Technical Note: Feasibility of CO<sub>2</sub> profile retrieval from limb viewing solar occultation made by the ACE-FTS instrument
Major limitations of our present knowledge of the global distribution of CO<sub>2</sub> 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 tangen...
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doaj-c69bd184520548b3b2d2af12302474582020-11-24T22:27:10ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242009-04-019828732890Technical Note: Feasibility of CO<sub>2</sub> profile retrieval from limb viewing solar occultation made by the ACE-FTS instrumentC. D. BooneP. BernathV. CapelleG. DufourA. ChédinP. Y. FoucherMajor limitations of our present knowledge of the global distribution of CO<sub>2</sub> 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 CO<sub>2</sub> 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 CO<sub>2</sub> profile, and (ii) the potential impact of uncertainties in the temperature knowledge on the retrieved CO<sub>2</sub> 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 CO<sub>2</sub> 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 CO<sub>2</sub> vertical profiles retrieved from real ACE-FTS occultations shown in this paper confirm the robustness of the method and applicability to real measurements. http://www.atmos-chem-phys.net/9/2873/2009/acp-9-2873-2009.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
C. D. Boone P. Bernath V. Capelle G. Dufour A. Chédin P. Y. Foucher |
spellingShingle |
C. D. Boone P. Bernath V. Capelle G. Dufour A. Chédin P. Y. Foucher Technical Note: Feasibility of CO<sub>2</sub> profile retrieval from limb viewing solar occultation made by the ACE-FTS instrument Atmospheric Chemistry and Physics |
author_facet |
C. D. Boone P. Bernath V. Capelle G. Dufour A. Chédin P. Y. Foucher |
author_sort |
C. D. Boone |
title |
Technical Note: Feasibility of CO<sub>2</sub> profile retrieval from limb viewing solar occultation made by the ACE-FTS instrument |
title_short |
Technical Note: Feasibility of CO<sub>2</sub> profile retrieval from limb viewing solar occultation made by the ACE-FTS instrument |
title_full |
Technical Note: Feasibility of CO<sub>2</sub> profile retrieval from limb viewing solar occultation made by the ACE-FTS instrument |
title_fullStr |
Technical Note: Feasibility of CO<sub>2</sub> profile retrieval from limb viewing solar occultation made by the ACE-FTS instrument |
title_full_unstemmed |
Technical Note: Feasibility of CO<sub>2</sub> profile retrieval from limb viewing solar occultation made by the ACE-FTS instrument |
title_sort |
technical note: feasibility of co<sub>2</sub> profile retrieval from limb viewing solar occultation made by the ace-fts instrument |
publisher |
Copernicus Publications |
series |
Atmospheric Chemistry and Physics |
issn |
1680-7316 1680-7324 |
publishDate |
2009-04-01 |
description |
Major limitations of our present knowledge of the global distribution of CO<sub>2</sub> 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 CO<sub>2</sub> 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 CO<sub>2</sub> profile, and (ii) the potential impact of uncertainties in the temperature knowledge on the retrieved CO<sub>2</sub> 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 CO<sub>2</sub> 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 CO<sub>2</sub> vertical profiles retrieved from real ACE-FTS occultations shown in this paper confirm the robustness of the method and applicability to real measurements. |
url |
http://www.atmos-chem-phys.net/9/2873/2009/acp-9-2873-2009.pdf |
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