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<p>By ERA-5 reanalysis data and maximum daily averaged 8&#xa0;h surface ozone concentration (SOC) station data, we investigate the interannual variability of mid-high-latitude Eurasian intraseasonal oscillation (ISO) during boreal summer, and its impact on the SOC in North China. The results indicate that both the maximum value and the largest variability of SOC within eastern China appear in North China, and the SOC in this region exbibits a significant periodicity of 10–30&#xa0;days. Compared with the tropical ISO, the southeastward-propagating mid-high-latitude Eurasian ISO (MHLE-ISO) is relative more crucial in causing the 10–30&#xa0;day variability of SOC in North China. Composite analysis demonstrates that although the propagation speed of the MHLE-ISO shows little disparity between strong and weak ISO years, the ISO intensity is more pronounced in strong ISO years. Further analysis indicates that, during strong ISO years, the ISO disturbance obtains more energy from the mean flow via barotropic kinetic and potential energy conversions, leading to a stronger intensity than that in weak ISO years. Analyses for key phases, namely phase 7 and 3, reveal that during phase 7 (3) of strong ISO years, more intense ISO signals propagate towards North China, suppressing (enhancing) the accumulation of humidity and cloud cover. This results in more (less) substantial downward solar radiation. These factors lead to positive (negative) surface air temperature anomalies in North China, while local wind inhibits (facilitates) ozone precursors dispersion, thereby making the SOC in this region higher (lower) in strong ISO years.</p>

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Interannual variability of mid-high-latitude Eurasian ISO and its impact on surface ozone concentration in North China during boreal summer

  • 期刊论文

  • 发表日期：

    2025年12月22日

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  • Shuangyan Yang,
  • Yanbin Fan,
  • Yashu Liu,
  • Qinghan Xu

摘要

By ERA-5 reanalysis data and maximum daily averaged 8 h surface ozone concentration (SOC) station data, we investigate the interannual variability of mid-high-latitude Eurasian intraseasonal oscillation (ISO) during boreal summer, and its impact on the SOC in North China. The results indicate that both the maximum value and the largest variability of SOC within eastern China appear in North China, and the SOC in this region exbibits a significant periodicity of 10–30 days. Compared with the tropical ISO, the southeastward-propagating mid-high-latitude Eurasian ISO (MHLE-ISO) is relative more crucial in causing the 10–30 day variability of SOC in North China. Composite analysis demonstrates that although the propagation speed of the MHLE-ISO shows little disparity between strong and weak ISO years, the ISO intensity is more pronounced in strong ISO years. Further analysis indicates that, during strong ISO years, the ISO disturbance obtains more energy from the mean flow via barotropic kinetic and potential energy conversions, leading to a stronger intensity than that in weak ISO years. Analyses for key phases, namely phase 7 and 3, reveal that during phase 7 (3) of strong ISO years, more intense ISO signals propagate towards North China, suppressing (enhancing) the accumulation of humidity and cloud cover. This results in more (less) substantial downward solar radiation. These factors lead to positive (negative) surface air temperature anomalies in North China, while local wind inhibits (facilitates) ozone precursors dispersion, thereby making the SOC in this region higher (lower) in strong ISO years.