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See detailProtégeons la beauté du ciel nocturne-II
Jehin, Emmanuel ULg; Demoulin, Philippe ULg

Article for general public (2000)

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See detailProtégeons la beauté du ciel nocturne-I
Jehin, Emmanuel ULg; Demoulin, Philippe ULg

Article for general public (2000)

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See detailMonitoring the stratospheric chlorine budget during the past decades: the Montreal Protocol at work
Mahieu, Emmanuel ULg; Zander, Rodolphe ULg; Mélen, Francine et al

in NASDA (Ed.) Proceedings of the Quadriennal ozone symposium - Sapporo 2000 (2000)

The study of series of ground-based solar observations performed within the frame of the NDSC indicates that the rate of increase of the atmospheric loading of inorganic chlorine has progressively slowed ... [more ▼]

The study of series of ground-based solar observations performed within the frame of the NDSC indicates that the rate of increase of the atmospheric loading of inorganic chlorine has progressively slowed down, then stabilized around 1996-97, with a subsequent tendency towards a decrease. The investigation is based on total column abundances of HCl and ClONO2 measured at the Jungfraujoch station in the Swiss Alps and on stratospheric columns of HCl derived from observations at Kitt Peak National Observatory (Arizona, USA). The observed changes are compared with near-global observations of HCl around the stratopause by HALOE and with a global, best-case emission scenario of Cl-bearing ground-level source gases compiled by UNEP [less ▲]

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See detailFifteen years-trend characteristics of key stratospheric constituents monitored by FTIR above the Jungfraujoch.
Mahieu, Emmanuel ULg; Zander, Rodolphe ULg; Demoulin, Philippe ULg et al

in Harris, N. R. P.; Guirlet, M.; Amanatidis, G. T. (Eds.) Air Pollution Report 73 EUR 19340 (2000)

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See detailInvestigation of height-resolved information in ground-based high-resolution Fourier infrared solar spectra above the Jungfraujoch
Barret, Brice; De Mazière, Martine; Demoulin, Philippe ULg et al

in Proceedings of the Quadriennal ozone symposium - Sapporo 2000 (2000)

Vertical profiles of HF, O3, and HNO3 have been retrieved from high-resolution solar spectra recorded at the Jungfraujoch observatory (Swiss Alps, 46.5°N latitude, 8.0°E longitude, 3.58 km altitude). Two ... [more ▼]

Vertical profiles of HF, O3, and HNO3 have been retrieved from high-resolution solar spectra recorded at the Jungfraujoch observatory (Swiss Alps, 46.5°N latitude, 8.0°E longitude, 3.58 km altitude). Two algorithms for the retrieval of vertical concentration profiles based on the Optimal Estimation Method have been used. The results of the vertical profile retrievals are compared to the Halogen Occultation Experiment (HALOE) profiles, to the Cryogenic Infrared Spectrometers and Telescope (CRISTA2) second mission (August 1997) profiles for HNO3 and O3 and also to nearby ozone sondes and lidar profile for O3. [less ▲]

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See detailLong-term evolution of the loading of CH4, N2O, CO, CCl2F2, CHClF2 and SF6 above Central Europe during the last 15 years
Zander, Rodolphe ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

in J. van Ham (Ed.) Non-CO2 greenhouse gases: scientific understanding, control and implementation (2000)

Long-term monitoring activities of some 20 atmospheric constituents are continuing at the International Scientific Station of the Jungfraujoch, Switzerland, based on remote infra-red solar observations ... [more ▼]

Long-term monitoring activities of some 20 atmospheric constituents are continuing at the International Scientific Station of the Jungfraujoch, Switzerland, based on remote infra-red solar observations with high spectral resolution Fourier transform spectrometers. As a contribution to non-CO2 greenhouse gas investigations, we report the trends observed in the vertical column abundances measured regularly since the mid-1980s for CH4, N2O, CO, CCl2F2, CHClF2 and SF6. With the exception of CO, all species show positive rates of change in their near past atmospheric loading, those of CH4, N2O and CCl2F2 having slowed significantly during the more recent years. The derived rates of change will be compared to findings resulting from ground-level in situ investigations at latitudes similar to that of the Jungfraujoch, and be interpreted in terms of resulting global loading changes. [less ▲]

