A new method for calibration of unidirectional double-peak spectra

Abstract

This study aims at presenting a new approach in calibrating standard two-peak design spectra for specific regions in absence of wind data. The main principle in these kinds of fitting for a new area is to minimize the least square error between measured and fitted spectra and there has been less attention to double-peak spectra individual characteristic as co-existence of wind-sea and swell parts in one spectrum. Here, separation frequency, approximately dividing such parts, is implemented to virtually extract wind-sea and swell components of a measured spectrum considering their intrinsic overlap near the separation frequency. Then, they have been easily utilized to calibrate two parts of standard double-peak spectrum in a revisory manner. To verify benefits of this new methodology, it has been applied on Ochi-Hubble as well as Torsethaugen spectra regarding field measurements in a coastal region at Gulf of Oman, Chabahar bay. Results obviously show a better adjustment of formula to field spectrum using this simple approach when compared with output of calibration on integrated field spectrum irrespective of its main characteristic such as availability of two-wave systems.

Analysis of Unidirectional Wave Spectral Characteristics in the Northeastern Waters of Taiwan

“…Another approach involves using a Gaussian spectrum to describe the primary component and JONSWAP to describe the secondary component [31]. The widely used bimodal spectrum is the Ochi-Hubble spectrum with six parameters, capable of separately describing swell spectra from distant sources and wind wave spectra generated by local wind fields, effectively capturing wave conditions during typhoon storm surges [32][33][34].…”