| Aerosol optical properties were analyzed, including the variation of light absorption and scattering of aerosols and aerosol optical depth, by using the data observed in Zhangye in spring 2008.. The main results are as follows:1)The average value(standard deviation) of hourly averaged aerosol absorption coefficient (Bap) was 11.9Mm-1(10.2Mm-1), and the averaged aerosol scattering coefficient values for (Bsp) was 96 Mm-1(115Mm-1). The results show that levels of aerosol light absorption and scattering over Zhangye were lower than those measured in other sites in east China,which was mainly influenced by anthropogenic pollutants emission. The average value of hourly averaged Aerosol Optical Depth (AOD) was 0.39, with a standard deviation of 0.322)During the observation period, Bap and Bsp varied greatly. The variation of absorption coefficient was mainly influenced by anthropogenic pollutants emission caused by local residents activities and atmospheric diffusion conditions. Besides these two factors, Bsp was influenced by dust events as well. In non-dust days, Bap and Bsp varied with two peaks in a day, and the value was higher in night than that in day time, which indicated that aerosol were emitted during the night time.3)Diurnal variation of AOD was gentle, with the value in rising from 7:00-10:00, in the other time of the day it was relatively steady. In non-dust days the daily averaged value of AOD was often lower than 0.5, while in dust days the value exceeded 0.5, even higher than 1.4)Because of the terrain of mountain and valley, the wind direction changed obviously during a day. In a day, the wind direction was southeastly from 0:00 to 10:00, and changed to be northwestly from 11:00 to 20:00,t he wind direction of rest time of a day would be southly.5) The daily averaged mass concentration of PM10 changed greatly,because of the dust emission.About 18 days daily averaged PM10 mass concentration exceed standard II of national ambient air quality standard of China,Which was about 30% of the total measuring days.While in non dust days the PM10 mass concentration was mostly around 100μg/m3.6)When the wind blown from the southeast, the Bap and Bsp measured at the site would often be higher than that when the wind was from northwest, while the AOD would be oppositely. Although the northeastly wind often brought dust, which would contributed to Bsp. However, the average levels of both Bap and Bsp were higher when the wind was from southeast than that from the northwest. But to the AOD,t he average value was higher when the wind was from northwest than the value when the wind was from southeast.7) In Zhangye there are two types of aerosol, namely dust aerosol and pollution aerosol.The mass absorption efficiencies and mass scattering efficiencies were greaty different, the mass scattering coefficient of pollution aerosol was about two times higher than that of dust aerosol,while the mass absorption coefficient of pollution aerosol was was a magnitude higher than that of dust aerosol.they often mixed together, which made the optical properties of aerosols more complicated.
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