Examining Changes in Ozone over the Western United States via Assimilation of Satellite Ozone Products in a Chemistry-Transport Model

We will present results from simulations of the GEOS-Chem CTM utilizing assimilation of different satellite ozone data products that we have performed as a preliminary step in a project to try to better characterize and understand changes in background ozone. As in our previous work using 2005-2010 data from the Tropospheric Emission Spectrometer (TES) (Verstraeten et al. [2015]), we focus on changes in ozone over the Western US and attribution of those changes to regional emissions, long-range transport from Asia and stratosphere-troposphere exchange. Here we use a new dataset retrieved from the NASA Atmospheric Infrared Sounder (AIRS) and Ozone Monitoring Instrument (OMI). This combined AIRS/OMI ozone dataset is based on the retrieval methods developed for TES and allows for the analysis to extend beyond 2010, when TES stopped making global measurements. We will show examples of the AIRS/OMI data, comparisons to ozonesondes, and results from assimilating satellite data into GEOS-Chem. We will also evaluate the GEOS-Chem results using surface data to show the effects of the satellite assimilation on surface ozone.