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Field optical clocks and sensitivity to mass anomalies for geoscience applications / Guillaume Lion (2023)  

Public Titre : Field optical clocks and sensitivity to mass anomalies for geoscience applications Type de document : Article/Communication Auteurs : Guillaume Lion , Auteur ; Gwendoline Pajot-Métivier , Auteur ; Kristel Chanard , Auteur ; Michel Diament , Auteur Editeur : Munich [Allemagne] : European Geosciences Union EGU Année de publication : 2023 Projets : ROYMAGE / Letargat, Rodolphe Conférence : EGU 2023, General Assembly 23/04/2023 28/04/2023 Vienne Autriche OA Abstracts only Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] analyse de sensibilité [Termes IGN] anomalie de pesanteur [Termes IGN] chronométrie [Termes IGN] horloge optique Index. décimale : 30.60 Géodésie spatiale Résumé : (auteur) 350 years ago, the pendulum clock for astronomical observations was diverted to become an instrument for measuring gravity. The measurement of the parallax of Mars by Richer and Cassini from Cayenne and Paris showed that the period of a periodic oscillator depends on the gravity field. A link was thus established between the improvement of time measurement and the knowledge of the phenomena that govern it. Since then, the performance and nature of clocks have evolved considerably. Today, atomic clocks are used in various fields that are essential to modern society, such as the realisation of international atomic time (TAI), satellite navigation (GNSS), geodesy, the traceability of trading events, etc. In the framework of the french ANR ROYMAGE, we are interested in the contribution of a transportable optical field clock for geoscience applications by using the principle of chronometric geodesy. The idea is based on the gravitational redshift, a relativistic effect that predicts that the beat of a clock depends on the speed at which it is moving and the strength of the surrounding gravitational potential. In practice, this means that if we compare the beat of two clocks, then it is possible to directly measure a difference in gravitational potential (or a change in height) between these two clocks. This type of measurement is original because classical geodetic techniques only allow to determine the potential indirectly from gravimetric and classical levelling data. In this work, we model the gravitational signature (potential, acceleration and tensor) of a mass anomaly as a function of its geometry, depth, size and density contrast. These synthetic simulations allow us to identify which types of structures can be detected by clock comparison measurements with a relative frequency uncertainty fixed at 10-17-18-19 (i.e. a vertical sensitivity of less than 10 cm - 1 cm - 1 mm respectively). We are also interested in the spatial resolution required for a clock measurement to detect two mass anomalies depending on its orientation. Finally, we show that this new chronometric observable combined with gravimetry and gradiometry data could allow a better separation of the sources by adding an additional constraint thanks to the medium and long wavelength gravitational information it provides. Numéro de notice : C2023-003 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Poster nature-HAL : Poster-avec-CL DOI : 10.5194/egusphere-egu23-3646 En ligne : https://doi.org/10.5194/egusphere-egu23-3646 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103216

From space to lithosphere: inversion of the GOCE gravity gradients. Supply to the Earth’s interior study / Matthieu Plasman in Geophysical journal international, vol 223 n° 1 (October 2020)  

