Centre de documentation
scientifique

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)  

Public [article]  inGeophysical journal international > vol 205 n° 1 (April 2016) . - pp 257 - 283 Titre : Joint analysis of GOCE gravity gradients data of gravitational potential and of gravity with seismological and geodynamic observations to infer mantle properties Type de document : Article/Communication Auteurs : Marianne Greff-Lefftz, Auteur ; Laurent Métivier , Auteur ; Isabelle Panet , Auteur ; Lambert Caron, Auteur ; Gwendoline Pajot-Métivier , Auteur ; Johannes Bouman, Auteur Année de publication : 2016 Projets : TOSCA / Article en page(s) : pp 257 - 283 Note générale : bibliographie This study was supported by CNES (Centre National d’Etudes Spatiales) through the TOSCA committee and is IPGP contribution number 3701. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] champ de pesanteur terrestre [Termes IGN] données GOCE [Termes IGN] facteur d'échelle [Termes IGN] gradient de gravitation [Termes IGN] manteau terrestre [Termes IGN] méthode de Monte-Carlo [Termes IGN] potentiel de pesanteur terrestre [Termes IGN] viscosité Résumé : (auteur) Joint analysis of the seismic velocities and geoid, gravity and gravity gradients are used to constrain the viscosity profile within the mantle as well as the lateral density variations. Recent ESA's Gravity field and steady-state Ocean Circulation Explorer measurements of the second-order derivatives of the Earth's gravity potential give new possibilities to determine these mantle properties. Using a simple mantle model and seismic tomography results, we investigate how the gravitational potential, the three components of the gravity vector and the gravity gradients can bring information on the radial viscosity profile and on the mantle mass anomalies. We start with lateral density variations in the Earth's mantle based either on slab history or deduced from seismic tomography. The main uncertainties are: for the latter case, the relationship between seismic velocity and density—the so-called density/velocity scaling factor—and for the former case, the variation with depth of the density contrast between the cold slabs and the surrounding mantle. We perform a Monte Carlo search for the viscosity and the density/velocity scaling factor profiles within the mantle, which allows to fit the observed geoid, gravity and gradients of gravity. We compute the posterior probability distribution of the unknown parameters, and find that the gravity gradients improve the estimate of the scaling factor within the upper mantle, because of their sensitivity to the masses within the upper mantle, whereas the geoid and the gravity better constrain the scaling factor in the lower mantle. In the upper mantle, it is less than 0.02 in the upper part and about 0.08–0.14 in the lower part, and it is significantly larger for depths greater than 1200 km (about 0.32–0.34). In any case, the density/velocity scaling factor between 670 and 1150 km depth is not well constrained. We show that the viscosity of the upper part of the mantle is strongly correlated with the viscosity of the lower part of the mantle and that the viscosity profile is characterized by a decrease in the lower part of the upper mantle (about 1020–2 × 1020 Pa s) and by an increase (about 1023–2 × 1023 Pa s) at the top of the lower mantle (between 670 and 1150 km). The viscosity of the mantle below 1150 km depth is well estimated in our Monte Carlo search and is about 1022–4 × 1022 Pa s. Numéro de notice : A2016--192 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/gji/ggw002 Date de publication en ligne : 16/02/2016 En ligne : https://doi.org/10.1093/gji/ggw002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91843 [article]

On computing ellipsoidal harmonics using Jekeli’s renormalization / J. Sebera in Journal of geodesy, vol 86 n° 9 (September 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 9 (September 2012) . - pp 713 - 726 Titre : On computing ellipsoidal harmonics using Jekeli’s renormalization Type de document : Article/Communication Auteurs : J. Sebera, Auteur ; Johannes Bouman, Auteur ; W. Bosch, Auteur Année de publication : 2012 Article en page(s) : pp 713 - 726 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Earth Gravity Model 2008 [Termes IGN] fonction hypergéométrique [Termes IGN] harmonique ellipsoïdale [Termes IGN] potentiel de pesanteur terrestre [Termes IGN] transformation de Legendre Résumé : (Auteur) Gravity data observed on or reduced to the ellipsoid are preferably represented using ellipsoidal harmonics instead of spherical harmonics. Ellipsoidal harmonics, however, are difficult to use in practice because the computation of the associated Legendre functions of the second kind that occur in the ellipsoidal harmonic expansions is not straightforward. Jekeli’s renormalization simplifies the computation of the associated Legendre functions. We extended the direct computation of these functions—as well as that of their ratio—up to the second derivatives and minimized the number of required recurrences by a suitable hypergeometric transformation. Compared with the original Jekeli’s renormalization the associated Legendre differential equation is fulfilled up to much higher degrees and orders for our optimized recurrences. The derived functions were tested by comparing functionals of the gravitational potential computed with both ellipsoidal and spherical harmonic syntheses. As an input, the high resolution global gravity field model EGM2008 was used. The relative agreement we found between the results of ellipsoidal and spherical syntheses is 10-14, 10-12 and 10-8 for the potential and its first and second derivatives, respectively. Using the original renormalization, this agreement is 10-12, 10-8 and 10-5, respectively. In addition, our optimized recurrences require less computation time as the number of required terms for the hypergeometric functions is less. Numéro de notice : A2012-468 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0549-4 Date de publication en ligne : 07/03/2012 En ligne : https://doi.org/10.1007/s00190-012-0549-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31914 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012091	RAB	Revue	Centre de documentation	En réserve L003	Disponible

