Seasonal Cycles of Surface Ozone and NOₓin Shanghai

A series of simultaneous observations of the surface ozone and NOₓhave been employed in Shanghai since 1990. Based on a 5-yr data series, seasonal cycles of O₃ and NOₓhave been acquired. Both cycles have a maximum occurring in spring and a minimum occurring in summer. The monsoon flow reversal is a major factor affecting the cycles; however, the influences are different with seasons. The strongly synchronous seasonal changes of NOₓwith ozone suggest that the anthropogenic emissions play an important role in the surface ozone cycle. Influences of the anthropogenic emissions also are different with the seasons. The effect of the monsoon on the ozone cycle is most strong in summer, and the effect of the anthropogenic emissions on that cycle is most strong in spring.