Evaluation and modification of JONSWAP spectral parameters in the Persian Gulf considering offshore wave characteristics under storm conditions

摘要

Some efforts have been done by previous researchers and scientists to represent the spectral behavior of wind waves in the Persian Gulf by analyzing real-time data, but in most of them, only wave data collected from nearshore stations with water depths of 25 m or less were considered. Therefore, in order to consider offshore wave characteristics of the region, a 5-month wave data through a mooring buoy around Farzad A natural gas field, at a water depth of 45 m, was collected and analyzed. Spectral analysis of offshore measured data along with the previous spectral analyses of coastal wave stations revealed that the wave spectra in the Persian Gulf are mainly single-peaked during all stages of the storms considering the possible uncertainty existing in the shape of wave spectrums depending on storm stage and can be represented by JONSWAP spectrum model using the newly proposed modified key parameters (i.e., Phillip's constant and peak-enhancement parameters). In addition, the spectral behavior of waves during various stages of extreme events/storms showed that the mean values of the key parameters for growing and developed portions of the storms are slightly different from the traditionally recommended values for the JONSWAP parameters, while the estimated average values of decaying portions are considerably different from generally utilized values.