Monitoring of Tropospheric Ozone From Ozone Monitoring Instrument (OMI)

Abstract

Ozone plays a key role in the chemical processes and energy budget of the troposphere. Near the surface, it is a major pollutant. Because of the sparseness of in situ observations of tropospheric ozone, satellite measurements are very important to monitor its spatiotemporal variation. In this study, we present the directly retrieved tropospheric ozone from Ozone Monitoring Instrument (OMI) hyperspectral radiance spectra in the ultraviolet (270-330 nm); ozone profiles at 24 2.5 km layers (with 4-7 layers in the troposphere) from surface to 60 km are derived at high spatial resolution (13x48 km2 at nadir) and with daily global coverage. The precision of tropospheric ozone is generally within 10% and the retrieval errors due to smoothing within 20-30%. The retrieved tropospheric ozone generally agrees well with ozonesonde measurements within combined uncertainties although our retrievals show seasonal and latitudinal dependent biases. The retrievals clearly show signals due to pollution, biomass burning, regional and intercontinental transport, convection, and stratospheric influence. Despite coarse vertical resolution (about 10 km or coarser) and limited vertical sensitivity to ozone in the boundary layer, OMI tropospheric ozone can still provide important information about the dynamical and chemical processes controlling tropospheric ozone and to constrain air quality models that are used to forecast and analyze surface concentrations of air pollutants.