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Auteur Karine Le Bail
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Affiner la recherche Interroger des sources externesQuantifying the correlation between the MEI and LOD variations by decomposing LOD with singular spectrum analysis / Karine Le Bail (2014)
Titre : Quantifying the correlation between the MEI and LOD variations by decomposing LOD with singular spectrum analysis Type de document : Article/Communication Auteurs : Karine Le Bail Congrès : IAG 2011, general assembly (28 juin - 2 juillet 2011; Melbourne, Australie), Commanditaire Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2014 Importance : pp 473 - 481 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] analyse de spectre singulier
[Termes descripteurs IGN] données ITGB
[Termes descripteurs IGN] interférométrie à très grande base
[Termes descripteurs IGN] positionnement par ITGB
[Termes descripteurs IGN] série temporelle
[Termes descripteurs IGN] variation temporelleRésumé : (auteur) Variations in the temporal length-of-day (LOD) contain information on phenomena related to the continuous evolution of Earth processes: tidal energy dissipation and core-mantle coupling (decadal, secular), meteorological and solar-lunar tide effects (annual, semi-annual). In this work, we studied an LOD time series obtained from VLBI measurements and extracted its principal components using the Singular Spectrum Analysis (SSA). After removing the long-term trend which explains 73. 8% of the signal, three remaining components explain a further 22. 0% of the signal: an annual and a semi-annual signals as well as a second trend. We compared the Multivariate ENSO index (MEI) with the variations in the amplitudes of the annual and semi-annual components and with the second trend. The correlations are significant: 0. 58 for the annual component, − 0. 48 for the semi-annual component and 0. 46 for the second trend. Numéro de notice : C2011-028 Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-37222-3_63 date de publication en ligne : 06/10/2013 En ligne : http://dx.doi.org/10.1007/978-3-642-37222-3_63 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80597
Titre : GSFC DORIS contribution to ITRF2008 Type de document : Article/Communication Auteurs : Karine Le Bail Année de publication : 2010 Article en page(s) : pp 1481 - 1499 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes descripteurs IGN] données DORIS
[Termes descripteurs IGN] International Terrestrial Reference Frame
[Termes descripteurs IGN] orbitographie
[Termes descripteurs IGN] orientation de la TerreRésumé : (Auteur) The NASA GSFC DORIS analysis center has provided weekly DORIS solutions from November 1992 to January 2009 (839 SINEX files) of station positions and Earth Orientation Parameters for inclusion in the DORIS contribution to ITRF2008. The NASA GSFC GEODYN orbit determination software was used to process the orbits and produce the normal equations. The weekly SINEX gscwd10 submissions included DORIS data from Envisat, TOPEX/Poseidon, SPOT-2, SPOT-3, SPOT-4, SPOT-5. The orbits were mostly seven days in length (except for weeks with data gaps or maneuvers). The processing used the GRACE-derived EIGEN-GL04S1 gravity model, updated modeling for time-variable gravity, the GOT4.7 ocean tide model and tuned satellite-specific macromodels for SPOT-2, SPOT-3, SPOT-4, SPOT-5 and TOPEX/Poseidon. The University College London (UCL) radiation pressure model for Envisat improves nonconservative force modeling for this satellite, reducing the median residual empirical daily along-track accelerations from 3.75 * 10-9 m/s2 with the a priori macromodel to 0.99 * 10-9 m/s2 with the UCL model. For the SPOT and Envisat DORIS satellite orbits from 2003 to 2008, we obtain average RMS overlaps of 0.8–0.9 cm in the radial direction, 2.1–3.4 cm cross-track, and 1.7–2.3 cm along-track. The RMS orbit differences between Envisat DORIS-only and SLR & DORIS orbits are 1.1 cm radially, 6.4 cm along-track and 3.7 cm cross-track and are characterized by systematic along-track mean offsets due to the Envisat DORIS system time bias of 15–10 ?s. We obtain a good agreement between the geometrically-determined geocenter parameters and geocenter parameters determined dynamically from analysis of the degree one terms of the geopotential. The intrinsic RMS weekly position repeatability with respect to the IDS-3 combination ranges from 2.5 to 3.0 cm in 1993–1994 to 1.5 cm in 2007–2008. Numéro de notice : A2010-362 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30556
