This study presents measurements of the initial cloud‐base droplet spectra of seeded and unseeded clouds observed during the Queensland Cloud Seeding Research Program field campaign. The measurements were stratified by the aerosol regime that the cloud formed within, and then analyzed statistically as well as compared to parcel model simulations. Initial droplet spectra were obtained within 300–600 m of cloud base to identify the spectra resulting from nucleation and to avoid effects from collision‐coalescence broadening processes. The goal of this study is to assess the impact of hygroscopic flare seeding on cloud‐droplet growth as a first step toward understanding the effect of hygroscopic seeding on rainfall. Results indicate that initial droplet spectra are altered by seeding, such that the mean diameter and tail of drops larger than 20 µm increased in seeded clouds within a given aerosol regime. This effect is most pronounced in the continental‐influenced aerosol regime, that generally lacked coarse mode aerosols, but was also observed to occur in the maritime‐influenced regime. To further investigate if the observational results were supported by theory, a parcel model was used to improve the process‐level understanding of the seeding impact on the initial evolution of the droplet spectra. The simulated results qualitatively agree with the observations that noted the seeding effect is more prominent in the continental‐influenced regime.

中文翻译：

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吸湿性火炬播种对昆士兰东南部液滴粒径分布的影响

这项研究提出了在昆士兰州云种研究计划野外活动期间观察到的种子和非种子云的初始云基液滴光谱的测量结果。通过在其中形成云的气溶胶状态对测量进行分层，然后进行统计分析以及与包裹模型模拟进行比较。最初的液滴光谱是在云底的300–600 m范围内获得的，以识别由成核产生的光谱，并避免碰撞-聚结扩展过程的影响。这项研究的目的是评估吸湿性火炬播种对云滴生长的影响，以此作为了解吸湿性播种对降雨的影响的第一步。结果表明，初始的液滴光谱会因播种而改变，因此，在给定的气溶胶范围内，播种云中大于20 µm的液滴的平均直径和滴尾会增加。这种影响在受大陆影响的气溶胶体系中最为明显，该体系通常没有粗糙模式的气溶胶，但在受海洋影响的体系中也观察到了这种效应。为了进一步研究观察结果是否得到理论的支持，使用了包裹模型来提高过程水平对种子对液滴光谱初始演化影响的理解。模拟结果在质量上与观测结果一致，该观测结果表明播种效应在受大陆影响的地区更为突出。但也观察到发生在受海事影响的政权中。为了进一步研究观察结果是否得到理论的支持，使用了包裹模型来提高过程水平对播种对液滴光谱初始演变影响的理解。模拟结果在质量上与观测结果一致，该观测结果表明播种效应在受大陆影响的地区更为突出。但也观察到发生在受海事影响的政权中。为了进一步研究观察结果是否得到理论的支持，使用了包裹模型来提高过程水平对种子对液滴光谱初始演化影响的理解。模拟结果在质量上与观测结果一致，该观测结果表明播种效应在受大陆影响的地区更为突出。