Future changes in stratosphere‐troposphere exchange and their impacts on future tropospheric ozone simulations

We assess future climate change impacts on stratosphere‐troposphere exchange (STE) and their influences on tropospheric O 3 , using a chemistry coupled climate model. Tropospheric O 3 distribution and budget were predicted decadally for 1990 to 2100 with emission changes (for O 3 precursors) and climate change specified by the IPCC SRES‐A2 scenario. Our simulations show increases in stratospheric O 3 transport to the troposphere as a result of enhancement in the tropospheric and stratospheric circulation with climate change in the model. With emission changes only, net stratospheric O 3 input to the troposphere was simulated to decrease by ∼20% during 1990–2100, but to increase by ∼80% with including climate change also. Simulated increases in net cross‐tropopause O 3 transport are most significant particularly after 2050.