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Titel |
Long-term series of tropospheric water vapour amounts and HDO/H2O ratio profiles above Jungfraujoch. |
VerfasserIn |
B. Lejeune, E. Mahieu, M. Schneider, F. Hase, C. Servais, P. Demoulin |
Konferenz |
EGU General Assembly 2012
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 14 (2012) |
Datensatznummer |
250065712
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Zusammenfassung |
Water vapour is a crucial climate variable involved in many processes which widely
determine the energy budget of our planet. In particular, water vapour is the dominant
greenhouse gas in the Earth’s atmosphere and its radiative forcing is maximum in the middle
and upper troposphere. Because of the extremely high variability of water vapour
concentration in time and space, it is challenging for the available relevant measurement
techniques to provide a consistent data set useful for trend analyses and climate studies.
Schneider et al. (2006a) showed that ground-based Fourier Transform Infrared (FTIR)
spectroscopy, performed from mountain observatories, allows for the detection of H2O
variabilities up to the tropopause. Furthermore, the FTIR measurements allow the
retrieval of HDO amounts and therefore the monitoring of HDO/H2O ratio profiles
whose variations act as markers for the source and history of the atmospheric water
vapour.
In the framework of the MUSICA European project (Multi-platform remote
Sensing of Isotopologues for investigating the Cycle of Atmospheric water,
http://www.imk-asf.kit.edu/english/musica.php), a new approach has been developed and
optimized by M. Schneider and F. Hase, using the PROFFIT algorithm, to consistently
retrieve tropospheric water vapour profiles from high-resolution ground-based infrared solar
spectra and so taking benefit from available long-term data sets of ground-based
observations. The retrieval of the water isotopologues is performed on a logarithmic scale
from 14 micro-windows located in the 2600-3100 cm-1 region. Other important
features of this new retrieval strategy are: a speed dependant Voigt line shape model, a
joint temperature profile retrieval and an interspecies constraint for the HDO/H2O
profiles.
In this contribution, we will combine the quality of the MUSICA strategy and of our
observations, which are recorded on a regular basis with FTIR spectrometers, under clear-sky
conditions, at the NDACC site (Network for the Detection of Atmospheric Composition
Change, http://www.ndacc.org) of the Jungfraujoch International Scientific Station (Swiss
Alps, 46.5Ë N, 8.0Ë E, 3580m asl). Information content analysis of the retrieved H2O
products allows us to produce a long-term trend from 1996 to 2011 for different tropospheric
levels. We will compare the annual cycle of tropospheric HDO/H2O ratio profiles with those
already produced at other sites (Schneider et al., 2010). We will also focus on the diurnal
variability of water vapour to determine a time limit in the inter-comparison of different water
vapour measurement techniques.
Acknowledgments
The University of Liège involvement has primarily been supported by the PRODEX
program funded by the Belgian Federal Science Policy Office, Brussels and by the Swiss
GAW-CH program. The FRS-FNRS and the Fédération Wallonie-Bruxelles are
further acknowledged for observational activities support. We thank the International
Foundation High Altitude Research Stations Jungfraujoch and Gornergrat (HFSJG,
Bern) for supporting the facilities needed to perform the observations. MUSICA
is funded by the European Research Council under the European Community’s
Seventh Framework Programme (FP7/2007-2013) / ERC Grant agreement nË
256961.
References
Schneider M., F. Hase, and T. Blumenstock, Water vapour profiles by ground-based FTIR
spectroscopy: study for an optimised retrieval and its validation, Atmospheric Chemistry and
Physics, 6, 811-830, 2006a.
Schneider M., F. Hase, and T. Blumenstock, Ground-based remote sensing of HDO/H2O
ratio profiles: introduction and validation of an innovative retrieval approach, Atmospheric
Chemistry and Physics, 6, 4705-4722, 2006b.
Schneider M. and F. Hase, Ground-based FTIR water vapour profile analyses,
Atmospheric Measurement Techniques, 2, 609-619, 2009.
Schneider M., K. Yoshimura, F. Hase, and T. Blumenstock, The ground-based FTIR
network’s potential for investigating atmospheric water cycle, Atmospheric Chemistry and
Physics, 10, 3427-3442, 2010. |
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