First Study on Air-Sea Coupled Ensemble Prediction for the Guangdong-Hong Kong-Macao Greater Bay Area

The Guangdong-Hong Kong-Macao Greater Bay Area (GBA) is situated along the southern coast of China and hence susceptible to hazards brought about by the passage of tropical cyclones (TC) including high winds, torrential rainfall and storm surge. Often in an operational setting, the prediction of atmospheric and oceanic phenomena is based on separate model systems, where the atmospheric model provides forcing to its oceanic counterpart in an offline manner. To represent the flow of forecast uncertainties from the atmospheric to oceanic state also calls for an ensemble-based approach. This paper presents a first study on air-sea coupled ensemble prediction for GBA using an experimental online coupling configuration involving a regional Mesoscale Ensemble Prediction System (MEPS) for the atmosphere together with corresponding ocean and wave model components. Preliminary findings from a high-impact TC case indicate that the experimental coupled ensemble is able to retain the atmospheric prediction skills of the MEPS while additionally providing useful indications of changes in the oceanic state. Results can potentially inform the development of multi-hazard prediction technology for high-impact weather over GBA.