Emission controls versus meteorological conditions in determining aerosol concentrations in Beijing during the 2008 Olympic Games

Abstract

A series of emission control measures were undertaken in Beijing and the adjacent provinces in China during the 2008 Beijing Olympic Games on 8–24 August 2008. This provides a unique opportunity for investigating the effectiveness of emission controls on air pollution in Beijing. We conducted a series of numerical experiments over East Asia for the period of July to September 2008 using a coupled meteorology-chemistry model (WRF-Chem). Model can generally reproduce the observed variation of aerosol concentrations. Consistent with observations, modeled concentrations of aerosol species (sulfate, nitrate, ammonium, black carbon, organic carbon, total particulate matter) in Beijing were decreased by 30–50 % during the Olympic period compared to the other periods in July and August in 2008 and the same period in 2007. Model results indicate that emission controls were effective in reducing the aerosol concentrations by comparing simulations with and without emission controls. However, our analysis suggests that meteorological conditions (e.g., wind direction and precipitation) are at least as important as emission controls in producing the low aerosol concentrations appearing during the Olympic period. Transport from the regions surrounding Beijing determines the temporal variation of aerosol concentrations in Beijing. Based on the budget analysis, we suggest that to improve the air quality over Beijing, emission control strategy should focus on the regional scale instead of the local scale

Influence of anthropogenic aerosols on the Asian monsoon: a case study using the WRF-Chem model

“…I am worried about the conclusion about the aerosol impact found in your study. WRF-Chem can simulate much better results than what you presented (e.g., Gao et al 2011). In addition, 2008 is a year of Beijing Olympic Game.…”

“…However, some studies (i.e. Gao et al, 2011) found that the local emission control does not affect the regional scale emissions much as the control was more local scale. Also, our study domain and focused regions are away from Beijing.…”

Evaluating the Impact of Emissions Regulations on the Emissions Reduction During the 2015 China Victory Day Parade With an Ensemble Square Root Filter

“…And there are large heavy industrial regions to the south of Beijing. As a result, high PM 2.5 concentrations in Beijing always correspond to the southerly wind, while low PM 2.5 concentrations in Beijing usually correspond to the northerly wind because of the specific terrain and the distribution of polluted industries (Gao et al, ). Therefore, the accurate simulation of wind direction is also very important in the emission data assimilation within this region.…”

Decomposition of the wind and nonwind effects on observed year‐to‐year air quality variation

“…However, other studies argued that the improvement was mostly due to changes in weather conditions (in particular, wind speed and direction) [ Simonich , ; Wang et al ., ]. Moreover, some studies suggested that both emission reduction and favorable meteorology contributed to the improvement in air quality [ Wang et al ., ; Gao et al ., ; Xing et al ., ].…”

“…Because of their interacting effects on air quality, it has been difficult to clearly separate the effects of wind and emissions directly from the observed data. To overcome this difficulty, various studies have used numerical models to help distinguish the effects of emissions and meteorological change [ Gilliland et al ., ; Jacob and Winner , ; Wang et al ., ; Gao et al ., ; Xing et al ., ]. For example, using the Community Multi‐scale Air Quality model (CMAQ), Xing et al .…”