Algorithm for NO/sub 2/ vertical column retrieval from the ozone monitoring instrument |
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Authors: | Bucsela E.J. Celarier E.A. Wenig M.O. Gleason J.F. Veefkind J.P. Boersma K.F. Brinksma E.J. |
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Affiliation: | NASA Goddard Space Flight Center, Greenbelt, MD, USA; |
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Abstract: | We describe the operational algorithm for the retrieval of stratospheric, tropospheric, and total column densities of nitrogen dioxide (NO/sub 2/) from earthshine radiances measured by the Ozone Monitoring Instrument (OMI), aboard the EOS-Aura satellite. The algorithm uses the DOAS method for the retrieval of slant column NO/sub 2/ densities. Air mass factors (AMFs) calculated from a stratospheric NO/sub 2/ profile are used to make initial estimates of the vertical column density. Using data collected over a 24-h period, a smooth estimate of the global stratospheric field is constructed. Where the initial vertical column densities exceed the estimated stratospheric field, we infer the presence of tropospheric NO/sub 2/, and recalculate the vertical column density (VCD) using an AMF calculated from an assumed tropospheric NO/sub 2/ profile. The parameters that control the operational algorithm were selected with the aid of a set of data assembled from stratospheric and tropospheric chemical transport models. We apply the optimized algorithm to OMI data and present global maps of NO/sub 2/ VCDs for the first time. |
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