Tropical cyclone-induced storm surges and continental trapped waves (CTWs) significantly impact coastal marine environments and lead to hazard risks. In the study, storm surges and CTWs induced by Super Typhoon Mangkhut (2018) are investigated using a three-dimensional ocean circulation model (ROMS-NSCS) for the northern South China Sea. Tides and storm surges in the NSCS are well simulated by the ROMS-NSCS compared to the TOPEX/Poseidon Global Inverse Ocean Tide Model (TPXO) tidal results and observed sea levels during Typhoon Mangkhut. The model results demonstrate that the pronounced asymmetry in three-dimensional ocean responses is related to the typhoon track. The resonant wind-current interactions amplify near-inertial oscillations on the typhoon’s right side. These oscillations penetrate deeper on the right side of the track (reaching 300 m depth) compared to the left (100 m depth). Nonlinear interaction between tides and storm surges (NTSIs) modulate surge magnitudes regionally. It suppresses peak surges by approximately 10% (− 0.37 m) in direct impact zones, while amplifying residual surges (+ 0.28 m) in remote regions influenced by CTWs, such as the Beibu Gulf (BG). CTWs propagate southwestward at approximately 11.69 m/s and bifurcate at the Qiongzhou Strait (QS). They subsequently converge in the Beibu Gulf (BG), producing dual-peaked sea-level anomalies with secondary surges lagging by about one day. In addition, Typhoon Mangkhut also induced strong ocean current and temperature responses. These findings enhance the mechanistic understanding of compound marine hazards and provide actionable insights for coastal risk mitigation in shallow shelf seas.
Rao et al. (Sun,) studied this question.