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Optimized formulas for the gravitational field of a tesseroid / Thomas Grombein in Journal of geodesy, vol 87 n° 7 (July 2013)
[article]
Titre : Optimized formulas for the gravitational field of a tesseroid Type de document : Article/Communication Auteurs : Thomas Grombein, Auteur ; Kurt Seitz, Auteur ; Bernard Heck, Auteur Année de publication : 2013 Article en page(s) : pp 645 - 660 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] coordonnées cartésiennes géocentriques
[Termes IGN] coordonnées sphériques
[Termes IGN] intégrale de Newton
[Termes IGN] tesseroidRésumé : (Auteur) Various tasks in geodesy, geophysics, and related geosciences require precise information on the impact of mass distributions on gravity field-related quantities, such as the gravitational potential and its partial derivatives. Using forward modeling based on Newton’s integral, mass distributions are generally decomposed into regular elementary bodies. In classical approaches, prisms or point mass approximations are mostly utilized. Considering the effect of the sphericity of the Earth, alternative mass modeling methods based on tesseroid bodies (spherical prisms) should be taken into account, particularly in regional and global applications. Expressions for the gravitational field of a point mass are relatively simple when formulated in Cartesian coordinates. In the case of integrating over a tesseroid volume bounded by geocentric spherical coordinates, it will be shown that it is also beneficial to represent the integral kernel in terms of Cartesian coordinates. This considerably simplifies the determination of the tesseroid’s potential derivatives in comparison with previously published methodologies that make use of integral kernels expressed in spherical coordinates. Based on this idea, optimized formulas for the gravitational potential of a homogeneous tesseroid and its derivatives up to second-order are elaborated in this paper. These new formulas do not suffer from the polar singularity of the spherical coordinate system and can, therefore, be evaluated for any position on the globe. Since integrals over tesseroid volumes cannot be solved analytically, the numerical evaluation is achieved by means of expanding the integral kernel in a Taylor series with fourth-order error in the spatial coordinates of the integration point. As the structure of the Cartesian integral kernel is substantially simplified, Taylor coefficients can be represented in a compact and computationally attractive form. Thus, the use of the optimized tesseroid formulas particularly benefits from a significant decrease in computation time by about 45 % compared to previously used algorithms. In order to show the computational efficiency and to validate the mathematical derivations, the new tesseroid formulas are applied to two realistic numerical experiments and are compared to previously published tesseroid methods and the conventional prism approach. Numéro de notice : A2013-399 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0636-1 Date de publication en ligne : 18/05/2013 En ligne : https://doi.org/10.1007/s00190-013-0636-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32537
in Journal of geodesy > vol 87 n° 7 (July 2013) . - pp 645 - 660[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2013071 SL Revue Centre de documentation Revues en salle Disponible Analytical error analysis for satellite gravity field determination based on two-dimensional Fourier method / Lin Cai in Journal of geodesy, vol 87 n° 5 (May 2013)
[article]
Titre : Analytical error analysis for satellite gravity field determination based on two-dimensional Fourier method Type de document : Article/Communication Auteurs : Lin Cai, Auteur ; Zebing Zhou, Auteur ; Houste Hsu, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 417 - 426 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] densité spectrale de puissance
[Termes IGN] erreur de positionnement
[Termes IGN] gravimétrie spatiale
[Termes IGN] harmonique sphérique
[Termes IGN] levé gravimétrique
[Termes IGN] modèle de géopotentielRésumé : (Auteur) The time-wise and space-wise approaches are generally applied to data processing and error analysis for satellite gravimetry missions. But both the approaches, which are based on least-squares method, address the whole effect of measurement errors and estimate the resolution of gravity field models mainly from a numerical point of view. Moreover, requirement for higher accuracy and resolution gravity field models could make the computation more difficult, and serious numerical instabilities arise. A direct analytical expression between power spectral density of the satellite gravimetry measurements and spherical harmonic coefficients of the Earth’s gravity model is derived based on two-dimensional Fourier description. This method provides a physical