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See detailVertical column abundances of COF2 above the Jungfraujoch Station: update and consolidation of the database with measurements in the nu4 band region.
Mélen, Francine; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

in Atmospheric Spectroscopy Applications 1999 - Proceedings (1999)

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See detailColumn Abundance measurements of formaldehyde above the Jungfraujoch.
Demoulin, Philippe ULg; Zander, Rodolphe ULg; Mélen, F. et al

in Atmospheric Spectroscopy Applications 1999 - Proceedings (1999)

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See detailQuantitative evaluation of the post-Mount Pinatubo NO2 reduction and recovery, based on 10 years of Fourier transform infrared and UV-visible spectroscopic measurements at Jungfraujoch
De Mazière, Martine; Van Roozendael, Michel; Hermans, Christian et al

in Journal of Geophysical Research (1998), 103(D9), 10849-10858

The colocation of two technically different instruments for ground-based remote sensing of NO2 total column amounts at the primary Network for the Detection of Stratospheric Change Alpine station of the ... [more ▼]

The colocation of two technically different instruments for ground-based remote sensing of NO2 total column amounts at the primary Network for the Detection of Stratospheric Change Alpine station of the Jungfraujoch (46.5°N, 8.0°E) has been exploited for mutual validation of the long-term NO2 time series from both instruments and for a quantitative evaluation of the impact of the Mount Pinatubo eruption on the NO2 abundance above this northern mid-latitude observatory. The two techniques are high-resolution Fourier transform infrared solar absorption spectrometry and zenith-sky differential optical absorption spectroscopy in the UV visible. The diurnal variation of NO2 has been simulated by a simple photochemical model that allows a comparison between the data from the two techniques. This model is shown to reproduce the observed morning to evening ratios to 2.3%, on average, which is fully adequate for the needs of this study. From the 1985–1996 combined time series of NO2 morning and evening abundances, it has been concluded that the enhanced aerosol load injected into the stratosphere by Mount Pinatubo caused a maximum NO2 reduction above the Jungfraujoch by 45% in early January 1992 that died out quasi-exponentially to zero by the beginning of 1995. [less ▲]

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See detailRecent Characteristic Budgets of Inorganic Chlorine and Fluorine above the Jungfraujoch Station
Mahieu, Emmanuel ULg; Zander, Rodolphe ULg; Mélen, Francine et al

in Harris, N. R. P.; Kilbane-Dawe, I.; Amanatidis, G.T. (Eds.) Proceedings of the 4th European Symposium on Polar Stratospheric Ozone 1997 (1998)

Within the frame of NDSC (Network for the Detection of Stratospheric Change)-related monitoring activities conducted at the International Scientific Station of the Jungfraujoch (Swiss Alps, 46.5°N, 8.0°E ... [more ▼]

Within the frame of NDSC (Network for the Detection of Stratospheric Change)-related monitoring activities conducted at the International Scientific Station of the Jungfraujoch (Swiss Alps, 46.5°N, 8.0°E, 3580 m a.s.l.), long-term investigations of the inorganic chlorine and fluorine budgets have been pursued during the last years. They are based on the analysis of high-resolution infrared solar spectra, recorded with grating and Fourier transform state-of-the-art spectrometers. Nonlinear least squares fittings of synthetic spectra to the observations are performed over selected intervals, encompassing characteristic absorptions of HCl, ClONO2, HF and COF2; this allows the retrieval of their total vertical column abundances above the Jungfraujoch and the evaluation of their budgets. [less ▲]

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See detailObservations coupled to the overpasses of the polar vortex over mid-latitude Europe in winter 1995-1996
Hennen, Olivier; De Mazière, Martine; Van Roozendael, Michel et al

in Harris, N. R. P.; Kilbane-Dawe, I.; Amanatidis, G.T. (Eds.) Polar stratospheric ozone 1997 (1998)

