The significant impact of aerosol vertical structure on lower atmosphere stability and its critical role in aerosol–planetary boundary layer (PBL) interactions
The significant impact of aerosol vertical structure on lower atmosphere stability and its critical role in aerosol–planetary boundary layer (PBL) interactions
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DOI：
10.5194/acp-20-3713-2020
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发表时间：
2020-03
影响因子：
6.3
通讯作者：
T. Su;Zhanqing Li;LI Chengcai;Jing Li;Wenchao Han;Wenchao Han;Chuanyang Shen;Wangshu Tan;
中科院分区：
文献类型：
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作者：
T. Su;Zhanqing Li;LI Chengcai;Jing Li;Wenchao Han;Wenchao Han;Chuanyang Shen;Wangshu Tan;
抽象的。气溶胶-行星边界层（PBL）相互作用被认为是稳定大气和加剧地面空气污染的重要机制。尽管在理解这一过程方面取得了巨大进展，但其强度和意义仍然存在很大的不确定性，并且随着气溶胶分布和气象条件的变化而变化。本文利用微脉冲激光雷达、太阳光度计和无线电探空仪在北京的观测资料，重点研究了气溶胶垂直分布在热力学稳定性和边界层发展中的作用。尽管气溶胶的垂直分布很复杂，但无云气溶胶结构大体上可以分为三种类型：充分混合型、随高度减小型和反向结构型。不同气溶胶垂直结构的气溶胶-边界层关系以及边界层高度和PM2.5的日变化具有不同的特征。气溶胶辐射强迫的垂直分布在三种类型之间有很大的差异，在低，中，高的PBL加热，分别强。这种加热速率的差异在三种不同的气溶胶结构中对大气浮力和稳定性的影响不同。吸收性气溶胶对低层大气的稳定作用在递减结构下比在反转结构下弱。结果表明，气溶胶-边界层相互作用可以通过气溶胶的反向结构得到加强，并可以通过减小的结构得到潜在的中和。此外，气溶胶可以增强和抑制PBL的稳定性，导致正负反馈回路。本研究试图提高我们的理解气溶胶PBL的相互作用，显示气溶胶垂直分布的观测约束模拟这种相互作用和随之而来的反馈的重要性。
Abstract. The aerosol–planetary boundary layer (PBL) interaction was proposed as an important mechanism to stabilize the atmosphere and exacerbate surface air pollution. Despite the tremendous progress made in understanding this process, its magnitude and significance still have large uncertainties and vary largely with aerosol distribution and meteorological conditions. In this study, we focus on the role of aerosol vertical distribution in thermodynamic stability and PBL development by jointly using micropulse lidar, sun photometer, and radiosonde measurements taken in Beijing. Despite the complexity of aerosol vertical distributions, cloud-free aerosol structures can be largely classified into three types: well-mixed, decreasing with height, and inverse structures. The aerosol–PBL relationship and diurnal cycles of the PBL height and PM 2.5 associated with these different aerosol vertical structures show distinct characteristics. The vertical distribution of aerosol radiative forcing differs drastically among the three types, with strong heating in the lower, middle, and upper PBL, respectively. Such a discrepancy in the heating rate affects the atmospheric buoyancy and stability differently in the three distinct aerosol structures. Absorbing aerosols have a weaker effect of stabilizing the lower atmosphere under the decreasing structure than under the inverse structure. As a result, the aerosol–PBL interaction can be strengthened by the inverse aerosol structure and can be potentially neutralized by the decreasing structure. Moreover, aerosols can both enhance and suppress PBL stability, leading to both positive and negative feedback loops. This study attempts to improve our understanding of the aerosol–PBL interaction, showing the importance of the observational constraint of aerosol vertical distribution for simulating this interaction and consequent feedbacks.