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See detailL'atmosphère de la grotte de Ramioul
Godissart, Jean; Ek, Camille ULg

in Bulletin de la Société Royale Belge d'Etudes Géologiques et Archéologiques "Les Chercheurs de Wallonie" (2010), hors-série n°3

Depuis 2004, un puits de 30 m de la grotte de Ramioul dégage du dioxyde de cargone à des concentrations atteignant 8%. Les concentrations de CO2, O2 et CO ont été enregistrées depuis 2008. Les ... [more ▼]

Depuis 2004, un puits de 30 m de la grotte de Ramioul dégage du dioxyde de cargone à des concentrations atteignant 8%. Les concentrations de CO2, O2 et CO ont été enregistrées depuis 2008. Les histogrammes de CO2 montrent des maximums hivernaux, des minimums en été, et une production 12 à 20 fois plus grande que les autres grottes de Belgique. Le CO2 provient probablement de l'oxydation de la pyrite par les eaux d'infiltration. [less ▲]

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See detailL'atmosphère de Mars
Stiepen, Arnaud ULg

Conference given outside the academic context (2014)

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See detailL’atmosphère et les cacahuètes. Simenon, matière de cinéma
Tomasovic, Dick ULg

in Demoulin, Laurent (Ed.) Cahier de l'Herne Simenon (2013)

Fasciné par la puissance de l’image cinématographique, méfiant à l’égard de l’industrie audiovisuelle , Simenon est aussi un cinéphile au goût très sûr. Le cinéma lui rendit cet amour ambivalent. D’une ... [more ▼]

Fasciné par la puissance de l’image cinématographique, méfiant à l’égard de l’industrie audiovisuelle , Simenon est aussi un cinéphile au goût très sûr. Le cinéma lui rendit cet amour ambivalent. D’une part, l’œuvre de Simenon apparaît comme une vache à lait de l’adaptation cinématographique, d’autre part, Simenon exerce une séduction sur un nombre important de cinéastes pour ses qualités descriptives, ses peintures sociales, et, surtout, pour une tonalité atmosphérique imageante qui lui serait propre. [less ▲]

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See detailThe atmosphere's response to solar irradiation
Hunten, D. M.; Gérard, Jean-Claude ULg; François, Louis ULg

in Sonnett, C. P.; Giampapa, M. S.; Matthews, M. S. (Eds.) The Sun in time (1991)

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See detailThe atmosphere's response to solar irradiation.
Hunten, D.M.; Gérard, Jean-Claude ULg; François, Louis ULg

Conference (1989)

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See detailAtmosphères planétaires et astrobiologie
Javaux, Emmanuelle ULg

Conference given outside the academic context (2005)

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See detailAtmospheric and oceanic climate forcing of the exceptional Greenland ice sheet surface melt in summer 2012
Hanna, E.; Fettweis, Xavier ULg; Mernild, S. et al

in International Journal of Climatology (2013), online

The NASA announcement of record surface melting of the Greenland ice sheet in July 2012 led us to examine the atmospheric and oceanic climatic anomalies that are likely to have contributed to these ... [more ▼]

The NASA announcement of record surface melting of the Greenland ice sheet in July 2012 led us to examine the atmospheric and oceanic climatic anomalies that are likely to have contributed to these exceptional conditions and also to ask the question of how unusual these anomalies were compared to available records. Our analysis allows us to assess the relative contributions of these two key influences to both the extreme melt event and ongoing climate change. In 2012, as in recent warm summers since 2007, a blocking high pressure feature, associated with negative NAO conditions, was present in the mid-troposphere over Greenland for much of the summer. This circulation pattern advected relatively warm southerly winds over the western flank of the ice sheet, forming a ‘heat dome’ over Greenland that led to the widespread surface melting. Both sea-surface temperature and sea-ice cover anomalies seem to have played a minimal role in this record melt, relative to atmospheric circulation. Two representative coastal climatological station averages and several individual stations in south, west and north-west Greenland set new surface air temperature records for May, June, July and the whole (JJA) summer. The unusually warm summer 2012 conditions extended to the top of the ice sheet at Summit, where our reanalysed (1994–2012) DMI Summit weather station summer (JJA) temperature series set new record high mean and extreme temperatures in 2012; 3-hourly instantaneous 2-m temperatures reached an exceptional value of 2.2°C at Summit on 11 July 2012. These conditions translated into the record observed ice-sheet wide melt during summer 2012. However, 2012 seems not to be climatically representative of future ‘average’ summers projected this century. [less ▲]