Public [article]  inGeophysical journal international > vol 223 n° 1 (October 2020) . - pp 398 - 419 Titre : From space to lithosphere: inversion of the GOCE gravity gradients. Supply to the Earth’s interior study Type de document : Article/Communication Auteurs : Matthieu Plasman, Auteur ; Christel Tiberi, Auteur ; Cécilia Cadio, Auteur ; Anita Thea Saraswati, Auteur ; Gwendoline Pajot-Métivier , Auteur ; Michel Diament , Auteur Année de publication : 2020 Projets : 3-projet - voir note / Letargat, Rodolphe Article en page(s) : pp 398 - 419 Note générale : bibliographie TOSCA project financing (PIGGS project) Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de pesanteur [Termes IGN] données GOCE [Termes IGN] géophysique interne [Termes IGN] gradient de gravitation [Termes IGN] gravimétrie spatiale [Termes IGN] lithosphère [Termes IGN] problème inverse Résumé : (auteur) The emergence of high resolution satellite measurements of the gravitational field (GOCE mission) offers promising perspectives for the study of the Earth’s interior. These new data call for the development of innovant analysis and interpretation methods. Here we combine a forward prism computation with a Bayesian resolution approach to invert for these gravity gradient data configuration. We apply and test our new method on satellite data configuration, that is 225 km height with a global and homogeneous geographic distribution. We first quantify the resolution of our method according to both data and parametrization characteristics. It appears that for reasonable density contrast values (0.1 g cm−3) crustal structures have to be wider than ∼28 km to be detectable in the GOCE signal. Deeper bodies are distinguishable for greater size (35 km size at 50 km depth, ∼80 km at 300 km depth). We invert the six tensor components, among which five are independent. By carefully testing each of them and their different combinations, we enlighten a trade off between the recovery of data and the sensitivity to inversion parameters. We particularly discussed this characteristic in terms of geometry of the synthetic model tested (structures orientation, 3-D geometry, etc.). In terms of RMS value, each component is always better explained if inverted solely, but the result is strongly affected by the inversion parametrization (smoothing, variances, etc.). On the contrary, the simultaneous inversion of several components displays a significant improvement for the global tensor recovery, more dependent on data than on density variance or on smoothness control. Comparing gravity and gradient inversions, we highlight the superiority of the GG data to better reproduce the structures especially in terms of vertical location. We successfully test our method on a realistic case of a complex subduction case for both gradient and gravity data. While the imaging of small crustal structures requires terrestrial gravity data set, the longest wavelength of the slab is well recovered with both data sets. The precision and homogeneous coverage of GOCE data however, counterbalance the heterogeneous and often quite non-existence coverage of terrestrial gravity data. This is particularly true in large areas which requires a coherent assemblage of heterogeneous data sets, or in high relief, vegetally covered and offshore zones. Numéro de notice : A2020-823 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/gji/ggaa318 Date de publication en ligne : 26/06/2020 En ligne : https://doi.org/10.1093/gji/ggaa318 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97260 [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 IGN] Belgique [Termes IGN] évapotranspiration [Termes IGN] feuillu [Termes IGN] forêt tempérée [Termes IGN] gravimètre supraconducteur [Termes IGN] humidité du sol [Termes IGN] levé gravimétrique [Termes 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 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) 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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Evidence for postglacial signatures in gravity gradients: A clue in lower mantle viscosity / Laurent Métivier in Earth and planetary science letters, vol 452 (October 2016)  

Public [article]  inEarth and planetary science letters > vol 452 (October 2016) . - pp 146 - 156 Titre : Evidence for postglacial signatures in gravity gradients: A clue in lower mantle viscosity Type de document : Article/Communication Auteurs : Laurent Métivier , Auteur ; Lambert Caron, Auteur ; Marianne Greff-Lefftz, Auteur ; Gwendoline Pajot-Métivier , Auteur ; Luce Fleitout, Auteur ; Hélène Rouby , Auteur Année de publication : 2016 Article en page(s) : pp 146 - 156 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Amérique du nord [Termes IGN] anomalie de pesanteur [Termes IGN] déformation de la croute terrestre [Termes IGN] gradient de gravitation [Termes IGN] manteau terrestre [Termes IGN] paléocontinent [Termes IGN] viscosité Résumé : (auteur) The Earth's surface was depressed under the weight of ice during the last glaciations. Glacial Isostatic Adjustment (GIA) induces the slow recession of the trough that is left after deglaciation and is responsible for a contemporary uplift rate of more than 1 cm/yr around Hudson Bay. The present-day residual depression, an indicator of still-ongoing GIA, is difficult to identify in the observed topography, which is predominantly sensitive to crustal heterogeneities. According to the most widespread GIA models, which feature a viscosity of 2–3×1021 Pa s2–3×1021 Pa s on top of the lower mantle, the trough is approximately 100 m deep and cannot explain the observed gravity anomalies across North America. These large anomalies are therefore usually attributed to subcontinental density heterogeneities in the tectosphere or to slab downwelling in the deep mantle. Here, we use observed gravity gradients (GG) to show that the uncompensated GIA trough is four times larger than expected and that it is the main source of the North American static gravity signal. We search for the contribution to these GGs from mantle mass anomalies, which are deduced from seismic tomography and are mechanically coupled to the global mantle flow. This contribution is found to be small over Laurentia, and at least 82% of the GGs are caused by GIA. Such a contribution from GIA in these GG observations implies a viscosity that is greater than 1022 Pa s1022 Pa s in the lower mantle. Our conclusions are a plea for GIA models with a highly viscous lower mantle, which confirm inferences from mantle dynamic models. Any change in GIA modelling has important paleoclimatological and environmental implications, encouraging scientists to re-evaluate the past ice history at a global scale. These implications, in turn, affect the contribution of bedrock uplift to the contemporaneous mass balance over Antarctica and Greenland and thus the present-day ice-melting rate as deduced from the GRACE space mission. Additionally, studies of the thermo-chemical structure of the lithosphere/crust under North America that exploit gravity or geodetic data should be corrected for a GIA model, which is not the case today. Numéro de notice : A2016-906 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.epsl.2016.07.034 Date de publication en ligne : 16/08/2016 En ligne : http://dx.doi.org/10.1016/j.epsl.2016.07.034 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83034 [article]