insight into the relation between mission parameters, instrument parameters and gravity field parameters. In contrast, the least-squares method is mainly based on a mathematical viewpoint. By taking advantage of the analytical expression, it is efficient and distinct for parameter estimation and error analysis of missions. It is easy to obtain from the analytical relationship that the low-frequency noise affects the gravity field recovery in all degrees for the instance of satellite gradiometer recovery mission, which agrees with the work before by the numerical error analysis methods Numéro de notice : A2013-252 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0615-6 Date de publication en ligne : 03/02/2013 En ligne : https://doi.org/10.1007/s00190-013-0615-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32390
in Journal of geodesy > vol 87 n° 5 (May 2013) . - pp 417 - 426[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2013051 SL Revue Centre de documentation Revues en salle Disponible
Titre : Atmospheric effects on measurements of the Earth gravity field Type de document : Thèse/HDR Auteurs : Maria Karbon, Auteur Editeur : Vienne [Autriche] : Technische Universität Wien Année de publication : 2013 Collection : Geowissenschaftliche Mitteilungen, ISSN 1811-8380 num. 94 Importance : 150 p. Format : 21 x 30 cm Note générale : bibliographie
Diese Arbeit wurde an der Fakultät für Mathematik und Geoinformation der Technischen Universität Wien zur Erlangung des akademischen Grades einer Doktorin der technischen Wissenschaften eingereichtLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] correction atmosphérique
[Termes IGN] données GRACE
[Termes IGN] effet atmosphérique
[Termes IGN] gravimètre supraconducteur
[Termes IGN] marée terrestre
[Termes IGN] modèle mathématique
[Termes IGN] rotation de la Terre
[Termes IGN] surcharge atmosphérique
[Termes IGN] surcharge océaniqueIndex. décimale : 30.40 Géodésie physique Résumé : (auteur) Atmospheric pressure variations are one of the major sources of surface gravity perturbations. The varying atmosphere introduces two disturbing forces in the gravity signal, the so called direct effect or Newtonian attraction, where the measuring object is attracted by the atmospheric mass itself, and secondly the indirect effect or atmospheric loading, where the masses deform the Earth’s surface, what again influences the measured gravity signal due to the slightly changes gravity field. In satellite gravity missions such signals are referred to as aliasing. To eliminate them, the de- termination of accurate atmospheric gravity field coefficients (AGC) is indispensable. For the determination of AGC it is state of the art to use high resolution numerical weather models which take into account the time-variable three-dimensional distribution of the atmospheric mass. By subtracting the gravity spherical harmonics of the instantaneous atmosphere from the ones of a long term mean field, the residual gravity spherical harmonic series is obtained. It describes the deviation of the actual gravity field from the mean gravity field due to atmospheric mass variations. Ground based gravimetric measurements encounter the same difficulty of eliminating the disturbing signal introduced by the atmosphere. Superconducting gravimeters are usually corrected using the local air pressure, which reduces up to 90-95 % of the atmospheric signal. However, modern superconducting gravimeters require an even better atmospheric correction if small signals are to be identified. For this task the use of three-dimensional modeling of atmospheric mass attraction based on operational numerical weather models has shown promising results. Note de contenu : 1. Introduction
2. The gravity field of the Earth
3. Atmospheric effects on the gravity field of the Earth
4. Mathematical description of the de-aliasing model for GRACE and its validation
5. Atmospheric corrections for superconducting gravimeters
6. Conclusion and outlookNuméro de notice : 14939 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : PhD : Mathematik und Geoinformation : Wien : 2013 En ligne : http://www.ub.tuwien.ac.at/diss/AC07815618.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77497
Titre : Essential astrophysics Type de document : Monographie Auteurs : Kenneth R. Lang, Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2013 Importance : 657 p. ISBN/ISSN/EAN : 978-3-642-35963-7 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Astrophysique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] champ électromagnétique
[Termes IGN] étoile
[Termes IGN] force de gravitation
[Termes IGN] loi de Képler
[Termes IGN] marée lunaire
[Termes IGN] marée terrestre
[Termes IGN] neutron
[Termes IGN] onde radioélectrique
[Termes IGN] proton
[Termes IGN] rayonnement solaire
[Termes IGN] rotation de la Terre
[Termes IGN] système stellaire
[Termes IGN] téléscope
