Multi-Horizon Significant Wave Height Forecasting Along Guangdong–Hong Kong Coast Using Tropical Cyclone Trajectory Information

Accurate forecasting of significant wave height (SWH) during tropical cyclones (TCs) is important for coastal risk management. This study develops a multi-horizon TC-aware sequence-to-sequence (MH-TCSeq2Seq) framework for 12 and 24 h lead time forecasting at eight Guangdong–Hong Kong stations, utilizing marine and historical TC data as baseline inputs. An enhanced variant integrated with 6–24 h future TC trajectory information (MH-TCSeq2Seq-FutureTC) is further established using retrospective best track data as an idealized upper bound benchmark. Evaluation against the ERA5 reanalysis data shows that MH-TCSeq2Seq-FutureTC achieves the lowest overall root mean square error (RMSE), reaching 0.207 m at 12 h and 0.307 m at 24 h. It reduces the TC-associated RMSE by 9.6% and 7.3% relative to the MH-TCSeq2Seq baseline. Statistical validation confirms the overall robustness of this forecasting improvement across TC events. Adding identical future TC predictors to Quantile Bidirectional Gated Recurrent Unit and TC-gated Bidirectional Gated Recurrent Unit degrades performance, indicating that such benefits are architecture dependent. Replacing these track inputs with operational forecast descriptors from the Automated Tropical Cyclone Forecasting System still reduces the TC-associated RMSE by 6.1% and 4.7% relative to MH-TCSeq2Seq. Interpretability analyses confirm the model’s reliance on future TC information for improving SWH forecasting.