References of "Servais, Christian"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailOur Changing Atmosphere: Evidence Based on Long-Term Infrared Solar Observations at the Jungfraujoch since 1950
Zander, Rodolphe ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

in Science of the Total Environment (2008), 391(2-3), 184-95

The Institute of Astrophysics of the University of Liege has been present at the High Altitude Research Station Jungfraujoch, Switzerland, since the late 1940s, to perform spectrometric solar observations ... [more ▼]

The Institute of Astrophysics of the University of Liege has been present at the High Altitude Research Station Jungfraujoch, Switzerland, since the late 1940s, to perform spectrometric solar observations under dry and weakly polluted high-mountain conditions. Several solar atlases of photometric quality, extending altogether from the near-ultra-violet to the middle-infrared, were produced between 1956 and 1994, first with grating spectrometers then with Fourier transform instruments. During the early 1970s, scientific concerns emerged about atmospheric composition changes likely to set in as a consequence of the growing usage of nitrogen-containing agricultural fertilisers and the industrial production of chlorine-bearing compounds such as the chlorofluorocarbons and hydro-chlorofluorocarbons. Resulting releases to the atmosphere with ensuing photolysis in the stratosphere and catalytic depletion of the protective ozone layer prompted a worldwide consortium of chemical manufacturing companies to solicit the Liege group to help in clarifying these concerns by undertaking specific observations with its existing Jungfraujoch instrumentation. The following pages evoke the main steps that led from quasi full sun-oriented studies to priority investigations of the Earth's atmosphere, in support of both the Montreal and the Kyoto Protocols. [less ▲]

Detailed reference viewed: 52 (26 ULg)
Full Text
See detailH2O retrievals from Jungfraujoch infrared spectra: some spectroscopic problems.
Demoulin, Philippe ULg; Trabelsi, Samy; Mahieu, Emmanuel ULg et al

in Proceedings of the 8th Atmospheric Spectroscopy Applications Meeting (2008)

Since 1949, solar absorption spectra have been acquired at the Jungfraujoch observatory (Swiss Alps, 46.5°N, 8.0°E, 3580 m a.s.l.), first with grating spectrometers, then with Fourier transform infrared ... [more ▼]

Since 1949, solar absorption spectra have been acquired at the Jungfraujoch observatory (Swiss Alps, 46.5°N, 8.0°E, 3580 m a.s.l.), first with grating spectrometers, then with Fourier transform infrared (FTIR) spectrometers. Most observations collected with these instruments encompass water vapor absorptions, even the narrow spectral domains regularly recorded with the grating instruments to monitor the evolution of important atmospheric constituents. The aim of this work is to analyze all available spectra containing usable H2O absorption lines, to derive a long-term record of its total column in the atmosphere above the Jungfraujoch. In addition, more recent FTIR broadband spectra, with better signal-to-noise ratio and resolution, will be analyzed with state of the art algorithm, in order to derive information on the vertical distribution of H2O. [less ▲]

Detailed reference viewed: 23 (3 ULg)
Full Text
Peer Reviewed
See detailEvaluation of tropospheric and stratospheric ozone trends over Western Europe from ground-based FTIR network observations.
Vigouroux, C.; De Mazière, M.; Demoulin, Philippe ULg et al

in Atmospheric Chemistry and Physics (2008), 362(8), 6865-6886

Detailed reference viewed: 47 (4 ULg)
Full Text
See detailRetrievals of C2H2 from high-resolution FTIR solar spectra recorded at the Jungfraujoch station (46.5ºN) and comparison with ACE-FTS observations
Mahieu, Emmanuel ULg; Duchatelet, Pierre ULg; Bernath, P. F. et al

in Geophysical Research Abstracts (2008), 10

Acetylene (C2H2) is among the nonmethane hydrocarbons (NMHCs) accessible to infrared remote sensing technique. As a product of combustion and biomass burning, it is emitted at the Earth’s surface and ... [more ▼]

