Examination of aerosol effects on precipitation in deep convective clouds during the 1997 ARM summer experiment
Examination of aerosol effects on precipitation in deep convective clouds during the 1997 ARM summer experiment
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1997 年 ARM 夏季实验期间气溶胶对深对流云中降水的影响的检验
DOI：
10.1002/qj.287
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发表时间：
2015
影响因子：
8.9
通讯作者：
Y. Ming
中科院分区：
文献类型：
--
作者：
Seoung;L. Donner;V. Phillips;Y. Ming
人们普遍认为，不断增加的气溶胶会抑制降水。通过对浅层状云的研究，提出了气溶胶对降水的抑制作用。最近对对流云的研究表明，气溶胶增加可能会增加降雨量。这些研究表明，在某些对流云情况下，气溶胶和云动力学之间的强烈反馈导致降水增加。这项研究通过分析导致降雨量增加的气溶胶的详细微物理和动力学变化来扩展这些研究。由于深对流云驱动的中尺度云系(MCE)占地球降水的很大比例，而气溶胶对MCE的影响研究还处于起步阶段，因此本文主要研究了三个观测到的深对流云驱动的中尺度云系集(MCE)。这些MCE是在1997年大气辐射测量(ARM)夏季实验期间观测到的。为了模拟气溶胶对深对流的影响，对每个MCES进行了两次数值试验。第一个气溶胶数浓度较高，第二个浓度较低。结果表明，由于MCE对流区地面辐合线较强所引发的上升气流较强、数量较多，使得高气溶胶下降水增多。较强的辐合线是由高气溶胶情况下云液体的蒸发增加所触发的，这是由于自动转换所需的云液体的较高值所致。
It has been generally accepted that increasing aerosols suppress precipitation. The aerosol‐induced precipitation suppression was suggested by the study of shallow stratiform clouds. Recent studies of convective clouds showed increasing aerosols could increase precipitation. Those studies showed that intense feedbacks between aerosols and cloud dynamics led to increased precipitation in some cases of convective clouds. This study expanded those studies by analyzing detailed microphysical and dynamical modifications by aerosols leading to increased precipitation. This study focused on three observed cases of mesoscale cloud ensemble (MCE) driven by deep convective clouds, since MCE accounts for a large proportion of the Earth's precipitation and the study of aerosol effects on MCE is at its incipient stage. Those MCEs were observed during the 1997 Atmospheric Radiation Measurement (ARM) summer experiment. Two numerical experiments were performed for each of the MCEs to simulate aerosol effects on deep convection. The first was with high aerosol number concentration, and the second was with low concentration. The results showed an increased precipitation at high aerosol, due to stronger, more numerous updraughts, initiated by stronger convergence lines at the surface in convective regions of the MCE. The stronger convergence lines were triggered by increased evaporation of cloud liquid in the high‐aerosol case, made possible by higher values of cloud liquid necessary for autoconversion.