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| Titel |
Technical Note: Feasibility of CO2 profile retrieval from limb viewing solar occultation made by the ACE-FTS instrument |
| VerfasserIn |
P. Y. Foucher, A. Chédin, G. Dufour, V. Capelle, C. D. Boone, P. Bernath |
| 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. 8 ; Nr. 9, no. 8 (2009-04-30), S.2873-2890 |
| Datensatznummer |
250007218
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| Publikation (Nr.) |
 copernicus.org/acp-9-2873-2009.pdf |
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| Zusammenfassung |
| Major limitations of our present knowledge of the global distribution of
CO2 in the atmosphere are the uncertainty in atmospheric transport
mixing and the sparseness of in situ concentration measurements. Limb
viewing space-borne sounders, observing the atmosphere along
tangential optical paths, offer a vertical resolution of a few kilometers
for profiles, which is much better than currently flying or
planned nadir sounding instruments can achieve. In this paper, we analyse
the feasibility of obtaining CO2 vertical profiles in the
5–25 km altitude range from the Atmospheric Chemistry Experiment Fourier
Transform Spectrometer (ACE-FTS, launched in August 2003), high spectral
resolution solar occultation measurements. Two main difficulties must be
overcome: (i) the accurate determination of the instrument pointing
parameters (tangent heights) and pressure/temperature profiles
independently from an a priori CO2 profile, and
(ii) the potential impact of uncertainties in the temperature knowledge on
the retrieved CO2 profile. The first difficulty has been solved using the
\N collision-induced continuum
absorption near 4 μm to determine tangent heights, pressure and
temperature from the ACE-FTS spectra. The second difficulty has been
solved by a careful selection of CO2 spectral
micro-windows. Retrievals using synthetic spectra made under realistic
simulation conditions show a vertical resolution close to 2.5 km and
accuracy of the order of 2 ppm after
averaging over 25 profiles. These results open the way to promising
studies of transport mechanisms and carbon fluxes from the ACE-FTS measurements.
First CO2 vertical profiles
retrieved from real ACE-FTS occultations shown in this paper confirm
the robustness of the method and applicability to
real measurements. |
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