Aerosol impacts on warm-cloud microphysics and drizzle in a moderately polluted environment
Aerosol impacts on warm-cloud microphysics and drizzle in a moderately polluted environment
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中等污染环境下气溶胶对暖云微物理和毛毛雨的影响
DOI：
10.5194/acp-2020-692
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发表时间：
2020-08
影响因子：
6.3
通讯作者：
Ying-Chieh Chen;Sheng-Hsiang Wang;Q. Min;Sarah Lu;P. Lin;N. Lin;Kao-Shan Chung;E. Joseph
中科院分区：
文献类型：
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作者：
Ying-Chieh Chen;Sheng-Hsiang Wang;Q. Min;Sarah Lu;P. Lin;N. Lin;Kao-Shan Chung;E. Joseph
抽象的。气溶胶严重影响气候，它通过辐射和微物理效应改变云的生命周期和降水分布。本研究利用AQUA卫星上MODIS(中分辨率影像光谱仪)的气溶胶和云特性资料，以及地面观测资料，包括气溶胶浓度、雨滴大小分布和气象参数，以统计量化气溶胶对台湾北部多个秋季(2005年10月15日至11月30日)低层暖云微物理和毛毛雨的影响。我们的结果表明，台湾西北部有几个人口稠密的城市，秋季以低层云(如温暖、稀薄和破碎的云)为主。观测到的气溶胶对暖云的影响表明，在固定的云水路径下，气溶胶的间接影响(即，气溶胶负荷的增加导致云有效半径(CER)减小)、云光学厚度增加、云量增加以及云顶温度降低。气溶胶-云相互作用(aci=-∂inCER∂in nα|CWP，CER相对于气溶胶量的变化)在我们的研究范围内为0.07，在周围的偏远地区(即海洋)和污染(即陆地)地区分别在0.09到0.06之间变化，表明偏远地区的气溶胶间接影响较强。从雨滴大小分布分析来看，高的气溶胶负荷导致细雨事件的频率减少，云水重新分布到更多更小的液滴中，并降低了碰撞-聚结率。然而，在小雨期间(≤1 mm h−1)，高浓度的气溶胶促使雨滴变得更小，并增加了毛毛雨滴的出现。这项研究使用长期地面和卫星资料来确定台湾北部的气溶胶变化、对云和降水的影响，以及未来气溶胶-云-降水相互作用研究的观测策略。
Abstract. Climate is critically affected by aerosols, which alter cloud lifecycles and precipitation distribution through radiative and microphysical effects. In this study, aerosol and cloud property datasets from MODIS (Moderate Resolution Imaging Spectroradiometer), onboard the Aqua satellite, and surface observations, including aerosol concentrations, raindrop size distribution, and meteorological parameters, were used to statistically quantify the effects of aerosols on low-level warm-cloud microphysics and drizzle over northern Taiwan during multiple fall seasons (from 15 October to 30 November of 2005–2017). Our results indicated that northwestern Taiwan, which has several densely populated cities, is dominated by low-level clouds (e.g., warm, thin, and broken clouds) during the fall season. The observed effects of aerosols on warm clouds indicated aerosol indirect effects (i.e., increased aerosol loading caused a decrease in cloud effective radius (CER)), an increase in cloud optical thickness, an increase in cloud fraction, and a decrease in cloud-top temperature under a fixed cloud water path. Quantitatively, aerosol–cloud interactions (ACI=-∂lnCER∂lnα|CWP, changes in CER relative to changes in aerosol amounts) were 0.07 for our research domain and varied between 0.09 and 0.06 in the surrounding remote (i.e., ocean) and polluted (i.e., land) areas, respectively, indicating aerosol indirect effects were stronger in the remote area. From the raindrop size distribution analysis, high aerosol loading resulted in a decreased frequency of drizzle events, redistribution of cloud water to more numerous and smaller droplets, and reduced collision–coalescence rates. However, during light rain (≤1 mm h−1), high aerosol concentrations drove raindrops towards smaller droplet sizes and increased the appearance of drizzle drops. This study used long-term surface and satellite data to determine aerosol variations in northern Taiwan, effects on clouds and precipitation, and observational strategies for future research on aerosol–cloud–precipitation interactions.