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| Titel |
Technical Note: Interference errors in infrared remote sounding of the atmosphere |
| VerfasserIn |
R. Sussmann, T. Borsdorff |
| 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 ; 7, no. 13 ; Nr. 7, no. 13 (2007-07-06), S.3537-3557 |
| Datensatznummer |
250005122
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| Publikation (Nr.) |
 copernicus.org/acp-7-3537-2007.pdf |
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| Zusammenfassung |
| Classical error analysis in remote sounding distinguishes between four
classes: "smoothing errors," "model parameter errors," "forward model
errors," and "retrieval noise errors". For infrared sounding
"interference errors", which, in general, cannot be described by these
four terms, can be significant. Interference errors originate from spectral
residuals due to "interfering species" whose spectral features overlap
with the signatures of the target species. A general method for
quantification of interference errors is presented, which covers all
possible algorithmic implementations, i.e., fine-grid retrievals of the
interfering species or coarse-grid retrievals, and cases where the
interfering species are not retrieved. In classical retrieval setups
interference errors can exceed smoothing errors and can vary by orders of
magnitude due to state dependency. An optimum strategy is suggested which
practically eliminates interference errors by systematically minimizing the
regularization strength applied to joint profile retrieval of the
interfering species. This leads to an interfering-species selective
deweighting of the retrieval. Details of microwindow selection are no longer
critical for this optimum retrieval and widened microwindows even lead to
reduced overall (smoothing and interference) errors. Since computational
power will increase, more and more operational algorithms will be able to
utilize this optimum strategy in the future. The findings of this paper can
be applied to soundings of all infrared-active atmospheric species, which
include more than two dozen different gases relevant to climate and ozone.
This holds for all kinds of infrared remote sounding systems, i.e.,
retrievals from ground-based, balloon-borne, airborne, or satellite
spectroradiometers. |
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