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| Titel |
Satellite observation of lowermost tropospheric ozone by multispectral synergism of IASI thermal infrared and GOME-2 ultraviolet measurements over Europe |
| VerfasserIn |
J. Cuesta, M. Eremenko, X. Liu, G. Dufour, Z. Cai, M. Höpfner, T. Clarmann, P. Sellitto, G. Foret, B. Gaubert, M. Beekmann, J. Orphal, K. Chance, R. Spurr, J.-M. Flaud |
| 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 ; 13, no. 19 ; Nr. 13, no. 19 (2013-10-02), S.9675-9693 |
| Datensatznummer |
250085725
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| Publikation (Nr.) |
 copernicus.org/acp-13-9675-2013.pdf |
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| Zusammenfassung |
| We present a new multispectral approach for observing lowermost tropospheric
ozone from space by synergism of atmospheric radiances in the thermal
infrared (TIR) observed by IASI (Infrared Atmospheric Sounding Interferometer) and earth reflectances in the ultraviolet
(UV) measured by GOME-2 (Global Ozone Monitoring Experiment-2). Both instruments are onboard the series of MetOp
satellites (in orbit since 2006 and expected until 2022) and their scanning
capabilities offer global coverage every day, with a relatively fine ground
pixel resolution (12 km-diameter pixels spaced by 25 km for IASI at nadir).
Our technique uses altitude-dependent Tikhonov–Phillips-type constraints,
which optimize sensitivity to lower tropospheric ozone. It integrates the
VLIDORT (Vector Linearized Discrete Ordinate Radiative Transfer) and KOPRA (Karlsruhe Optimized and Precise Radiative transfer Algorithm)
radiative transfer codes for simulating UV reflectance and
TIR radiance, respectively. We have used our method to analyse real
observations over Europe during an ozone pollution episode in the summer of
2009. The results show that the multispectral synergism of IASI (TIR) and
GOME-2 (UV) enables the observation of the spatial distribution of ozone
plumes in the lowermost troposphere (LMT, from the surface up to 3 km a.s.l.,
above sea level), in good agreement with the CHIMERE regional
chemistry-transport model. In this case study, when high ozone
concentrations extend vertically above 3 km a.s.l., they are similarly
observed over land by both the multispectral and IASI retrievals. On the
other hand, ozone plumes located below 3 km a.s.l. are only clearly depicted
by the multispectral retrieval (both over land and over ocean). This is
achieved by a clear enhancement of sensitivity to ozone in the lowest
atmospheric layers. The multispectral sensitivity in the LMT peaks at 2 to
2.5 km a.s.l. over land, while sensitivity for IASI or GOME-2 only peaks at
3 to 4 km a.s.l. at lowest (above the LMT). The degrees of freedom for the
multispectral retrieval increase by 0.1 (40% in relative terms) with
respect to IASI only retrievals for the LMT. Validations with ozonesondes
(over Europe during summer 2009) show that our synergetic approach for
combining IASI (TIR) and GOME-2 (UV) measurements retrieves lowermost
tropospheric ozone with a mean bias of 1% and a precision of 16%,
when smoothing by the retrieval vertical sensitivity (1% mean bias and
21% precision for direct comparisons). |
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