hopa, Gelendzhik) were used to obtain the fetch dependencies of wind-waves. First, the developing sea records were identified analyzing the 1-D spectra. Then, these records were further investigated for identifying the data that belonged to developing sea generated by stable wind conditions. Since the wind conditions were not measured simultaneously while carrying out the wave measurements, ECMWF analysis wind fields were utilized as the wind information corresponding to the records. Rather rigid criteria were applied for the wind direction and the wind speed for the identification process. Fetch dependencies of dimensionless spectral variables (variance, peak frequency) and JONSWAP parameter a were investigated. Consistent with the previous studies, dimensionless energy is found to increase with dimensionless fetch while dimensionless peak frequency and a decrease at three locations. Scatter in the values of a and energy is high but it is relatively low for peak frequency. Also, mean parameters of the JONSWAP model spectrum were given for this data sub-set.