Researches On Aerosol Optical Properties Of Kunming Using CE318Sunphotometer And MODIS Measurements

In this dissertation, CE318automatic Sunphotometer Measurement was conducted and three kinds of Aerosol Optical Depth (AOD) data were used based on Moderate Resolution Imaging Spectroradiometer (MODIS) at Kunming station (25.06°N,102.7°E). The CE318Sunphotometer and MODIS data were handled by ASTPwin and ENVI/IDL respectively, combining with some statistical methods. Then the AOD seasonal variation characteristics in Kunming were obtained and comparative analysis of the MODIS/AOD and CE318/AOD on both spatial and temporal variation were discussed. The conclusions can be drawn as follows:(1) From2011to2013, the largest seasonal mean value of AOD is in summer, followed by spring, autumn, winter, as a obvious single peak structure. And the visibility has a significant inverse relationship with AOD, and the AOD in different seasons of the same visibility has small deviation.(2) By the confirmation of the HYSPLIT-4backward trajectory, the aerosols in Kunming are mainly from somewhere between the Indian and Arabia subcontinent.(3) From the comparison between the CE318/AOD and MODIS/AOD, all the DT(T), DT(A) and DB(A) are smaller than the based observation. Among them, the dark object methods are better than the deep blue method. But DT(T) shows superiority over DT(A) in number of samples, correlation coefficient and so on. Meanwhile, all the three MODIS/AOD have seasonal characteristics on the inversion quality and the results in spring and autumn are more reliable than in summer and winter.(4) Studies show that the AOD in Kunming had lost about25%in the recent10years from2004to2013. But whether the decreasing trend is true need further confirmation.(5) In summer, AOD is larger as the distance is further from the city center of Kunming. But the AOD is smaller as the distance is further from the city center of Kunming in winter. The spatial distribution do not show accordant variation trend in spring or autumn, but both minimum values are in0.5×0.5degree square, and the reasons need more detailed investigation.