Articles | Volume 16, issue 23
Research article
06 Dec 2016
Research article |  | 06 Dec 2016

Changes in regional meteorology induced by anthropogenic heat and their impacts on air quality in South China

Min Xie, Kuanguang Zhu, Tijian Wang, Wen Feng, Da Gao, Mengmeng Li, Shu Li, Bingliang Zhuang, Yong Han, Pulong Chen, and Jingbiao Liao

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.

Short summary
In this paper, we present our new findings on (1) the spatial and temporal characteristics of AH emissions in South China, (2) how to implement the inhomogeneous AH data into the air quality model WRF/Chem, (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. Our results show that the meteorology and air pollution predictions in and around big cities are highly sensitive to AH.
Final-revised paper