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| Titel |
Profiling wind and greenhouse gases by infrared-laser occultation: results from end-to-end simulations in windy air |
| VerfasserIn |
A. Plach, V. Proschek, G. Kirchengast |
| 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. 7 ; Nr. 8, no. 7 (2015-07-16), S.2813-2825 |
| Datensatznummer |
250116482
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| Publikation (Nr.) |
 copernicus.org/amt-8-2813-2015.pdf |
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| Zusammenfassung |
| The new mission concept of microwave and infrared-laser occultation
between low-Earth-orbit satellites (LMIO) is designed to provide
accurate and long-term stable profiles of atmospheric thermodynamic
variables, greenhouse gases (GHGs), and line-of-sight (l.o.s.) wind
speed with focus on the upper troposphere and lower stratosphere
(UTLS). While the unique quality of GHG retrievals enabled by LMIO
over the UTLS has been recently demonstrated based on end-to-end
simulations, the promise of l.o.s. wind retrieval, and of joint GHG
and wind retrieval, has not yet been analyzed in any realistic
simulation setting. Here we use a newly developed
l.o.s. wind retrieval algorithm, which we embedded in an end-to-end
simulation framework that also includes the retrieval of
thermodynamic variables and GHGs, and analyze the performance of
both stand-alone wind retrieval and joint wind and GHG retrieval.
The wind algorithm utilizes LMIO laser signals placed on the
inflection points at the wings of the highly symmetric C18OO
absorption line near 4767 cm−1 and exploits
transmission differences from a wind-induced Doppler shift. Based on
realistic example cases for a diversity of atmospheric conditions,
ranging from tropical to high-latitude winter, we find that the
retrieved l.o.s. wind profiles are of high quality over the lower
stratosphere under all conditions, i.e., unbiased and accurate to
within about 2 m s−1 over about 15 to 35 km.
The wind accuracy degrades into the upper troposphere
due to the decreasing signal-to-noise ratio of the wind-induced
differential transmission signals. The GHG retrieval in windy air is
not vulnerable to wind speed uncertainties up to about
10 m s−1 but is found to benefit in the case of higher speeds from
the integrated wind retrieval that enables correction of
wind-induced Doppler shift of GHG signals. Overall both the
l.o.s. wind and GHG retrieval results are strongly encouraging
towards further development and implementation of a LMIO mission. |
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