Inversion And Spatial-temporal Change Analysis Of Aerosol Optical Depth In Nanjing Based On HJ-1Satellite

With the rapid development of industrial production, air pollution has become an important issue of human development. As an important component of the atmosphere, aerosols not only plays an important role in radiation energy balance, but also closely linked with the quality of atmospheric environment. Aerosol optical depth is defined as the integration of the extinction coefficient of the medium in the vertical direction, describing the attenuation caused by atmospheric aerosols in the transmission. Accurately monitoring the aerosol optical depth can not only deepen the understanding of the energy balance of the climate system, but also play an important role in the prevention and management of air pollution. Currently the research on the aerosol optical depth of cities’is not so much, therefore, it has important theoretical significance and application value for the study of aerosol optical thickness distribution in the cities.Firstly, based on the16HJ-1CCD images in2013-2014in Nanjing, use6S radiative transfer model to build a lookup table, do band correction on the MODIS surface reflectance product,16images of the distribution of aerosol optical depth of Nanjing were made. And combined with the data observed by CE-318sun photometer, the accuracy of the result was verified. The results showed that the most suitable solution for the lookup table input parameters of Nanjing:in most cases, the absorbent of the aerosol particles over Nanjing is weak or moderate weak, and it is most similar with the continental aerosol type of6S radiative transfer model; comparing the results with the ground measurement data, the average absolute error of0.135, the average relative error is22.743%.Secondly, do overlay statistics over the results and the NDVI, NDBI of the images; according to different sources of emissions, a statistical analysis was made between the areas of YPC and Xin Jie Kou. The results showed that:the correlation between aerosol optical depth and NDVI was negative, the correlation between aerosol optical depth and NDBI was positive; Both of the aerosol optical depth of YPC and Xin Jie Kou were high. YPC contributes a little bit more to the whole aerosol optical depth of the city than Xin Jie Kou, and its changes of spatial distribution was larger, the changes in Xin Jie Kou was more uniform.Finally, combined with ground truth data and meteorological data, a slight contamination process was monitored, a statistical analysis was made with the mean of aerosol optical depth in different seasons. The results showed that:taking advantage of high temporal resolution of HJ-1 satellite, atmospheric pollution process can be monitored; the aerosol optical depth in summer was significantly higher than in spring and winter, and in spring, it was slightly higher than in winter, and its changes are more intense.