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Separation of global time-variable gravity signals into maximally independent components / E. Forootan in Journal of geodesy, vol 86 n° 7 (July 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 7 (July 2012) . - pp 477 - 497 Titre : Separation of global time-variable gravity signals into maximally independent components Type de document : Article/Communication Auteurs : E. Forootan, Auteur ; J. Kusche, Auteur Année de publication : 2012 Article en page(s) : pp 477 - 497 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] analyse en composantes indépendantes [Termes IGN] analyse en composantes principales [Termes IGN] champ de pesanteur terrestre [Termes IGN] données GRACE [Termes IGN] filtrage du signal [Termes IGN] traitement de données Résumé : (Auteur) The Gravity Recovery and Climate Experiment (GRACE) products provide valuable information about total water storage variations over the whole globe. Since GRACE detects mass variations integrated over vertical columns, it is desirable to separate its total water storage anomalies into their original sources. Among the statistical approaches, the principal component analysis (PCA) method and its extensions have been frequently proposed to decompose the GRACE products into space and time components. However, these methods only search for decorrelated components that on the one hand are not always interpretable and on the other hand often contain a superposition of independent source signals. In contrast, independent component analysis (ICA) represents a technique that separates components based on assumed statistical independence using higher-order statistical information. If one assumes that independent physical processes generate statistically independent signal components added up in the GRACE observations, separating them by ICA is a reliable strategy to identify these processes. In this paper, the performance of the conventional PCA, its rotated extension and ICA are investigated when applied to the GRACE-derived total water storage variations. These analyses have been tested on both a synthetic example and on the real GRACE level-2 monthly solutions derived from GeoForschungsZentrum Potsdam (GFZ RL04) and Bonn University (ITG2010). Within the synthetic example, we can show how imposing statistical independence in the framework of ICA improves the extraction of the ‘original’ signals from a GRACE-type superposition. We are therefore confident that also for the real case the ICA algorithm, without making prior assumptions about the long-term behaviour or on the frequencies contained in the signal, improves over the performance of PCA and its rotated extension in the separation of periodical and long-term components. Numéro de notice : A2012-355 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0532-5 Date de publication en ligne : 22/11/2011 En ligne : https://doi.org/10.1007/s00190-011-0532-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31801 [article]

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266-2012071	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Basic equations for constructing geopotential models from the gravitational potential derivatives of the first and second orders in the terrestrial reference frame / M. Petrovskaya in Journal of geodesy, vol 86 n° 7 (July 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 7 (July 2012) . - pp 521 - 530 Titre : Basic equations for constructing geopotential models from the gravitational potential derivatives of the first and second orders in the terrestrial reference frame Type de document : Article/Communication Auteurs : M. Petrovskaya, Auteur ; A. Vershkov, Auteur Année de publication : 2012 Article en page(s) : pp 521 - 530 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] gradient de gravitation [Termes IGN] harmonique sphérique [Termes IGN] modèle de géopotentiel [Termes IGN] repère de référence [Termes IGN] système de référence mondial Résumé : (Auteur) This research represents a continuation of the investigation carried out in the paper of Petrovskaya and Vershkov (J Geod 84(3):165–178, 2010) where conventional spherical harmonic series are constructed for arbitrary order derivatives of the Earth gravitational potential in the terrestrial reference frame. The problem of converting the potential derivatives of the first and second orders into geopotential models is studied. Two kinds of basic equations for solving this problem are derived. The equations of the first kind represent new non-singular non-orthogonal series for the geopotential derivatives, which are constructed by means of transforming the intermediate expressions for these derivatives from the above-mentioned paper. In contrast to the spherical harmonic expansions, these alternative series directly depend on the geopotential coefficients Cn,m and Sn,m . Each term of the series for the first-order derivatives is represented by a sum of these coefficients, which are multiplied by linear combinations of at most two spherical harmonics. For the second-order derivatives, the geopotential coefficients are multiplied by linear combinations of at most three spherical harmonics. As compared to existing non-singular expressions for the geopotential derivatives, the new expressions have a more simple structure. They depend only on the conventional spherical harmonics and do not depend on the first- and second-order derivatives of the associated Legendre functions. The basic equations of the second kind are inferred from the linear equations, constructed in the cited paper, which express the coefficients of the spherical harmonic series for the first- and second-order derivatives in terms of the geopotential coefficients. These equations are converted into recurrent relations from which the coefficients Cn,m and Sn,m are determined on the basis of the spherical harmonic coefficients of each derivative. The latter coefficients can be estimated from the values of the geopotential derivatives by the quadrature formulas or the least-squares approach. The new expressions of two kinds can be applied for spherical harmonic synthesis and analysis. In particular, they might be incorporated in geopotential modeling on the basis of the orbit data from the CHAMP, GRACE and GOCE missions, and the gradiometry data from the GOCE mission. Numéro de notice : A2012-356 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0535-2 Date de publication en ligne : 31/12/2011 En ligne : https://doi.org/10.1007/s00190-011-0535-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31802 [article]

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The affine constrained GNSS attitude model and its multivariate integer least-squares solution / Peter J.G. Teunissen in Journal of geodesy, vol 86 n° 7 (July 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 7 (July 2012) . - pp 547 - 563 Titre : The affine constrained GNSS attitude model and its multivariate integer least-squares solution Type de document : Article/Communication Auteurs : Peter J.G. Teunissen, Auteur Année de publication : 2012 Article en page(s) : pp 547 - 563 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] affaiblissement de la précision [Termes IGN] antenne GNSS [Termes IGN] méthode des moindres carrés [Termes IGN] phase GNSS [Termes IGN] précision du positionnement [Termes IGN] résolution d'ambiguïté Résumé : (Auteur) A new global navigation satellite system (GNSS) carrier-phase attitude model and its solution are introduced in this contribution. This affine-constrained GNSS attitude model has the advantage that it avoids the computational complexity of the orthonormality-constrained GNSS attitude model, while it still has a significantly improved ambiguity resolution performance over its unconstrained counterpart. The functional and stochastic model is formulated in multivariate form, for one-, two- and three-dimensional antenna arrays, tracking GNSS signals on an arbitrary number of frequencies with two or more antennas. The stochastic model includes the capability to capture variations in the antenna-quality within the array. The multivariate integer least-squares solution of the model parameters is given and the model’s ambiguity success-rate is analysed by means of the ambiguity dilution of precision (ADOP). A general closed-form expression for the affine-constrained ADOP is derived, thus providing an easy-to-use and insightful rule-of-thumb for the ambiguity resolution capabilities of the affine constrained GNSS attitude model. Numéro de notice : A2012-357 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0538-z Date de publication en ligne : 28/12/2011 En ligne : https://doi.org/10.1007/s00190-011-0538-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31803 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012071	RAB	Revue	Centre de documentation	En réserve L003	Disponible