The spring 1996 polar vortex was very deep and cold, with temperatures down to the ice formation threshold, and persisted until March. The northern hemisphere ozone decrease in winter 1995-1996 was larger ... [more ▼]

The spring 1996 polar vortex was very deep and cold, with temperatures down to the ice formation threshold, and persisted until March. The northern hemisphere ozone decrease in winter 1995-1996 was larger than ever before in the nineties. Particularly at the European mid-latitudes, transport of air masses from the polar vortex towards mid-latitudes had a noticeable impact on the stratospheric temperatures and composition. Such was not observed that clearly in the latest winter 1996-1997. In this work, signatures of polar vortex overpasses in spring 1996 at several European mid-latitude stations are indicated. Most significant events have been observed at these stations with a delay of one to four days, on the following days: 18-22/1, 14-20/2, 1-6/3, 29/3, 15-17/4. The focus here will be on the two events in March. [less ▲]

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See detailGround-based FTIR Measurements from a Series of European sites during the Winter of 1995/96 and a Comparison with a 3D Chemical Transport Model: Evidence of Chlorine Activation and Ozone depletion
Paton Walsh, C.; Bell, W.; Blumenstock, T. et al

in Harris, N. R. P.; Kilbane-Dawe, I.; Amanatidis, G.T. (Eds.) Polar stratospheric ozone 1997 (1998)

Fourier transform infra-red (FTIR) measurements of stratospheric trace species have been made at a network of five ground-based sites from 79°N to 47°N during the Northern hemisphere winter of 1995/1996 ... [more ▼]

Fourier transform infra-red (FTIR) measurements of stratospheric trace species have been made at a network of five ground-based sites from 79°N to 47°N during the Northern hemisphere winter of 1995/1996. This winter was extremely cold with temperatures below the threshold for type 1 polar stratospheric cloud (PSC) formation from mid December 1995 until early March 1996 when there was a rapid warming of the stratosphere. Over 25 days experienced temperatures low enough for ice cloud (PSC type 2) formation. Vertical columns values for HCl, ClONO2, HF and HNO3 have been derived from FTIR measurements at the following sites: Ny Alesund, Spitzbergen (79°N, 12°E); Kiruna, Sweden (67°N, 21°E); Harestua, Norway (60°N, 11°E); London, England (51°N, 0°E) and the Jungfraujoch, Switzerland (48°N, 8°E), with measurements of other stratospheric trace gases, including O3 and ClO available from some of the sites. All of these sites are equipped with high resolution Bruker 120HR or 120M spectrometers, recording atmospheric spectra in the mid infrared using the Sun as a source. These measurements have been used to provide both evidence of substantial activation within large areas of the polar vortex and a subsequent O3 depletion. The measurements suggest a well mixed central vortex area surrounded by a vortex edge that may be highly variable in composition. The measurements also provide evidence of substantial mixing of activated air from the edge of the polar vortex into middle latitudes. Comparison with the SLIMCAT 3D chemical transport model highlights the underestimation of ClONO2 concentrations in the model, with subsequent implications for underestimating O3 loss. [less ▲]

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See detailTowards improved evaluations of total ozone at the Jungfraujoch, using vertical profile estimations based on auxiliary data
De Mazière, Martine; Hennen, Olivier; Van Roozendael, Michel et al

in Proceedings of "The XXVIII Quadrennial Ozone Symposium", L’Aquila, Italy, September 12-21, 1996 (1998)

The currently available database of total ozone amounts observed at the Jungfraujoch site in the Swiss Alps starts in 1984, based on high-resolution infrared solar absorption spectroscopic measurements ... [more ▼]