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See detailAtmospheric Carbon Dioxide and Climate Over Phanerozoic Times
François, Louis ULg; Lefèbvre, Vincent; Goddéris, Yves et al

Conference (2006, December)

The atmospheric CO2 mixing ratio has fluctuated widely over the Phanerozoic, according to the estimates from available proxy records. Because atmospheric CO2 is a major greenhouse gas, these fluctuations ... [more ▼]

The atmospheric CO2 mixing ratio has fluctuated widely over the Phanerozoic, according to the estimates from available proxy records. Because atmospheric CO2 is a major greenhouse gas, these fluctuations should have led to significant climatic variations. The "classical" view is indeed that atmospheric CO2 has been the main driver of the Earth's climate history. On long-term time scales, the atmospheric CO2 level is the result of the balance between CO2 inputs from volcanoes or oxidation of old organic carbon (kerogen) in exposed rocks and outputs through silicate weathering or organic carbon deposition. Existing model reconstructions of the Phanerozoic history of atmospheric CO2 are based on such budgets. Recent data and model experiments currently challenge these models. First, the carbon cycle may be more complex than represented in the earliest models. In particular, silicate weathering depends on numerous factors, which are not obvious to model or are poorly known over the Phanerozoic. Mountain uplift is one such factor, which has been much debated in the last decade. Lithology is another example: basalts weather much more rapidly than other silicate rocks and the emplacement of large basaltic areas on the continents may trigger glaciations. Continental configuration is also more important than previously thought, as indicated by recent model experiments on super-continent fragmentation coupling geochemical and climate models. Problems of "classical" Phanerozoic CO2 models are also well illustrated by the fact that the most recent estimates of CO2 degassing show very little variation between the Cretaceous and the present, a period when large changes in CO2 have occurred, whereas degassing is the most important forcing of CO2 evolution in long-term carbon cycle models. Second, CO2 is not the only driver of climate evolution. This obvious fact has largely been forgotten in Phanerozoic studies. What the proxies tell us on paleo-atmospheric CO2 is not always in line with what we know about paleoclimatic records. For instance, the proxies suggest relatively high CO2 levels during the Late Ordovician glaciations. Similarly, the Late Jurassic now appears to be colder than earlier thought, while again proxies suggest high atmospheric CO2 at that time. The mid-Miocene climate warming, which occurs simultaneously with a drop in CO2, provides another example. This latter change in CO2 is unanimously reflected in all proxies and, so, this decoupling between CO2 and climate cannot arise from uncertainties on the reconstructed CO2 levels or from dating problems, as might be the case of the former two examples. Other climatic drivers than CO2 clearly need to be considered. In this respect, vegetation- climate feedbacks have been completely disregarded in long-term climatic studies. Cenozoic cooling is, however, accompanied by a progressive transition from closed forests to more widespread grasslands and deserts on the continental areas, a change which must have had major impacts on the surface albedo and the water cycle. [less ▲]

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See detailAtmospheric Chemistry Experiment (ACE): Mission overview
Bernath, Peter; McElroy, C. T.; Abrams, Mark et al

in Geophysical Research Letters (2005), 32(15),

SCISAT-1, also known as the Atmospheric Chemistry Experiment ( ACE), is a Canadian satellite mission for remote sensing of the Earth's atmosphere. It was launched into low Earth circular orbit ( altitude ... [more ▼]

