Characteristics of Convective Clouds During an Autumn Heavy Rainstorm in Sanya

Yin Qun; Zhu Mei; Feng Jie; Jing Qi; Fang Mian; Sheng Lifang

doi:10.16765/j.cnki.1673-7148.2024.06.002

Abstract：Based on hourly precipitation data,ERA5 reanalysis data and Himawari-8 satellite data,the physical characteristics of convective clouds in the heavy rainstorm that occurred on October 18,2020 in Sanya are analyzed.The results show that the interaction between the strong Intertropical Convergence Zone in the South China Sea and the southward continental high pressure,and low-level easterly jet stream,provided favorable dynamic and moisture conditions for the occurrence of the heavy rainstorm.The mesoscale convective clouds moved westward under the guidance of the easterly jet,resulting in two periods of heavy rainfall in Sanya.The brightness temperature difference between infrared window chan-nel and water vapor channel of the convective clouds could effectively reflect rainfall intensity.When the precipitation intensity exceeded 20.0 mm·h-1,there was a bright temperature reversal phenomenon with a brightness temperature difference less than 0 ℃.The correlation of the cloud top height and cloud opti-cal thickness with rainfall intensity was superior to the correlation between cloud top temperature and rain-fall intensity,while the correlation between cloud particle effective radius and rainfall intensity was poor.When the cloud top temperature was-67.9 ℃,the cloud top height was 15.1 km and the cloud optical thickness was 114,the rainfall intensity exceeded 20.0 mm·h-1.The important features obtained by in-depth analysis of the brightness temperature and cloud characteristic parameters of mesoscale convective cloud clusters in a favorable large-scale circulation background could provide a reference basis for short-time nowcasting and early warning of severe convection weather.