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La gravimétrie mobile en champ proche : outil essentiel pour la haute résolution en géodésie physique et en géosciences / Jérome Verdun (2017)
Titre : La gravimétrie mobile en champ proche : outil essentiel pour la haute résolution en géodésie physique et en géosciences Type de document : Thèse/HDR Auteurs : Jérome Verdun , Auteur Editeur : Le Mans : Ecole Supérieure des Géomètres et Topographes ESGT Année de publication : 2017 Importance : 476 p. Note générale : bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur local
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] gravimètre
[Termes IGN] gravimétrie
[Termes IGN] gravimétrie mobile
[Termes IGN] modèle mathématique
[Termes IGN] simulation numériqueRésumé : (auteur) La gravimétrie consiste en la mesure de la gravité de la Terre restituée par la cartographie et la modélisation des équipotentielles, accélérations et gradients de gravité, pour obtenir des images intégrées de la distribution interne de densité, d’autant mieux résolues que la hauteur d’acquisition est faible. L’un des défis majeurs relevé par la gravimétrie moderne consiste en la détermination de modèles mathématiques et de cartes numériques du champ de gravité de la Terre dont la fiabilité est identique quelle que soit l’échelle spatiale considérée en domaines terrestre, littoral, marin et sous-marin. Aujourd’hui, la gravimétrie spatiale opérée depuis des satellites altimétriques ou gravimétriques, permet la production de tels modèles de la gravité jusqu’à une résolution spatiale de 100 km et une précision allant jusqu’à 1 mGal (10-5 m/s2 soit un millionième de la pesanteur moyenne). Le principal obstacle à l’amélioration de la résolution et la précision des modèles vient de ce que les systèmes marins ou aériens de gravimétrie et gradiométrie mobiles, seuls instruments qui permettent des acquisitions à précision et à résolution spatiale homogènes, demeurent encore encombrants et gros consommateurs d’énergie, ce qui interdit en particulier leur installation sur des drones terrestres, aériens, navals de surface et sous-marins. L’intérêt de ce type de porteur est de pouvoir opérer des acquisitions très proches des sources ce qui accroît considérablement la restitution des variations locales de la gravité. Le mémoire présenté en vue de l’habilitation à diriger des recherches dresse un bilan de mes travaux sur les développements instrumentaux de gravimètres mobiles légers, et les recherches associées pour la mise au point et l’amélioration des méthodes mathématiques de traitement des données. Deux systèmes français novateurs, « LIMO-g » et « GRAVIMOB », qui peuvent opérer en domaines terrestre, aérien, marin et sous-marin, y sont décrits en détail, depuis leur constitution matérielle jusqu’au campagnes d’essai qui ont permis d’éprouver leurs performances. Les nouveaux champs d’application ouverts par ce type d’instruments, notamment pour l’exploration des zones littorales, fluviatiles et estuariennes, sont évoqués en soulignant les avancées possibles pour l’étude du trait de côte. Enfin, tout développement méthodologique en gravimétrie requiert des simulations dans lesquelles la gravité est calculée à partir d’un modèle de ses sources. Les méthodes numériques de calcul de champ élaborées pour la réalisation de ces calculs de champ sont également présentées et discutées. Numéro de notice : 17725 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : HDR Organisme de stage : Laboratoire Géomatique et foncier LGF (ESGT) DOI : sans En ligne : https://hal.archives-ouvertes.fr/tel-03183761 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100382
Titre : Gravity forward modeling with a tesseroid-based rock-water-ice approach : Theory and applications in the context of the GOCE mission and height system unification Type de document : Thèse/HDR Auteurs : Thomas Grombein, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2017 Collection : DGK - C Sous-collection : Dissertationen num. 798 Importance : 222 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5210-9 Note générale : bibliographie
Inaugural dissertation for the fulfillment of the requirements for the academic degree of Doctor of Engineering (Dr.-Ing.) accepted by the Department of Civil Engineering, Geo and Environmental Sciences of the Karlsruhe Institute of Technology (KIT)
Diese Dissertation ist auf dem Server der Deutschen Geodätischen Kommission unter <http://dgk.badw.de/> sowie auf dem Server des Karlsruher Instituts für Technologie unter <http://dx.doi.org/10.5445/KSP/1000068500> elektronisch publiziertLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] données GOCE
[Termes IGN] eau de surface
[Termes IGN] glace
[Termes IGN] gradient de gravitation
[Termes IGN] isostasie
[Termes IGN] levé gravimétrique
[Termes IGN] ondelette
[Termes IGN] problème des valeurs limites
[Termes IGN] tesseroidRésumé : (auteur) Due to the increasing availability of global high-resolution digital terrain models (DTMs), it has nowadays become possible to obtain a detailed image of the Earth’s topography. This enables to precisely determine the gravitational effect of the topographic masses on the Earth’s gravity field. The central technique for this aim is gravity forward modeling (GFM), which is based on Newton’s law of universal gravitation, and allows to convert topographic heights along with suitable density assumptions into corresponding values of the gravitational potential and its derivatives. This topographic gravity forward modeling attracts a growing interest in various areas of geodetic gravity field determination and geophysical studies of the Earth’s composition and structure (e.g., solid-earth sciences). However, previous GFM methods have proven unsuitable for the increasing accuracy requirements stemming from an improved precision of geodetic measurements. This is due to commonly used simplifications