Study On Optical Properties Of Haze Aerosol At Shanghai With Micro-Pulse Lidar

Current research on haze, which is a hot issue of environmental problems, has been focused on the analysis of weather and climatic characteristics, meteorological cause and chemical composition. The study on the aerosol vertical distribution of haze has still rarely been reported. In this study some new meaningful information for operation of warning and forecasting of haze at Shanghai was revealed.Using the observational data from the ground-based Micro-Pulse Lidar (MPL) and Sun-photometry at Shanghai Urban Environment Meteorology Center from March 2009 to February 2010, the aerosol extinction coefficient and opticle depth were retrieved according toWelton method. The trend of the parameters was consistent with the ideal profile of numerical simulation. In spite of this, there were some errors in the low atmosphere and moving average could minimize the influence of remote signal noise. The results showed that the variation tendencies of inversion and observation of aerosol optical depth (AOD) were almost the same; Because AOD observed by sun-photometry was for the entire atmospheric column and that of lidar inversion was only for the atmosphere near surface,80% of the inversion values were lower than the observations. Due to the large fluctuations of inversion values, the retrieval process needs to be further improved.With the data from Milos500-Finland Vaisala Company's seven elements automatically observational weather station and the newly issued standard for meteorologically observational operation, days of haze and haze-free, dry and damp haze and haze of different intensity were statistically analyzed. The results revealed that the number of haze days varied ranging from the largest to the fewest in winter, summer, spring and autumn sequently. Dry haze days, which occurred most in winter, appeared more frequently than damp haze days, which occurred most in summer. For haze of different intensity, slight haze occurred most in spring and summer, while severe haze in winter. Diurnal and seasonal variation of the aerosol extinction coefficient and the distribution of AOD for different heights in troposphere were analyzed, using the data retrieved by Micro-Pulse Lidar at Shanghai Urban Environment Meteorology Center from March 2009 to February 2010. The results indicated that AOD below lkm accounts for 64% of that betweem 0-6km when haze occurred at Shanghai and 44% during haze-free periods. The AOD values are greater than 0.04 during haze periods and less than 0.04 during haze-free periods. This shows that increasing aerosols at low atmosphere is the main cause of haze. The vertical gradient change in seasonally average extinction coefficient for haze was significant, ranging from the largest to the fewest in winter, summer, spring and autumn sequently. During damp haze (80%