Nitrogen Dioxide (NO2) Total and Tropospheric Vertical Column Densities from OMI on EOS Aura

NO2 is a trace gas, important in the chemistry of the stratosphere and troposphere. The Ozone Monitoring Instrument (OMI), which is on the EOS AURA satellite, retrieves vertical column densities (VCDs) of NO2, along with those of several other trace gases. The relatively high spatial resolution and daily global coverage of the instrument make it particularly well-suited to monitoring tropospheric pollution at scales on the order of 20 km. The OMI NO2 algorithm distinguishes polluted regions from background stratospheric NO2 using a separation algorithm that relies on the smoothly varying stratospheric NO2 and estimations of both stratospheric and tropospheric air mass factors (AMFs). The AMFs are calculated from a simplified set of profiles derived from GSFC CTM and Harvard GEOS-CHEM model output. We present total and tropospheric vertical column densities of NO2 from several days of OMI data and discuss the effects of algorithm assumptions on the retrieved VCD values and their uncertainties.