Impact of East and Central Pacific El Ninos on Tropospheric Ozone in China

Tropospheric ozone has become one of the dominant pollution species in China. The production of tropospheric ozone is closely related to meteorological conditions, which is largely controlled by large scale climate variability. In this study, we examine the tropospheric ozone change in China associated with the two types of El Niño events, namely the East Pacific (EP) and Central Pacific (CP) type, using both satellite observations and GEOS-Chem simulations. During the autumn, ozone always shows an increase over southern China or southeastern China. These patterns are influenced by the meteorological changes controlled by the development of EP and CP El Niño. In winter and spring, observed and simulated ozone decrease over most of China for EP event. In spring, local production contributed more to the ozone decrease than regional transport over the large area of China for the CP event. In summer, the ozone change is opposite for the EP and CP event. Further examination of different EP and CP events indicates that the summer pattern is dominated more by the subsequent ENSO phase than the previous El Niño type.