Characterization of multiple atmospheric pollutants during haze and non-haze episodes in Beijing, China: Concentration, chemical components and transport flux variations

Nonlinear influence of winter meteorology and precursor on PM2.5 based on mathematical and numerical models: A COVID-19 and Winter Olympics case study

“…Beijing is surrounded by the Yan Mountains and Taihang Mountains in the north and west directions, respectively. Because of the high emission load related to the relatively larger proportion of secondary production in its southern cities, the PM 2.5 concentration is more likely to increase under weak southern wind conditions ( Zhang et al, 2019 , 2021 ). On the basis of the wind field-concentration analysis and backward trajectory results, the input of the polluted air masses transported along the weak southerly wind with high frequency might be one of the predominant reasons leading to the heavy pollution in 2020.…”

“…One the other hand, environmental observations showed that the sulfur pollutants in the atmosphere decreased significantly more than those of NO x , especially during heavy pollution in autumn and winter in Beijing, and the SO 4 2− and NO 3 − pollution processes decreased and increased, respectively. This is due to the more completed conversion of NO x to NO 3 − than SO 2 to SO 4 2− ( Zhang et al, 2021 ; Tang et al, 2021). O 3 is an important oxidant in atmospheric environments; polluted days with O 3 as the primary air pollutant appeared in spring and summer in Beijing.…”

“…O 3 is an important oxidant in atmospheric environments; polluted days with O 3 as the primary air pollutant appeared in spring and summer in Beijing. Following the PM 2.5 improvement, a high O 3 concentration was also evident in winter, which affected the liquid phase and heterogeneous transformation of precursors ( Zhang et al, 2021 ). Additionally, for NO 3 − , the low temperature in winter weakened its transformation to the gas phase, and the increased concentration of O 3 promotes the distribution of NO 3 − into the particulate phase ( Li et al, 2020 ).…”

“…The WRF (version 4.0) model, developed by the National Center for Atmospheric Research, was employed to generate the meteorological background of the air quality simulation. To ensure that the simulation scheme was applicable to this study area, we referred to the literature to select the parameterization schemes: the Purdue Lin microphysics scheme, RRTM scheme, Goddard scheme, Noah scheme, Yonsei University scheme, and Monin–Obukhov scheme for the microphysics option, longwave radiation option, shortwave radiation option, land surface option, planetary boundary layer option, and surface layer option ( Wei et al, 2022 ; Zhang et al, 2021 ). We employed the CMAQ model (version 5.3), which reflects the physical and chemical processes of various pollutants in a complete environment, to simulate the spatial distribution and temporal variation in PM 2.5 concentration within the study region.…”

“Military Parade Blue Skies” in Beijing: Decisive Influence of Meteorological Factors on Transport Channel and Atmospheric Pollutant Concentration Level

“…Addi tionally, in 2016, the transport patterns altered evidently in three periods and the whole research period (Figure 10b,d,f,h). The overall transport pattern was mainly concentrated In fact, research on the potential source areas and transmission characteristics of the Beijing-Tianjin-Hebei region and its surrounding areas has been ongoing in recent years [37,[45][46][47][48][49][50][51]. In this regard, more studies will analyze the transboundary transmission characteristics in this region from the perspective of models.…”