Research And System Development Of Aerosol Retrieval Based On MODIS Image In Jinan

Aerosol content is an important indicator of air quality,which plays an important role in the global energy balance and the benign cycle of terrestrial ecosystem.Atmospheric aerosol optical depth(Aerosol Optical Thickness,AOT)is an important physical parameter to characterize the atmospheric turbidity and is one of the most important parameters of aerosol.This study uses MODIS images and measured data from solar photometer CE318 and uses improved dark pixel method,Flaash and 6S radiative transfer model to establish customized aerosol model of Jinan city.Based on the aerosol model of Jinan,a precise AOT look-up table can be make to retrieve AOT in Jinan area;Establish the mathematical model of AOT with PM2.5 content in Jinan area;By comparing with test data,we can verify the validity of the model.Combining with IDL language,we flow inversion process and develop the aerosol retrieval system.The main research contents and conclusions are as follows:(1)The improved dark pixel method combined with Flaash atmospheric correction method is used to calculate the surface reflectance of MODIS images.The improved dark pixel method is used to calculate the dark surface reflectance in the study area,and the Flaash atmospheric correction method is used to calculate the bright surface reflectance of the study area.Both of them can be used to calculate the surface reflectance of the MODIS images in the study area.Comparing AOT inversion results,the inversion results of this method are better than that of single dark pixel method.(2)The aerosol model and PM2.5 inversion model in Jinan were established to realize the AOT inversion and PM2.5 inversion.According to the atmospheric conditions and regional characteristics of Jinan City,the paper makes an assumption that the proportion of the four components in the aerosol,then combines MODIS image with the observation data of the ground solar photometer to build the aerosol model of Jinan.The aerosol model shows the proportion of the dust aerosol is 40%,the proportion of water soluble aerosol is about 56%,the proportion of marine aerosol is about 1%,and the proportion of soot aerosol is about 3%.Based on customized aerosol model,land aerosol model,city aerosol model,we make respective AOT look-up table for AOT inversion.Comparing the inversion results with MOD04 aerosol products and sun photometer data,we can find that the inversion precision of custom aerosol model is obviously higher than land and city aerosol model,the inversion of customized AOT model has great potential in Jinan city.The mathematical modelxy(10)(28)008.0049.0 of AOT and PM2.5 content in Jinan area is established and2 R is 0.424.The correlation between the PM2.5 inversion results and the test data is verified,and the correlation is 0.767.(3)Develop aerosol inversion system and make the inversion process flow.IDL compiles AOT and PM2.5 inversion program and develops aerosol retrieval system to improve the retrieval efficiency of AOT and PM2.5 in Jinan city.