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Fourier-series representation and projection of spherical harmonic functions / H. Cheong in Journal of geodesy, vol 86 n° 11 (November 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 11 (November 2012) . - pp 975 - 990 Titre : Fourier-series representation and projection of spherical harmonic functions Type de document : Article/Communication Auteurs : H. Cheong, Auteur ; J. Park, Auteur ; H. Kang, Auteur Année de publication : 2012 Article en page(s) : pp 975 - 990 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Statistiques [Termes IGN] harmonique sphérique [Termes IGN] relief sous-marin [Termes IGN] série de Fourier [Termes IGN] théorème de Legendre [Termes IGN] variance Résumé : (Auteur) Computations of Fourier coefficients and related integrals of the associated Legendre functions with a new method along with their application to spherical harmonics analysis and synthesis are presented. The method incorporates a stable three-step recursion equation that can be processed separately for each colatitudinal Fourier wavenumber. Recursion equations for the zonal and sectorial modes are derived in explicit single-term formulas to provide accurate initial condition. Stable computations of the Fourier coefficients as well as the integrals needed for the projection of Legendre functions are demonstrated for the ultra-high degree of 10,800 corresponding to the resolution of one arcmin. Fourier coefficients, computed in double precision, are found to be accurate to 15 significant digits, indicating that the normalized error is close to the machine round-off error. The orthonormality, evaluated with Fourier coefficients and related integrals, is shown to be accurate to O(10-15) for degrees and orders up to 10,800. The Legendre function of degree 10,800 and order 5,000, synthesized from Fourier coefficients, is accurate to the machine round-off error. Further extension of the method to even higher degrees seems to be realizable without significant deterioration of accuracy. The Fourier series is applied to the projection of Legendre functions to the high-resolution global relief data of the National Geophysical Data Center of the National Oceanic and Atmospheric Administration, and the spherical harmonic degree variance (power spectrum) of global relief data is discussed. Numéro de notice : A2012-576 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0558-3 Date de publication en ligne : 11/04/2012 En ligne : https://doi.org/10.1007/s00190-012-0558-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32022 [article]

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Zero-difference GPS ambiguity resolution at CNES–CLS IGS Analysis Center / Sylvain Loyer in Journal of geodesy, vol 86 n° 11 (November 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 11 (November 2012) . - pp 991 - 1003 Titre : Zero-difference GPS ambiguity resolution at CNES–CLS IGS Analysis Center Type de document : Article/Communication Auteurs : Sylvain Loyer, Auteur ; Félix Perosanz, Auteur ; F. Mercier, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 991 - 1003 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] données GPS [Termes IGN] GINS [Termes IGN] International GNSS Service [Termes IGN] international GPS service for geodynamics [Termes IGN] orbitographie [Termes IGN] orientation de la Terre [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté [Termes IGN] simple différence [Termes IGN] traitement de données GNSS Résumé : (Auteur) CNES (Centre National d’Etudes Spatiales) and CLS (Collecte Localisation Satellites) became an International GNSS Service (IGS) Analysis Center (AC) the 20th of May 2010. Since 2009, we are using the integer ambiguity fixing at the zero-difference level strategy in our software package (GINS/Dynamo) as an alternative to classical differential approaches. This method played a key role among all the improvements in the GPS processing we made during this period. This paper provides to the users the theoretical background, the strategies and the models used to compute the products (GPS orbits and clocks, weekly station coordinate estimates and Earth orientation parameters) that are submitted weekly to the IGS. The practical realization of the two-step, ambiguity-fixing scheme (wide-lane and narrow-lane) is described in detail. The ambiguity fixing improved our orbit overlaps from 6 to 3 cm WRMS in the tangential and normal directions. Since 2008, our products have been also regularly compared to the IGS final solutions by the IGS Analysis Center Coordinator. The joint effects of ambiguity fixing and dynamical model changes (satellite solar radiation pressure and albedo force) improved the consistency with IGS orbits from 35 to 18 mm 3D-WRMS. Our innovative strategy also gives additional powerful properties to the GPS satellite phase clock solutions. Single receiver (zero-difference) ambiguity resolution becomes possible. An overview of the applications is given. Numéro de notice : A2012-577 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0559-2 Date de publication en ligne : 03/04/2012 En ligne : https://doi.org/10.1007/s00190-012-0559-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32023 [article]

