Evaluating AURA/OMI ozone profiles using ozonesonde data and EPA surface measurements for August 2006

Abstract

We evaluate the Ozone Monitoring Instrument (OMI) ozone profile retrieval against ozonesonde data and the Environmental Protection Agency (EPA) surface measurements for August 2006. Comparison of individual OMI ozone profile with ozonesonde indicates that OMI ozone profile can explain the general vertical variation of ozone but is limited in observing the boundary layer ozone, due to weak sensitivity to boundary layer ozone and thick lowest layer (∼2.5 km). We made pair-wise comparison between OMI and ozonesondes on 24 OMI vertical layers, as well as the 39 sigma-P vertical layers of the Community Multi-scale Air Quality (CMAQ) modeling system, respectively. OMI shows reasonable agreement with ozonesonde in the lower- to mid-troposphere. In the upper troposphere, while the bias increases, the normalized bias does not show much variation and remains below 10%. Comparison with EPA’s surface-monitoring data indicates that OMI observations at the lowest layer (surface to 2.5 km altitude) represent the mean values. While OMI underestimates elevated ozone concentrations, it explains the larger-scale spatial variation seen in the surface monitors. ► We evaluate OMI ozone profile retrieval against ozonesonde and EPA surface data. ► OMI shows reasonable agreement with ozonesonde in the lower- to mid-troposphere. ► In the upper troposphere, the normalized bias of OMI remains below 10%. ► OMI underestimates elevated ozone concentrations observed by EPA surface monitors. ► OMI explains the larger-scale spatial variation seen in the surface monitors.