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| Titel |
An improved glyoxal retrieval from OMI measurements |
| VerfasserIn |
L. M. A. Alvarado, A. Richter, M. Vrekoussis, F. Wittrock, A. Hilboll, S. F. Schreier, J. P. Burrows |
| 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. 12 ; Nr. 7, no. 12 (2014-12-03), S.4133-4150 |
| Datensatznummer |
250115976
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| Publikation (Nr.) |
 copernicus.org/amt-7-4133-2014.pdf |
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| Zusammenfassung |
Satellite observations from the SCIAMACHY, GOME-2 and OMI spectrometers have
been used to retrieve atmospheric columns of glyoxal (CHOCHO) with the DOAS
method. High CHOCHO levels were found over regions with large biogenic
and pyrogenic emissions, and hot-spots have been identified over areas of
anthropogenic activities.
This study focuses on the development of an improved retrieval for
CHOCHO from measurements by the OMI instrument. From sensitivity
tests, a fitting window and a polynomial degree are determined. Two different
approaches to reduce the interference of liquid water absorption over oceanic
regions are evaluated, achieving significant reduction of the number of
negative columns over clear water regions. The impact of using different
absorption cross-sections for water vapour is evaluated and only small
differences are found. Finally, a high-temperature (boundary layer ambient:
294 K) absorption cross-section of nitrogen dioxide (NO2) is
introduced in the DOAS retrieval to account for potential interferences of
NO2 over regions with large anthropogenic emissions, leading to improved
fit quality over these areas. A comparison with vertical CHOCHO columns
retrieved from GOME-2 and SCIAMACHY measurements over continental regions is
performed, showing overall good consistency. However, SCIAMACHY CHOCHO
columns are systematically higher than those obtained from the other
instruments.
Using the new OMI CHOCHO data set, the link between fires and glyoxal columns
is investigated for two selected regions in Africa. In addition, mapped
averages are computed for a fire event in Russia between mid-July and
mid-August 2010. In both cases, enhanced CHOCHO levels are found in close
spatial and temporal proximity to elevated levels of MODIS fire radiative
power, demonstrating that pyrogenic emissions can be clearly identified in
the new OMI CHOCHO product. |
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