The currently available database of total ozone amounts observed at the Jungfraujoch site in the Swiss Alps starts in 1984, based on high-resolution infrared solar absorption spectroscopic measurements, and has been complemented by daily SAOZ data since mid-1990. The latter instrument (Système d'Analyse par Observations Zénithales) measures the ozone column by application of the DOAS (Differential Optical Absorption Spectroscopy) method to zenith-sky scattered-light spectra in the ultraviolet-visible range, taken at twilight. The actual intercomparison for the overlapping period reveals a negative systematic offset of the FTIR with respect to the SAOZ data of 3.8 % on average, but showing a seasonal variation in the difference. Part of the observed difference probably originates in the model atmospheres that influence the retrieved column differently for each technique. This work shows the development of a climatological ozone vertical distribution model that is more representative of the real atmosphere, exploiting daily meteorological data that are commonly available at the Jungfraujoch site. It argues that the use of this climatological model may improve the accuracy of the retrieved total columns, and hence the agreement between the SAOZ and FTIR datasets; some possible improvements to the model are suggested. Application of this concept to a re-analysis of past observations, making use of existing meteorological long-term records, will enhance the validity of the ozone database at the Jungfraujoch. [less ▲]

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See detailThe 3nu3 bands of isotopic ozone 668 and 686
Chichery, A.; Barbe, Alain; Bourgeois, M.T. et al

in Atmospheric Spectroscopy Applications 1999 - Proceedings (1998)

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See detailThe current budget of NOy above the Jungfraujoch as derived from IR solar observations
Demoulin, Philippe ULg; Mahieu, Emmanuel ULg; Zander, Rodolphe ULg et al

in Harris, N. R. P.; Kilbane-Dawe, I.; Amanatidis, G. T. (Eds.) Polar stratospheric ozone 1997 (1998)

This paper reports on an investigations of a series of compounds of the NOy family, based on high resolution infrared solar observations made at the ISSJ (International Scientific Station of the ... [more ▼]

This paper reports on an investigations of a series of compounds of the NOy family, based on high resolution infrared solar observations made at the ISSJ (International Scientific Station of the Jungfraujoch), Switzerland (46.55ºN, 7.99ºE, 3580 m a.s.l.). These observations are part of a long-term monitoring effort undertaken by the Liège group since the mid-1970s, and integrated more recently as a contribution to the Network for the Detection of Stratospheric Change (NDSC). Currently, vertical column abundances of over 20 molecules are retrieved from solar spectra recorded under clear sky conditions as regularly as possible, using two high resolution Fourier transform infrared (2 to 15 microns) spectrometers. [less ▲]

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See detailAn overview of NDSC-related activities at the Jungfraujoch through high-resolution infrared solar observations
Zander, Rodolphe ULg; Demoulin, Philippe ULg; Mahieu, Emmanuel ULg et al

in Bojkov, R.; Visconti, G. (Eds.) Proceedings of "The XXVIII Quadrennial Ozone Symposium" (1998)

Since the mid-1970s, infrared remote sensing at the Jungfraujoch, Switzerland, has been performed in response to the need to measure the concentrations and assess the seasonal and long-term changes of an ... [more ▼]

Since the mid-1970s, infrared remote sensing at the Jungfraujoch, Switzerland, has been performed in response to the need to measure the concentrations and assess the seasonal and long-term changes of an increasing number of atmospheric constituents. Currently, the vertical column abundances of over 20 telluric gases are being monitored, based on the analysis of solar spectra recorded regularly between 2 and 14 microns, using two high-resolution Fourier transform spectrometers. In this paper, emphasis is placed on those activities more specifically performed within the framework of the NDSC (Network for the Detection of Stratospheric Change) whose objectives are briefly described in the introduction. [less ▲]

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See detailVertical column abundances of COF2 above the Jungfraujoch Station, derived from ground-based infrared solar observations
Mélen, F.; Mahieu, Emmanuel ULg; Zander, Rodolphe ULg et al

in Journal of Atmospheric Chemistry (1998), 29(2), 119-134

Total vertical column abundances of carbonyl fluoride (COF2) have been derived from observations made at the International Scientific Station of the Jungfraujoch (ISSJ; altitude 3.58 km, latitude 46.5 ... [more ▼]

