Abstract
A special period in Beijing from 6 August to 17 September 2015, during which the World Athletics Championships and Victory Day military parade took place, and which involved measures to restrict traffic and reduce factory emissions, was selected to analyze the aerosol optical properties and the impact of meteorological conditions on pollution levels. The study was based on AERONET observational and retrieval data, particulate matter measurements (TEOM 1405), meteorological data, and then the HYSPLIT model was used to analyze the pollution sources. The study period was divided into three sub-periods according to the different stages of implementation of the control measures, and the main conclusions can be summarized as follows. During the period in which the restrictive measures were applied, the air quality improved significantly, with the average value of the AOD being 0.34 ± 0.20, about 69% less than before. Meanwhile, the average Ångström exponent was about 9.5% higher than before, with an average value of 1.38 ± 0.25, indicating that the main pollutants were fine particles. Single scattering albedo decreased as wavelength increased, being higher than in the other two stages (mean value of 0.944 ± 0.045). This showed that the strong scattering capacity and absorption aerosol optical depth was at its lowest, at about 0.008 ± 0.009. The peaks of aerosol volume concentration in the fine and coarse mode were significantly reduced. Meteorological conditions also had a certain effect on the aerosol optical properties, with the blowing of clean and dry wind and the occurrence of precipitation contributing to the overall improvement in air quality.
Highlights
Aerosol particles play an important role in global and regional climate because particulate matter (PM) can scatter or absorb solar radiation, depending on the particles’ composition, size and Atmosphere 2016, 7, 47; doi:10.3390/atmos7030047 www.mdpi.com/journal/atmosphere spatio-temporal distribution [1]
The daily mean values of the observed andcomplex complexrefractive refractive depth (AOD) data and PM measurements are shown in Figure 2; the missing AOD data are due to cloud accumulation and precipitation, and the error bars represent the standard deviation
On 7 August, the weather was moderate rain and the AOD was the highest (2.99), which was possibly affected by the hygroscopic growth of aerosol particles [36]
Summary
Aerosol particles play an important role in global and regional climate because particulate matter (PM) can scatter or absorb solar radiation, depending on the particles’ composition, size and Atmosphere 2016, 7, 47; doi:10.3390/atmos7030047 www.mdpi.com/journal/atmosphere spatio-temporal distribution [1]. They can indirectly influence cloud physics, e.g. the spatio-temporal [1].and. One of the main reasons is the large temporal and spatial is true for regional air quality studies.
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