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See detailGround-based Network of NDVI measurements for tracking temporal dynamics of canopy structure and vegetation phenology in different biomes
Soudani, K.; Hmimina, K.; Delpierre, N. et al

in Remote Sensing of Environment (2012), 123

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See detailGround-based observations of the beta Cephei CoRoT main target HD 180 642: abundance analysis and mode identification
Briquet, Maryline ULg; Uytterhoeven, K.; Morel, Thierry ULg et al

in Astronomy and Astrophysics (2009), 506

The known β Cephei star HD 180 642 was observed by the CoRoT satellite in 2007. From the very high-precision light curve, its pulsation frequency spectrum could be derived for the first time (Degroote ... [more ▼]

The known β Cephei star HD 180 642 was observed by the CoRoT satellite in 2007. From the very high-precision light curve, its pulsation frequency spectrum could be derived for the first time (Degroote and collaborators). In this paper, we obtain additional constraints for forthcoming asteroseismic modeling of the target. Our results are based on both extensive ground-based multicolour photometry and high-resolution spectroscopy. We determine T_eff = 24 500± 1000 K and log g = 3.45± 0.15 dex from spectroscopy. The derived chemical abundances are consistent with those for B stars in the solar neighbourhood, except for a mild nitrogen excess. A metallicity Z = 0.0099± 0.0016 is obtained. Three modes are detected in photometry. The degree â is unambiguously identified for two of them: â = 0 and â = 3 for the frequencies 5.48694 d[SUP]-1[/SUP] and 0.30818 d[SUP]-1[/SUP], respectively. The radial mode is non-linear and highly dominant with an amplitude in the U-filter about 15 times larger than the strongest of the other modes. For the third frequency of 7.36673 d[SUP]-1[/SUP] found in photometry, two possibilities remain: â = 0 or 3. In the radial velocities, the dominant radial mode presents a so-called stillstand but no clear evidence of the existence of shocks is observed. Four low-amplitude modes are found in spectroscopy and one of them, with frequency 8.4079 d[SUP]-1[/SUP], is identified as (â ,m)=(3,2). Based on this mode identification, we finally deduce an equatorial rotational velocity of 38± 15 km s[SUP]-1[/SUP]. Based on data gathered with the 1.2m Mercator telescope Roque de los Muchachos, La Palma, the 90cm telescope at Sierra Nevada Observatory, Spain, the 1.5 m telescope at San Pedro Mártir Observatory, Mexico, the 1m RCC and 50 cm telescope at the PiszkéstetÅ Mountain Station of Konkoly Observatory, Hungary, the 2.2 m ESO telescope (ESO Programme 077.D-0311; ESO Large Programme 178.D-0361) at La Silla, Chile, the 1.93 m and 1.52 m telescopes at the Haute-Provence Observatory, France. Current address: Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot; CEA, IRFU, SAp, centre de Saclay, 91191 Gif-sur-Yvette, France. [less ▲]

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See detailGround-based observations of the beta Cephei CoRoT main target HD 180642
Briquet, Maryline ULg; Uytterhoeven, K.; Aerts, C. et al

Conference (2008, July)

We present the preliminary results of a detailed study of ground-based photometric and spectroscopic observations dedicated to the β Cephei CoRoT main target HD 180642. Besides the non-linear dominant ... [more ▼]

We present the preliminary results of a detailed study of ground-based photometric and spectroscopic observations dedicated to the β Cephei CoRoT main target HD 180642. Besides the non-linear dominant radial mode several low-amplitude modes are detected in both kinds of datasets. Our aim is to derive the wavenumbers (ℓ,m) of these modes, as additional constraints to the CoRoT pulsation frequencies, for forthcoming asteroseismic modelling of the star. [less ▲]

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See detailGround-based observations of the beta Cephei CoRoT main target HD 180642
Briquet, Maryline ULg; Uytterhoeven, K.; Aerts, C. et al

in Communications in Asteroseismology (2009), 158

We present the preliminary results of a detailed study of ground-based photometric and spectroscopic observations dedicated to the β Cephei CoRoT main target HD~180642. Besides the non-linear dominant ... [more ▼]

We present the preliminary results of a detailed study of ground-based photometric and spectroscopic observations dedicated to the β Cephei CoRoT main target HD~180642. Besides the non-linear dominant radial mode several low-amplitude modes are detected in both kinds of datasets. Our aim is to derive the wavenumbers (â ,m) of these modes, as additional constraints to the CoRoT pulsation frequencies, for forthcoming asteroseismic modelling of the star. [less ▲]

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See detailGround-based photometric observations of the type A aurora of 17-18 December 1971
Gérard, Jean-Claude ULg

in Annales de Géophysique (1974), 30

Ground-based observations have been made during the event of 17-18 Dec. 1971 from northern Norway, using a tilting-filter photometer monitoring the intensities of N2(plus) 1.Neg., H-beta, 6300-A O-I, and ... [more ▼]

