The Signal of Stratosphere Troposphere Exchange in the GEOS-5 Ozone Assimilation Tropospheric Column Ozone

The GEOS-5 Ozone Assimilation System uses data from the Ozone Monitoring Instrument (OMI) and the Microwave Limb Sounder (MLS) on the Aura satellite to constrain the total column and stratospheric profiles of ozone. The most recent version of the assimilation system is well constrained to the total column and provides tropospheric ozone columns that better compare with ozonesonde data relative to previous systems. This current system includes surface ozone deposition and accounts for OMI's low sensitivity to surface ozone by including the OMI weighting function. The improved system is used in a multi-year analysis with 2° x 2.5° latitude-longitude resolution and about 1 km vertical resolution in the UTLS. In this presentation, we will demonstrate the variability and accuracy of this analysis in the troposphere relative to sonde data, OMI-MLS tropospheric ozone residuals, and model simulations. The results of the multi-year analysis are used to estimate the stratosphere to troposphere transport of ozone using an established mass continuity diagnostic. We then examine the impact of interannual and seasonal variability in the stratospheric ozone flux on tropospheric column ozone variability in the extratropics.