High Spatial And Temporal Resolution Remote Sensing Based Aerosol Optical Depth Retrieval And Its Application In Atmospheric Environment

Tranditional atmospheric environmental researches mainly depend on ground-based monitoring stations.Due to influences of unscheduled maintenance and site layout distribution,the ground monitoring data usually has problems such as temporally data missing or spatially uneven distribution.In contrast to the limitations of ground monitoring,satellite remote sensing techniques can provide spatially continuous observations and has therefore been adopted to conduct atmospheric environmental research and dynamic analysis.This study aims to analyze two key issues of atmospheric pollution emission sources and atmospheric pollution transport from the air pollution joint prevention and control in China,based on aerosol observation from satellite remote sensing with high spatial resolution and temporal resolution,respectively.Based on aerosol retrieval algorithm from satellite remote sensing,our research is guided by specific application requirement from air pollution prevention,respectively exploring the technical feasibility and application value of i)locating and quantifying air pollution emissions sources using high spatial resolution satellite aerosol observations and ii)air pollution transport analysis and flux estimation using high temporal resolution satellite aerosol observations.It is expected that the relevant research results of this study could figure out the potential of satellite remote sensing technology in the atmospheric environmental pollution,in order to contribute to the atmospheric pollution prevention and control in China.The primary research work of this article is carried out from the following two aspects:a)Location and quantification of atmospheric pollution emission sources based on Gaofen-1 satelliteThe multi-band minimum reflectance optimization aerosol retrieval algorithm is adopted based on Gaofen-1 WFV sensor.Utilizing 6S atmospheric radiation transmission model and localized aerosol model to build look-up-tables,the AOD at550 nm with 160 m spatial resolution is retrived in three cities of China,namely Wuhan,Beijing,and Shanghai.The validation results based on ground-level sun-photometers show that the determination coefficients R² of the linear fitting of overall scattered matchups in Wuhan,Beijing,and Shanghai reach up to 0.80,0.77,and 0.71,respectively;the root mean square error is 0.25,0.33,and 0.18,respectively.The daily PM_2.5 concentrations with a 160 m spatial resolution are estimated using the AOD data retrieved by the Gaofen-1 WFV along with the nested linear mixed effects model and ancillary variables from the WRF meteorological simulation data.The ultrahigh resolution PM_2.5 estimations offer substantial advantages for providing finer spatially resolved PM_2.5 trends.Additionally,it offers new approaches to locate main PM_2.5 emission sources,evaluate the local PM_2.5 contribution proportion,and quantify the daily PM 2.5 emission level via remote sensing techniques.Along with joint observations using other high-resolution satellites,GF PM_2.5 will gradually become a convenient approach to analyze the urban inner PM_2.5 problems and offer an efficient way for government to evaluate the efficacy of emission management and reduction policies in urban areas.b)transport analysis and flux estimation based on Himawari-8 satelliteThe obvious change of atmosphere is generally considered as approximately half an hour,thus high temporal resolution atmospheric observations based on satellite remote sensing could provide new method to study atmospheric pollution transport.In this study,the multi-band minimum reflectance optimization aerosol retrieval algorithm is adopted based on the Himawari-8 AHI sensor to retrieve AOD at 550 nm for every 10minutes in East Asia,utilizing MODTRAN atmospheric radiation transmission model and candidate aerosol models to build look-up-tables.The validation results from ground-based AERONET aerosol observations in East Asia show that the determination coefficient R² of the linear fitting of overall scattered matchups in East Asia reaches up to 0.88,and about 69%of the validated matchups fall within the expected error envelops.In addition,comparing with the AHI AOD officially released by JMA,the temporal variation in AOD distribution retrieved in this study is smooth between two temporally adjacent images,which could provide data support for the subsequent research on atmospheric pollution transmission based on satellite high temporal resolution atmospheric observations.The H8 AOD retrievals are then fused with MODIS/CALIOP observations and ground measurements using Bayesian maximum entropy method,to obtain diurnal AOD datasets with applicable recovery accuracy and high spatial coverage.Since these AOD image sequences could be regarded as video frames in computer vision,the multi-scale pyramid HS optical flow method,which is used to estimate the motion direction and motion speed for each pixel,is adopted to estimate aerosol transport in each geographic grid.It is demonstrated that the results of the multi-scale pyramid HS optical flow could describe the process of atmospheric pollution transport,provide qualitative and quantitative motion field of atmospheric pollution transport,and calculate the air pollution transport flux based on the AOD spatial distribution and the motion field estimated by remote sensing optical flow.It is shown that the transport flux estimation result from remote sensing optical flow method is generally consistent with the transport flux result simulated by CMAQ model,which indicates the observation-based remote sensing optical flow method can help improve the reliability in estimating the atmospheric transport flux.Comparing with the classical atmospheric model simulation method,the estimation of air pollution transport based on satellite remote sensing technology could restore the process of air pollution transmission more finely.Moreover,the results in this study offer a new perspective to effectively and efficiently analyze haze transport at low cost,contributing significantly to the regional joint emission control and policy making in China.