Abstract
Abstract. Anthropogenic heat (AH) emissions from human activities can change the urban circulation and thereby affect the air pollution in and around cities. Based on statistic data, the spatial distribution of AH flux in South China is estimated. With the aid of the Weather Research and Forecasting model coupled with Chemistry (WRF/Chem), in which the AH parameterization is developed to incorporate the gridded AH emissions with temporal variation, simulations for January and July in 2014 are performed over South China. By analyzing the differences between the simulations with and without adding AH, the impact of AH on regional meteorology and air quality is quantified. The results show that the regional annual mean AH fluxes over South China are only 0.87 W m−2, but the values for the urban areas of the Pearl River Delta (PRD) region can be close to 60 W m−2. These AH emissions can significantly change the urban heat island and urban-breeze circulations in big cities. In the PRD city cluster, 2 m air temperature rises by 1.1° in January and over 0.5° in July, the planetary boundary layer height (PBLH) increases by 120 m in January and 90 m in July, 10 m wind speed is intensified to over 0.35 m s−1 in January and 0.3 m s−1 in July, and accumulative precipitation is enhanced by 20–40 % in July. These changes in meteorological conditions can significantly impact the spatial and vertical distributions of air pollutants. Due to the increases in PBLH, surface wind speed and upward vertical movement, the concentrations of primary air pollutants decrease near the surface and increase in the upper levels. But the vertical changes in O3 concentrations show the different patterns in different seasons. The surface O3 concentrations in big cities increase with maximum values of over 2.5 ppb in January, while O3 is reduced at the lower layers and increases at the upper layers above some megacities in July. This phenomenon can be attributed to the fact that chemical effects can play a significant role in O3 changes over South China in winter, while the vertical movement can be the dominant effect in some big cities in summer. Adding the gridded AH emissions can better describe the heterogeneous impacts of AH on regional meteorology and air quality, suggesting that more studies on AH should be carried out in climate and air quality assessments.
Highlights
Urbanization and its impacts on regional meteorology and air quality have been widely acknowledged, observed and investigated (Rizwan et al, 2008; Mirzaei and Haghighat, 2010)
To fill the abovementioned knowledge gap, we present our new findings on the impact mechanism of anthropogenic heat regarding urban climate and regional air quality over South China in this paper, including (1) the spatial and temporal characteristics of Anthropogenic heat (AH) emissions in South China, (2) how to implement the inhomogeneous AH data into the air quality model WRF/chemical modules (Chem) (Weather Research and Forecasting model coupled with Chemistry), (3) the impacts of AH fluxes on meteorological fields, and (4) the impacts of meteorology changes on the air quality in different cities in South China
As for the annual mean AH flux over the whole administrative district of a different province, the value in Guangdong continuously increases from 0.30 W m−2 for 1990 to 1.68 W m−2 for 2014, while the heat release in Guangxi and Hainan remains at a low level (< 0.5 W m−2) but with an obwww.atmos-chem-phys.net/16/15011/2016/
Summary
Urbanization and its impacts on regional meteorology and air quality have been widely acknowledged, observed and investigated (Rizwan et al, 2008; Mirzaei and Haghighat, 2010). Previous studies have illustrated that urbanization can affect the atmospheric environment in many ways, which are mainly associated with the increase in air pollutant emissions from the intensification of energy consumption (Akbari et al, 2001; Civerolo et al, 2007; Jiang et al, 2008; Stone, 2008; Chen et al, 2014b), the change in land cover from natural. L. Zhang et al, 2009; Lu et al, 2010; Wu et al, 2011; Chen et al, 2014b; Liao et al, 2015; Zhu et al, 2015; Li et al, 2016) and the release of anthropogenic heat from human activities in cities (Ryu et al, 2013; Yu et al, 2014; Xie et al, 2016). Anthropogenic heat (AH) can increase turbulent fluxes in sensible and latent heat (Oke, 1988), implying that it can modulate local and regional meteorological processes (Ichinose et al, 1999; Block et al, 2004; Fan and Sailor, 2005; Ferguson and Woodbury, 2007; Chen et al, 2009; Zhu et al, 2010; Feng et al, 2012, 2014; Menberg et al, 2013; Ryu et al, 2013; Wu and Yang, 2013; Bohnenstengel et al, 2014; Chen et al, 2014a; Meng et al, 2011; Yu et al, 2014; Xie et al, 2016) and thereby exert an important influence on the formation and the distribution of ozone (Ryu et al, 2013; Yu et al, 2014; Xie et al, 2016) as well as aerosols (Yu et al, 2014; Xie et al, 2016)
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