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| Titel |
Operational total and tropospheric NO2 column retrieval for GOME-2 |
| VerfasserIn |
P. Valks, G. Pinardi, A. Richter, J.-C. Lambert, N. Hao, D. Loyola, M. Roozendael, S. Emmadi |
| 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 ; 4, no. 7 ; Nr. 4, no. 7 (2011-07-26), S.1491-1514 |
| Datensatznummer |
250002059
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| Publikation (Nr.) |
 copernicus.org/amt-4-1491-2011.pdf |
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| Zusammenfassung |
| This paper presents the algorithm for the operational near real time
retrieval of total and tropospheric NO2 columns from the Global Ozone
Monitoring Experiment (GOME-2). The retrieval is performed with the GOME
Data Processor (GDP) version 4.4 as used by the EUMETSAT Satellite
Application Facility on Ozone and Atmospheric Chemistry Monitoring
(O3M-SAF). The differential optical absorption spectroscopy (DOAS) method is
used to determine NO2 slant columns from GOME-2 (ir)radiance data in
the 425–450 nm range. Initial total NO2 columns are computed using
stratospheric air mass factors, and GOME-2 derived cloud properties are used
to calculate the air mass factors for scenarios in the presence of clouds.
To obtain the stratospheric NO2 component, a spatial filtering approach
is used, which is shown to be an improvement on the Pacific reference sector
method. Tropospheric air mass factors are computed using monthly averaged
NO2 profiles from the MOZART-2 chemistry transport model. An error
analysis shows that the random error in the GOME-2 NO2 slant columns is
approximately 0.45 × 1015 molec cm−2. As a result of the
improved quartz diffuser plate used in the GOME-2 instrument, the systematic
error in the slant columns is strongly reduced compared to GOME/ERS-2. The
estimated uncertainty in the GOME-2 tropospheric NO2 column for
polluted conditions ranges from 40 to 80 %. An end-to-end ground-based
validation approach for the GOME-2 NO2 columns is illustrated based on
multi-axis MAXDOAS measurements at the Observatoire de Haute Provence (OHP).
The GOME-2 stratospheric NO2 columns are found to be in good overall
agreement with coincident ground-based measurements at OHP. A time series of
the MAXDOAS and the GOME-2 tropospheric NO2 columns shows that
pollution episodes at OHP are well captured by GOME-2. Monthly mean
tropospheric columns are in very good agreement, with differences generally
within 0.5 × 1015 molec cm−2. |
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