Enhanced Late Spring Ozone in Southern China by Early Onset of the South China Sea Summer Monsoon

Xiaorui Zhang, Xiao Lu*, Fan Wang, Wen Zhou, Peng Wang, Meng Gao*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review


The onset of the South China Sea summer monsoon (SCSSM) has profound impacts on meteorological conditions over East Asia. However, whether the interannual variability in monsoon onset date impacts ozone (O3) pollution remains unclear. Here, we investigate the relationship between early onset of SCSSM and late spring O3 in southern China. Our results show notable differences in surface O3 concentrations before and after SCSSM onset during early onset events in southern China. The enhanced O3 of 11.1 μg m−3 is supported by increased air temperature and solar radiation of 1.1 K and 30.9 W m−2 and reduced relative humidity of −5.7%. Both observation and model simulations confirm that O3-favorable meteorological conditions modulated by early SCSSM onset can be found in May. It increases the boundary layer height and biogenic emissions of volatile organic compounds, enhancing O3 by 10 μg m−3 over southern China. Chemical processes dominate such increases in O3 with enhanced chemical production of 0.27 Tg month−1. Descending motion in southern China vertically transports O3 to surface by 0.10 Tg month−1, whereas horizontal advection reduces O3 concentration by 0.12 Tg month−1. The meteorological responses to colder sea surface temperature (SST) in the central equatorial Pacific are pronounced, leading to higher O3 concentrations over the Yangtze River Delta, while warmer SST in the Philippine Sea contributes O3 over the Pearl River Delta and eastern China. This study highlights the importance of SCSSM onset with respect to O3 in southern China, with promising applications in management of air pollution and agriculture.
Original languageEnglish
Article numbere2023JD039029
Number of pages14
JournalJournal of Geophysical Research: Atmospheres
Issue number4
Early online date21 Feb 2024
Publication statusPublished - 28 Feb 2024

Scopus Subject Areas

  • Geophysics
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Atmospheric Science

User-Defined Keywords

  • South China Sea summer monsoon
  • early onset event
  • meteorological conditions
  • ozone pollution


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