Changes in Tropospheric Ozone 1850-2100: A Multi-Model Study Using ACCMIP Data

We will present tropospheric ozone changes from a suite of models that participated in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), expanding on some of the results from a recently submitted paper. For the period 1850-2000, model runs were completed using estimates historical ozone precursor emissions and climate data (SSTs and sea ice). Future runs, covering 2000-2100, were also completed, using climate and precursor emissions data based on the Representative Concentration Pathways (RCPs), as also used by the climate model simulations in support of IPCC AR5. As well as examining the modeled annual mean changes in the tropospheric ozone burden, and surface and zonal mean ozone concentrations, we will look at seasonal patterns of the changes and the individual roles of climate and precursor emission changes. Where suitable ozone budget data are available, we will analyze some of the drivers for the changes, in particular considering the role of the stratospheric influx of ozone. Analysis of the future simulations from ACCMIP suggests that stratospheric ozone recovery and changes in the Brewer-Dobson circulation are driving a large portion of the modeled tropospheric ozone changes.