Currently, modeling studies tend to significantly underestimate observed space-based glyoxal （CHOCHO） vertical column densities （VCDs）, implying the existence of missing sources of giyoxal. Several recent studies ...Currently, modeling studies tend to significantly underestimate observed space-based glyoxal （CHOCHO） vertical column densities （VCDs）, implying the existence of missing sources of giyoxal. Several recent studies suggest that the emissions of aromatic compounds and molar yields of glyoxal in the chemical mechanisms may both be underestimated, which can affect the simulated glyoxal concentrations. In this study, the influences of these two factors on glyoxal amounts over China were investigated using the RAMS-CMAQ modeling system for January and July 2014. Four sensitivity simulations were performed, and the results were compared to satellite observations. These results demonstrated significant impacts on glyoxal concentrations from these two factors. In case 1, where the emissions of aromatic compounds were increased three-fold, improvements to glyoxal VCDs were seen in high anthropogenic emissions regions. In case 2, where molar yields of glyoxal from isoprene were increased five-fold, the resulted concentrations in July were B-B-fold higher, achieving closer agreement between the modeled and measured glyoxal VCDs. The combined changes from both cases 1 and 2 were applied in case B, and the model succeeded in further reducing the underestimations of glyoxal VCDs. However, the results over most of the regions with pronounced anthropogenic emissions were still underestimated. So the molar yields of giyoxal from anthropogenic precursors were considered in case 4. With these additional mole yield changes （a two-fold increase）, the improved concentrations agreed better with the measurements in regions of the lower reaches of the Yangtze River and Yellow River in January but not in July.展开更多
The regional air quality modeling system RAMS-CMAQ was applied to simulate the aerosol concentration for the period 2045-2050 over China based on the downscaled meteorological field of three RCP scenarios from CESM(N...The regional air quality modeling system RAMS-CMAQ was applied to simulate the aerosol concentration for the period 2045-2050 over China based on the downscaled meteorological field of three RCP scenarios from CESM(NCAR’s Community Earth System Model)in CMIP5.The downscaling simulation of the meteorological field of the three RCP scenarios showed that,compared with that under RCP2.6,the difference in near-surface temperature between North and South China is weakened and the wind speed increases over North and South China and decreases over central China under RCP4.5 and RCP8.5.Under RCP2.6,from 2045 to 2050,the modeled average PM2.5 concentration is highest,with a value of 40-50μg m^(-3),over the North China Plain,part of the Yangtze River Delta,and the Sichuan Basin.Meanwhile,it is 30-40μg m^(-3)over central China and part of the Pearl River Delta.Compared with RCP2.6,PM2.5 increases by 4-12μg m^(-3)under both RCP4.5 and RCP8.5,of which the SO_(4)^(2-)and NH_(4)^+concentration increases under both RCP4.5 and RCP8.5;the NO^(3-)concentration decreases under RCP4.5 and increases under RCP8.5;and the black carbon concentration changes very slightly,and organic carbon concentration decreases,under RCP4.5 and RCP8.5,with some increase over part of Southwest and Southeast China under RCP8.5.The difference between RCP4.5 and RCP2.6 and the difference between RCP8.5 and RCP2.6 have similar annual variation for different aerosol species,indicating that the impact of climate change on different species tends to be consistent.展开更多
基金supported by the National Natural Science Foundation of China (No. 91544221)the National Key R&D Programs of China (Nos. 2017YFC0209803, 2017YFC0210000)the CAS Strategic Priority Research Program Grant (No. XDB05020000)
文摘Currently, modeling studies tend to significantly underestimate observed space-based glyoxal （CHOCHO） vertical column densities （VCDs）, implying the existence of missing sources of giyoxal. Several recent studies suggest that the emissions of aromatic compounds and molar yields of glyoxal in the chemical mechanisms may both be underestimated, which can affect the simulated glyoxal concentrations. In this study, the influences of these two factors on glyoxal amounts over China were investigated using the RAMS-CMAQ modeling system for January and July 2014. Four sensitivity simulations were performed, and the results were compared to satellite observations. These results demonstrated significant impacts on glyoxal concentrations from these two factors. In case 1, where the emissions of aromatic compounds were increased three-fold, improvements to glyoxal VCDs were seen in high anthropogenic emissions regions. In case 2, where molar yields of glyoxal from isoprene were increased five-fold, the resulted concentrations in July were B-B-fold higher, achieving closer agreement between the modeled and measured glyoxal VCDs. The combined changes from both cases 1 and 2 were applied in case B, and the model succeeded in further reducing the underestimations of glyoxal VCDs. However, the results over most of the regions with pronounced anthropogenic emissions were still underestimated. So the molar yields of giyoxal from anthropogenic precursors were considered in case 4. With these additional mole yield changes （a two-fold increase）, the improved concentrations agreed better with the measurements in regions of the lower reaches of the Yangtze River and Yellow River in January but not in July.
基金supported by the Strategic Priority Research Program(A)of the Chinese Academy of Sciences grant number XDA19040204the National Natural Science Foundation of China grant number41830966the Major Scientific and Technological Innovation Projects of Shandong Province grant number 2018YFJH0901。
文摘The regional air quality modeling system RAMS-CMAQ was applied to simulate the aerosol concentration for the period 2045-2050 over China based on the downscaled meteorological field of three RCP scenarios from CESM(NCAR’s Community Earth System Model)in CMIP5.The downscaling simulation of the meteorological field of the three RCP scenarios showed that,compared with that under RCP2.6,the difference in near-surface temperature between North and South China is weakened and the wind speed increases over North and South China and decreases over central China under RCP4.5 and RCP8.5.Under RCP2.6,from 2045 to 2050,the modeled average PM2.5 concentration is highest,with a value of 40-50μg m^(-3),over the North China Plain,part of the Yangtze River Delta,and the Sichuan Basin.Meanwhile,it is 30-40μg m^(-3)over central China and part of the Pearl River Delta.Compared with RCP2.6,PM2.5 increases by 4-12μg m^(-3)under both RCP4.5 and RCP8.5,of which the SO_(4)^(2-)and NH_(4)^+concentration increases under both RCP4.5 and RCP8.5;the NO^(3-)concentration decreases under RCP4.5 and increases under RCP8.5;and the black carbon concentration changes very slightly,and organic carbon concentration decreases,under RCP4.5 and RCP8.5,with some increase over part of Southwest and Southeast China under RCP8.5.The difference between RCP4.5 and RCP2.6 and the difference between RCP8.5 and RCP2.6 have similar annual variation for different aerosol species,indicating that the impact of climate change on different species tends to be consistent.