SCISAT-1, also known as the Atmospheric Chemistry Experiment ( ACE), is a Canadian satellite mission for remote sensing of the Earth's atmosphere. It was launched into low Earth circular orbit ( altitude 650 km, inclination 74 degrees) on 12 Aug. 2003. The primary ACE instrument is a high spectral resolution (0.02 cm(-1)) Fourier Transform Spectrometer (FTS) operating from 2.2 to 13.3 mm ( 750 - 4400 cm(-1)). The satellite also features a dual spectrophotometer known as MAESTRO with wavelength coverage of 285 - 1030 nm and spectral resolution of 1 - 2 nm. A pair of filtered CMOS detector arrays records images of the Sun at 0.525 and 1.02 mu m. Working primarily in solar occultation, the satellite provides altitude profile information ( typically 10 - 100 km) for temperature, pressure, and the volume mixing ratios for several dozen molecules of atmospheric interest, as well as atmospheric extinction profiles over the latitudes 85 degrees N to 85 degrees S. This paper presents a mission overview and some of the first scientific results. [less ▲]

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See detailAtmospheric CO2 consumption by continental erosion: present-day controls and implications for the last glacial maximum
Ludwig, Wolfgang; Amiotte-Suchet, Philippe; Munhoven, Guy ULg et al

in Global and Planetary Change (1998), 16-17

The export of carbon from land to sea by rivers represents a major link in the global carbon cycle, For all principal carbon forms, the main factors that control the present-day fluxes at the global scale ... [more ▼]

The export of carbon from land to sea by rivers represents a major link in the global carbon cycle, For all principal carbon forms, the main factors that control the present-day fluxes at the global scale have been determined in order to establish global budgets and to predict regional fluxes. Dissolved organic carbon fluxes are mainly related to drainage intensity, basin slope, and the amount of carbon stored in soils. Particulate organic carbon fluxes are calculated as a function of sediment yields and of drainage intensity. The consumption of atmospheric/soil CO2 by chemical rock weathering depends mainly on the rock type and on the drainage intensity. Our empirical models yield a total of 0.721 Gt of carbon (Gt C) that is exported from the continents to the oceans each year. From this figure, 0.096 Gt C come from carbonate mineral dissolution and the remaining 0.625 Gt C stem from the atmosphere (F-CO2). Of this atmospheric carbon, 33% is discharged as dissolved organic carbon, 30% as particulate organic carbon, and 37% as bicarbonate ions. Predicted inorganic carbon fluxes were further compared with observed fluxes for a set of 35 major world rivers, and possible additional climatic effects on the consumption of atmospheric CO2 by rock weathering were investigated in these river basins. Finally, we discuss the implications of our results for the river carbon fluxes and the role of continental erosion in the global carbon cycle during the last glacial maximum. [less ▲]

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See detailAtmospheric CO2 flux from mangrove surrounding waters
Borges, Alberto ULg; Djenidi, Salim ULg; Lacroix, Geneviève et al

in Geophysical Research Letters (2003), 30(11),

[1] The partial pressure of CO2 (pCO(2)) was measured at daily and weekly time scales in the waters surrounding mangrove forests in Papua New Guinea, the Bahamas and India. The pCO(2) values range from ... [more ▼]

[1] The partial pressure of CO2 (pCO(2)) was measured at daily and weekly time scales in the waters surrounding mangrove forests in Papua New Guinea, the Bahamas and India. The pCO(2) values range from 380 to 4800 muatm. These data, together with previously published data, suggest that overall oversaturation of CO2 with respect to atmospheric equilibrium in surface waters is a general feature of mangrove forests, though the entire ecosystems (sediment, water and vegetation) are probably sinks for atmospheric CO2. The computed CO2 fluxes converge to about +50 mmolC m(-2) day(-1). If this conservative value is extrapolated for worldwide mangrove ecosystems, the global emission of CO2 to the atmosphere is about 50 10(6) tC year(-1). Based on this tentative estimate, mangrove waters appear to be regionally a significant source of CO2 to the atmosphere and should be more thoroughly investigated, especially at seasonal time scale. [less ▲]