Acetylene (C2H2) is among the nonmethane hydrocarbons (NMHCs) accessible to infrared remote sensing technique. As a product of combustion and biomass burning, it is emitted at the Earth’s surface and further transported and mixed into the troposphere. Destruction by OH is the main removal process. The average tropospheric lifetime of C2H2 is estimated at about 1 month on the global scale; at mid-latitudes, it varies between 20 days in summer to 160 days in winter. This compound is appropriate to study tropospheric pollution and transport, and is often used in conjunction with other tracers of fires. C2H2 presents exploitable infrared absorption features near 3 and 15 μm, where weak isolated lines of the nu5 and the nu2 + nu4 + nu5 bands are found, respectively. Several of these lines can be used to retrieve abundances of C2H2 from high-resolution groundbased infrared solar spectra. Typical observations recorded at the Jungfraujoch station (46.5ºN, 8.0ºE, 3580m asl, Swiss Alps) by the NDACC (Network for the Detection of Atmospheric Composition Change)-affiliated Bruker instrument have been fitted with the OEM-SFIT-2 (v3.91) algorithm. Various approaches and combination of lines have been tested, seeking for the optimum inversion strategy. The HITRAN-2004 spectroscopic line parameters including the August 2006 updates for water vapor have been adopted in the retrievals. These approaches will be presented and critically compared, with the help of error budget and information content analyses, taking into account the impact of major interferences such as water vapor. The time series of C2H2 tropospheric column abundances above Jungfraujoch will also be presented, including determination of its long-term trend and strong seasonal cycle. The ground-based results will further be compared with zonal mean observations performed by the ACE-FTS space-based instrument since early 2004. [less ▲]

Detailed reference viewed: 58 (5 ULg)
Full Text
See detailRetrievals of HCN from high-resolution FTIR solar spectra recorded at the Jungfraujoch station
Mahieu, Emmanuel ULg; Duchatelet, Pierre ULg; Demoulin, Philippe ULg et al

in Geophysical Research Abstracts (2007, April)

Recent investigations have resulted in the revision of the lifetime of hydrogen cyanide (HCN) from 2.5 years to 2-5 months, more in line with its important and well documented variability in the ... [more ▼]

Recent investigations have resulted in the revision of the lifetime of hydrogen cyanide (HCN) from 2.5 years to 2-5 months, more in line with its important and well documented variability in the troposphere. The main HCN source is believed to be biomass burning, making this species a useful tracer of fires, e.g. the widespread and intense 2004 boreal fires. Oxidation by the OH radical is among the identified sinks, while uptake by oceans has been hypothesized as the dominant sink. As shown by previous investigations, several lines from the nu3 fundamental HCN band at 3 μm can be used to retrieve information on vertical distribution of hydrogen cyanide from high-resolution FTIR solar absorption spectra. The major interfering gas in this region is water vapor. A series of typical observations recorded at the Jungfraujoch station (46.5ºN, 8.0ºE, 3580m asl, Swiss Alps) by the NDACC (Network for the Detection of Atmospheric Composition Change)-affiliated Bruker instrument have been fitted using various approaches to determine the optimum strategy to be used for HCN retrievals at that site, even under very wet conditions. The selected approach is made of 7 windows encompassing 5 HCN lines. The a priori information (HCN vertical distribution and covariance matrix) is based on ACE-FTS measurements performed over northern midlatitudes. The HITRAN-2004 spectroscopic line parameters including the August 2006 updates for water vapor have been adopted in the retrievals performed with the OEM-SFIT-2 (v3.91) algorithm. This contribution will give a full description of the adopted retrieval approach, including error budget and information content analysis. Tropospheric column time series of HCN from 1994 onwards will also be presented and discussed. [less ▲]

Detailed reference viewed: 66 (6 ULg)
See detailFTIR Observations at the Jungfraujoch Station for long-term monitoring of the Troposphere and Validation of the Space-based Sensors.
Mahieu, Emmanuel ULg; Zander, Rodolphe ULg; Demoulin, Philippe ULg et al

in Burrows, J.; Borrell, P. (Eds.) Measuring Tropospheric Trace Constituents from Space. (2007)

Detailed reference viewed: 16 (8 ULg)
See detailOptimisation of retrieval strategies using Jungfraujoch high-resolution FTIR observations for long-term trend studies and satellite validation.
Mahieu, Emmanuel ULg; Servais, Christian ULg; Duchatelet, Pierre ULg et al

in Burrows, J.; Borrell, P. (Eds.) Observing Tropospheric Trace Constituents from Space. (2007)

Detailed reference viewed: 4 (2 ULg)
Full Text
See detailFTIR signal acquisition based on simultaneous analog sampling of the laser reference and IR detectors.
Servais, Christian ULg; Blavier, J. F.; Toon, G. C. et al

Scientific conference (2007)