Ground-based observations have been made during the event of 17-18 Dec. 1971 from northern Norway, using a tilting-filter photometer monitoring the intensities of N2(plus) 1.Neg., H-beta, 6300-A O-I, and 5200-A N-I. The high 6300-A/N2(plus) 1.Neg ratio classes this event among type A auroras. The 6300-A/5200-A ratio varies during the night and remains higher than the usual value of nearly 20. These observations are compatible with a soft electron flux as the origin of the red line enhancement as illustrated by comparison with a model aurora. It is also found that N(2Do) is deactivated by collisions with electrons at a rate foreseen by theoretical calculations. An upper limit of about 40 seconds is derived for the N(2Do) effective lifetime, though no simple relationship gives a good fit to the observations. [less ▲]

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See detailGround-based photometry of space-based transit detections: Photometric follow-up of the CoRoT mission
Deeg, H. J.; Gillon, Michaël ULg; Shporer, A. et al

in Astronomy and Astrophysics (2009), 506

The motivation, techniques and performance of the ground-based photometric follow-up of transit detections by the CoRoT space mission are presented. Its principal raison d’être arises from the much higher ... [more ▼]

The motivation, techniques and performance of the ground-based photometric follow-up of transit detections by the CoRoT space mission are presented. Its principal raison d’être arises from the much higher spatial resolution of common ground-based telescopes in comparison to CoRoT’s cameras. This allows the identification of many transit candidates as arising from eclipsing binaries that are contaminating CoRoT’s lightcurves, even in low-amplitude transit events that cannot be detected with ground-based obervations. For the ground observations, “on” – “off” photometry is now largely employed, in which only a short timeseries during a transit and a section outside a transit is observed and compared photometrically. CoRoTplanet candidates’ transits are being observed by a dedicated team with access to telescopes with sizes ranging from 0.2 to 2 m. As an example, the process that led to the rejection of contaminating eclipsing binaries near the host star of the Super-Earth planet CoRoT-7b is shown. Experiences and techniques from this work may also be useful for other transit-detection experiments, when the discovery instrument obtains data with a relatively low angular resolution. [less ▲]

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See detailGround-based remote sensing of tropospheric water vapour isotopologues within the project MUSICA
Schneider, M.; Barthlott, S.; Hase, F. et al

in Atmospheric Measurement Techniques (2012), 5(2012), 3007-3027

Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologue data records are provided for ... [more ▼]

Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologue data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change). We present a new method allowing for an extensive and straightforward characterisation of the complex nature of such isotopologue remote sensing datasets. We demonstrate that the MUSICA humidity profiles are representative for most of the troposphere with a vertical resolution ranging from about 2 km (in the lower troposphere) to 8 km (in the upper troposphere) and with an estimated precision of better than 10%. We find that the sensitivity with respect to the isotopologue composition is limited to the lower and middle troposphere, whereby we estimate a precision of about 30‰ for the ratio between the two isotopologues HD16O and H216O. The measurement noise, the applied atmospheric temperature profiles, the uncertainty in the spectral baseline, and the cross-dependence on humidity are the leading error sources. We introduce an a posteriori correction method of the cross-dependence on humidity, and we recommend applying it to isotopologue ratio remote sensing datasets in general. In addition, we present mid-infrared CO2 retrievals and use them for demonstrating the MUSICA network-wide data consistency. In order to indicate the potential of long-term isotopologue remote sensing data if provided with a well-documented quality, we present a climatology and compare it to simulations of an isotope incorporated AGCM (Atmospheric General Circulation Model). We identify differences in the multi-year mean and seasonal cycles that significantly exceed the estimated errors, thereby indicating deficits in the modeled atmospheric water cycle. [less ▲]

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See detailGround-based transmission spectrum of WASP-80 b, a gas giant transiting an M-dwarf
Delrez, Laetitia ULg; Gillon, Michaël ULg; Lendl, Monika ULg et al

Poster (2014, June 09)

We present here some results from our ground-­based multi-­object spectroscopy program aiming to measure the transmission spectrum of the transiting hot Jupiter WASP-80b using the VLT/FORS2 instrument ... [more ▼]

We present here some results from our ground-­based multi-­object spectroscopy program aiming to measure the transmission spectrum of the transiting hot Jupiter WASP-80b using the VLT/FORS2 instrument. WASP-­80b is a unique object as it is the only known specimen of gas giant orbiting an M-dwarf that is bright enough for high SNR follow-­up measurements. Due to the nature of its host star, this hot Jupiter is actually more `warm' than `hot', with an estimated equilibrium temperature of only 800K. It is thus a prime target to improve our understanding of giant exoplanet atmospheres in this temperature range. [less ▲]

