The balance of effects of deep convective mixing on tropospheric ozone

The balance of effects that vertical transport associated with deep cumulus convection has on tropospheric O 3 is discussed. We first show theoretically that convective mixing of O 3 can substantially reduce its column mean lifetime over clean regions, while a much smaller increase is generally expected over polluted regions. The global chemistry‐transport model MATCH‐MPIC confirms this, computing a 6% decrease in the annual mean tropospheric O 3 burden and a 7% decrease in its lifetime due to convective transport of O 3 alone. We find, however, that the net effect of convective transport of all trace gases (O 3 and precursors together) is a 12% increase in the tropospheric O 3 burden. Thus, in contrast to previous literature, our results indicate that the enhanced O 3 production due to precursor transport from polluted regions significantly outweighs the reduction in O 3 lifetime due to mixing over clean regions.