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| Titel |
H216O and HDO measurements with IASI/MetOp |
| VerfasserIn |
H. Herbin, D. Hurtmans, C. Clerbaux, L. Clarisse, 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 ; 9, no. 24 ; Nr. 9, no. 24 (2009-12-15), S.9433-9447 |
| Datensatznummer |
250007801
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| Publikation (Nr.) |
 copernicus.org/acp-9-9433-2009.pdf |
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| Zusammenfassung |
| In this paper we analyze distributions of water vapour isotopologues in the
troposphere using infrared spectra recorded by the Infrared Atmospheric
Sounding Interferometer (IASI), which operates onboard the Metop satellite
in nadir geometry. The simultaneous uncorrelated retrievals of
H216O and HDO are performed on radiance measurements using a
line-by-line radiative transfer model and an inversion procedure based on
the Optimal Estimation Method (OEM). The characterizations of the retrieved
products in terms of vertical sensitivity and error budgets show that IASI
measurements contain up to 6 independent pieces of information on the
vertical distribution of H216O and up to 3.5 for HDO from the
surface up to the upper troposphere (0–20 km). Although the purpose of the
paper is not validation, a restricted comparison with sonde measurements
shows that the retrieved H216O profiles capture the
seasonal/latitudinal variations of the water content, with good accuracy in
the lowest layer but with larger uncertainties higher in the free and upper
troposphere. Our results then demonstrate the ability of the IASI instrument
to monitor atmospheric isotopologic water vapour distributions and to
provide information on the partitioning of HDO as compared to
H216O. The derivation of the δD is challenging and
associated with large errors in the uncorrelated retrieval approach chosen
here. As a result averaging on the vertical to produce a column-averaged
δD is required to produce meaningful results for geophysical
interpretation. As a case study, we analyse concentration distributions and
spatio-temporal variations of H216O and δD during the
October 2007 Krosa super-typhoon over South-East Asia. We show that
individual δD have uncertainties of 37‰ for the vertically
averaged values. Using the latter, we suggest that the typhoon produces a
so-called amount-effect, where the δD is negatively correlated
to the water amounts as a result of intense depletion of the deuterated
species. |
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