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See detailGround-Target Tracking in Multiple Cameras Using Collaborative Particle Filters and Principal Axis-Based Integration
Du, Wei ULg; Hayet, Jean-Bernard; Verly, Jacques ULg et al

in IPSJ Transactions on Computer Vision and Applications (2009), 1

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See detailGroundwater - surface water interaction at the catchment scale - case studies in the Meuse basin
Bürger, Claudius M.; Watanabe, N.; Orban, Philippe ULg et al

in Davis, G. B.; Johntson, C. D.; Trefry, M. G. (Eds.) Groundwater Quality 2007 Securing Groundwater Quality in Urban and Industrial Environments (2007)

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See detailGroundwater flow and transport delivered for groundwater quality trend forecasting by TREND T2
Orban, Philippe ULg; Brouyère, Serge ULg

Report (2006)

In the framework of Workpackage R3 Meuse, the Hydrogeology Group of the University of Liège (HGULg) develops a groundwater flow and transport model for the Geer sub-catchment (tributary of the Meuse ... [more ▼]

In the framework of Workpackage R3 Meuse, the Hydrogeology Group of the University of Liège (HGULg) develops a groundwater flow and transport model for the Geer sub-catchment (tributary of the Meuse) (Figure 1, Deliverable R3.16 (Orban et al 2006)). In the scope of TREND T2, the model will be used to develop trend forecasting tools. The objective of the deliverable is to describe new concepts for large-scale transport modelling, more particularly a modelling approach, the Hybrid Finite Element Mixing Cell (HFEMC) developed by HGULg and implemented in the 3D simulator SUFT3D. First steps for the application to the Geer basin are also presented. [less ▲]

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See detailGroundwater flow and transport model for the Flémalle cokery site
Batlle-Aguilar, Jordi; Brouyère, Serge ULg

Report (2008)

This deliverable describes the groundwater flow and transport model performed for the Flémalle test site. Calibration of the groundwater model has been done using both, zoning and pilot points approaches ... [more ▼]

This deliverable describes the groundwater flow and transport model performed for the Flémalle test site. Calibration of the groundwater model has been done using both, zoning and pilot points approaches, while model transport calibration has been performed using tracer tests carried out. Different scenarios of pollutant concentration and degradation constant rates have been simulated. Results point out that biodegradation is likely to occur, as evidenced by former studies within BGC in the scope of the AquaTerra project. [less ▲]

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See detailGroundwater flow modelling in the central zone of Hanoi, Vietnam
Jusseret, Simon; Vu, Thanh Tam; Dassargues, Alain ULg

in Hydrogeology Journal (2009), 17(4), 915-934

On the basis of a review of the Quaternary sedimentary architecture in the area of Hanoi city (Vietnam), a numerical, deterministic and three-dimensional groundwater flow model has been built for a ... [more ▼]

On the basis of a review of the Quaternary sedimentary architecture in the area of Hanoi city (Vietnam), a numerical, deterministic and three-dimensional groundwater flow model has been built for a simulation between 1995 and 2004. The sedimentary architecture has been constructed on the basis of the data from 32 drillings covering the entire Quaternary sequence (but with little sedimentological detail), as well as hydrographical and hydrogeological data. Both steady- and transient-state conditions were tested. Results calculated by the model seem to indicate that the conceptual hypotheses adopted are reasonable for the modelled domain and period. The simulation allows for calculation of the regional groundwater flow trends. It is also used for assessing the relative importance of the various recharge sources of the shallow aquifer system in Hanoi, and for estimating the interactions between groundwater and the Red River. [less ▲]

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See detailGroundwater flow modelling of the regional aquifer of the Pampa del Tamarugal, northern Chile
Rojas, Rodrigo; Dassargues, Alain ULg

in Hydrogeology Journal (2007), 15(3), 537-551

The Pampa del Tamarugal Aquifer (PTA) is an important source of groundwater in northern Chile. In this study, a groundwater flow model of this aquifer is developed and calibrated for the period 1983-2004 ... [more ▼]

The Pampa del Tamarugal Aquifer (PTA) is an important source of groundwater in northern Chile. In this study, a groundwater flow model of this aquifer is developed and calibrated for the period 1983-2004. The model reproduces the observed flow-field and the water balance components reasonably well. Five scenarios are defined to evaluate the response to different pumping situations. These scenarios show that groundwater heads will continue to decrease with the present pumping discharge rates. To account for variations in the model results due to uncertainties in average recharge rates, randomly generated recharge realizations with different levels of uncertainty are simulated. Evaporation flow rates and groundwater flowing out of the modelled area seem unaffected by the recharge uncertainty, whereas the storage terms can vary considerably. For the most intensive pumping scenario under the generated random recharge rates, it is unlikely that the cumulative discharged volume from the aquifer, at the end of the simulation period, will be larger than 12% of the estimated groundwater reserve. Fluctuations in simulated groundwater heads due to uncertainties in the average recharge values are more noticeable in certain areas. These fluctuations could explain unusual behaviour in the observed groundwater heads in these areas. [less ▲]

