Microphysical Evolution Throughout the Unprecedented Short-Term Heavy Precipitation Caused by Typhoon Haikui (2023)

Typhoon Haikui (2023) brought an unprecedented rainstorm to Fuzhou, with a rainfall record of 360.4 mm in 12 hr and an instantaneous rain rate of 234 mm hr⁻¹. This study investigates the evolution of precipitation microphysics during this short-term period. High rain rates exceeding 100 mm hr⁻¹ along with large mass-weighted diameter D_m were predominantly observed in the first 3 hr (Stage I), while the next 9 hr (Stage II) experienced less than 100 mm hr⁻¹. At the onset of Stage I, it is warm-cloud processes that mainly contributed to the increased rain rate, yet the rain rates hardly exceeded 200 mm hr⁻¹. Approximately 1 hr later, a rain rate of 234 mm hr⁻¹ occurred due to a joint contribution of ice- and warm-cloud processes, characterized by the increased horizontal reflectivity throughout the troposphere. Moreover, this study provides a new insight into the correlation between rainfall intensity and convective intensity.