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 similar to20% during 1990-2100, but to increase by similar to80% with including climate change also. Simulated increases in net cross-tropopause O-3 transport are most significant particularly after 2050.