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| Titel |
Glyoxal retrieval from the Ozone Monitoring Instrument |
| VerfasserIn |
C. Chan Miller, G. González Abad, H. Wang, X. Liu, T. Kurosu, D. J. Jacob, K. Chance |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 11 ; Nr. 7, no. 11 (2014-11-25), S.3891-3907 |
| Datensatznummer |
250115959
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| Publikation (Nr.) |
 copernicus.org/amt-7-3891-2014.pdf |
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| Zusammenfassung |
| We present an algorithm for the retrieval of glyoxal from
backscattered solar radiation, and apply it to spectra measured by
the Ozone Monitoring Instrument (OMI). The algorithm is based on
direct spectrum fitting, and adopts a two-step fitting routine to
account for liquid water absorption. Previous studies have shown
that glyoxal retrieval algorithms are highly sensitive to the
position of the spectral fit window. This dependence was
systematically tested on real and simulated OMI spectra. We find
that a combination of errors resulting from uncertainties in
reference cross sections and spectral features associated with the
Ring effect are consistent with the fit-window dependence observed
in real spectra. This implies an optimal fitting window of
435–461 nm, consistent with previous satellite glyoxal
retrievals. The results from the retrieval of simulated spectra also
support previous findings that have suggested that glyoxal is
sensitive to NO2 cross-section temperature. The retrieval
window limits of the liquid water retrieval are also
tested. A retrieval window 385–470 nm reduces interference
with strong spectral features associated with sand. We show that
cross-track dependent offsets (stripes) present in OMI can be
corrected using offsets derived from retrieved slant columns over
the Sahara, and apply the correction to OMI data. Average glyoxal
columns are on average lower than those of previous studies likely
owing to the choice of reference sector for offset correction. OMI
VCDs (vertical column densities)are lower compared to other satellites over the tropics and
Asia during the monsoon season, suggesting that the new retrieval is
less sensitive to water vapour abundance. Consequently we do not see
significant glyoxal enhancements over tropical oceans. OMI-derived
glyoxal-to-formaldehyde ratios over biogenic and anthropogenic
source regions are consistent with surface observations. |
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