Detailed reference viewed: 18 (9 ULg)
See detailAURA validation by the baloon-borne MkIV Interferometer.
Toon, G. C.; Kleinboehl, A.; Salawitch, R. J. et al

Scientific conference (2006)

Detailed reference viewed: 7 (1 ULg)
See detailEvolution of a dozen non-CO2 greenhouse gases above Central Europe since the mid-1980s.
Zander, Rodolphe ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

in Proceedings of the 4th International Symposium on Non-CO2 Greenhouse Gases (2006)

Detailed reference viewed: 9 (1 ULg)
Full Text
Peer Reviewed
See detailEvolution of a dozen non-CO2 greenhouse gases above central Europe since the mid-1980s
Zander, Rodolphe ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

in Environmental Sciences (2005), 2(2-3), 295-303

High-resolution infrared solar observations have been conducted consistently since the mid-1980s at the International Scientific Station of the Jungfraujoch, Switzerland, by the GIRPAS-ULg team (Groupe ... [more ▼]

High-resolution infrared solar observations have been conducted consistently since the mid-1980s at the International Scientific Station of the Jungfraujoch, Switzerland, by the GIRPAS-ULg team (Groupe Infra-Rouge de Physique Atmosphrique et Solaire-University of Lige), and by colleagues from the Belgian Institute for Space Aeronomy and from the Royal Observatory of Belgium, Brussels. These observations were performed with state-of-the-art Fourier transform infrared (FTIR) spectrometers, revealing specific absorption features of over 20 atmospheric gases in the middle-infrared. Related spectrometric analyses have allowed the derivation of their burdens, seasonal and inter-annual variability, as well as their long-term evolution. In addition to updates of long-term changes for CCl2F2, CHClF2, CH4, N2O, SF6, CO, C2H6 and C2H2 already dealt with at previous Non-CO2 Greenhouse Gases (NCGG) symposia, this paper further reports temporal evolutions observed during the past two decades for a series of other source gases, namely OCS, HCN, CCl3F and CCl4, which also have direct or indirect effects on the radiation balance of the troposphere and on the stratospheric ozone layer. [less ▲]

Detailed reference viewed: 42 (7 ULg)
Full Text
See detailRecent Evolution of atmospheric OCS above the Jungfraujoch station : implications for the stratospheric aerosol layer.
Mahieu, Emmanuel ULg; Zander, Rodolphe ULg; Demoulin, Philippe ULg et al

in Proceedings of the Atmospheric Spectroscopy Applications. (2005)

Detailed reference viewed: 5 (0 ULg)
Full Text
See detailThe evolution of inorganic chlorine above the Jungfraujoch station: an update.
Mahieu, Emmanuel ULg; Duchatelet, Pierre ULg; Zander, Rodolphe ULg et al

in Zerefos, C. S. (Ed.) Proceedings of the 20th Quadrennial Ozone Symposium (2004)

Within the frame of the NDSC, the total vertical column abundances of HCl and ClONO2, by far the two most important inorganic chlorine reservoirs at northern mid-latitudes, have been further monitored ... [more ▼]

Within the frame of the NDSC, the total vertical column abundances of HCl and ClONO2, by far the two most important inorganic chlorine reservoirs at northern mid-latitudes, have been further monitored above the Jungfraujoch station (Swiss Alps, 46.5ºN, 8.0ºE, 3580m a.s.l.), by analyzing infrared solar absorption spectra recorded with very high-resolution Fourier spectrometers. The mean temporal evolution of the sum of their monthly mean abundance time series indicates that the total stratospheric inorganic chlorine loading (Cly) has decreased slowly (-0.7+/-0.3%/yr, 1-sigma) since it peaked in late 1996, at the limit of being statistically significant at the 2-sigma level. Comparison with model calculations and with the evolution of surface total organic chlorine will also be discussed. [less ▲]

Detailed reference viewed: 32 (2 ULg)
See detailMonitoring of the variability and long-term evolution of tropospheric constituents by Infrared solar absorption spectrometry at the Jungfraujoch, Switzerland.
Zander, Rodolphe ULg; Mahieu, Emmanuel ULg; Duchatelet, Pierre ULg et al

in Borrell, P.; Borrell, P. M.; Burrows, J. P. (Eds.) et al Sounding the Troposphere from Space: A new era for Atmospheric Chemistry. (2003)

Detailed reference viewed: 5 (1 ULg)