and approximations, such as (i) the use of condensed heights for water and ice masses (rock-equivalent heights), (ii) mass discretizations or arrangements based on planar and spherical approximations, and (iii) assumptions regarding the spectral consistency between band-limited topographic heights and induced gravity, as in residual terrain modeling (RTM) techniques. This thesis contributes to state-of-the-art GFM in the space domain by providing effective techniques and refinements that overcome these limitations. More concretely, the theory of the Rock-Water-Ice (RWI) approach is developed that encompasses a more realistic modeling of the Earth’s topographic and isostatic masses, i.e., the masses of the continents, oceans, lakes, ice sheets and shelves, as well as their deeper lying (isostatic) compensation masses in the Earth’s interior. The RWI method is characterized by a three-layer decomposition of the Earth’s topography that accounts for a rigorous separate modeling of the rock, water, and ice masses with variable density values. Furthermore, a modified Airy-Heiskanen isostatic concept is applied that is enhanced by additional geophysical information in terms of a seismologically derived depth model of the Mohorovicic discontinuity, i.e., the boundary surface between the Earth’s crust and mantle. To counteract the increased computational demand of the more complex modeling, an efficient numerical algorithm is needed for the forward modeling. For space domain GFM, it has become more and more customary to use a mass discretization based on tesseroids, which are mass bodies bounded by geocentric spherical coordinate lines, and hence are directly linked to the curvature of the Earth. Several studies have demonstrated their superiority over classical prism methods with respect to precision and computation time. However, for global applications based on high-resolution DTMs, any computational speed-up with respect to a single mass body leads to a massive improvement in the overall computation time. This thesis presents a considerable optimization of previously used tesseroid formulas, where the gravitational field of a tesseroid and its derivatives up to second-order are represented in a compact and computationally attractive form. This allows an efficient numerical evaluation that reduces the overall runtime by about 20 to 55%, depending on the evaluated gravity field functional. Additionally, to correctly locate topographic masses in space, tesseroids are arranged on an ellipsoidal reference surface. Within this thesis, the novel tesseroid-based RWI approach is applied to different topographic input data and is used for various gravity field functionals in two main applications. Both are connected to ESA’s satellite mission GOCE (Gravity field and steady-state Ocean Circulation Explorer) that measured the second-order derivatives of the gravitational potential, commonly known as gravity gradients. In the first application, RWI-based topographic-isostatic effects are calculated along the orbit of the GOCE satellite and are subtracted from the gravity gradient observations. In this way, the measurement signal is smoothed so that interpolation and prediction tasks, such as harmonic downward continuation of the gradients from satellite altitude to the Earth’s surface, can be executed with an improved numerical stability. While in previous studies such a concept was applied to simulated gravity gradients, this thesis presents the application to real GOCE measurements. As the smoothing effect strongly depends on the variability of the topography crossed by the satellite, this procedure is particularly suitable for regional applications. For a time series when the satellite passed the Himalayan region, a comparison of the observed gradients to the reduced ones reveals significant smoothing effects that are quantified by analyses in the space and frequency domain. The second application contributes to the task of height system unification, which aims to connect the different locally defined reference levels, conventionally used for national height systems. This is achieved by a satellite-based method which employs global geopotential models derived from data of the GOCE mission, whose limited spectral resolution is extended by high-frequency topographic effects of the RWI approach. To extract these high-frequency signals, a novel (residual) gravity forward modeling method is proposed that allows to perform the required high pass filtering directly in the gravity domain, thus, avoiding the above-mentioned assumption (iii) of the RTM method. By using three representative study areas in Germany, Austria, and Brazil, the benefit and importance of high-frequency topography-implied gravity signals for an accurate estimation of height datum offsets is demonstrated. As a highlight of this thesis, the RWI approach is utilized to generate a series of topographic-isostatic gravity field models. These RWI models provide a high-resolution representation of the Earth’s topographic-isostatic gravitational potential in terms of spherical harmonics expanded up to degree and order 1800 (Release 2012), and 2190 (Release 2015). The spherical harmonic coefficients of these models are obtained from a spherical harmonic analysis of global gridded potential values, which have been calculated by massive parallel computing on high-performance computer systems. By using spherical harmonic synthesis, the RWI model can be used to efficiently calculate various functionals of the topographic-isostatic potential in different heights. For this purpose, the RWI models are publicly available via the database of the International Centre for Global Earth Models (ICGEM) and have already been used in a wide range of studies by other research groups. Note de contenu : 1. Introductory chapter
2. Optimized formulas for the gravitational field of a tesseroid
