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Monitoring of extreme land hydrology events in central Poland using GRACE, land surface models and absolute gravity data / Joanna Kuczynska-Siehien in Journal of applied geodesy, vol 13 n° 3 (July 2019)  

Public [article]  inJournal of applied geodesy > vol 13 n° 3 (July 2019) . - pp 229 – 243 Titre : Monitoring of extreme land hydrology events in central Poland using GRACE, land surface models and absolute gravity data Type de document : Article/Communication Auteurs : Joanna Kuczynska-Siehien, Auteur ; Dimitrios Piretzidis, Auteur ; Michael G. Sideris, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 229 – 243 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] analyse diachronique [Termes descripteurs IGN] analyse spectrale [Termes descripteurs IGN] données GLDAS [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] gravimètre absolu [Termes descripteurs IGN] inondation [Termes descripteurs IGN] levé gravimétrique [Termes descripteurs IGN] modèle numérique de surface [Termes descripteurs IGN] Pologne [Termes descripteurs IGN] risque naturel [Termes descripteurs IGN] sécheresse [Termes descripteurs IGN] surveillance hydrologique [Termes descripteurs IGN] variation temporelle Résumé : (auteur) This study deals with the analysis of temporal gravity variations in central Poland, deduced from multiple sources and covering the period from 2002–2016. The gravity data sets used comprise GRACE monthly solutions, GLDAS land surface models and absolute gravimeter measurements from the FG-5 gravimeter located in Józefosław, Poland. All data are corrected using standard processing methods in order to include the same gravity effects. After removing the annual and semi-annual components from all data using least-squares spectral analysis and seasonal-trend decomposition, the deseasoned time series are derived and examined for signatures of extreme hydrological events. The signatures of several severe drought and flood conditions affecting Poland and central Europe are identified. A complementary correlation analysis is performed to assess the level of agreement between different data sources. A higher correlation is shown when the analysis is restricted in the 2009–2012 period that includes the 2010 extreme flood and 2011 increased precipitation events, both affecting Poland. Numéro de notice : A2019-286 Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2019-0003 date de publication en ligne : 20/04/2019 En ligne : https://doi.org/10.1515/jag-2019-0003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93121 [article]

FFT swept filtering: a bias-free method for processing fringe signals in absolute gravimeters / Petr Křen in Journal of geodesy, vol 93 n° 2 (February 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 2 (February 2019) . - pp 219 - 227 Titre : FFT swept filtering: a bias-free method for processing fringe signals in absolute gravimeters Type de document : Article/Communication Auteurs : Petr Křen, Auteur ; Vojtech Pálinkáš, Auteur ; Pavel Mašika, Auteur ; Miloš Val’ko, Auteur Année de publication : 2019 Article en page(s) : pp 219 - 227 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] distorsion du signal [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] filtre passe-bande [Termes descripteurs IGN] gravimètre absolu [Termes descripteurs IGN] pesanteur terrestre [Termes descripteurs IGN] régression linéaire [Termes descripteurs IGN] transformation rapide de Fourier Résumé : (auteur) Absolute gravimeters, based on laser interferometry, are widely used for many applications in geoscience and metrology. Although currently the most accurate FG5 and FG5X gravimeters declare standard uncertainties at the level of 2−3μGal, their inherent systematic errors affect the gravity reference determined by international key comparisons based predominately on the use of FG5-type instruments. The measurement results for FG5-215 and FG5X-251 clearly showed that the measured g-values depend on the size of the fringe signal and that this effect might be approximated by a linear regression with a slope of up to 0.030μGal/mV. However, these empirical results do not enable one to identify the source of the effect or to determine a reasonable reference fringe level for correcting g-values in an absolute sense. Therefore, both gravimeters were equipped with new measuring systems (according to Křen et al. in Metrologia 53:27–40, 2016. https://doi.org/10.1088/0026-1394/53/1/27 applied for FG5), running in parallel with the original systems. The new systems use an analogue-to-digital converter HS5 to digitize the fringe signal and a new method of fringe signal analysis based on FFT swept bandpass filtering. We demonstrate that the source of the fringe size effect is connected to a distortion of the fringe signal due to the electronic components used in the FG5(X) gravimeters. To obtain a bias-free g-value, the FFT swept method should be applied for the determination of zero-crossings. A comparison of g-values obtained from the new and the original systems clearly shows that the original system might be biased by approximately 3−5μGal due to improperly distorted fringe signal processing. Numéro de notice : A2019-079 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1154-y date de publication en ligne : 19/05/2018 En ligne : https://doi.org/10.1007/s00190-018-1154-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92197 [article]