Fast computation of general forward gravitation problems / Fabien Casenave in Journal of geodesy, vol 90 n° 7 (July 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 7 (July 2016) . - pp 655 – 675 Titre : Fast computation of general forward gravitation problems Type de document : Article/Communication Auteurs : Fabien Casenave , Auteur ; Laurent Métivier , Auteur ; Gwendoline Pajot-Métivier , Auteur ; Isabelle Panet , Auteur Année de publication : 2016 Article en page(s) : pp 655 – 675 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] France (géographie physique) [Termes IGN] masse de la Terre [Termes IGN] potentiel de pesanteur terrestre [Termes IGN] vitesse Résumé : (auteur) We consider the well-known problem of the forward computation of the gradient of the gravitational potential generated by a mass density distribution of general 3D geometry. Many methods have been developed for given geometries, and the computation time often appears as a limiting practical issue for considering large or complex problems. In this work, we develop a fast method to carry out this computation, where a tetrahedral mesh is used to model the mass density distribution. Depending on the close- or long-range nature of the involved interactions, the algorithm automatically switches between analytic integration formulae and numerical quadratic formulae, and relies on the Fast Multipole Method to drastically increase the computation speed of the long-range interactions. The parameters of the algorithm are empirically chosen for the computations to be the fastest possible while guarantying a given relative accuracy of the result. Computations that would load many-core clusters for days can now be carried out on a desk computer in minutes. The computation of the contribution of topographical masses to the Earth’s gravitational field at the altitude of the GOCE satellite and over France are proposed as numerical illustrations of the method. Numéro de notice : A2016-427 Affiliation des auteurs : LASTIG LAREG (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0900-2 Date de publication en ligne : 08/04/2016 En ligne : http://dx.doi.org/ 10.1007/s00190-016-0900-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81321 [article]

Joint analysis of GOCE gravity gradients data of gravitational potential and of gravity with seismological and geodynamic observations to infer mantle properties / Marianne Greff-Lefftz in Geophysical journal international, vol 205 n° 1 (April 2016)  

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

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Ultra-sensitive electrostatic planar acceleration gradiometer for airborne geophysical surveys / Karim Douch in Measurement Science and Technology, vol 25 n° 10 (October 2014)  

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Mapping the mass distribution of Earth's mantle using satellite-derived gravity gradients / Isabelle Panet in Nature geoscience, vol 7 n° 2 (February 2014)  

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A new planar electrostatic gravity gradiometer for airborne surveys / Karim Douch (2013)  

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Détermination du champ de pesanteur par gradiométrie spatiale [diaporama] / Gwendoline Pajot-Métivier (2012) 

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Geophysical methods for CO2 plume imaging: Comparison of performances / H. Fabriol in Energy Procedia, vol 4 ([01/02/2011])  

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Monitoring of the bouillante geothermal exploitation (Guadeloupe, French West Indies) and the impact on its immediate environnement / Bernard Sanjuan (2010)    

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Relative campaign during the International Comparison of Absolute Gravimeters ICAG-2005 and the strategy of data treatment combined with the absolute results / Zhiheng Jiang (2007) 

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