Abstract Vertical transport carries airmasses from different sources of tropospheric O 3 including photochemical production and stratospheric intrusions, and is crucial for vertical O 3 variability. Based on temporally dense ozonesondes over northern China, this study reports an anomalous vertical O 3 distribution characterized by a “bottom‐heavy” structure. Specifically, O 3 well exceeded the normal values in the middle‐to‐lower troposphere due to the stratospherically intruded airmasses (SIA), but was sharply reduced in the upper troposphere and lower stratosphere region because of convectively lofted air transported from the Tibetan Plateau. Guided by the discovery of such a vertical O 3 structure, we further assess the SIA contribution to tropospheric O 3 using multi‐year AIRS satellite observations, and find that SIA appear frequently during summer and lead to short‐term O 3 enhancements 35% above the normal values at 500 hPa. These results reveal the linkages between vertical O 3 variations and synoptic processes, highlighting the non‐negligible contribution of SIA to tropospheric O 3 .
Chen et al. (Wed,) studied this question.