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See detailGroundwater issues create challenges for engineers
Dassargues, Alain ULg

Scientific conference (2012, June 15)

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See detailGroundwater model parameter identification using a combination of cone-penetration tests and borehole data
Rogiers, Bart; Schiltz, Marco; Beerten, Koen et al

in International Groundwater Symposium 2010, IAHR (2010, September)

In the framework of the disposal of short-lived low- and intermediate-level radioactive waste in a near-surface disposal facility in Dessel, Belgium, additional extensive site characterisation has been ... [more ▼]

In the framework of the disposal of short-lived low- and intermediate-level radioactive waste in a near-surface disposal facility in Dessel, Belgium, additional extensive site characterisation has been performed in 2008. The gathered data now include 388 hydraulic conductivity measurements on samples from 8 cored boreholes. Detailed characterisation of these cored boreholes, together with geophysical logging, enabled to identify various hydrostratigraphical units at 8 discrete locations in the research area. Various analyses were performed on the cores, yielding information on grain size, mineralogy, density and total porosity. Geophysical logging parameters were derived from gamma-ray and resistivity measurements. Subsequently, an extensive geotechnical logging campaign was performed in order to establish a 3D-model of the hydrostratigraphical units, based on a dense network of investigation points. About 180 cone penetration tests (CPTs) were executed and lithology was deduced in detail based on existing soil classi cation charts. As such, a description of the regional subsurface up to depths of nearly 50 m was established, and this information was integrated with the borehole data. Most importantly, the lateral extent, depth and thickness of a hydrogeologically important aquitard was identi fied. Based on the 2008 site characterisation results and their interpretation, an update of a ground- water fl ow model used in safety assessments was made. The CPT-based stratigraphic model and the hydraulic conductivity data determined at different scales were combined into a new 3D hydrostratigraphical model. The small-scale measurements (on 100 cm³ core samples) are compared with hydraulic conductivity values obtained from pumping tests and the large-scale parameters derived by inverse modelling. The performance of the original and the updated flow model are compared. The presented approach was succesfull in substantially decreasing the conceptual model and parameter uncertainty and resulted in an improved calibration of the groundwater flow model. [less ▲]

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See detailGroundwater modelling to predict the impact of a tunnel on the behaviour of a water table aquifer in urban conditions
Dassargues, Alain ULg

in Chilton, J. (Ed.) Groundwater in the Urban Environment : Problems, Processes and Management, Proc. of XXVII IAH Congress (1997)

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See detailGroundwater pollution in an agricultural catchment on sandstone : evaluation of water and nitrogen losses from soils.
Lecomte, Marielle; Salvia, Merce; Iffly, Jean-François et al

Conference (2000)

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See detailGroundwater quality assessment of one former industrial site in Belgium using a TRIAD-like approach.
Crévecoeur, Sophie; Debacker, Virginie ULg; Joaquim-Justo, Célia ULg et al

in Environmental Pollution (2011), 159(10), 2461-2466

Contaminated industrial sites are important sources of pollution and may result in ecotoxicological effects on terrestrial, aquatic and groundwater ecosystems. An effect-based approach to evaluate and ... [more ▼]

Contaminated industrial sites are important sources of pollution and may result in ecotoxicological effects on terrestrial, aquatic and groundwater ecosystems. An effect-based approach to evaluate and assess pollution-induced degradation due to contaminated groundwater was carried out in this study. The new concept, referred to as “Groundwater Quality TRIAD-like” (GwQT) approach, is adapted from classical TRIAD approaches. GwQT is based on measurements of chemical concentrations, laboratory toxicity tests and physico-chemical analyses. These components are combined in the GwQT using qualitative and quantitative (using zero to one subindices)integration approaches. The TRIAD approach is applied for the first time on groundwater from one former industrial site located in Belgium. This approach will allow the classification of sites into categories according to the degree of contaminant-induced degradation. This new concept is a starting point for groundwater characterization and is open for improvement and adjustment. [less ▲]

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See detailGroundwater quality mapping in the Belgian and Dutch provinces of Limburg and Liège: availability of data and methodology
Dassargues, Alain ULg; Peters, Valérie; Rutten, J. et al

in Proc. of the Int. Conf. on Quality, Management and Availability of Data for Hydrology and Water Resources Management (1999)

Detailed reference viewed: 38 (2 ULg)