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Abstract:
Six World Meteorological Organization (WMO)/Global Atmosphere Watch (GAW) stations are located at background sites in China, which constitute a network for monitoring surface ozone, including its long-term temporal variation. In this study, we evaluated the seasonal variation in surface ozone simulated by the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model with the measurements made at these WMO/GAW background stations for the period of 2010–2012, and investigated the regional representativeness of each station with respect to the seasonal variation in surface ozone. We determined the contributions of ozone originating from various tropospheric and stratospheric latitude bands based on EMAC simulations using a tagged tracer approach. The results showed that the predominant contribution to surface ozone was from the troposphere in northern middle-high and tropical latitudes. For each station there was a large surrounding area in which the yearly ozone maximum occurred in the same month as it did at the station, reflecting the regional characteristics of the seasonal variation in surface ozone recorded at the WMO/GAW background stations. Surface ozone in China was found to generally peak in summer over non-monsoon and mid-latitude monsoon regions and in spring over low-latitude monsoon regions, indicating that the regional representativeness of ozone variability in China is significantly influenced by the Asian summer monsoon.