Direct measurement of evapotranspiration from a forest using a superconducting gravimeter / Michel Van Camp in Geophysical research letters, vol 43 n° 19 (15 October 2016)    

Public [article]  inGeophysical research letters > vol 43 n° 19 (15 October 2016) . - pp 10225 - 10231 Titre : Direct measurement of evapotranspiration from a forest using a superconducting gravimeter Type de document : Article/Communication Auteurs : Michel Van Camp, Auteur ; Olivier de Viron, Auteur ; Gwendoline Pajot-Métivier , Auteur ; Fabien Casenave, Auteur ; Arnaud Watlet, Auteur ; Alain Dassargues, Auteur ; Marnik Vanclooster, Auteur Année de publication : 2016 Article en page(s) : pp 10225 - 10231 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] Belgique [Termes descripteurs IGN] évapotranspiration [Termes descripteurs IGN] feuillu [Termes descripteurs IGN] forêt tempérée [Termes descripteurs IGN] gravimètre supraconducteur [Termes descripteurs IGN] humidité du sol [Termes descripteurs IGN] levé gravimétrique [Termes descripteurs IGN] variation diurne Résumé : (auteur) Evapotranspiration (ET) controls the flux between the land surface and the atmosphere. Assessing the ET ecosystems remains a key challenge in hydrology. We have found that the ET water mass loss can be directly inferred from continuous gravity measurements: as water evaporates and transpires from terrestrial ecosystems, the mass distribution of water decreases, changing the gravity field. Using continuous superconducting gravity measurements, we were able to identify daily gravity changes at the level of, or smaller than 10-9 nm.s-2 (or 10-10 g) per day. This corresponds to 1.7 mm of water over an area of 50 ha. The strength of this method is its ability to enable a direct, traceable and continuous monitoring of actual ET for years at the mesoscale with a high accuracy. Numéro de notice : A2016-684 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/2016GL070534 date de publication en ligne : 07/10/2016 En ligne : http://dx.doi.org/10.1002/2016GL070534 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81973 [article]

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Optimized strategy for the calibration of superconducting gravimeters at the one per mille level / Michel Van Camp in Journal of geodesy, vol 90 n° 1 (January 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 1 (January 2016) . - pp 91- 99 Titre : Optimized strategy for the calibration of superconducting gravimeters at the one per mille level Type de document : Article/Communication Auteurs : Michel Van Camp, Auteur ; Bruno Meurers, Auteur ; Olivier de Viron, Auteur ; Thomas Forbriger, Auteur Année de publication : 2016 Article en page(s) : pp 91- 99 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] étalonnage d'instrument [Termes descripteurs IGN] gravimètre absolu [Termes descripteurs IGN] gravimètre supraconducteur [Termes descripteurs IGN] marée terrestre Résumé : (auteur) This paper reports on different sources of errors that occur in the calibration process of a superconducting gravimeter (SG), determined by comparison with a ballistic absolute gravimeter (AG); some of them have never been discussed in the literature. We then provide methods to mitigate the impact of those errors, to achieve a robust calibration estimate at the http://static-content.springer.com/image/art%3A10.1007%2Fs00190-015-0856-7/MediaObjects/190_2015_856_IEq1_HTML.gif level. We demonstrate that a standard deviation at the level of http://static-content.springer.com/image/art%3A10.1007%2Fs00190-015-0856-7/MediaObjects/190_2015_856_IEq2_HTML.gif can be reached within 48 h by measuring at spring tides and by increasing the AG sampling rate. This is much shorter than what is classically reported in previous empirical studies. Measuring more than 5 days around a tidal extreme does not improve the precision in the calibration factor significantly, as the variation in the error as a function of 1/N−−√ does not apply, considering the decrease in signal amplitude due to the tidal modulation. However, we investigate the precision improvement up to 120 days, which can be useful if an AG is run continuously: at mid-latitude it would require 21 days to ensure a calibration factor at the http://static-content.springer.com/image/art%3A10.1007%2Fs00190-015-0856-7/MediaObjects/190_2015_856_IEq4_HTML.gif level with a 99.7 % confidence interval. We also show that restricting the AG measurement periods to tidal extrema can reduce instrument demand, while this does not affect the precision on the calibration factor significantly. Then, we quantify the effect of high microseismic noise causing aliasing in the AG time series. We eventually discuss the attenuation bias that might be induced by noisy time series of the SG. When experiments are performed at the http://static-content.springer.com/image/art%3A10.1007%2Fs00190-015-0856-7/MediaObjects/190_2015_856_IEq5_HTML.gif level, 7 are needed to ensure that the error in the calibration estimate will be at the 1 per mille level with a 99 % confidence. Numéro de notice : A2016-021 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://link.springer.com/article/10.1007/s00190-015-0856-7/fulltext.html Format de la ressource électronique : Url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79469 [article]

