Summertime ozone pollution in China affected by stratospheric quasi-biennial oscillation

[摘要] In recent years, the near-surface ozone (O 3 ) level has been rising fast inChina, with increasing damage to human health and ecosystems. In thisstudy, the impact of stratospheric quasi-biennial oscillation (QBO) oninterannual variations in summertime tropospheric O 3 over China isinvestigated based on GEOS-Chem model simulations and satellite retrievals.QBO has a significant positive correlation with near-surface O 3 concentrations over central China (92.5–112.5 ∘  E,26–38 ∘  N) when the sea surface temperature (SST) overthe eastern tropical Pacific is warmer than normal, with a correlationcoefficient of 0.53, but QBO has no significant effect on O 3 under thecold SST anomaly. Compared to the easterly phase of QBO, the near-surfaceO 3 concentrations have an increase of up to 3 ppb (5 % relative tothe average) over central China during its westerly phase under the warm SSTanomaly. O 3 also increases above the surface and up to the uppertroposphere, with a maximum increase of 2–3 ppb (3 %–5 %) in 850–500 hPaover central China when comparing westerly phase to easterly phase. Process-basedanalysis and sensitivity simulations suggest that the O 3 increase overcentral China is mainly attributed to the anomalous downward transport ofO 3 during the westerly phase of QBO when a warm SST anomaly occurs inthe eastern tropical Pacific, while the local chemical reactions andhorizontal transport processes partly offset the O 3 increase. This worksuggests a potentially important role of QBO and the related verticaltransport process in affecting near-surface O 3 air quality, with anindication for O 3 pollution prediction and prevention.

[学科分类] 医学（综合）