Ensemble sensitivity analysis and k-means clustering of intense coastal rainfall dynamics during TAHOPE-IOP3

Abstract In this study, the features and mechanisms characterizing a heavy rainfall event associated with the Mei-Yu front near the coast of Taiwan on June 7, 2022, were examined through ensemble simulations. Additionally, the correspondence between favorable environmental conditions and heavy precipitation in ensemble simulations was assessed to verify the relationships among the primary factors contributing to precipitation. The study performed ensemble sensitivity analysis (ESA) to capture the relationship between precipitation and dynamic and thermodynamic fields, and it classified ensemble members on the basis of similarities in precipitation or model variables through k -means clustering. ESA revealed wind and water vapor features as crucial drivers of heavy rainfall near the coast. The clustering process effectively separated members with higher rainfall amounts and favorable rainfall conditions from those without such conditions. The large-scale frontal system and mesoscale dynamic processes both contributed to the heavy rainfall along the coast.