A Statistical Algorithm for Retrieving Background Value of Absorbing Aerosol Index Based on TROPOMI Measurements  

作　　者：Fuying TANG Weihe WANG Fuqi SI Haijin ZHOU Yuhan LUO Dongshang YANG Yuanyuan QIAN 

机构地区：[1]Key Laboratory of Environmental Optics and Technology,Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China [2]University of Science and Technology of China,Hefei 230026,China [3]Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites,FengYun Meteorological Satellite Innovation Center(FY-MSIC),China Meteorological Administration(LRCVES/CMA),Beijing 100081,China

出　　处：《Advances in Atmospheric Sciences》2023年第6期1104-1116,共13页大气科学进展（英文版）

摘　　要：The ultraviolet aerosol index(UVAI) is essential for monitoring the absorbing aerosols during aerosol events. UVAI depends on the absorbing aerosol concentration, the viewing geometry, and the temporal drift of radiometric sensitivity. To efficiently detect absorbing aerosols with the highest precision and to improve the accuracy of long-term UVAI estimates,the background UVAI must be examined through the UVAI retrieval. This study presents a statistical method that calculates the background value of UVAI using TROPOspheric Monitoring Instrument(TROPOMI) observation data over the Pacific Ocean under clear-sky scenes. Radiative transfer calculations were performed to simulate the dependence of UVAI on aerosol type and viewing geometry. We firstly applied the background UVAI to reducing the effects of viewing geometry and the degradation of the TROPOMI irradiance measurements on the UVAI. The temporal variability of the background UVAI under the same viewing geometry and aerosol concentration was identified. Radiative transfer calculations were performed to study the changes in background UVAI using Aerosol Optical Depth from the Moderate Resolution Imaging Spectroradiometer(MODIS) and reflectance measurements from TROPOMI as input. The trends of the temporal variations in the background UVAI agreed with the simulations. Alterations in the background UVAI expressed the reflectance variations driven by the changes in satellite state. Decreasing trends in solar irradiance at 340 and 380 nm due to instrument degradation were identified. Our findings are valuable because they can be applied to future retrievals of UVAI from the Environmental Trace Gases Monitoring Instrument(EMI) onboard the Chinese GaoFen-5 satellite.

关 键 词：ultraviolet aerosol index background UVAI TROPOMI reflectance DEGRADATION 

分 类 号：P407[天文地球—大气科学及气象学]