Monitoring Atmospheric Aerosol Optical Depth In Yangtze River Delta Using Remote Sensor Data

Aerosol optical depth can reflect regional air pollution, it is important to evaluate atmospheric pollution and radiative effects, 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 coverage, it is convenient for data access and data transmission, etc. Satellite remote sensing is fast and efficient to access atmospheric aerosol. Ground detection method can only get the data at certain site and is not available to have large area spatial and temporal distribution of aerosol. Using satellite remote sensing observations can make the shortage of lack of monitoring data, and it is convenient for people to understand region changes of aerosol timely. This article includes the following aspects:1. The aerosol optic depth of Yangtze River delta was retrieved using V5.2 algorithm developed by Robertc.Levy from Terra/MODIS level1B data. The results were given for each season. Because of more rain and farm work in spring, the composition of aerosol particles was more complex. Maximum of aerosol optical depth appeared in Nanjing and Taixing, Jiangsu Province, center maximum was 0.98, atmospheric aerosol optical depth in Haining, Linan, and other surrounding areas was much smaller than that in urban areas. In summer, aerosol optical depth was smaller in northern Yangtze River delta(Jiangsu Province, Nanjing, Yangzhou, etc) and southern region (coastal Zhejiang Province, Ninghai, Xinchang, etc), average value was 0.35. Aerosol optical depth was smaller in fall, maximum appeared in the south of Taihu Lake (Nanjing, Zhenjiang, Wuxi, Yangzhou, etc) and Shanghai, center maximum of aerosol optical depth was about 1.7. Minimum of aerosol optical depth was 0.19 and appeared in southwest of the Yangtze River Delta. The area with high value in winter mainly appeared in central and southern coastal cities of Yangtze River delta, regions with maximum appeared in Shanghai and central maximum was 0.85, while aerosol was not greater than 0.2 in most parts of Zhejiang Province. The comparison between atmospheric aerosols and land use land cover data from 2001 to 2009 showed that aerosol optical depth's change was closely related to urban land use's change.2. The comparison between aerosol MOD04 MODIS satellite remote sensing products and CE-318 ground observations showed that the accuracy met the 99% believability accuracy requirements. Nine years' MOD04 data products from 2001 to 2009 in Yangtze River delta were analyzed for spatial and temporal variations. Aerosol optical depth in spring and summer was larger than that in fall and winter. The largest average aerosol optical depth was 0.7141 in spring and had minimum of 0.4952 in winter. AOD decreased gradually after 2002, became larger after 2005, with a maximum of 0.6712 in 2007, and then it declined gradually. Spatial characteristics of aerosol in Yangtze River Delta:high value of aerosol mainly distributed in southern Jiangsu, Shanghai and Hangzhou Bay area. Analysis of wavelength exponent of aerosols indicated that the wavelength exponent was small in spring, indicating that large particles were main control particle size and aerosol particles were larger. The wavelength exponent was larger in fall and winter, indicating that human-generated aerosol was mainly small particles aerosol.