Enhanced storm surge simulations in Hong Kong coastal waters an atmosphere-wave-circulation coupled model under the earth system modeling framework

Abstract

Storm surges pose serious threats to densely populated coastlines and demand accurate forecasting. This study develops a fully coupled wind–wave–circulation forecasting system for Hong Kong coastal waters within the Earth System Modeling Framework (ESMF). The system integrates the Weather Research and Forecasting (WRF) model for atmospheric forcing, the Simulating Waves Nearshore (SWAN) model for wave dynamics, and the Finite-Volume Community Ocean Model (FVCOM) for ocean circulation. Validation against tide-gauge records for five typhoons, Hato (2017), Mangkhut (2018), Higos (2020), Kompasu (2021), and Saola (2023), shows that the coupled system consistently outperforms both an uncoupled ocean model and a wave–current coupled model. It achieves domain-averaged root-mean-square errors (RMSEs) of about 0.10 m, reduces errors by 31%–61% across events, and maintains high correlation coefficients (CCs). Peak surge timing generally follows north-westward storm tracks but displays irregular inter-station lags, reflecting complex local hydrodynamics. The largest improvements occur in semi-enclosed bays such as Tolo Harbour, where RMSE reductions of 0.10–0.16 m underscore the importance of wave setup, sea-state-dependent wind stress, and current–wave feedbacks. Overall, the findings confirm that full coupling is essential for reliable surge prediction in complex coastal environments, and the achieved accuracy supports near-term operational application. Remaining challenges include sensitivity to atmospheric forcing and computational demands, though advances in high-performance computing and hybrid physics–AI approaches offer promising solutions.

Graphical abstract

Keywords

storm surge / water level / WRF-SWAN-FVCOM coupled model / ESMF / Hong Kong coastal waters

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