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| Titel |
Retrieval of carbon dioxide vertical profiles from solar occultation observations and associated error budgets for ACE-FTS and CASS-FTS |
| VerfasserIn |
C. E. Sioris, C. D. Boone, R. Nassar, K. J. Sutton, I. E. Gordon, K. A. Walker, P. F. Bernath |
| 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 ; 7, no. 7 ; Nr. 7, no. 7 (2014-07-22), S.2243-2262 |
| Datensatznummer |
250115855
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| Publikation (Nr.) |
 copernicus.org/amt-7-2243-2014.pdf |
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| Zusammenfassung |
| An algorithm is developed to retrieve the vertical
profile of carbon dioxide in the 5 to 25 km altitude range using
mid-infrared solar occultation spectra from the main instrument of the ACE
(Atmospheric Chemistry Experiment) mission, namely the Fourier transform
spectrometer (FTS). The main challenge is to find an atmospheric phenomenon
which can be used for accurate tangent height determination in the lower
atmosphere, where the tangent heights (THs) calculated from geometric and
timing information are not of sufficient accuracy. Error budgets for the
retrieval of CO2 from ACE-FTS and the FTS on a potential follow-on
mission named CASS (Chemical and Aerosol Sounding Satellite) are calculated
and contrasted. Retrieved THs have typical biases of 60 m relative to those retrieved
using the ACE version 3.x software after revisiting the temperature
dependence of the N2 CIA (collision-induced absorption) laboratory
measurements and accounting for sulfate aerosol extinction. After correcting
for the known residual high bias of ACE version 3.x THs expected from
CO2 spectroscopic/isotopic inconsistencies, the remaining bias for
tangent heights determined with the N2 CIA is −20 m. CO2 in the
5–13 km range in the 2009–2011 time frame is validated against aircraft
measurements from CARIBIC
(Civil Aircraft for the Regular Investigation of the atmosphere Based on an
Instrument Container), CONTRAIL (Comprehensive Observation
Network for Trace gases by Airline), and HIPPO (HIAPER Pole-to-Pole
Observations), yielding typical biases of
−1.7 ppm in the 5–13 km range. The standard error of these biases in this
vertical range is 0.4 ppm. The multi-year ACE-FTS data set is valuable in
determining the seasonal variation of the latitudinal gradient which arises
from the strong seasonal cycle in the Northern Hemisphere troposphere. The
annual growth of CO2 in this time frame is determined to be 2.6 ± 0.4 ppm year−1, in agreement with the currently accepted global growth rate
based on ground-based measurements. |
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