A numerical study of influences of urban land-use change on ozone distribution over the Pearl River Delta region, China

Abstract

A B S T R A C T Atmospheric dynamical and chemical models are conducted to explore impacts of urban land-use change on ozone concentrations over the Pearl River Delta (PRD) region, China. Two scenarios of land-use distributions are used to represent early 1990s and current urban land-use distributions. Urbanization increases 2-d averaged daytime (nighttime) temperature by 0.8 • C (1.5 • C) and reduces wind speed by about 20% over the PRD urban areas. The daytime boundary layer depth is up to 400 m deeper, while there is a 50-m increase during nighttime. The combination of these seemly subtle changes in meteorological conditions is able to prompt detectable changes in surface O 3 concentration (4-15 ppbv) over major PRD urban areas. Nighttime O 3 concentration enhancement is greater than daytime in the urban expansion regions (e.g. 10 ppbv daytime and 15 ppbv nighttime). Areas with main O 3 concentrations increase coincide with the areas of increased temperature and decreased wind speed, and the timing of maximum ozone concentration increase occurs a few hours later than maximum temperature increase and wind-speed reduction. Moreover, planetary boundary layer depth also plays an important role in modulating vertical transport of O 3 , which can lead to daytime surface ozone concentrations reduction in some regions even with increasing temperatures.

Impacts of weather conditions modified by urban expansion on surface ozone: Comparison between the Pearl River Delta and Yangtze River Delta regions

“…Nevertheless, it should be noted that, in the daytime, the surface ozone increase (by 2.9%-4.2%) is less than that for the nighttime (about 4.7%-8.5%). This study confirms the finding of Wang et al (2007) that the temperature enhancement and the wind speed decrease alone are not sufficient to explain changes in the surface O 3 concentrations, and the PBL-depth change plays a very important role in surface ozone concentration. At the same time, we found urbanization increases converging over the urban areas, especially in the PRD.…”

“…The results revealed that air temperature, wind field, humidity, and the height of the atmosphere boundary layer induced by the land-use change (Grossman-Clarke et al, 2005;Liu et al, 2006;Lo et al, 2006;Civerolo et al, 2000;Jiang et al, 2008) can affect the production and distribution of air pollutants (Taha et al, 1998;Civerolo et al, 2007;Wang et al, 2007). In this study, we focused on three parameters: 2-m air temperature, PBL heights, and 10-m wind speed because of their significant roles in the formation and evolution of surface ozone concentrations (Ordonez et al, 2005).…”

“…Lin et al (2007) used the MM5 model to simulate the impact of urban expansion on monthly climate in the PRD region. Wang et al (2007) used a regional atmospheric chemistry model to study the effects of urbanization on surface ozone concentrations in the PRD. These investigations were based on case studies, and the impacts of urbanization on air quality in YRD region have not been quantified.…”

Modelling the impact of urbanisation on regional climate in the Greater London Area

“…The magnitude of UHII s compares well to the results for other numerical studies. For example, Lee and Kim (2008) found an increase of 1.5 K in the Daegu region in Korea, Wang et al (2007) observed a 1.5 K increase during night time and 0.8 K increased during daytime in the Pearl Delta region, China, and Lamptey et al (2005) found an increase of more than 1 K due to urbanisation in the North-Eastern United States. Results for a case study by Bohnenstengel et al (2011) also suggest a nocturnal urban temperature increment of more than one 1 K in most of the urban area of London.…”

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

“…surfaces to artificial ones (Civerolo et al, 2007;Lo et al, 2007;Wang et al, 2007;Jiang et al, 2008;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;Zhu et al, 2010;Feng et al, 2012Feng et al, , 2014Menberg 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).…”