Research On The Inversion Method Of AOD In Beijing-Tianjin-Hebei Region By FY-4A Meteorological Satellite

Aerosol optical depth is characterization of aerosol concentration and the amount of atmospheric turbidity,with decades of rapid industrialization and urbanization,China has become a significant high-value area of the global Aerosol Optical Depth(AOD).The currently widely used remote sensing AOD products are mainly from polar orbit satellites,with limited observation frequency,which is difficult to satisfy the dynamic monitoring needs of the management of the atmospheric environment.FY-4A is among the new generation of geostationary meteorological satellite in China.Advanced Geostationary Radiation Imager(AGRI)is one of the main sensors boarding on FY-4A.In order to investigate the reliability of the Aerosol Optical Depth(AOD)retrieval using FY-4A measurements,based on the geostationary satellite FY-4A/AGRI,the following research works have been carried out in this study:(1)The dark target algorithm is optimized to apply to the data of Fengyun-4 satellite.By preprocessing FY-4A/AGRI data,the apparent reflectance and geometric parameter information of the dark pixels were obtained,and the feartures of dark pixels were extracted,then the dark target algorithm was carried out to perform the AOD over Beijing-Tianjin-Hebei region.The results show that the dark target algorithm agrees with the AERONET data in general trend.(2)The influences of geometric parameters,surface reflectance and different aerosol models in the input parameters of the 6S radiative transport model,on the inversion effects of aerosol optical depth were studied.The 6S model does not include the spectral response function of the FY-4A/AGRI sensor.Therefore,the AGRI spectral response function is introduced into the 6S model,and then the input parameters are set according to the geographic characteristics of the study area and other parameters and information for iterative simulation,their corresponding look-up tables are established by 6S model.(3)The inversion model of the deep blue algorithm was built.From the inversion results,it can be seen that the deep blue algorithm has good applicability to inversion of aerosol optical thickness in Beijing-Tianjin-Hebei region,and its inversion results are more continuous than the dark target method.A fusion method of dark target method and deep blue algorithm is used to inversion of AOD,the results are more in line with the requirements and actual distribution of urban aerosol optical depth inversion.(4)The accuracy of the inversion results of the three algorithms was evaluated with the AERONET ground-network observations,the FY-4A AOD inversion results are compared with the different time series data of AERONET product data have a good consistency,and the AOD retrieval of FY-4A satellite is reliable.