Comparative analysis of precipitation differences in the similar LMCS rainbands at the rear of two typhoons landing in Fujian

Typhoon Doksuri (2305) and Gaemi (2403) penetrated northern Jiangxi after landing in Fujian, with their trailing edges forming linear mesoscale convective systems (LMCS) along the Fujian coast. Although the two LMCS rainband shapes were extremely similar, their resulting precipitation intensities differed significantly. Basing on the ground automatic meteorology stations data, three-dimensional lightning data, dual-polarization radar data, wind profiler radar data and ERA5 reanalysis data, the differences in precipitation intensity, lightning activity, microphysical structures of precipitating clouds and precipitation formation mechanisms on the two similar rainbands were comparative analyzed using statistical and diagnostic methods in this paper. The results are as follows. (1) Both LMCS cases are characterized by large accumulated precipitation, long duration, obvious heavy rainfall occurring nighttime, rainfall intensity extreme high, backward propagation of rainfall echoes and precipitation train effects. But heavy rainfall in LMCS of Typhoon Doksuri is more extreme. (2) Over the strong rainfall intensity of the LMCS rainbands, Typhoon Doksuri exhibites active cloud flashes with pronounced characteristics of severe thunderstorms, while Typhoon Gaemi show sparse cloud flashes activity and displays features of weak thunderstorms. (3) The vertical structure characteristics of cloud microphysics show: In the heavy rainfall upper air of Typhoon Doksuri, the strong convective core of strong echo is above the 0 ℃level. The dual-polarization HCL product shows that the solid-liquid mixture particles are the main dominant factor above and below the 0 ℃level, which is a non-warm cloud aggregation collision and growth process, and characteristic is similar to the continental convective precipitation.To Typhoon Gaemi, the strong convective core of strong echo is below the 0 ℃level, and liquid rain droplet particles are the main dominant factor, which is a warm cloud microphysical growth process, and this characteristic is consistent with the of tropical oceanic convective precipitation. (4) The key factor for the difference in the accumulated precipitation lies in the fact that the atmospheric vertical motion of Typhoon Doksuri LMCS case is stronger and lasts longer and the former has a significantly higher concentration of particles than the latter, resulting in a significant increase in rainfall intensity. The dual-polarization parameters Z_H≥52 dBz, Z_DR>2.5 dB, K_DP>1.6 (°)∙km⁻¹ and a duration of more than 30 min can be used as a reference for 100 mm∙h⁻¹ rainfall intensity forecasts.