Investigation of wave spectral climate at key location of the Northern South China sea using a novel modeling framework

Abstract

Wave spectral climate explains the complexity of local marine environments. The dynamic variations of dominating wave components hamper wave spectral climate analysis, necessitating a precise modeling of climatic wave spectra. In this study, wave spectral datasets are constructed using WavewatchIII for the key location of the Northern South China Sea (NSCS-K). By the improved watershed algorithm, the datasets were classified into five distinct spectral classes, namely wind systems (ClassI), swell systems (ClassII), wind and swell systems (ClassIII), two swell systems (ClassIV), and complex multipeak systems (ClassV). The transformational patterns of wave systems in NSCS-K are revealed using a Markov chain approach. The main spectral class data are modeled by spectrum models. It is found that ClassI (64.80 %) and ClassIII (20.37 %) are the dominant ones in NSCS-K. In addition to the intra-spectral transformations that exceed 85 % in each class, the transformation from ClassI to ClassIII and ClassII to ClassIV deserves to be noticed, with a proportion of 6.66 % and 9.65 %, respectively. The JONSWAP spectrum model provides the most optimal applicability for ClassI, with γ typically between 1.8 and 2.2. For ClassIII, the Ochi-Hubble spectrum model achieves an accurate representation with λ₁ mostly in 2.0–2.5 and λ₂ mostly in 1.5–2.0.