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| Titel |
Influence of line mixing on the retrievals of atmospheric CO2 from spectra in the 1.6 and 2.1 μm regions |
| VerfasserIn |
J.-M. Hartmann, H. Tran, G. C. Toon |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 19 ; Nr. 9, no. 19 (2009-10-01), S.7303-7312 |
| Datensatznummer |
250007661
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| Publikation (Nr.) |
 copernicus.org/acp-9-7303-2009.pdf |
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| Zusammenfassung |
| We present the first study of the influence of line mixing among CO2
lines on the remote sensing retrieval of atmospheric carbon dioxide. This is
done in the bands near 1.6 and 2.1 μm which will be used by the
Greenhouse Gases Observatory Satellite (GOSAT) instrument and eventual
successors of the Orbiting Carbon Observatory (OCO). A purely theoretical
analysis is first made, based on simulations of atmospheric spectra. It
shows that line mixing cannot be neglected since disregarding this process
induces significant errors in the calculated absorption coefficients,
leading to systematic structures in the spectral fit residuals and
airmass-dependent biases in the retrieved CO2 amounts. These
theoretical predictions are then confirmed by using atmospheric
solar-absorption spectra measured by a ground-based Fourier transform
spectrometer. It is first shown that including line mixing in the forward
model used for the inversion leads to a very significant reduction of the
residuals in the 2.1 μm region. Secondly, the inclusion of line mixing
reduces the dependence of the retrieved CO2 on the airmass and greatly
improves the consistency between values obtained independently from spectra
in the 1.6 and 2.1 μm bands. These results open promising prospects for
various ground-based and space-borne experiments monitoring the carbon
dioxide atmospheric amounts. |
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