Total vertical column abundances of carbonyl fluoride (COF2) have been derived from observations made at the International Scientific Station of the Jungfraujoch (ISSJ; altitude 3.58 km, latitude 46.5 degrees N, longitude 8.0 degrees E), Switzerland. A systematic analysis of two microwindows containing lines of the vi band was performed, based on a large set of high resolution infrared solar absorption spectra recorded with Fourier transform spectrometers, from 1985 to 1995. Examination of the whole available database indicates a significant increase of the burden of COF2 during the 1988-1995 period. The average exponential rate and the average linear rate referenced to 1992, calculated from daily mean measurements, are both equal to (4.0 +/- 0.5)% yr(-1) (one sigma error). The results are also evaluated and discussed within the context of seasonal variability and correlation between carbonyl fluoride and hydrogen fluoride (HF) columns above the ISSJ. [less ▲]

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See detailNorthern and southern hemisphere ground-based infrared spectroscopic measurements of tropospheric carbon monoxide and ethane
Rinsland, C. P.; Jones, N. B.; Connor, B. J. et al

in Journal Of Geophysical Research. Atmospheres (1998), 103(D21), 28197-28217

Time series of CO and C2H6 measurements have been derived from high-resolution infrared solar spectra recorded in Lauder, New Zealand (45.0 degrees S, 169.7 degrees E, altitude 0.37 km), and at the U.S ... [more ▼]

Time series of CO and C2H6 measurements have been derived from high-resolution infrared solar spectra recorded in Lauder, New Zealand (45.0 degrees S, 169.7 degrees E, altitude 0.37 km), and at the U.S. National Solar Observatory (31.9 degrees N, 111.6 degrees W, altitude 2.09 km) on Kitt Peak. Lauder observations were obtained between July 1993 and November 1997, while the Kitt Peak measurements were recorded between May 1977 and December 1997. Both databases were analyzed with spectroscopic parameters that included significant improvements for C2H6 relative to previous studies. Target CO and C2H6 lines were selected to achieve similar vertical samplings based on averaging kernels. These calculations show that partial columns from layers extending from the surface to the mean tropopause and from the mean tropopause to 100 km are nearly independent. Retrievals based on a semiempirical application of the Rodgers optimal estimation technique are reported for the lower laver, which has a broad maximum in sensitivity in the upper troposphere. The Lauder CO and C2H6 partial columns exhibit highly asymmetrical seasonal cycles with minima in austral autumn and sharp peaks in austral spring. The spring maxima are the result of tropical biomass burning emissions followed by deep convective vertical transport to the upper troposphere and long-range horizontal transport. Significant year-to-year variations are observed for both CO and C2H6, but the measured trends, (+0.37 +/- 0.57)% yr(-1) and (-0.64 +/- 0.79)% yr(-1), 1 sigma, respectively, indicate no significant long-term changes. The Kitt Peak data also exhibit CO and C2H6 seasonal variations in the lower layer with trends equal to (-0.27 +/- 0.17)% yr(-1) and (-1.20 +/- 0.35')% yr(-1), 1 sigma, respectively. Hence a decrease in the Kitt Peak tropospheric C2H6 column has been detected, though the CO trend is not significant. Both measurement sets are compared with previous observations, reported trends, and three-dimensional model calculations. [less ▲]

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See detailGround-based infrared solar spectroscopic measurements of carbon monoxide during 1994 Measurement of Air Pollution From Space flights
Pougatchev, N. S.; Jones, N. B.; Connor, B. J. et al

in Journal Of Geophysical Research. Atmospheres (1998), 103(D15), 19317-19325

Results of the comparison of carbon monoxide ground-based infrared solar spectroscopic measurements with data obtained during 1994 Measurement of Air Pollution From Space (MAPS) flights are presented ... [more ▼]

Results of the comparison of carbon monoxide ground-based infrared solar spectroscopic measurements with data obtained during 1994 Measurement of Air Pollution From Space (MAPS) flights are presented. Spectroscopic measurements were performed correlatively with April and October MAPS flights by nine research groups from Belgium, Canada, Germany, Japan, New Zealand, Russia, and the United States. Characterization of the techniques and error analysis were performed. The role of the CO a priori profile used in the retrieval was estimated. In most cases an agreement between spectroscopic and MAPS data is within estimated MAPS accuracy of +/-10%. [less ▲]

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