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High performance clocks and gravity field determination / Jurgen Müller in Space Science Reviews, vol 214 n° 1 (February 2018)  

Public [article]  inSpace Science Reviews > vol 214 n° 1 (February 2018) Titre : High performance clocks and gravity field determination Type de document : Article/Communication Auteurs : Jurgen Müller, Auteur ; D. Dirkx, Auteur ; S. M. Kopeikin, Auteur ; Guillaume Lion , Auteur ; Isabelle Panet , Auteur ; Gérard Petit, Auteur ; Pieter N.A.M. Visser, Auteur Année de publication : 2018 Projets : 3-projet - voir note / , AdOC / Note générale : bibliographie Jürgen Müller gratefully acknowledges support by the DFG Sonderforschungsbereich (SFB 1128: geo-Q) Relativistic Geodesy and Gravimetry with Quantum Sensors. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] chronométrie [Termes IGN] échelle de temps [Termes IGN] gravimétrie spatiale [Termes IGN] horloge atomique [Termes IGN] International Terrestrial Reference Frame [Termes IGN] potentiel de pesanteur terrestre [Termes IGN] relativité générale Résumé : (auteur) Time measured by an ideal clock crucially depends on the gravitational potential and velocity of the clock according to general relativity. Technological advances in manufacturing high-precision atomic clocks have rapidly improved their accuracy and stability over the last decade that approached the level of 10−18. This notable achievement along with the direct sensitivity of clocks to the strength of the gravitational field make them practically important for various geodetic applications that are addressed in the present paper. Based on a fully relativistic description of the background gravitational physics, we discuss the impact of those highly-precise clocks on the realization of reference frames and time scales used in geodesy. We discuss the current definitions of basic geodetic concepts and come to the conclusion that the advances in clocks and other metrological technologies will soon require the re-definition of time scales or, at least, clarification to ensure their continuity and consistent use in practice. The relative frequency shift between two clocks is directly related to the difference in the values of the gravity potential at the points of clock’s localization. According to general relativity the relative accuracy of clocks in 10−18 is equivalent to measuring the gravitational red shift effect between two clocks with the height difference amounting to 1 cm. This makes the clocks an indispensable tool in high-precision geodesy in addition to laser ranging and space geodetic techniques. We show how clock measurements can provide geopotential numbers for the realization of gravity-field-related height systems and can resolve discrepancies in classically-determined height systems as well as between national height systems. Another application of clocks is the direct use of observed potential differences for the improved recovery of regional gravity field solutions. Finally, clock measurements for space-borne gravimetry are analyzed along with closely-related deficiencies of this method like an extra-ordinary knowledge of the spacecraft velocity, etc. For all these applications besides the near-future prospects, we also discuss the challenges that are related to using those novel clock data in geodesy. Numéro de notice : A2018-197 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s11214-017-0431-z Date de publication en ligne : 30/11/2017 En ligne : https://doi.org/10.1007/s11214-017-0431-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89864 [article]

Assessment of observing time-variable gravity from GOCE GPS and accelerometer observations / Pieter N.A.M. Visser in Journal of geodesy, vol 88 n° 11 (November 2014)  

Public [article]  inJournal of geodesy > vol 88 n° 11 (November 2014) . - pp 1029 - 1046 Titre : Assessment of observing time-variable gravity from GOCE GPS and accelerometer observations Type de document : Article/Communication Auteurs : Pieter N.A.M. Visser, Auteur ; W. Van der Wal, Auteur ; E.J.O. Schrama, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 1029 - 1046 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] données GOCE [Termes IGN] données GPS [Termes IGN] effet atmosphérique [Termes IGN] gravimétrie spatiale [Termes IGN] orbite [Termes IGN] variable Résumé : (Auteur) An assessment has been made of the possibility to estimate time-variable gravity from GPS-derived orbit perturbations and common-mode accelerometer observations of ESA’s GOCE Earth Explorer. A number of 20-day time series of Earth’s global long-wavelength gravity field have been derived for the period November 2009 to November 2012 using different parameter setups and estimation techniques. These techniques include a conventional approach where for each period, one set of gravity coefficients is estimated, either excluding or including empirical accelerations, and the so-called Wiese approach where higher frequency coefficients are estimated for the very long wavelengths. A principal component analysis of especially the time series of gravity field coefficients obtained by the Wiese approach and the conventional approach with empirical accelerations reveals an annual signal. When fitting this annual signal directly through the time series, the sine component (maximum in spring) displays features that are similar to well-known continental hydrological mass changes for the low latitude areas, such as mass variations in the Amazon basin, Africa and Australia for spatial scales down to 1,500 km. The cosine component (maximum in winter), however, displays large signals that can not be attributed to actual mass variations in the Earth system. The estimated gravity field changes from GOCE orbit perturbations are likely affected by missing GPS observations in case of high ionospheric perturbations during periods of increased solar activity, which is minimal in Summer and maximal towards the end of autumn. Numéro de notice : A2014-563 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0741-9 Date de publication en ligne : 27/06/2014 En ligne : https://doi.org/10.1007/s00190-014-0741-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74749 [article]

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2014111	SL	Revue	Centre de documentation	Revues en salle	Disponible

SAR [Synthetic Aperture Radar] land subsidence monitoring / M.W. Van Der Kooij (1995)

Public Titre : SAR [Synthetic Aperture Radar] land subsidence monitoring Type de document : Monographie Auteurs : M.W. Van Der Kooij, Auteur ; D. Van Halsema, Auteur ; W. Groenewoud, Auteur ; G.J. Mets, Auteur ; B. Overgaauw, Auteur ; Pieter N.A.M. Visser, Auteur Editeur : Delf : BeleidsCommissie Remote Sensing BCRS Année de publication : 1995 Importance : 125 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-90-5411-160-3 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] image ERS-SAR [Termes IGN] image radar moirée [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] précision [Termes IGN] satellite artificiel [Termes IGN] surveillance géologique Index. décimale : 35.22 Télédétection en hyperfréquence - Traitement d'image radar Numéro de notice : 67412 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=61753

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
67412-01	35.22	Livre	Centre de documentation	Télédétection	Disponible