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| Titel |
Global distributions of water vapour isotopologues retrieved from IMG/ADEOS data |
| VerfasserIn |
H. Herbin, D. Hurtmans, S. Turquety, C. Wespes, B. Barret, J. Hadji-Lazaro, C. Clerbaux, P.-F. Coheur |
| 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. 14 ; Nr. 7, no. 14 (2007-07-25), S.3957-3968 |
| Datensatznummer |
250005145
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| Publikation (Nr.) |
 copernicus.org/acp-7-3957-2007.pdf |
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| Zusammenfassung |
| The isotopologic composition of water vapour in the atmosphere provides
valuable information on many climate, chemical and dynamical processes. The
accurate measurements of the water isotopologues by remote-sensing techniques
remains a challenge, due to the large spatial and temporal variations.
Simultaneous profile retrievals of the main water isotopologues
(i.e. H216O, H218O and HDO) and their ratios are presented
here for the first time, along their retrieved global distributions. The
results are obtained by exploiting the high resolution infrared spectra
recorded by the Interferometric Monitor for Greenhouse gases (IMG)
instrument, which has operated in the nadir geometry onboard the ADEOS
satellite between 1996 and 1997. The retrievals are performed on cloud-free
radiances, measured during ten days of April 1997, considering two
atmospheric windows (1205–1228 cm−1; 2004–2032 cm−1) and using a
line-by-line radiative transfer model and an inversion procedure based on the
Optimal Estimation Method (OEM). Characterizations in terms of vertical
sensitivity and error budget are provided. We show that a relatively high
vertical resolution is achieved for H216O (~4–5 km), and
that the retrieved profiles are in fair agreement with local sonde
measurements, at different latitudes. The retrieved global distributions of
H216O, H218O, HDO and their ratios are presented and found to
be consistent with previous experimental studies and models. The
Ocean-Continent difference, the latitudinal and vertical dependence of the
water vapour amount and the isotopologic depletion are notably well
reproduced. Others trends, possibly related to small-scale variations in the
vertical profiles are also discussed. Despite the difficulties encountered
for computing accurately the isotopologic ratios, our results demonstrate the
ability of infrared nadir sounding for monitoring atmospheric isotopologic
water vapour distributions on a global scale. |
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