| Atmospheric aerosol is one of the important factors affect the environment and climate.The aerosol optical depth(AOD) is one of most important parameters of aerosol. It is also an important physical parameter to attribute the atmospheric turbidity. Aerosol optical depth can reflect regional air pollution, So it is of great significance to detect accurate atmospheric aerosol optical depth for climate change and regional pollution.Compared with traditional methods,satellite remote sensing has wide area eoverage,it is convenient for data access and data transmission, Satellite remote sensing is fast and efficient to access atmospheric aerosol.In recent years, it has already been made many progress in the retrieval of AOD from satellite remote sensing.In this paper,firstly, NASA MODIS Level-2 production from 2011 to 2012 was utilized in order to analysis the characteristics of distribution and inter-annual,monthly,seasonal, Urban spatial distribution variation of aerosol optical depth over Jiangsu、Zhejiang、Shanghai region.Then,we used V5.2 algorithm to retrieve the aerosol optical depth by the 6S Radiative Transfer Model, with a case study was conducted using the MODIS 1B data of May,2011, and got the spatial distribution of AOD in Jiangsu province.A certain error was found in the AOD obtained by V5.2 algorithm,when compared with AERONET solar direct radiance measurements from Nanjing University of Information Science and Technology(Jiang su province), which reason was analyzed in the paper.(1)Seasonal change of AOD in Jiangsu,zhejiang,shanghai region, Jiangsu region aerosol optical depth peak appeared in spring and summer, spring,on average, aerosol optical thickness, the largest value of 0.71, average summer aerosol optical thickness value is 0.69, the autumn average aerosol optical thickness value is 0.54, the average winter aerosol optical thickness and minimum value of 0.42. Alpha wavelength index analysis, the summer alpha averages of 1.05, in the fall of alpha averages of 1.13, is given priority to with fine particles in summer and autumn, spring is smaller than summer fall, winter two season alpha average spring alpha average is 0.62, average winter alpha 0.68, spring winter two season is given priority to with coarse particles.(2)Month change of AOD) in Jiangsu,zhejiang,shanghai region jiangsu, AOD month change is normally distributed, AOD in January to June rise gradually, to achieve maximum June, a value of 0.95, AOD in 7-12 month begins to decrease gradually,7,8 month AOD sharply reduced, AOD value of 0.81 in July, August of the AOD is 0.62, November 9-reduce tends to be stable, AOD minimum appeared in December, a value of 0.37.(3)Jiangsu,zhejiang,shanghai regional comparisons,2011 two years AOD 2012 comparisons, AOD maximum value appeared in the May 2011 years, AOD maximum value appeared in 2012 in July,2011,2012 months AOD in May, the biggest difference between AOD value was 0.67 in May 2012, in May 2011 the AOD value of 0.98, and 0.31 in July 2012 the AOD is 1.05, in July 2011 the AOD value 0.81, both differ 0.24. In 2011 in the first five months of AOD value is higher than the same period in 2012 in the first five months of AOD value.(4)Urban spatial distribution of the AOD jiangsu region, due to the objective existence of terrain, makes the level of aerosol in the boundary layer diffusion is restrained, in Shanghai and lishui, for example, Shanghai’s AOD in the spring, summer, autumn, winter average respectively 0.76,0.92,0.61,0.45, lishui AOD spring, summer, autumn, winter average were 0.56,0.79,0.52, 0.37. In the Shanghai area of the AOD is higher than the same period in every season average oflishui city each season average of the AOD, plain cities AOD is generally higher than the mountains. In Shanghai, huzhou, nanjing, huaian as an example, Shanghai’s AOD the monthly average of 0.61, huzhou of AOD month average value is 0.45, on average higher than that of huzhou, AOD in Shanghai nanjing AOD the monthly average of 0.57, huaian AOD month average value is 0.48, the AOD in nanjing on average higher than that of huaian, so the industry developed cities generally higher than less developed cities.(5)Through the study of the inversion of aerosol optical thickness in jiangsu province, the result found in south jiangsu, nanjing-wuxi, suzhou as the center of the city area, the area of AOD value between 0.61, because these cities are industry is relatively developed, and a large population, and the vegetation coverage area is relatively small, the aerosol optical thickness is higher. Subei regions, much of the AOD value between 0.2 to 0.3, compared with the low level of industrialization, in the areas of southern city of a less developed, population is hydrophobic, vegetation coverage is more, but the xuzhou region of aerosol optical thickness between 0.4 to 0.5, due to xuzhou heavy industrial base, higher than that of north jiangsu suqian area, huaian surrounding city, etc. Between southern jiangsu and northern jiangsu mainly concentrated in the middle region of the aerosol optical thickness between 0.3 to 0.5, the transition zone of considerably. But the aerosol optical thickness appeared in nantong high value of 0.5-0.6, this is mainly because offshore nantong region, are greatly influenced by the sea salt aerosol, is also a middle area industrial industrial base, the higher than middle area surrounding the taizhou, yangzhou region of aerosol optical thickness, conform to the time and space distribution characteristics of the AOD jiangsu region.(6)Inversion using V5.2 algorithm the aerosol optical thickness distribution of jiangsu province, on May 3,2011 and 2011 on May 24, the inversion results compared with the data of the ground the sun photometer, validation, on May 3,2011, the relative error is 7.31%, on May 24,2011, the relative error is 11.19%, both within the effective range of error, and analyzes the error is the main reason of the aerosol type and affected by the uncertainty on the inversion results of the surface reflectance. |
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