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 O3 is discussed. We first show theoretically that convective mixing of O3 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 O3 burden and a 7% decrease in its lifetime due to convective transport of O3 alone. We find, however, that the net effect of convective transport of all trace gases (O3 and precursors together) is a 12% increase in the tropospheric O3 burden. Thus, in contrast to previous literature, our results indicate that the enhanced O3 production due to precursor transport from polluted regions significantly outweighs the reduction in O3 lifetime due to mixing over clean regions.