The interdecadal worsening of weather conditions affecting aerosol pollution in the Beijing area in relation to climate warming

Abstract

Abstract. The weather conditions affecting aerosol pollution in Beijing and its vicinity (BIV) in wintertime have worsened in recent years, particularly after 2010. The relation between interdecadal changes in weather conditions and climate warming is uncertain. Here, we analyze long-term variations of an integrated pollution-linked meteorological index (which is approximately and linearly related to aerosol pollution), the extent of changes in vertical temperature differences in the boundary layer (BL) in BIV, and northerly surface winds from Lake Baikal during wintertime to evaluate the potential contribution of climate warming to changes in meteorological conditions directly related to aerosol pollution in this area; this is accomplished using NCEP reanalysis data, surface observations, and long-term vertical balloon sounding observations since 1960. The weather conditions affecting BIV aerosol pollution are found to have worsened since the 1960s as a whole. This worsening is more significant after 2010, with PM2.5 reaching unprecedented high levels in many cities in China, particularly in BIV. The decadal worsening of meteorological conditions in BIV can partly be attributed to climate warming, which is defined by more warming in the higher layers of the boundary layer (BL) than the lower layers. This worsening can also be influenced by the accumulation of aerosol pollution, to a certain extent (particularly after 2010), because the increase in aerosol pollution from the ground leads to surface cooling by aerosol–radiation interactions, which facilitates temperature inversions, increases moisture accumulations, and results in the extra deterioration of meteorological conditions. If analyzed as a linear trend, weather conditions have worsened by ∼ 4 % each year from 2010 to 2017. Given such a deterioration rate, the worsening of weather conditions may lead to a corresponding amplitude increase in PM2.5 in BIV during wintertime in the next 5 years (i.e., 2018 to 2022). More stringent emission reduction measures will need to be conducted by the government.

Dominant role of emission reduction in PM<sub>2.5</sub> air quality improvement in Beijing during 2013–2017: a model-based decomposition analysis

“…Therefore, the adjustment and optimization of the energy structure would be the most effective and dominant pathway for mitigating coal combustion pollution in the future. According to several studies on the source apportionment of PM2.5 in Beijing, the transportation sector accounted for a major part of PM2.5 pollution in 2013, and its contribution has become much higher since then (Li et al, 2015;Hua et al, 2018;Zhang et al, 2018). Vehicle emission control, including both on-road and off-road vehicles, was the biggest contributor to NOx emission reductions with an estimated total reduction of 44 kt NOx, accounting for 47% of the total reductions ( Figure 6 (a); SI, Table S3).…”

“…However, regional cities in these two directions, such as Baoding, Changzhou, Hengshui, Shijiazhuang, Tangshan, and Tianjin, suffer even worse air pollution . A combination of PM2.5 formation and transport results in regionally complex air pollution characteristics in Beijing (Lang et al, 2013;Chen et al, 2016;Zhang et al, 2018;Zhong et al, 2018). In addition to the impact of pollutant emissions and transport, PM2.5 concentrations are also highly influenced by some other factors, including atmospheric advection, atmospheric diffusion and secondary aerosol formulation.…”

“…(Sun et al, 2015;Yin et al, 2016;. Several studies have also reported that frequent stable meteorological conditions play an important role in severe pollution episodes (Elser et al, 2016;Ma et al, 2017;Zhang et al, 2018). Based on emission inventories and air quality models, existing studies have established a mature sensitivity decomposition framework to assess the contributions of emission control to air quality improvements (Zhao et al, 2013;.…”

“…Based on emission inventories and air quality models, existing studies have established a mature sensitivity decomposition framework to assess the contributions of emission control to air quality improvements (Zhao et al, 2013;. However, some studies have investigated the effects of meteorological conditions on air quality by controlling the meteorological inputs of chemical transport models (Zhang et al, 2018).…”

Aerosol vertical mass flux measurements during heavy aerosol pollution episodes at a rural site and an urban site in the Beijing area of the North China Plain

“…Even if it is a southerly or southwesterly wind, if the wind speed is too small (< 1 m s −1 ), AS will not appear. Only the southerly or southwesterly wind with a wind speed greater than a specific value (> 1.5 m s −1 ), and the concentration of PM 10 in the area to the south of Beijing is higher than that in Beijing, and then there will be AS after a small wind (Zhong et al, 2018b, c;Zhang et al, 2018).…”