Planetary boundary layer height modulates aerosol - water vapour interactions during winter in the megacity of Delhi
Planetary boundary layer height modulates aerosol - water vapour interactions during winter in the megacity of Delhi
复制标题
行星边界层高度调节德里大城市冬季气溶胶-水蒸气的相互作用
DOI：
10.1002/essoar.10506835.2
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Raj S
中科院分区：
文献类型：
--
作者：
Raj S
印度-恒河平原（IGP）是全球空气污染的主要来源之一。在冬季，强烈的辐射逆温驱动的行星边界层（PBL）高度的变化，影响区域空气污染扩散。到目前为止，气溶胶-水蒸气相互作用，特别是云凝结核（CCN）活动的测量，在印度次大陆是有限的，造成很大的不确定性的气溶胶-云相互作用的辐射强迫估计。我们提出了一个为期一个月的实地活动（2018年2月至3月）的结果，在大城市，德里，在IGP的一个重要的污染源。我们测量了细颗粒物（PM 1）的组成和尺寸分辨CCN性能在很宽的范围内的水蒸气过饱和度。分析包括PBL建模，向后的轨迹，和火点，以阐明PBL和空气质量的起源对气溶胶的影响。气溶胶特性强烈依赖于PBL的高度，一个简单的幂律拟合可以参数化所观察到的PM 1质量，气溶胶粒子数，和CCN数与PBL高度的相关性，表明PBL引起的气溶胶积累的变化。在低边界层高度（<100 m）下，低无机质量分数、低气溶胶吸湿性和高外部混合的弱CCN活性粒子表明边界层对气溶胶老化过程的影响。相比之下，气溶胶特性并不强烈地依赖于空气质量的来源或风向，这意味着所观察到的气溶胶和云凝结核来自当地的排放。误差函数可以参数化整个活动中CCN数和过饱和度之间的关系。
The Indo-Gangetic Plain (IGP) is one of the dominant sources of air pollution worldwide. During winter, the variations in planetary boundary layer (PBL) height, driven by a strong radiative thermal inversion, affect the regional air pollution dispersion. To date, measurements of aerosol-water vapour interactions, especially cloud condensation nuclei (CCN) activity, are limited in the Indian sub-continent, causing large uncertainties in the radiative forcing estimates of aerosol-cloud interactions. We present the results of a one-month field campaign (February-March 2018) in the megacity, Delhi, a significant polluter in the IGP. We measured the composition of fine particulate matter (PM1) and size-resolved CCN properties over a wide range of water vapour supersaturations. The analysis includes PBL modelling, backward trajectories, and fire spots to elucidate the influence of PBL and air mass origins on the aerosols. The aerosol properties depended strongly on the PBL height, and a simple power-law fit could parameterize the observed correlations of PM1 mass, aerosol particle number, and CCN number with PBL height, indicating PBL induced changes in aerosol accumulation. The low inorganic mass fractions, low aerosol hygroscopicity and high externally mixed weakly CCN-active particles under low PBL height (<100 m) indicated the influence of the PBL on aerosol aging processes. In contrast, aerosol properties did not depend strongly on air mass origins or wind direction, implying that the observed aerosol and CCN are from local emissions. An error function could parameterize the relationship between CCN number and supersaturation throughout the campaign.