[Termes IGN] trou noirRésumé : (éditeur) Essential Astrophysics is a book to learn or teach from, as well as a fundamental reference volume for anyone interested in astronomy and astrophysics. It presents astrophysics from basic principles without requiring any previous study of astronomy or astrophysics. It serves as a comprehensive introductory text, which takes the student through the field of astrophysics in lecture-sized chapters of basic physical principles applied to the cosmos. This one-semester overview will be enjoyed by undergraduate students with an interest in the physical sciences, such as astronomy, chemistry, engineering or physics, as well as by any curious student interested in learning about our celestial science. The mathematics required for understanding the text is on the level of simple algebra, for that is all that is needed to describe the fundamental principles. The text is of sufficient breadth and depth to prepare the interested student for more advanced specialised courses in the future. Astronomical examples are provided throughout the text, to reinforce the basic concepts and physics, and to demonstrate the use of the relevant formulae. In this way, the student learns to apply the fundamental equations and principles to cosmic objects and situations. Astronomical and physical constants and units as well as the most fundamental equations can be found in the appendix. Essential Astrophysics goes beyond the typical textbook by including references to the seminal papers in the field, with further reference to recent applications, results, or specialised literature. Note de contenu : 1- Observing the Universe
2- Radiation
3- Gravity
4- Cosmic Motion
5- Moving Particles
6- Detecting Atoms in Stars
7- Transmutation of the Elements
8- What Makes the Sun Shine?
9- The Extended Solar Atmosphere
10- The Sun Amongst the Stars
11- The Material Between the Stars
12- Formation of the Stars and Their Planets
13- Stellar End States
14- A Larger, Expanding Universe
15- Origin, Evolution, and Destiny of the Observable UniverseNuméro de notice : 25760 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie En ligne : https://doi.org/10.1007/978-3-642-35963-7 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94955 Estimation of mass change trends in the Earth’s system on the basis of GRACE satellite data, with application to Greenland / C. Siemes in Journal of geodesy, vol 87 n° 1 (January 2013)
[article]
Titre : Estimation of mass change trends in the Earth’s system on the basis of GRACE satellite data, with application to Greenland Type de document : Article/Communication Auteurs : C. Siemes, Auteur ; Pavel Ditmar, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 69 - 87 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] bilan de masse
[Termes IGN] calotte glaciaire
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] données GRACE
[Termes IGN] filtre de Wiener
[Termes IGN] gravimétrie spatiale
[Termes IGN] Groenland
[Termes IGN] harmonique sphérique
[Termes IGN] isostasie
[Termes IGN] levé gravimétrique
[Termes IGN] matrice de covarianceRésumé : (Auteur) The Gravity Recovery and Climate Experiment (GRACE) satellite mission measures the Earth’s gravity field since March 2002. We propose a new filtering procedure for post-processing GRACE-based monthly gravity field solutions provided in the form of spherical harmonic coefficients. The procedure is tuned for the optimal estimation of linear trends and other signal components that show a systematic behavior over long time intervals. The key element of the developed methodology is the statistically optimal Wiener-type filter which makes use of the full covariance matrices of noise and signal. The developed methodology is applied to determine the mass balance of the Greenland ice sheet, both per drainage system and integrated, as well as the mass balance of the ice caps on the islands surrounding Greenland. The estimations are performed for three 2-year time intervals (2003–2004, 2005–2006, and 2007–2008), as well as for the 6-year time interval (2003–2008). The study confirms a significant difference in the behavior of the drainage systems over time. The average 6-year rate of mass loss in Greenland is estimated as 165 + 15 Gt/year. The rate of mass loss of the ice caps on Ellesmere Island (together with Devon Island), Baffin Island, Iceland, and Svalbard is found to be 22 + 4, 21 + 6, 17 + 9, and 6 + 2 Gt/year, respectively. All these estimates are corrected for the effect of glacial isostatic adjustment. Numéro de notice : A2013-071 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0580-5 Date de publication en ligne : 12/07/2012 En ligne : https://doi.org/10.1007/s00190-012-0580-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32209
in Journal of geodesy > vol 87 n° 1 (January 2013) . - pp 69 - 87[article]Réservation
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