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| Titel |
An examination of the long-term CO records from MOPITT and IASI: comparison of retrieval methodology |
| VerfasserIn |
M. George, C. Clerbaux, I. Bouarar, P.-F. Coheur, M. N. Deeter, D. P. Edwards, G. Francis, J. C. Gille, J. Hadji-Lazaro, D. Hurtmans, A. Inness, D. Mao, H. M. Worden |
| 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 ; 8, no. 10 ; Nr. 8, no. 10 (2015-10-15), S.4313-4328 |
| Datensatznummer |
250116640
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| Publikation (Nr.) |
 copernicus.org/amt-8-4313-2015.pdf |
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| Zusammenfassung |
| Carbon monoxide (CO) is a key atmospheric compound that can be remotely
sensed by satellite on the global scale. Fifteen years of continuous
observations are now available from the MOPITT/Terra mission (2000 to
present). Another 15 and more years of observations will be provided by
the IASI/MetOp instrument series (2007–2023 >). In order to
study long-term variability and trends, a homogeneous record is required,
which is not straightforward as the retrieved quantities are instrument and
processing dependent. The present study aims at evaluating the consistency
between the CO products derived from the MOPITT and IASI missions, both for
total columns and vertical profiles, during a 6-year overlap period
(2008–2013). The analysis is performed by first comparing the available 2013
versions of the retrieval algorithms (v5T for MOPITT and v20100815 for IASI),
and second using a dedicated reprocessing of MOPITT CO profiles and columns
using the same a priori information as the IASI product. MOPITT total columns
are generally slightly higher over land (bias ranging from 0 to 13 %)
than IASI data. When IASI and MOPITT data are retrieved with the same a
priori constraints, correlation coefficients are slightly improved. Large
discrepancies (total column bias over 15 %) observed in the Northern
Hemisphere during the winter months are reduced by a factor of 2 to 2.5. The
detailed analysis of retrieved vertical profiles compared with collocated
aircraft data from the MOZAIC-IAGOS network, illustrates the advantages and
disadvantages of a constant vs. a variable a priori. On one hand, MOPITT
agrees better with the aircraft profiles for observations with persisting
high levels of CO throughout the year due to pollution or seasonal fire
activity (because the climatology-based a priori is supposed to be closer to
the real atmospheric state). On the other hand, IASI performs better when
unexpected events leading to high levels of CO occur, due to a larger
variability associated with the a priori. |
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