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See detailAtmospheric concentrations of PCDD/Fs, dl-PCBs and some pesticides in northern Algeria using passive air sampling.
Moussaoui, Y.; Tuduri, L.; Kerchich, Y. et al

in Chemosphere (2012), 88

Two monitoring campaigns were conducted in northern Algeria to assess the contamination level of pesticides and persistent organic pollutants (POPs) in ambient air. Six pesticides (alpha- and gamma ... [more ▼]

Two monitoring campaigns were conducted in northern Algeria to assess the contamination level of pesticides and persistent organic pollutants (POPs) in ambient air. Six pesticides (alpha- and gamma-hexachlorocyclohexane, fenitrothion, malathion, chlorpyrifos and lambda-cyhalothrin) were monitored at two different sampling locations during the first campaign. The passive sampling was performed at a semi urban/industrial site but also in a rural area between July to September 2008. The pesticides levels, analyzed by GC/MS/MS, ranged from 16pgm(-3) to 11ngm(-3). The second campaign was carried out from May to November 2009. The polychlorodibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) concentrations were evaluated at an urban/industrial and at an industrial site. The PCDD/Fs and dl-PCBs, analyzed by HRGC/HRMS, ranged from 249 to 923fg TEQ m(-3). In addition to passive sampling, active sampling using an isokinetic sampler was also performed at an industrial waste incinerator. The PCDD/Fs and dl-PCBs found was 268pg TEQ m(-3). This paper presents the first measurements of PCDD/Fs, dl-PCBs and pesticides in rural, urban and industrial areas of northern Algeria. [less ▲]

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See detailAtmospheric lead and heavy metal pollution records from a Belgian peat bog spanning the last two millenia: Human impact on a regional to global scale
De Vleeschouwer, Francois; Gerard, Laetitia; Goormaghtigh, Catherine et al

in Science of the Total Environment (2007), 377(2-3), 282-295

Europe has been continuously polluted throughout the last two millennia. During the Roman Empire, these pollutions were mainly from ore extraction and smelting across Europe. Then, during the Middle Ages ... [more ▼]

Europe has been continuously polluted throughout the last two millennia. During the Roman Empire, these pollutions were mainly from ore extraction and smelting across Europe. Then, during the Middle Ages and the Early times of Industrial revolution (i.e. 1750), these pollutions extended to coal burning and combustion engine. Belgian ombrotrophic peat bogs have proved an effective archive of these pollutants and provide the opportunity to reconstruct the history of atmospheric deposition in NW Europe. The results of recent and past trace metal accumulation and Pb isotopes from a one-meter peat core (in the Misten peat bog) have been derived using XRF and Nu-plasma MC-ICP-MS. Combined with C-14 and Pb-210 dates these data have enabled us to trace fluxes in anthropogenic pollution back to original Roman times. Several periods of well-known Pb pollution events are clearly recorded including the Early and Late Roman Empire, the Middle Ages and the second industrial revolution. Also recorded is the introduction of leaded gasoline, and more recently the introduction of unleaded gasoline. Lead isotopes in this site have also enabled us to fingerprint several regional and global sources of anthropogenic particles. (c) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailAtmospheric lead deposition in an ombrotrophic peat bog of Southern Poland
Fiałkiewicz-Kozieł, B.; De Vleeschouwer, F.; Smieja-Król, B. et al

Poster (2010)

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See detailAtmospheric Lifetime of Fossil Fuel Carbon Dioxide
Archer, David; Eby, Michael; Brovkin, Victor et al

in Annual Review of Earth & Planetary Sciences (2009), 37

CO2 released from combustion of fossil fuels equilibrates among the various carbon reservoirs of the atmosphere, the ocean, and the terrestrial biosphere on timescales of a few centuries. However, a ... [more ▼]

CO2 released from combustion of fossil fuels equilibrates among the various carbon reservoirs of the atmosphere, the ocean, and the terrestrial biosphere on timescales of a few centuries. However, a sizeable fraction of the CO2 remains in the atmosphere, awaiting a return to the solid earth by much slower weathering processes and deposition of CaCO3. Common measures of the atmospheric lifetime of CO2, including the e-folding time scale, disregard the long tail. Its neglect in the calculation of global warming potentials leads many to underestimate the longevity of anthropogenic global warming. Here, we review the past literature on the atmospheric lifetime of fossil fuel CO2 and its impact on climate, and we present initial results from a model intercomparison project on this topic. The models agree that 20–35% of the CO2 remains in the atmosphere after equilibration with the ocean (2–20 centuries). Neutralization by CaCO3 draws the airborne fraction down further on timescales of 3 to 7 kyr. [less ▲]

