The development of a high-resolution regional ocean –atmosphere forecast system for the East Asia and western North Pacific

Accurate prediction of weather and climate conditions is vital for ensuring the safety of human environments. In this study, we developed a regional air-sea coupled weather forecasting model and conducted a preliminary evaluation of its performance concerning basic variables such as precipitation, typhoons, and 10-meter wind fields. The forecasting system covers the region from 15° to 40°N latitude and 108° to 146°E longitude, utilizing the Weather Research and Forecasting Model (WRF) for atmospheric components and the Regional Ocean Modeling System (ROMS) for oceanic components, integrated via the National Center for Atmospheric Research Coupler version 7 (CPL7). The system operates at a horizontal resolution of approximately 3 km. We performed daily rolling 96-hour forecast experiments, starting at 00:00 each day from January 1, 2024, to December 31, 2024. The results indicate that the annual mean rainfall root mean square error (RMSE) for the entire region is 13.7 mm/day for a 24-hour forecast and 16.3 mm/day for a 96-hour forecast. Spatially, the RMSE is generally smaller in the northwest land area of the region (inland China) compared to the ocean, with notably larger RMSE near Taiwan and the Philippines due to higher average precipitation in these areas. Southern Japan also exhibits relatively large RMSE values. The forecast skill demonstrates significant seasonal variation, with higher RMSE in summer compared to winter. For typhoon forecasts, the mean error distance is 74.1 km for 24–48 hours and 118.9 km for 48–72 hours. The RMSE of 10-meter wind over the oceans shows similar patterns to rainfall, with an annual mean RMSE of 1.5 m/s for a 24-hour forecast and 2.5 m/s for a 96-hour forecast.