地表臭氧(O3)的时空分布,变体,根据空气质量监测网络数据和臭氧监测仪(OMI)的卫星检索,揭示了济南2015年至2020年的原因。结果表明,2015年至2020年,济南市臭氧浓度逐渐升高。日最大8-h平均值(MDA8)O3(即年度评估值)和MDA8O3(4月至9月)的年度第90百分位数分别增加了4.8μg·(m3·a)-1和3.8μg·(m3·a)-1。高浓度范围内臭氧水平的趋势比低浓度范围内臭氧水平的趋势增加更快。6月MDA8增加7.4μg·(m3·a)-1,在凉爽季节(12月至2月)增加的速率范围为2.6-3.9μg·(m3·a)-1;冬季O3的控制不容忽视。从2015年至2020年4月至9月的臭氧日变化可以明显看出,近年来平均臭氧水平有所上升。白天的生长速率高于夜间。光化学生产能力不断提高,尤其是近年来。此外,值得注意的是,臭氧水平的峰值时间大约提前了1-2小时。近年来,不同站点之间的臭氧浓度差异逐渐减小。与2015年相比,2019-2020年O3浓度高的地区范围进一步扩大。在济南16.1%和22.6%的监测点中,MDA8-90和MDA8(4月至9月)观察到显着的正趋势(P<0.05),其中大部分位于市区和靠近市区的郊区。2015年以来,济南市臭氧的时空变化受到VOCs和NOx排放变化的影响。2015年至2020年的卫星遥感数据显示,NO2对流层柱(4月至9月)减少了20.6%,下降速率为0.3×1015摩尔·(cm2·a)-1,尤其是在市区和郊区。检测到的对流层HCHO的变化趋势微弱且不明显,这表明NOx排放的减少远远大于VOCs排放的减少,这种差距在城市地区变得更加明显。随着对前体排放的反应,O3形成的化学敏感性一直在变化。VOCs限制制度持续下降,混合NOx/VOC敏感制度和NOx限制制度增加。总的来说,臭氧前驱体NOx/VOCs的这种极不恰当的控制比例导致了济南O3波动缓慢增加的总体趋势。研究结果表明,济南VOCs的减排力度还远远不够,加强当前VOCs排放控制是近期控制济南O3污染增长趋势的有效措施,尤其是在城市和周边郊区。
The surface ozone (O3) spatiotemporal distribution, variations, and its causes in Ji\'nan from 2015 to 2020 were revealed based on the air quality monitoring network data and satellite retrievals from the Ozone Monitoring Instrument (OMI). The results showed that the ozone concentration in Ji\'nan gradually increased from 2015 to 2020. The annual 90th percentile of the daily maximum 8-h average (MDA8) O3(namely the annual evaluation value) and the MDA8 O3(April-September) increased by 4.8 μg·(m3·a)-1 and 3.8 μg·(m3·a)-1, respectively. The trend of the ozone levels in the high-concentration range increased faster than that in the low-concentration range. The MDA8 in June increased by 7.4 μg·(m3·a)-1, and the rate range of increases was 2.6-3.9 μg·(m3·a)-1 in the cool seasons (December-February); thus, the O3 control in winter cannot be ignored. It is apparent from the diurnal variations in ozone from 2015 to 2020 in April-September that the average ozone levels have risen in recent years. The growth rate in the daytime was higher than that at night. The capacity of photochemical production has been increasing, especially in recent years. Additionally, it is noteworthy that the peak time for ozone levels occurred approximately 1-2 h earlier. The disparity of ozone concentrations among different stations gradually decreased in recent years. Compared with that in 2015, the range of areas with high O3 concentrations in 2019-2020 was further expanded. The significant positive trends in MDA8-90th and MDA8 (April-September) were observed in 16.1% and 22.6% of the monitoring sites in Ji\'nan (P<0.05), most of which were located in urban areas and the suburbs close to urban areas. The temporal and spatial changes in ozone in Jinan had been affected by the changes in VOCs and NOx emissions since 2015. Satellite remote sensing data from 2015 to 2020 revealed that the NO2 tropospheric columns (April-September) showed reductions of 20.6%, with a decreasing rate of 0.3×1015 mole·(cm2·a)-1, especially in the urban areas and suburbs. The detected variation trends of tropospheric HCHO were weak and insignificant, which suggested that the decrease in NOx emissions was much greater than the decrease in VOCs emissions, and the gap had become more obvious in the urban areas. With responses to precursor emissions, the chemical sensitivity of O3 formation had been changing. The VOCs-limited regimes continuously decreased, and the mixed NOx/VOCs-sensitive regimes and NOx-limited regimes increased. In general, such an extremely inappropriate control ratio of ozone precursor NOx/VOCs led to an overall trend of slow increasing fluctuations of O3 in Ji\'nan. The findings clearly indicate that the reduction of VOCs in Ji\'nan was far from sufficient, and strengthening the current control of VOCs emissions is an effective measure to control the growth trend of O3 pollution in Ji\'nan in the near future, especially in urban and surrounding suburban areas.