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3D coseismic displacement of 2010 Darfield, New Zealand earthquake estimated from multi-aperture InSAR and D-InSAR measurements / J. Hu in Journal of geodesy, vol 86 n° 11 (November 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 11 (November 2012) . - pp 1029 - 1041 Titre : 3D coseismic displacement of 2010 Darfield, New Zealand earthquake estimated from multi-aperture InSAR and D-InSAR measurements Type de document : Article/Communication Auteurs : J. Hu, Auteur ; X. Li, Auteur ; X. Ding, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 1029 - 1041 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] déformation de la croute terrestre [Termes IGN] données localisées 3D [Termes IGN] faille géologique [Termes IGN] image ALOS-PALSAR [Termes IGN] image radar moirée [Termes IGN] interferométrie différentielle [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] Nouvelle-Zélande [Termes IGN] propagation ionosphérique [Termes IGN] séisme Résumé : (Auteur) Differential interferometric synthetic aperture radar (D-InSAR) measures ground deformation only along the line-of-sight (LOS) of the radar, which limits the capability of D-InSAR in investigating the surface damages and the focus mechanisms of earthquakes. We do a three-dimensional (3D) decomposition of the coseismic displacement of the Darfield, New Zealand earthquake that occurred on 3 September 2010 by exploiting the Multi-Aperture InSAR (MAI) and D-InSAR measurements from both ascending and descending L-band PALSAR data. Due to the dispersive nature of the ionosphere and the slight Doppler shift between the forward- and backward-looking interferograms, the ionospheric effects can be more serious in MAI measurements than in D-InSAR. We propose mitigating the ionospheric effects in the MAI processing with the directional filtering and interpolation procedure that has been applied in Offset-tracking. The rupture revealed by the 3D surface displacement fits closely to the Greendale fault, which is believed to be responsible for the earthquake. The horizontal ground motions, mostly eastwards in the hanging wall and westwards in the footwall, reached up to 2.5 m and are anti-symmetric with respect to the Greendale fault. Up to 2.5 m subsidence occurred in the hanging wall, while uplift is found in the footwall with an extreme case of 1.6 m in the far left of the fault. This makes us conclude that the Greendale fault is a normal and dextral strike-slip. It is seen that the MAI measurements are very helpful in the derivation of 3D coseismic displacement fields as it provides more accurate displacement estimation in the north–south direction. Numéro de notice : A2012-578 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0563-6 Date de publication en ligne : 20/04/2012 En ligne : https://doi.org/10.1007/s00190-012-0563-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32024 [article]

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Nontidal ocean loading: amplitudes and potential effects in GPS height time series / Tonie M. van Dam in Journal of geodesy, vol 86 n° 11 (November 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 11 (November 2012) . - pp 1043 - 1057 Titre : Nontidal ocean loading: amplitudes and potential effects in GPS height time series Type de document : Article/Communication Auteurs : Tonie M. van Dam, Auteur ; Xavier Collilieux , Auteur ; Jan Wuite, Auteur ; Zuheir Altamimi , Auteur ; Jim Ray, Auteur Année de publication : 2012 Article en page(s) : pp 1043 - 1057 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] effet de charge [Termes IGN] hauteurs de mer [Termes IGN] masse [Termes IGN] positionnement par GPS [Termes IGN] série temporelle [Termes IGN] surcharge océanique Résumé : (Auteur) Ocean bottom pressure (OBP) changes are caused by a redistribution of the ocean’s internal mass that are driven by atmospheric circulation, a change in the mass entering or leaving the ocean, and/or a change in the integrated atmospheric mass over the ocean areas. The only previous global analysis investigating the magnitude of OBP surface displacements used older OBP data sets (van Dam et al. in J Geophys Res 129:507–517, 1997). Since then significant improvements in meteorological forcing models used to predict OBP have been made, augmented by observations from satellite altimetry and expendable bathythermograph profiles. Using more recent OBP estimates from the Estimating the Circulation and Climate of the Ocean (ECCO) project, we reassess the amplitude of the predicted effect of OBP on the height coordinate time series from a global distribution of GPS stations. OBP-predicted loading effects display an RMS scatter in the height of between 0.2 and 3.7 mm, larger than previously reported but still much smaller (by a factor of 2) than the scatter observed due to atmospheric pressure loading. Given the improvement in GPS hardware and data analysis techniques, the OBP signal is similar to the precision of weekly GPS height coordinates. We estimate the effect of OBP on GPS height coordinate time series using the MIT reprocessed solution, mi1. When we compare the predicted OBP height time series with mi1, we find that the scatter is reduced over all stations by 0.1 mm on average with reductions as high as 0.7 mm at some stations. More importantly we are able to reduce the scatter on 65 % of the stations investigated. The annual component of the OBP signal is responsible for 80 % of the reduction in scatter on average. We find that stations located close to semi-enclosed bays or seas are affected by OBP loading to a greater extent than other stations. Numéro de notice : A2012-579 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0564-5 Date de publication en ligne : 06/05/2012 En ligne : https://doi.org/10.1007/s00190-012-0564-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32025 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012111	RAB	Revue	Centre de documentation	En réserve L003	Disponible