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Transformation of amplitudes and frequencies of precession and nutation of the earth’s rotation vector to amplitudes and frequencies of diurnal polar motion / Bernd Richter in Journal of geodesy, vol 84 n° 1 (January 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 1 (January 2010) . - pp 1 - 18 Titre : Transformation of amplitudes and frequencies of precession and nutation of the earth’s rotation vector to amplitudes and frequencies of diurnal polar motion Type de document : Article/Communication Auteurs : Bernd Richter, Auteur ; J. Engels, Auteur ; Erik W. Grafarend, Auteur Année de publication : 2010 Article en page(s) : pp 1 - 18 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] équation différentielle [Termes IGN] mouvement du pôle [Termes IGN] nutation [Termes IGN] précession [Termes IGN] rotation de la Terre Résumé : (Auteur) The temporal change of the rotation vector of a rotating body is, in the first order, identical in a space-fixed system and in a body-fixed system. Therefore, if the motion of the rotation axis of the earth relative to a space-fixed system is given as a function of time, it should be possible to compute its motion relative to an earth-fixed system, and vice versa. This paper presents such a transformation. Two models of motion of the rotation axis in the space-fixed system are considered: one consisting only of a regular (i.e., strictly conical) precession and one extended by circular nutation components, which are superimposed upon the regular precession. The Euler angles describing the orientation of the earth-fixed system with respect to the space-fixed system are derived by an analytical solution of the kinematical Eulerian differential equations. In the first case (precession only), this is directly possible, and in the second case (precession and nutation), a solution is achieved by a perturbation approach, where the result of the first case serves as an approximation and nutation is regarded as a small perturbation, which is treated in a linearized form. The transformation by means of these Euler angles shows that the rotation axis performs in the earth-fixed system retrograde conical revolutions with small amplitudes, namely one revolution with a period of one sidereal day corresponding to precession and one revolution with a period which is slightly smaller or larger than one sidereal day corresponding to each (prograde or retrograde) circular nutation component. The peculiar feature of the derivation presented here is the analytical solution of the Eulerian differential equations. Copyright Springer Numéro de notice : A2010-032 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0339-9 Date de publication en ligne : 16/09/2009 En ligne : https://doi.org/10.1007/s00190-009-0339-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30228 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2010011	SL	Revue	Centre de documentation	Revues en salle	Disponible

Global optimization of core station networks for space geodesy: application to the referencing of the SLR EOP with respect to ITRF / David Coulot in Journal of geodesy, vol 84 n° 1 (January 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 1 (January 2010) . - pp 31 - 50 Titre : Global optimization of core station networks for space geodesy: application to the referencing of the SLR EOP with respect to ITRF Type de document : Article/Communication Auteurs : David Coulot , Auteur ; Arnaud Pollet , Auteur ; Xavier Collilieux , Auteur ; Philippe Berio, Auteur Année de publication : 2010 Article en page(s) : pp 31 - 50 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] algorithme génétique [Termes IGN] données TLS (télémétrie) [Termes IGN] International Terrestrial Reference Frame [Termes IGN] optimisation (mathématiques) [Termes IGN] orientation de la Terre [Termes IGN] programmation stochastique [Termes IGN] station de référence Résumé : (Auteur) We apply global optimization in order to optimize the referencing (and consequently the stability) of the Earth Orientation Parameters (EOP) with respect to ITRF2005. These EOP are derived at a daily sampling from SLR data, simultaneously with weekly station positions. The EOP referencing is carried out with minimum constraints applied weekly to the three rotations and over core station networks. Our approach is based on a multi objective genetic algorithm, a particular stochastic global optimization method, the reference system effects being the objectives to minimize. We thus use rigorous criteria for the optimal weekly core station selection. The results evidence an improvement of 10% of the stability for Polar Motion (PM) series in comparison to the results obtained with the network specially designed for EOP referencing by the Analysis Working Group of the International Laser Ranging Service. This improvement of nearly 25 ?as represents 50% of the current precision of the IERS 05 C04 PM reference series. We also test the possibility of averaging the weekly networks provided by our algorithm (the Genetically Modified Networks—GMN) over the whole time period. Although the dynamical nature of the GMN is clearly a key point of their success, we can derive such a global mean core network, which could be useful for practical applications regarding EOP referencing. Using this latter core network moreover provides more stable EOP series than the conventional network does. Copyright Springer Numéro de notice : A2010-033 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0342-1 En ligne : https://doi.org/10.1007/s00190-009-0342-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30229 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2010011	SL	Revue	Centre de documentation	Revues en salle	Disponible

Absolute seafloor vertical positioning using combined pressure gauge and kinematic GPS data / Valérie Ballu in Journal of geodesy, vol 84 n° 1 (January 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 1 (January 2010) . - pp 65 - 77 Titre : Absolute seafloor vertical positioning using combined pressure gauge and kinematic GPS data Type de document : Article/Communication Auteurs : Valérie Ballu, Auteur ; Marie-Noëlle Bouin , Auteur ; Stéphane Calmant, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 65 - 77 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] coordonnées GPS [Termes IGN] données marégraphiques [Termes IGN] fond marin [Termes IGN] GPS en mode cinématique [Termes IGN] Pacifique (océan) [Termes IGN] positionnement absolu [Termes IGN] profondeur [Termes IGN] séisme [Termes IGN] subduction [Termes IGN] tectonique des plaques [Termes IGN] Vanuatu Résumé : (Auteur) Knowledge of the position and motion of points on the seafloor can be critically important in both fundamental research (for example, global geodesy and plate tectonics) and for more practical applications such as seismic risk evaluation, off-shore construction and pipeline monitoring. In the Vanuatu subduction zone, for example, measuring deformation underwater could provide valuable information for modeling deformation and understanding the seismic cycle. We report a shallow water experiment in Vanuatu to measure the relative and absolute depth of seafloor points. The experiment differs from previous efforts mainly in that it uses the height of the sea surface determined by kinematic GPS, allowing us to locate the points in a global reference frame. The ITRF2005 ellipsoidal height of a seafloor benchmark was determined with a 1-sigma uncertainty of 0.7–2.1 cm. The estimated ellipsoidal height differs only by a few tenths of a centimeter between measurements made in 2004 and another set made in 2006. These results are encouraging and open new perspectives for vertical underwater deformation monitoring in shallow water areas. Sea-surface GPS measurements can also help to reduce the uncertainty in depth difference determination for relative measurements. Copyright Springer Numéro de notice : A2010-034 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0345-y Date de publication en ligne : 19/09/2009 En ligne : https://doi.org/10.1007/s00190-009-0345-y Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30230 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2010011	SL	Revue	Centre de documentation	Revues en salle	Disponible