GOCE gravitational gradients along the orbit / Johannes Bouman in Journal of geodesy, vol 85 n° 11 (November /2011)  

Public [article]  inJournal of geodesy > vol 85 n° 11 (November /2011) . - pp 791 - 805 Titre : GOCE gravitational gradients along the orbit Type de document : Article/Communication Auteurs : Johannes Bouman, Auteur ; S. Fiorot, Auteur ; M. Fuchs, Auteur ; Thomas Gruber, Auteur Année de publication : 2011 Article en page(s) : pp 791 - 805 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] GOCE [Termes IGN] gradient de gravitation Résumé : (Auteur) GOCE is ESA’s gravity field mission and the first satellite ever that measures gravitational gradients in space, that is, the second spatial derivatives of the Earth’s gravitational potential. The goal is to determine the Earth’s mean gravitational field with unprecedented accuracy at spatial resolutions down to 100 km. GOCE carries a gravity gradiometer that allows deriving the gravitational gradients with very high precision to achieve this goal. There are two types of GOCE Level 2 gravitational gradients (GGs) along the orbit: the gravitational gradients in the gradiometer reference frame (GRF) and the gravitational gradients in the local north oriented frame (LNOF) derived from the GGs in the GRF by point-wise rotation. Because the V XX , V YY , V ZZ and V XZ are much more accurate than V XY and V YZ , and because the error of the accurate GGs increases for low frequencies, the rotation requires that part of the measured GG signal is replaced by model signal. However, the actual quality of the gradients in GRF and LNOF needs to be assessed. We analysed the outliers in the GGs, validated the GGs in the GRF using independent gravity field information and compared their assessed error with the requirements. In addition, we compared the GGs in the LNOF with state-of-the-art global gravity field models and determined the model contribution to the rotated GGs. We found that the percentage of detected outliers is below 0.1% for all GGs, and external gravity data confirm that the GG scale factors do not differ from one down to the 10-3 level. Furthermore, we found that the error of V XX and V YY is approximately at the level of the requirement on the gravitational gradient trace, whereas the V ZZ error is a factor of 2–3 above the requirement for higher frequencies. We show that the model contribution in the rotated GGs is 2–35% dependent on the gravitational gradient. Finally, we found that GOCE gravitational gradients and gradients derived from EIGEN-5C and EGM2008 are consistent over the oceans, but that over the continents the consistency may be less, especially in areas with poor terrestrial gravity data. All in all, our analyses show that the quality of the GOCE gravitational gradients is good and that with this type of data valuable new gravity field information is obtained. Numéro de notice : A2011-468 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0464-0 Date de publication en ligne : 18/10/2011 En ligne : https://doi.org/10.1007/s00190-011-0464-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31362 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2011111	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Assessment of systematic errors in the computation of gravity gradients from satellite altimeter data / Johannes Bouman in Marine geodesy, vol 34 n° 2 (April - June 2011)  

