Preprints
https://doi.org/10.5194/egusphere-2024-2206
https://doi.org/10.5194/egusphere-2024-2206
14 Aug 2024
 | 14 Aug 2024

Distinct effects of Fine and Coarse Aerosols on Microphysical Processes of Shallow Precipitation Systems in Summer over Southern China

Fengjiao Chen, Yuanjian Yang, Lu Yu, Yang Li, Weiguang Liu, Yan Liu, and Simone Lolli

Abstract. The densely populated South China, adjacent to the South China Sea, which is associated with shallow precipitation during summer, makes it a natural experimental region for studying the impact of aerosols on shallow precipitation events. Using 8 years of GPM DPR, MERRA-2 aerosol, and ERA reanalysis data, this study investigates the potential influence of coarse and fine aerosol modes on the precipitation structure and microphysical processes of shallow precipitation in South China. Statistical results indicate that during coarse aerosol-polluted conditions, shallow precipitation clouds have a lower median Storm Top Height (STH, ~3.2 km), but a higher mean near-surface rainfall (RR, ~1.78 mm h-1), characterized by high concentrations of large raindrops, mainly driven by significant collision-coalescence processes (accounting for 74.1 %). Conversely, during fine aerosol-polluted conditions, shallow precipitation clouds develop deeper median STH ~3.7 km with lower surface RR characterized by a low concentration of small hydrometeors, resulting from increased breakup processes (33.1 %) and reduced collision-coalescence processes (69.6 %). The coarse (fine) aerosols act as promoters (inhibitors) of the radar and radar reflectivity in the profile of shallow precipitation, regardless of dynamic and humid conditions. The effect of coarse aerosols in promoting precipitation and the inhibiting effect of fine aerosols are the most significant under low humidity conditions, mainly attributed to the significantly enhanced collision-coalescence processes, exceeding 22.2 %. Furthermore, the increase in RR above 3 km during coarse aerosol-polluted environments is mainly driven by the high concentration of hydrometeors in low instability conditions, while by large hydrometeors in high instability environments.

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Fengjiao Chen, Yuanjian Yang, Lu Yu, Yang Li, Weiguang Liu, Yan Liu, and Simone Lolli

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2024-2206', Xiong Hu, 29 Aug 2024
    • AC3: 'Reply on CC1', Yuanjian Yang, 26 Oct 2024
  • RC1: 'Comment on egusphere-2024-2206', Anonymous Referee #1, 05 Sep 2024
    • AC1: 'Reply on RC1', Yuanjian Yang, 26 Oct 2024
  • RC2: 'Comment on egusphere-2024-2206', Anonymous Referee #2, 14 Sep 2024
    • AC2: 'Reply on RC2', Yuanjian Yang, 26 Oct 2024
Fengjiao Chen, Yuanjian Yang, Lu Yu, Yang Li, Weiguang Liu, Yan Liu, and Simone Lolli
Fengjiao Chen, Yuanjian Yang, Lu Yu, Yang Li, Weiguang Liu, Yan Liu, and Simone Lolli

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Short summary
The precipitation microphysical mechanisms responsible for the varied impacts of aerosols on shallow precipitation remain unclear. This study reveals that coarse aerosols invigorate shallow rainfall through enhanced coalescence processes, whereas fine aerosols suppress shallow rainfall via intensified breakup microphysical processes. These impacts are independent of thermodynamic environments but are more significant in low-humidity conditions.