Research Of Aerosol Properties And Radiative Effect Over Central And East China Based On Satellite Observations

With the development of economic and society,the increase of population and human activities,great anthropogenic emissions enter the atmosphere.Aerosol is one of the most important part of anthropogenic emissions and has attached great attention from society and researchers.Given the great influence of aerosols on the global energy budget,hydrologic cycle and human health,long-term accurate observation on the content and characteristics of atmospheric aerosols and estimation of its influence are essential.Satellite observations has advantages of wild range and low cost,some of the satellites even could have a temporal resolution similar with ground-based observations.Thus makes satellite data become the major data source of aerosol researches.However,ground-based observation still obtains more trust on data accuracy.This work processes a detailed validation and make analyses for satellite-based aerosol optical depth(AOD)product from multi satellites basing on long-term ground-based observation.The vertical information of aerosols from satellite-based observations are also analyzed and discussed.Results are used to choose suitable data to process the following works.A method to calculate long-term and wild-range surface aerosol direct radiative effect(ADRE)using look-up table and surface albedo correction is developed.18 years(2001-2018)surface aerosol direct radiative effect over China is calculated through this method and its spatial-temporal distributions are also analyzed.This work expands the application range of satellite products.The main research contents of this paper are as follows:1)Validations and analyses for satellite-based aerosol optical depth products over Central and East China.To choose the proper data source of AOD for ADRE calculations,this work validates the AOD product from Moderate Resolution Imaging Spectroradiometer(MODIS)and Himawari based on aerosol robotic network(AERONET)ground-based observations.Correlation analyses show that the determination coefficient(R~2)get the highest value(～0.8)in north China,and MOD AOD product form MODIS performs best in the study area through comparison between multi-source datasets.Aiming at the blank of validation in central China,long-term ground-based observation in Wuhan is used to process a detailed validation for Himawari AOD product.The error sources are discussed through aerosol size distribution simulation and sun-earth-satellite relative positions.The result shows that the underestimate of default median radius set by Hmawari AOD retrieval method leads to the underestimate of AOD,and the poor simulation of phase function leads the change of retrieval performance with the relative position differs.This part provides the basis for the following experimental data selection.2)Analyses for aerosol vertical distribution information over Central and East China.To overcome the influence of different aerosol vertical distribution on the calculation of aerosol radiation effect.This work uses the aerosol vertical profile product of CALIPSO to accurately calculate boundary layer height(BLH)and the aerosol vertical distribution information in the boundary layer.The analysis shows that the difference of multi-year averaged BLH and vertical extinction profile is negligible between regions in the study area,and the seasonal variations could be divided in two kinds like spring-summer and autumn-winter.Furthermore,the aerosol distribution and composition in the nocturnal residual layer(RL)are also discussed,and the influence of aerosol on the surface pollutants of the next day is also analyzed.The results show that most of aerosol at night assembles in the RL(>50%),the main type of aerosols are dust and continental aerosols.AOD in RL is positive relative with ground pollution in the next day,the higher correlation coefficient is 0.4.This part provides the reference of aerosol vertical information for the following calculation of aerosol radiative effect.3)Development of a fast method for calculating surface ADRE.It costs much time to calculate the aerosol shortwave direct radiative effect in long-term and over wild range directly using the radiative transfer model.Therefore,it is necessary to simplify the calculation process.In this paper,we firstly use a lookup table to avoid repeated calculation,then use surface reflection simplification method to reduce the dimension of lookup table and reduce the time of the lookup table building.Finally,the validation of our calculation reveals that our method greatly simplified the calculation and maintains high accuracy.In this part,surface aerosol shortwave direct radiative effect from 2001 to 2018 over China is successfully calculated.4)Analyses for spatial-temporal distribution of surface ADRE and its controlling factors.The spatial and temporal distribution of surface ADRE in China are studied by using the above calculation results.Similar with the AOD spatial distribution,great cooling effect appears in North China Plain,Yangtze River Delta and Jianghan Plain.For temporal distribution,the cooling effect shows a firstly increasing and finally decreasing trend,and the boundary is 2011.The factors that affect daily surface ADRE are also analyzed,comparing with aerosol optical properties except AOD,the sunshine duration have more influence on daily surface ADRE.