Abstract: This study focuses on Typhoon Doksuri in 2023, which intensified in the northern South China Sea before entering the Taiwan Strait from its southern end. An atmosphere-wave-ocean fully coupled model is employed to simulate the super typhoon passing through the Taiwan Strait. Simulation results are effectively validated through comparisons with multi-source observations, including buoy and remote sensing measurements. Based on model outputs, variation characteristics of wind, waves, and ocean currents in the Taiwan Strait under the typhoon influence are investigated.
Results show that when the typhoon is approximately 1000 km away from the Strait, strong northeasterly winds exceeding 15 m·s^-1 emerged in advance along coastal waters of Fujian and the northern tip of the Taiwan Island. The current direction within the Strait reverses to southwestward, with velocities reaching 1.2 m·s^-1. Significant wave height increases from 1 m to 5 m at both ends of the Strait, with a notable dominance of swells, which exhibites a swell wave height of 3 m and wind-wave directional components at angles of 60° and 90°-135°.
Upon entering the Taiwan Strait, the typhoon’s core tightens due to the channeling effect. Southerly winds within the right quadrant are obstructed by mountainous terrain, resulting in two distinct high-wind-speed zones within the Strait. Under the influence of strong winds, current velocities increased to 2.5 m·s^-1, while the significant wave height reaches up to 10 m, primarily consisting of wind waves. However, the wave magnitudes within the Strait remains smaller than those observed under comparable wind conditions in open sea. This may be attributed to the topography of the Taiwan Island, which fragments the wind field and shortens the fetch, thereby inhibiting wind-wave development. Additionally, the main component of typhoon-generated waves, swell waves, cannot propagate into the Strait.
Following the typhoon’s landfall, the southwesterly winds prevails over the Taiwan Strait, and currents revert to a northeastward direction. Due to combined effects of pressure gradients and tidal forces, current velocities intensify to 2 m·s^-1 near the northern tip of the Taiwan Island. These findings provide a crucial scientific basis for enhancing disaster prevention and mitigation measures, as well as ensuring the safety of marine engineering operations in the region.