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| Titel |
Improved water vapour spectroscopy in the 4174-4300 cm−1 region and its impact on SCIAMACHY HDO/H2O measurements |
| VerfasserIn |
R. A. Scheepmaker, C. Frankenberg, A. Galli, A. Butz, H. Schrijver, N. M. Deutscher, D. Wunch, T. Warneke, S. Fally, I. Aben |
| 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 ; 6, no. 4 ; Nr. 6, no. 4 (2013-04-08), S.879-894 |
| Datensatznummer |
250017866
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| Publikation (Nr.) |
 copernicus.org/amt-6-879-2013.pdf |
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| Zusammenfassung |
| The relative abundance of the heavy water isotopologue HDO provides a deeper insight into the atmospheric hydrological cycle. The
SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) allows for global retrievals of the ratio
HDO/H2O in the 2.3 micron wavelength range. However, the spectroscopy of water lines in this region remains a large
source of uncertainty for these retrievals. We therefore evaluate and improve the water spectroscopy in the range
4174–4300 cm−1 and test if this reduces systematic uncertainties in the SCIAMACHY retrievals of HDO/H2O.
We use a laboratory spectrum of water vapour to fit line intensity, air broadening and wavelength shift parameters. The
improved spectroscopy is tested on a series of ground-based high resolution FTS spectra as well as on SCIAMACHY retrievals of
H2O and the ratio HDO/H2O. We find that the improved spectroscopy leads to lower residuals in the FTS spectra
compared to HITRAN 2008 and Jenouvrier et al. (2007) spectroscopy, and the retrievals become more robust against changes in
the retrieval window. For both the FTS and SCIAMACHY measurements, the retrieved total H2O columns decrease by
2–4% and we find a negative shift of the HDO/H2O ratio, which for SCIAMACHY is partly compensated by changes
in the retrieval setup and calibration software. The updated SCIAMACHY HDO/H2O product shows somewhat steeper
latitudinal and temporal gradients and a steeper Rayleigh distillation curve, strengthening previous conclusions that current
isotope-enabled general circulation models underestimate the variability in the near-surface HDO/H2O ratio. |
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