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Study on the Impacts of Aerosols on Surface Ozone in Shanghai

Author: LiuQiong
Tutor: GengFuHai；ChenYongHang
School: Donghua University
Course: Environmental Engineering
Keywords: aerosol optical depth single scattering albedo ozone NCAR MM model NCAR TUV model
CLC: X513
Type: Master's thesis
Year: 2012
Downloads: 118
Quote: 0
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Abstract

According to the data derived from the surface observations of Urban Environmental Meteorological Center in Pudong and Dongtan in Shanghai, the physical and the optical characteristics of aerosols and the current ozone pollution situation in Shanghai area were analyzed. At last, the impacts of aerosols on ozone, UV radiation and the key photochemical reactions were evaluated by NCAR MM model and NCAR TUV model. These conclusions have certain theoretical meaning and practical application value to the managing and controlling the ozone in Shanghai. The main conclusions are as follows:(1) Fine particles were major pollutants in Shanghai, the particle size of which was mostly less than 2.5μm and the ratio of PM2.5/PM10 was greater than 0.68 and that of PM1/PM2.5 was greater than 0.78, dominated by scattering aerosols; the diurnal variations of particulate matter and black carbon both in Pudong and Dongtan stations had a similar bimodal structure, which of Pudong station were more obvious; the trends of mass concentrations in two stations were almost the same and the average concentrations in summer were the minimum and those in winter were the maximum.(2) The ozone data from 2006-2010 in Shanghai, including Xuhui, Chongming, Baoshan, Pudong and Jinshan, showed that ozone concentrations in Shanghai were low in central city and high in suburban areas; the higher concentrations of NOx in central city and heavy downtown areas suppress the generation of ozone, which was the reason of the lower ozone concentration in central city; diurnal variation of five ozone stations had a similar apparent single peak sinusoidal distribution, and summer diurnal variation of ozone was the most significant, followed by spring, autumn and winter. Considering the weather conditions, wind speed, sunshine duration and ozone precursor (NOx and VOCs) concentrations, the lower concentrations of VOCs and the lower ratios of VOCs and NOx were the major reasons causing low ozone concentrations in 2006 in Shanghai. (3) In order to further explore the impacts of aerosols on surface ozone generating mechanism, the influences of aerosol and ozone precursor to ozone were simulated by using NCAR MM model through changing AOD, NOx and VOCs, respectively. The results showed that the increase of AOD could only reduce the ozone production and would not change the time which maximum ozone concentration appeared, and as the concentrations of VOCs which contributed more to the photochemical reaction reduced, the inhibition of aerosols to ozone would become weak. Keeping the concentrations of ozone precursor in a certain level, ozone concentrations under different AOD and SSA were simulated, and the results showed that ozone concentrations increased with the decrease of AOD and the increase of SSA. When AOD added 0.1 unite, the maximum attenuation rate of ozone concentrations could be 23.3%, and when SSA added 0.05 unit, the maximum growth rate of ozone concentrations could up to 20.5%;(4) The impacts of AOD and SSA on ultraviolet radiation and key photochemical reactions were also evaluated by NCAR TUV radiation transfer model, and the results indicated that the influence of aerosols to ozone mainly displayed both in the negative effect of AOD and the positive effect of SSA.

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