Characteristics of Typhoon-Induced Wave Fields in the Beibu Gulf Under Different Typhoon Track Types

Typhoons frequently affect the Beibu Gulf under the present climate regime. Owing to its complex geographical setting, typhoon-induced waves in the gulf exhibit pronounced regional variability. Their spatial distribution and spectral evolution are largely controlled by typhoon tracks. Therefore, it is necessary to establish a regional classification of typhoon wave characteristics in the Beibu Gulf. This classification should be based on typical typhoon tracks and topographic effects, aiming to support refined typhoon hazard prevention and mitigation. In this study, three typical typhoon tracks were considered: type Ⅰ (westward-moving typhoons crossing the Qiongzhou Strait and the Leizhou Peninsula), type Ⅱ (westward-moving typhoons crossing Hainan Island), and type Ⅲ (northward-moving typhoons). Typhoon events representing these tracks were simulated using the COAWST model (Coupled ocean-atmosphere-wave-sediment transport). The spatiotemporal variability of wave parameters and spectral characteristics within the Beibu Gulf was examined. The results show that the locations of maximum wave height vary substantially among the three track types. Type Ⅰ mainly affects the northern gulf. Type Ⅱ affects the central and eastern regions. Type Ⅲ affects the central and western regions. Hainan Island and the Leizhou Peninsula act as effective barriers to swell propagation for type Ⅰ and type Ⅱ typhoons. Wave spectral evolution is jointly influenced by the relative position of the typhoon and local bathymetry. Directional spreading is broader on the left side of the track than on the right, while shallow-water regions exhibit larger variations in peak frequency and directional spreading than deep-water areas. In nearshore zones, wave energy attenuation is controlled by both wind direction changes and the angle between wave propagation and the coastline. Typhoon-induced waves associated with northward-moving tracks (type Ⅲ) show a more pronounced offshore swell component. Wave spectral characteristics are strongly correlated with the distance from the typhoon center. Bimodal spectra occur at approximately 4R for type Ⅰ typhoons and 3R for type Ⅱ and typeⅢ typhoons, where R denotes the radius of maximum wind. These bimodal spectra are typically observed in nearshore shallow waters or within the left quadrant of the storm.