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See detailAtmospheric mercury deposition during the last 1500 years in We Europe: The Misten peat bog record (Hautes Fagnes - Belgium)
Allan, Mouhamd ULg; Fagel, Nathalie ULg; De Vleeschouwer, François et al

Poster (2011, April)

The current rate of global atmospheric Hg deposition is approximately three times higher than the preindustrial record and it even increased by a factor of 2-10 in the industrialized regions ... [more ▼]

The current rate of global atmospheric Hg deposition is approximately three times higher than the preindustrial record and it even increased by a factor of 2-10 in the industrialized regions.....()(Hylander and Meili 2003). To determine the extent of such increase, it is necessary to quantify the atmospheric mercury concentration and its temporal variation. For this purpose four 1m Wardenaar peat cores (MIS01W, 04W, 0W5 and 06W) were collected in 2008 in the ombrotrophic Misten bog (Hautes Fagnes Plateau, East Belgium). Mercury was measured using a DMA 80 at the Laboratory of Mechanisms and Transfers in Geology in Toulouse (LMTG, France). The strongest mercury concentrations are measured in the upper half peat record, in a depth interval corresponding to the Industrial Revolution period. Mercury accumulation rate was estimated by applying a coupled 210Pb- 14C age model. The mercury accumulation rate remains relatively small, ranging between 0.9 and 3.3 g.m 2.y 1 during periods corresponding to the decline of Roman Empire and during the Middle Ages. Hg accumulation rate starts to increase when 25 cm, reaching a maximum value (> 115 g.m 2.y 1) at 13.7 cm (i.e.; 1923-1938 AD). Then the values oscillate to reach 9 g.m 2.y 1 at the peat surface (2000-2007AD). In the Misten bog, the evolution of Hg accumulation rate is in agreement with the chronology of other European peat records .......()(Roos-Barraclough et al. 2002). [less ▲]

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See detailAtmospheric parameters of 169 F-, G-, K- and M-type stars in the Kepler field
Molenda-Żakowicz, J.; Sousa, S. G.; Frasca, A. et al

in Monthly Notices of the Royal Astronomical Society (2013), 434

The asteroseismic and planetary studies, like all research related to stars, need precise and accurate stellar atmospheric parameters as input. We aim at deriving the effective temperature (T[SUB]eff[/SUB ... [more ▼]

The asteroseismic and planetary studies, like all research related to stars, need precise and accurate stellar atmospheric parameters as input. We aim at deriving the effective temperature (T[SUB]eff[/SUB]), the surface gravity (log g), the metallicity ([Fe/H]), the projected rotational velocity (v sin i) and the MK type for 169 F-, G-, K- and M-type Kepler targets which were observed spectroscopically from the ground with five different instruments. We use two different spectroscopic methods to analyse 189 high-resolution, high-signal-to-noise spectra acquired for the 169 stars. For 67 stars, the spectroscopic atmospheric parameters are derived for the first time. KIC 9693187 and 11179629 are discovered to be double-lined spectroscopic binary systems. The results obtained for those stars for which independent determinations of the atmospheric parameters are available in the literature are used for a comparative analysis. As a result, we show that for solar-type stars the accuracy of present determinations of atmospheric parameters is ±150 K in T[SUB]eff[/SUB], ±0.15 dex in [Fe/H] and ±0.3 dex in log g. Finally, we confirm that the curve-of-growth analysis and the method of spectral synthesis yield systematically different atmospheric parameters when they are applied to stars hotter than 6000 K. [less ▲]

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See detailAtmospheric perturbations on GNSS signals and their influence on time transfer
Warnant, René ULg

in Proceedings of the XXVII URSI General Assembly (2002, August)

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