Error analysis of a new planar electrostatic gravity gradiometer for airborne surveys / Karim Douch in Journal of geodesy, vol 89 n° 12 (december 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 12 (december 2015) . - pp 1217 - 1231 Titre : Error analysis of a new planar electrostatic gravity gradiometer for airborne surveys Type de document : Article/Communication Auteurs : Karim Douch, Auteur ; Isabelle Panet , Auteur ; Gwendoline Pajot-Métivier , Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 1217 - 1231 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] gravimètre [Termes descripteurs IGN] gyroscope [Termes descripteurs IGN] lever aérien Mots-clés libres : Airborne gravitational gradiometry  Error analysis  Electrostatic accelerometer Résumé : (auteur) Moving-base gravity gradiometry has proven to be a convenient method to determine the Earth’s gravity field. The ESA mission GOCE (Gravity field and steady-state Ocean Circulation Explorer) has enabled to map the Earth gravity field and its gradients with a resolution of 80 km, leading to significant advances in physical oceanography and solid Earth physics. At smaller scales, airborne gravity gradiometry has been increasingly used during the past decade in mineral and hydrocarbon exploration. In both cases the sensitivity of gradiometers to the short wavelengths of the gravity field is of crucial interest. Here, we quantify and characterize the error on the gravity gradients estimated from measurements performed with a new instrument concept, called GREMLIT, for typical airborne conditions. GREMLIT is an ultra-sensitive planar gravitational gradiometer which consists in a planar acceleration gradiometer together with 3 gyroscopes. To conduct this error analysis, a simulation of a realistic airborne survey with GREMLIT is carried out. We first simulate realistic GREMLIT synthetic data, taking into account the acceleration gradiometer and gyroscope noises and biases and the variation of orientation of the measurement reference frame. Then, we estimate the gravity gradients from these data. Special attention is paid to the processing of the gyroscopes measurements whose accuracy is not commensurate with the ultra-sensitive gradiometer. We propose a method to calibrate the gyroscopes biases with a precision of the order 10−8 rad/s. In order to transform the tensor from the measurement frame to the local geodetic frame, we estimate the error induced when replacing the non-measured elements of the gravity gradient tensor by an a priori model. With the appropriate smoothing, we show that it is possible to achieve a precision better than 2E for an along-track spatial resolution of 2 km. Numéro de notice : A2015-887 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0847-8 date de publication en ligne : 07/08/2015 En ligne : https://doi.org/10.1007/s00190-015-0847-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79435 [article]

Essai sur la découverte du g et son incidence en topographie / Paul Courbon in XYZ, n° 139 (juin - août 2014)

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The quest for a consistent signal in ground and GRACE gravity time-series / Michel Van Camp in Geophysical journal international, vol 197 n° 1 (April 2014)  

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Elaboration du réseau de référence gravimétrique en Guadeloupe : Compte-rendu de mission et rapport de calcul, Version 1 / Anaïs Cazaubon (2014) 

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Analysis of the repeated absolute gravity measurements in the Czech Republic, Slovakia and Hungary from the period 1991–2010 considering instrumental and hydrological effects / S. Zhang in Journal of geodesy, vol 87 n° 1 (January 2013)  

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Atmospheric effects on measurements of the Earth gravity field / Maria Karbon (2013)    

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On the detectability of synthetic disturbances in FG5 absolute gravimetry data using lomb-scargle analysis / M. Orlob in Geomatica, vol 66 n° 2 (June 2012)  

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High precision levelling supporting the International Comparison of Absolute Gravimeters / Z. Jiang in Metrologia, vol 49 n° 1 (February 2012)  

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Relative gravity measurement campaign during the 8th international comparison of absolute gravimeters (2009) / Z. Jiang in Metrologia, vol 49 n° 1 (February 2012)  

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Sensitivity of superconducting gravimeters in central Europe on variations in regional river and drainage basins / C. Kroner in Journal of geodesy, vol 85 n° 10 (October 2011)  

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Estimation de la pesanteur terrestre par gravimétrie mobile / B. Li in Bulletin d'information scientifique et technique de l'IGN, n° 77 (avril 2011)

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