|Title:||The impact of 2000-2050 climate change on ozone and secondary organic aerosol in China|
|Subject:||Climatic changes -- Environmental aspects -- China.|
Ozone -- Environmental aspects -- China.
Aerosols -- Environmental aspects -- China.
Hong Kong Polytechnic University -- Dissertations
|Department:||Department of Civil and Environmental Engineering|
|Pages:||xx, 175 p. : ill. (come col.) ; 30 cm.|
|Abstract:||Significant changes in global climate could affect the meteorological conditions in the future. The emission reduction policies aimed at reducing the negative impacts of air pollution should account for this potential change. Thus, this study uses air quality model system WRF/Chem to evaluate the impact of changes in climate, biogenic emission and anthropogenic emission on surface ozone (O₃) and secondary organic aerosol (SOA) concentrations based on coupled global climate model.regional climate and chemistry model approach (GCM-CTM). The first concern of this study is to assess the WRF/Chem's ability in simulating the meteorological and chemical variables over China. The simulation has been implemented over East China domain and run for April 2008. The comparison between modeled and measured meteorological fields, hourly O₃ mixing ratios illustrates that the model well captured the real condition. The results show that the simulated near surface temperature and wind speed are all slightly higher than the observed data, with mean bias of 0.7 °C and 2.1 m s⁻¹, respectively. Hourly O₃ at 8 monitoring stations exhibits a correlation with observations among 0.57 to 0.80, and the mean biases are among -12.0 to 11.3 ppb. Then a series of numerical experiments are conducted to investigate the relative contributions of climate and emission change to surface O₃ over South China for the period of October in 2005-2007 and 2055-57. WRF/Chem was driven by the outputs of Community Climate System Model version 3 (CCSM3). The change of climate and biogenic emission can result in a change of -5 to 5 ppb of afternoon surface O₃ mixing ratios, with an average of 1.6 ppb over the land region in South China. Our analysis suggests that the anthropogenic emissions have greater impact on the change of surface O₃ concentration (12.8 ppb) over South China compared to climate change. The combined effect of climate and emission can increase afternoon mean surface O₃ over South China by an average of 18.2 ppb in the land region. With WRF/Chem updated with the parameterization scheme for the isoprene SOA formation, the sensitivities of biogenic SOA concentration to changes in climate and biogenic emissions over China are investigated under IPCC A1B and B1 scenarios using the same approach. Projected changes in regional climate, the subsequent changes in biogenic emissions and BSOA concentrations are scenarios dependent. Under A1B scenario, significant increase of biogenic isoprene and monoterpenes emission occurs over South, Southwest, and Northeast China. In response to the change in climate and biogenic emissions, the surface BSOA concentration increases 0.22 μg m⁻³ over China, with the highest increase up 1.2 μg m⁻³ occurring over the South China and Central China. The simulations predict that the mean surface BSOA concentration increases 0.26 μg m-3 over China under B1 scenario. Over Southeast China, a significant increase of biogenic monoterpenes emission is observed over Southwest China (32.7%). As a result, highest increases in MSOA levels were simulated over Sichuan province, with peaks exceeding 1.0 μg m⁻³.|
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