Abstract:
Based on surface ozone (O
3) mass concentrations and meteorological data in Jinan and Qingdao during 2014 to 2021, the variation characteristics of daily maximum 8-hour moving averages of ozone concentrations (O
3-8h concentrations) and its relationship with meteorological factors were studied. Backward trajectories were also combined with O
3 concentrations for trajectories clustering and potential source regions of O
3 analysis. The results showed that level of O
3 pollution in Jinan was generally higher than that in Qingdao. The O
3 pollution episodes were observed from April to October. The annual trend of 90
th percentile of O
3-8h concentrations (O
3-8h 90
th concentrations ) in Jinan generally showed an upward trend and then a downward trend from 2014 to 2021. Moreover, the peak value of annual O
3-8h 90
th concentrations in Jinan was observed in 2019. The annual O
3-8h 90
th concentrations of Qingdao in 2019 and 2017 showed a little higher than those in other years. The annual O
3-8h 90
th concentrations of Qingdao in the other years showed little difference. The monthly variations of O
3-8h 90
th concentrations in Jinan were more significant, with a unimodal distribution. However, the monthly variations of O
3-8h 90
th concentrations in Qingdao had a bimodal distribution, due to the influence of summer rainy season and clean maritime air mass dilution. The high O
3 concentrations were more easily caused by unfavorable weather conditions, such as high temperature, low relative humidity and light wind. Compared with that in Qingdao, O
3-8h concentrations in Jinan had a closer correlation with meteorological factors, especially with mean air temperature from 8:00 to 17:00 (
T8-17). When
T8-17 was greater than 15 ℃, for every 1 ℃ increase in
T8-17, O
3-8h concentrations in Jinan was increased by 6.1 μg/m
3. O
3-8h concentrations in Qingdao was fluctuated increased with the increase of
T8-17. However, for every 1 ℃ increase in
T8-17, O
3-8h concentrations in Qingdao was only increased by 1.5 μg/m
3. The O
3 concentrations in Jinan were much higher, with mean of (113±51) and (109±57) μg/m
3, respectively, when the airflow came from southwesterly and south-southeasterly areas, which was the central and eastern junction of Jiangsu-Anhui-Shandong-Henan region. The O
3 concentration in Qingdao was (106±45) μg/m
3, together with the southwesterly airflow beginning at the inland regions. The main potential source regions of O
3 in Jinan and Qingdao shared a same region, mainly located at the central and eastern of junction Jiangsu-Anhui-Shandong-Henan region and the central Shandong region. Based on all the above research results, the O
3 pollution in Jinan and Qingdao were mainly driven by local emission. The regions of coordinated inter-regional O
3 prevention and control for Jinan and Qingdao should focus on the central and eastern of junction Jiangsu-Anhui-Shandong-Henan region and the central Shandong region.