3. A wavelet-based assessment of topographic-isostatic reductions for GOCE gravity gradients
4. The Rock-Water-Ice topographic gravity field model RWI TOPO 2015 and its comparison to a conventional rock-equivalent version
5. On high-frequency topography-implied gravity signals for height system unification 6. Height system unification based on the fixed GBVP approachNuméro de notice : 17488 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : dissertation : : Karlsruhe Institute of Technology : 2017 DOI : 10.5445/KSP/1000068500 En ligne : http://doi.org/10.5445/KSP/1000068500 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89828 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)
[article]
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 diurneRésumé : (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
in Geophysical research letters > vol 43 n° 19 (15 October 2016) . - pp 10225 - 10231[article]Documents numériques
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Direct measurement of evapotranspiration ... - pdf éditeurAdobe Acrobat PDF Utilization of high-resolution EGM2008 gravity data for geological exploration over the Singhbhum-Orissa Craton, India / S.K. Pal in Geocarto international, vol 31 n° 7 - 8 (July - August 2016)
[article]
Titre : Utilization of high-resolution EGM2008 gravity data for geological exploration over the Singhbhum-Orissa Craton, India Type de document : Article/Communication Auteurs : S.K. Pal, Auteur ; T.J. Majumdar, Auteur ; Vipin Kumar Pathak, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 783 - 802 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] carte géologique
[Termes IGN] Earth Gravity Model 2008
[Termes IGN] European Improved Gravity Model of the Earth by New techniques
[Termes IGN] géologie locale
[Termes IGN] gravimétrie spatiale
[Termes IGN] prospection minéraleRésumé : (Auteur) High-resolution EIGEN6C4 and EGM2008 Bouguer gravity data of 2190 degree spherical harmonic over the Singhbhum-Orissa Craton, India, have been generated from the International Centre for Global Earth Models. The Bouguer gravity anomaly difference maps of (i) in situ and EIGEN6C4, (ii) in situ and EGM2008 and iii) EIGEN6C4 and EGM2008 of the study area are compared. It reveals that EIGEN6C4 has lesser systematic error than EGM2008. However, from different profile plots of Bouguer gravity, east–west horizontal derivative and north–south horizontal derivative anomalies of the in situ, EIGEN6C4 and EGM2008, it is observed that most of the signatures of lithounits and geological structural elements are delineated very well by EGM2008 and match 94–98% with those of EIGEN6C4. Further, the Bouguer gravity, east–west horizontal derivative and north–south horizontal derivative anomalies of EGM2008 data over the study area have been used effectively for identifying various lithounits and geological structural elements. Numéro de notice : A2016-444 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/10106049.2015.1076064 Date de publication en ligne : 11/09/2015 En ligne : http://dx.doi.org/10.1080/10106049.2015.1076064 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81351
in Geocarto international > vol 31 n° 7 - 8 (July - August 2016) . - pp 783 - 802[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 059-2016041 RAB Revue Centre de documentation En réserve L003 Disponible On the impact of airborne gravity data to fused gravity field models / Dimitrios Bolkas in Journal of geodesy, vol 90 n° 6 (June 2016)
[article]
Titre : On the impact of airborne gravity data to fused gravity field models Type de document : Article/Communication Auteurs : Dimitrios Bolkas, Auteur ; Georgia Fotopoulos, Auteur ; Alexander Braun, Auteur Année de publication : 2016 Article en page(s) : pp 561 – 571 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] fusion de données multisource
[Termes IGN] gravimétrie aérienne
[Termes IGN] gravimétrie terrestre
[Termes IGN] modèle de géopotentielRésumé : (auteur) In gravity field modeling, fused models that utilize satellite, airborne and terrestrial gravity observations are often employed to deal with erroneous terrestrially derived gravity datasets. These terrestrial datasets may suffer from long-wavelength systematic errors and inhomogeneous data coverage, which are not prevalent in airborne and satellite datasets. Airborne gravity acquisition plays an essential role in gravity field modeling, providing valuable information of the Earth’s gravity field at medium and short wavelengths. Thus, assessing the impact of airborne gravity data to fused gravity field models is important for identifying problematic regions. Six study regions that represent different gravity field variability and terrestrial data point-density characteristics are investigated to quantify the impact of airborne gravity data to fused gravity field models. The numerical assessments of these representative regions resulted in predictions of airborne gravity impact for individual states and provinces in the USA and Canada, respectively. Prediction results indicate that, depending on the terrestrial data point-density and gravity field variability, the expected impact of airborne gravity can reach up to 3mGal (in terms of standard deviation) in Canada and Alaska (over areas of 1∘×1∘). However, in the mainland US region, small changes are expected (0.2–0.4 mGal over areas of 1∘×1∘) due to the availability of high spatial resolution terrestrial data. These results can serve as a guideline for setting airborne gravity data acquisition priorities and for improving future planning of airborne gravity surveys. Numéro de notice : A2016-423 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0893-x Date de publication en ligne : 07/03/2016 En ligne : https://doi.org/10.1007/s00190-016-0893-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81316
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