Abstract
Haze and dust pollution have a significant impact on human production, life, and health. In order to understand the pollution process, the study of these two pollution characteristics is important. In this study, a one-year observation was carried out at the Beijing Southern Suburb Observatory using the MAX-DOAS instrument, and the pollution characteristics of the typical haze and dust events were analyzed. First, the distribution of aerosol extinction (AE) and H2O concentrations in the two typical pollution events were studied. The results showed that the correlation coefficient (r) between H2O and AE at different heights decreased during dust processes and the correlation slope (|k|) increased, whereas r increased and |k| decreased during haze periods. The correlation slope increased during the dust episode due to low moisture content and increased O4 absorption caused by abundant suspended dry crustal particles, but decreased during the haze episode due to a significant increase of H2O absorption. Secondly, the gas vertical column density (VCD) indicated that aerosol optical depth (AOD) increased during dust pollution events in the afternoon, while the H2O VCD decreased; in haze pollution processes, both H2O VCD and AOD increased. There were significant differences in meteorological conditions during haze (wind speed (WD) was <2 m/s, and relative humidity (RH) was >60%) and dust pollution (WD was >4 m/s, and RH was <60%). Next, the vertical distribution characteristics of gases during the pollution periods were studied. The AE profile showed that haze pollution lasted for a long time and changed slowly, whereas the opposite was true for dust pollution. The pollutants (aerosols, NO2, SO2, and HCHO) and H2O were concentrated below 1 km during both these typical pollution processes, and haze pollution was associated with a strong temperature inversion around 1.0 km. Lastly, the water vapor transport fluxes showed that the water vapor transport from the eastern air mass had an auxiliary effect on haze pollution at the observation location. Our results are of significance for exploring the pollution process of tropospheric trace gases and the transport of water vapor in Beijing, and provide a basis for satellite and model verification.
Highlights
This study aimed to provide a reference for the future analysis of the vertical distribution characteristics of pollutants and water vapor during haze and dust pollution in Beijing
The monthly averaged results of aerosol optical depth (AOD), H2 O vertical column density (VCD), NO2 VCD, SO2 VCD, and HCHO VCD were calculated based on the MAX-DOAS measurements (Figure 3a,b)
This study carried out one-year observations at the Beijing Southern Suburb Observatory using MAX-DOAS and analyzed the characteristics of pollutant gases and meteorological factors during the two typical processes of haze and dust
Summary
Air pollution has become a serious environmental problem in China, especially in economically developed and densely populated areas, such as Beijing–Tianjin–Hebei [1,2,3]. With a large population and numerous vehicles; it has frequently suffered from haze pollution in recent years, especially during winter [4,5,6]. The transport of dust from the northwest aggravates the pollution in Beijing during the spring. The inhalation of aerosols from haze and dust during heavy pollution outbreaks has noticeably adverse effects on human health. Studies have shown that millions of people die prematurely every year due to outdoor air pollution [7]. There has been an enhanced focus on haze and dust pollution in China
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