Spatiotemporal Variation In CO Over Anhui Using Measurements From Satellite And Ground Stations

CO is a key constituent to measure regional air pollution.Anhui is located in the Yangtze River Delta with an active economy and rapid industrial development,that has faced severe atmospheric CO pollution.The spaceborne TROPOMI CO vertical column densities(VCDs)retrieved by iterative maximum a posterior-DOAS algorithm and the near surface CO concentrations directly measured by the ground stations were used to analyze the spatiotemporal distribution characteristics of atmospheric CO in Anhui from June 2018 to May 2019.Then the data of social economy,physical geography,meteorology and emission inventory together with the result of model simulation were used to explore the influencing factors of the spatiotemporal distribution of atmospheric CO in Anhui.The main research contents and conclusions are as follows:1.TROPOMI CO retrieval based on iterative maximum a posteriori-DOAS algorithm was carried out.First,the characteristic of the trace gas inversion in the shortwave infrared region was quantitatively analyzed using the strong absorption constituent CH4 as the research object.Then the parameters analysis and setting of the inversion were summarized.Finally,the CO VCDs retrieved from the iterative maximum a posterior-DO AS algorithm were verified,during which they were highly correlated with the measurements from the FTIR spectrometer with the correlation coefficient of 0.84,and had similar spatial distribution characteristics as the inversion of the spaceborne SICOR algorithm,with the correlation coefficient of 0.94,the average difference of+0.17%,and the standard deviation of 3.55%.2.The study on the spatiotemporal distribution characteristics of atmospheric CO over Anhui was carried out.CO VCDs' high values observed by satellite remote sensing are mainly distributed in the north-central region and along the Yangtze River,while its low values are mainly distributed in the high-altitude mountain areas of western and southern Anhui.CO VCDs' high value period occurs in winter,with the highest in December,while the low value period occurs in summer,with the lowest in July.The daily distributions of near surface CO concentrations directly measured by the ground stations show the double-peak type in Hefei and Huangshan,and the single-peak type in Maanshan.The differences of the daily distributions between weekdays and weekends of near surface CO measured by the certain ground stations respectively in Hefei and Maanshan show the weekend effect where the concentrations in weekdays are higher than weekends,while it measured by the certain ground station in Huangshan shows an anti-weekend effect where the concentrations in weekdays are lower than weekends.3.The factors affecting the spatiotemporal distribution of atmospheric CO in Anhui were analyzed.The spatial distribution difference of the CO VCDs observed by satellite remote sensing originates from the difference in emission intensity,and the time distribution differences in terms of months and seasons come from the concentration change of CO-consuming OH radical.The average of the daily distribution of near surface CO concentrations in each city monitored by the ground stations depends on the city's energy consumption,and its volatility depends on changes in the city's traffic volume,OH radical concentration,and atmospheric diffusion conditions.The differences in the daily distribution of near-surface CO concentrations at various stations between weekdays and weekends stem from differences in regional industrial and transportation energy consumptions.In addition,the analysis of atmospheric CO transport path and potential source area in Hefei shows that Jiangsu,Shanghai and Zhejiang in the Yangtze River Delta,Beijing-Tianjin-Hebei region,and neighboring provinces Jiangxi,Henan and Shandong are the main potential sources affecting its CO pollution in winter.