北极气溶胶时空变化特征及其对向下短波辐射的影响OA

Based on reanalysis data from the modern-era retrospective analysis for research and applications,ver-sion 2(MERRA-2)and experimental data from the Coupled Model Intercomparison Project Phase 6(CMIP6)De-tection and Attribution Model Intercomparison Project(DAMIP),the temporal and spatial variations of Arctic aer-osols over the past 40 years and their influence on surface downward shortwave radiation are analyzed.The results reveal that Arctic aerosol optical depth(AOD)shows a continuous but gradually decreasing trend,with a decline rate significantly higher than that in middle and low latitudes.The composition of Arctic aerosol shows significant seasonal and regional differences:the concentrations of black and organic carbon are higher in spring and summer,mainly driven by long-distance transport and biological activities;dust levels increase significantly in spring due to stronger winds and frequent sandstorm activities.Sulfate dominates in spring and winter,correlating closely with industrial emissions and atmospheric chemical reactions.Aerosol concentration in the Chukchi Sea is generally higher than in other Arctic waters,whereas Greenland is characterized by low concentrations because of its high terrain and ice cover.A strong negative correlation exists between AOD and downward shortwave radiation in clear skies,and its radiation forcing effect is most significant in summer(r=-0.72).The average atmospheric attenua-tion ratios of downward shortwave radiation in the MERRA-2 and CMIP6 historical scenarios under clear skies and obtained from a hist-aer experiment in the Arctic region are 0.31,0.28,and 0.27,respectively.Due to the influence of the geometric path of radiation through the atmosphere on aerosol effects,MERRA-2 reanalysis data and the CMIP6 model display a phenomenon where the radiation attenuation ratios intensify at high Arctic latitudes.