Reference : Impact of different spectroscopic datasets on CH4 retrievals from Jungfraujoch FTIR s...
Scientific congresses and symposiums : Poster
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
http://hdl.handle.net/2268/6947
Impact of different spectroscopic datasets on CH4 retrievals from Jungfraujoch FTIR spectra
English
Duchatelet, Pierre mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe infra-rouge de phys. atmosph. et solaire (GIRPAS) >]
Mahieu, Emmanuel mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe infra-rouge de phys. atmosph. et solaire (GIRPAS) >]
Demoulin, Philippe mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe infra-rouge de phys. atmosph. et solaire (GIRPAS) >]
Frankenberg, Chrisitian [> >]
Hase, Frank [> >]
Notholt, Justus [> >]
Petersen, Katinka [> >]
Spietz, Peter [> >]
De Mazière, Martine [> >]
Vigouroux, Corinne [> >]
Aug-2008
No
International
8th Atmospheric Spectroscopy Applications
du 27 au 30 août 2008
Reims
France
[en] Methane (CH4) is released in the atmosphere by natural processes (e.g. wetlands, termites) as well as by anthropogenic activities (e.g. fossil fuel exploitation, rice agriculture, biomass burning, etc). Due to its high warming potential and its relatively long chemical lifetime (~9 years), atmospheric methane plays a major role in the radiative forcing responsible of the greenhouse effect. Methane also affects climate by influencing tropospheric ozone and stratospheric water. The cycle of methane is complex and to understand it requires a complete study of its emissions and its budget of sources and sinks. High quality methane data sets are needed to perform such studies.

CH4 vertical distributions as well as total and partial column time series can be retrieved from high-resolution ground-based FTIR spectra, using, e.g., the SFIT-2 algorithm which implements the Optimal Estimation Method of Rodgers. A set of 5 microwindows - located in the 2 to 5.5 µm range and jointly adopted by all partners involved in the European HYMN project (www.knmi.nl/samenw/hymn/) - are fitted simultaneously during the retrieval procedure. Although this approach provides relatively high information content, CH4 retrieved profiles very often present large oscillations in the troposphere, which might result partly from inappropriate or inconsistent spectroscopic parameters. Significant improvements on retrieval quality could be reached by using more accurate CH4 spectroscopic parameters.

This contribution compares 3 different sets of CH4 spectroscopic parameters (including HITRAN 2004 and 2 versions where HITRAN 2004 have been updated by recent laboratory measurements), which have been tested using one year of high resolution FTIR solar observations performed at the International Scientific Station of the Jungfraujoch (Swiss Alps, 46.5°N, 8.0 °E, 3580m a.s.l.). The impact of these different spectroscopic datasets on retrieved CH4 partial columns and vertical profiles, as well as on the fitting quality (residuals) and on the error budget characterizing our CH4 products will be evaluated and discussed.
http://hdl.handle.net/2268/6947

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