Publications of Maxime Prignon
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See detailObservation and simulation of ethane (C2H6) at 23 FTIR sites
Mahieu, Emmanuel ULiege; Franco, B; Pozzer, A et al

Poster (2017, December 13)

Ethane is the most abundant non-methane hydrocarbon (NMHC) in the Earth atmosphere. Its main sources are of anthropogenic origin, with globally 62% from leakage during production and transport of natural ... [more ▼]

Ethane is the most abundant non-methane hydrocarbon (NMHC) in the Earth atmosphere. Its main sources are of anthropogenic origin, with globally 62% from leakage during production and transport of natural gas, 20% from biofuel combustion and 18% from biomass burning. In the Southern hemisphere, anthropogenic emissions are lower which makes biomass burning emissions a more significant source. The main removal process is oxidation by the hydroxyl radical (OH), leading to a mean atmospheric lifetime of 2 months. Until recently, a prolonged decrease of its abundance has been documented, at rates of -1 to -2.7%/yr, with global emissions dropping from 14 to 11 Tg/yr over 1984-2010 owing to successful measures reducing fugitive emissions from its fossil fuel sources. However, subsequent investigations have reported on an upturn in the ethane trend, characterized by a sharp rise from about 2009 onwards. The ethane increase is attributed to the oil and natural gas production boom in North America, although significant changes in OH could also be at play.In the present contribution, we report the trend of ethane at 23 ground-based Fourier Transform Infrared (FTIR) sites spanning the 80ºN to 79ºS latitude range. Over 2010-2015, a significant ethane rise of 3-5%/yr is determined for most sites in the Northern Hemisphere, while for the Southern hemisphere the rates of changes are not significant at the 2-sigma uncertainty level. Dedicated model simulations by EMAC (ECHAM5/MESSy Atmospheric Chemistry; ~1.8×1.8 degrees) implementing various emission scenarios are included in order to support data interpretation. The usual underestimation of the NMHCs emissions in the main inventories is confirmed here for RCP85 (Representative Concentration Pathway Database v8.5). Scaling them by 1.5 is needed to capture the background levels of atmospheric ethane. Moreover, additional and significant emissions (~7 Tg over 2009-2015) are needed to capture the ethane rise in the Northern hemisphere. Attributing them to the oil and gas sector and locating them in North America allows EMAC to produce adequate trends in the Northern hemisphere, but not in the Southern hemisphere, where they are overestimated. Possible causes for this difference are discussed. [less ▲]

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See detailSurveillance de l'atmosphère terrestre depuis la station du Jungfraujoch : une épopée liégeoise entamée voici plus de 65 ans !
Mahieu, Emmanuel ULiege; Bader, Whitney ULiege; Bovy, Benoît ULiege et al

in Bulletin de la Société Géographique de Liège (2017), 68

It’s in the early 1950s that researchers from the University of Liège started to investigate the Earth’s atmosphere from the Jungfraujoch scientific station, in the Swiss Alps, at a time when concerns ... [more ▼]

It’s in the early 1950s that researchers from the University of Liège started to investigate the Earth’s atmosphere from the Jungfraujoch scientific station, in the Swiss Alps, at a time when concerns related to atmospheric composition changes were nonexistent. Since then, an infrared observational data base unique worldwide has been carefully collected. The exploitation of these observations has allowed constituting multi-decadal time series crucial for the characterization of the changes that affected our atmosphere and for the identification of their causes. In this paper, we first remind about the successive steps which led to establishing the observational program of the Liège team at the Jungfraujoch and we evoke important findings which justified its continuation. Then we present some recent results relevant to the Montreal and Kyoto Protocols, or related to the monitoring of air quality. [less ▲]

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See detailObservation and simulation of ethane at 22 FTIR sites
Mahieu, Emmanuel ULiege; Franco, Bruno ULiege; Pozzer, Andrea et al

Conference (2017, May 30)

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See detailImpact of circulation changes on the long-term trend of stratospheric hydrogen fluoride at five NDACC stations
Prignon, Maxime ULiege; Bernath, P.F.; Blumenstock, T. et al

Poster (2017, May 29)

Hydrogen fluoride is mainly produced by the photolysis of anthropogenic source gases such as the chlorofluorocarbons (CFC), the hydrochlorofluorocarbons (HCFC) and the hydrofluorocarbons (HFC). These ... [more ▼]

Hydrogen fluoride is mainly produced by the photolysis of anthropogenic source gases such as the chlorofluorocarbons (CFC), the hydrochlorofluorocarbons (HCFC) and the hydrofluorocarbons (HFC). These families of species are known for contributing to ozone depletion and/or to the greenhouse effect. It is thus essential to regulate and monitor their emissions. Despite the fact that the Montreal protocol (1987) has succeeded to reduce and then suppress the CFC emissions, HF is still increasing in the stratosphere because of ongoing emissions of the HCFC and HFC substitution products. In the framework of the recent studies demonstrating the influence of stratospheric circulation changes on the trend of long-lived tracers (e.g. hydrogen chlorine), we decided to investigate the impact of these circulation changes on HF. To achieve this objective, the rates of changes over time of HF total/partial columns at various latitudes of the globe will be determined and critically discussed. Fourier Transform Infrared data produced at five NDACC sites (Kiruna – 68°N, Jungfraujoch – 46°N, Izana – 28°N, Lauder 45°S and Arrival-heights – 78°S) and satellite data (HALOE and ACE) will be used for this study. This preliminary selection of ground-based stations allows to cover both hemispheres and our period of investigation (last two decades). Finally, in order to support our data interpretation, two SLIMCAT simulations (standard and fixed dynamics) will also be included. [less ▲]

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See detailVery high resolution surface mass balance over Greenland modeled by the regional climate model MAR with a downscaling technique
Kittel, Christoph ULiege; Lang, Charlotte; Agosta, Cécile ULiege et al

Poster (2016, April 20)

This study presents surface mass balance (SMB) results at 10 km resolution with the regional climate MAR model over the Greenland ice sheet. Here, we use the last MAR version (v3.6) where the land-ice ... [more ▼]

This study presents surface mass balance (SMB) results at 10 km resolution with the regional climate MAR model over the Greenland ice sheet. Here, we use the last MAR version (v3.6) where the land-ice module (SISVAT) using a high resolution grid (10km) for surface variables is fully coupled while the MAR atmospheric module running at a lower resolution of 20km. This online downscaling technique enables to correct near-surface temperature and humidity from MAR by a gradient based on elevation before forcing SISVAT. The 20 km precipitations are not corrected. Corrections are stronger over the ablation zone where topography presents more variations. The model has been force by ERA-Interim between 1979 and 2014. We will show the advantages of using an online SMB downscaling technique in respect to an offline downscaling extrapolation based on local SMB vertical gradients. Results at 10 km show a better agreement with the PROMICE surface mass balance data base than the extrapolated 20 km MAR SMB results. [less ▲]

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