Seeding invigoration effect of ice-containing clouds on lower convective clouds during MeiYu season in 2020.

Cloud seeding is a process that adjusts cloud physical properties and processes, including both natural and human measures. This study aims to assess the effects of natural ice seeding from upper ice-containing clouds on low convective clouds through in-situ aircraft observations during an Integrative Monsoon Frontal Rainfall Experiment (IMFRE-II) in the summer of 2020. We mainly focus on two distinct shallow convective clouds, one with and the other without upper ice-containing layer, namely Cloud A and Cloud D. The in-situ data demonstrate that snowfall from the upper ice-containing layer to the lower Cloud A, leading to significant changes in cloud top height, median value of radar echo as well as vertical velocity. Compared to shallow convective cloud D without upper-level seeding, cloud A had an approximately 84% less concentration of cloud droplets (diameter <100 μm) and had a slightly smaller cloud droplet effective diameter. For drizzle particles and cloud ice particles with sizes larger than 100 μm, cloud A had a concentration one order of magnitude larger than that of cloud D, also with a larger spectral broadening ratio. These findings reveal the influence of "Seeder-Feeder" effects on microphysical properties of cloud A. The physical mechanisms of Bergeron, riming, and coalescence most likely play a role in the rapid formation of large drizzle/precipitation particles. The natural seeding effect of "seeder-feeder" through snow-virga also likely forms local turbulence, accelerates turbulent entrainment mixing, and promotes the development of the seeded shallow convective cloud. • Ice-containing cloud favors the precipitation formation of convective cloud below. • Ice particles fasten the Bergeron process within low cloud with supercooled droplets. • Evaporation of falling particles helps invigorate the cloud development below. [ABSTRACT FROM AUTHOR]