Public [article]  inMarine geodesy > vol 34 n° 2 (April - June 2011) . - pp 85 - 107 Titre : Assessment of systematic errors in the computation of gravity gradients from satellite altimeter data Type de document : Article/Communication Auteurs : Johannes Bouman, Auteur ; W. Bosch, Auteur ; J. Sebera, Auteur Année de publication : 2011 Article en page(s) : pp 85 - 107 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] altimétrie satellitaire par radar [Termes IGN] champ de pesanteur terrestre [Termes IGN] données altimétriques [Termes IGN] données GOCE [Termes IGN] erreur systématique [Termes IGN] geoïde marin [Termes IGN] gradient de gravitation [Termes IGN] océanographie dynamique Résumé : (Auteur) With satellite radar altimetry, the oceanic geoid can be determined with high precision and resolution. Double differentiation of these data along satellite altimeter ground tracks yields along-track gravity gradients that can be used to compute vertical gravity gradients at ground track crossovers. One way to counteract the noise amplification due to the differentiation is to smooth the data using smoothing splines. Although the effect of satellite altimeter data noise has been investigated to some extent, the associated systematic errors have not been assessed so far. Here we show that some of the systematic errors cannot be neglected. In particular, we found that the negligence of the dynamic ocean topography (DOT) may introduce errors that are greater than the measurement noise induced errors. If the gravity gradients are to be used for GOCE validation, then also in this case the DOT may not be neglected as the signal at GOCE altitude of 260 km may be above the GOCE requirements. In addition, we show that the altimetry derived gravity gradients cannot be compared one-to-one with those in a local Cartesian frame. The differences are small compared with the total signal, but they may be larger than the satellite altimetry induced stochastic errors and may be above the GOCE requirements. The cubic splines second derivative truncation error requires the use of 10 Hz altimeter data for the computation of gravity gradients at the Earth's surface, while 1 Hz data are sufficient for validation at GOCE altitude. Numéro de notice : A2011-409 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2010.518498 Date de publication en ligne : 16/05/2011 En ligne : https://doi.org/10.1080/01490419.2010.518498 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31188 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
230-2011021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Quality assessment of satellite-based global gravity fields models / Johannes Bouman (2000)  

Public Titre : Quality assessment of satellite-based global gravity fields models Type de document : Thèse/HDR Auteurs : Johannes Bouman, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2000 Collection : Netherlands Geodetic Commission Publications on Geodesy Sous-collection : New series num. 48 Importance : 114 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-90-6132-270-2 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] erreur moyenne quadratique [Termes IGN] erreur systématique [Termes IGN] estimation statistique [Termes IGN] qualité des données Index. décimale : 30.40 Géodésie physique Note de contenu : 1 INTRODUCTION 2 Parameter estimation and the associated mean square error 2.1 Introduction 2.2 Inverse problems and regularisation - 2.2.1 Illposed problems - 2.2.2 Global regularisation methods 2.3 Choice of regularisation parameters - 2.3.1 Minimum MSE - 2.3.2 Single regularisation parameter - 2.3.3 Multiple regularisation parameters 3 QUALITY, MEASURES 3.1 Introduction 3.2 Spherical harmonic expansion of the gravitational potential 3.3 Biased and unbiased estimation 3.4 Error propagation - 3.4.1 Full error matrix - 3.4.2 Blockdiagonal error matrix 3.5 Ratio measures 3.6 Contribution measures - 3.6.1 Contribution measure for the unbiased solution - 3.6.2 Contribution measure for the biased solution 4 GRAVITY FIELD OBSERVATIONS 4.1 Introduction 4.2 Observation model and iterative solution 4.3 Series expansion of the potential in orbital coordinates 4.4 Satellite gravity gradiometry - 4.4.1 Principle - 4.4.2 Timewise approach - 4.4.3 Blockdiagonal normal matrix 4.5 Satellite to satellite tracking - 4.5.1 Hill equations - 4.5.2 Observation equations - 4.5.3 Blockdiagonal normal matrix 4.6 Airborne gravimetry - 4.6.1 Observation model - 4.6.2 Structure of the normal matrix 5 GRAVITY FIELD MODELS FROM SGG ONLY 5.1 Introduction 5.2 Synthesis and analysis. - 5.2.1 Synthesis - 5.2.2 Analysis 5.3 Observations without noise. - 5.3.1 Circular polar orbit - 5.3.2 Circular inclined orbit - 5.3.3 Noncircular GOCE orbit 5.4 Noisy observations - 5.4.1 Tikhonov regularisation - 5.4.2 Biased estimation 6 COMBINED SOLUTIONS 6.1 Introduction 6.2 SGG results for different mission scenarios 6.3 Combination of SW, and SST 6.4 Combination of SW and airborne gravimetry 6.5 Combination of SGG, SST and gravimetry 7 CONCLUSIONS AND RECOMMENDATIONS A Compact operators and spectral decomposition. B A few remarks on local regularisation methods C Synthesis of SGG observations D Additional results Numéro de notice : 11430 Affiliation des auteurs : non IGN Autre URL associée : Complément Thématique : POSITIONNEMENT Nature : Thèse étrangère En ligne : https://www.ncgeo.nl/downloads/48Bouman_1.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54404

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
11430-01	30.40	Livre	Centre de documentation	Géodésie	Disponible