in Advances in space research > vol 45 n° 12 (15/06/2010) . - pp 1481 - 1499[article]Réservation
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Titre : Stability of VLBI, SLR, DORIS, and GPS positioning Type de document : Article/Communication Auteurs : Martine Feissel-Vernier, Auteur ; Olivier de Viron, Auteur ; Karine Le Bail Année de publication : 2007 Article en page(s) : pp 475 - 497 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes descripteurs IGN] positionnement par DORIS
[Termes descripteurs IGN] positionnement par GPS
[Termes descripteurs IGN] positionnement par ITGB
[Termes descripteurs IGN] positionnement par télémétrie laser sur satellite
[Termes descripteurs IGN] résidu
[Termes descripteurs IGN] stabilité
[Termes descripteurs IGN] station de référence
[Termes descripteurs IGN] variance d'AllanRésumé : (auteur) The residual signal in VLBI, SLR, DORIS and GPS station motion, after a linear trend and seasonal components have been removed, is analysed to investigate site-specific and technique-specific error spectra. The study concentrates on 60 sites with dense observation history by two or more space geodetic techniques. Statistical methods include the Allan variance analysis and the three-cornered hat algorithm. The stability of time-series is defined by two parameters, namely the Allan deviation for a one-year sampling time (noise level) and the slope of the Allan variance graph with its spectral interpretation (noise type). The site-specific noise level is found to be in the range 0.5–3.5 mm in either horizontal direction and 1–4.5 mm in height for most sites. The distribution of site-specific noise type includes both white noise and flicker noise. White noise is predominant in the East direction. Both types of noise are found in the North direction, with no particular geographical clustering. In the Up direction, the Northern hemisphere sites seem to be split in two large geographical sectors characterised either by white noise or by flicker noise signatures. Technique-specific noise characteristics are estimated in several ways, leading to a white noise diagnostic for VLBI and SLR in all three local directions. DORIS has also white noise in the horizontal directions, whereas GPS has a flicker noise spectrum. The vertical noise spectrum is indecisive for both DORIS and GPS. The three-dimensional noise levels for the one-year sampling time are 1.7 mm for VLBI, 2.5 mm for SLR, 5.2 mm for DORIS, and 4.1 mm for GPS. For GPS, the long-term analysis homogeneity has a strong influence. In the case of a test solution reanalysed in a fully consistent way, the noise level drops to the VLBI level in horizontal and to the SLR level in vertical. The three-dimensional noise level for a one-year sampling time decreases to 1.8 mm. In addition, the percentage of stations with flicker noise drops to only about 20% of the network. Numéro de notice : A2007-679 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1186/BF03352712 date de publication en ligne : 27/06/2007 En ligne : http://dx.doi.org/10.1186/BF03352712 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93369
in Earth, Planets and Space > vol 59 n° 6 (June 2007) . - pp 475 - 497[article]Documents numériques
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Stability of VLBI, SLR, DORIS, and GPS positioning - pdf éditeurAdobe Acrobat PDF
Titre : Estimating the noise in space-geodetic positioning: the case of DORIS Type de document : Article/Communication Auteurs : Karine Le Bail Année de publication : 2006 Article en page(s) : pp 541 - 565 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] bruit blanc
[Termes descripteurs IGN] bruit rose
[Termes descripteurs IGN] données DORIS
[Termes descripteurs IGN] ENVISAT
[Termes descripteurs IGN] filtrage du bruit
[Termes descripteurs IGN] méthode du maximum de vraisemblance (estimation)
[Termes descripteurs IGN] positionnement par DORIS
[Termes descripteurs IGN] série temporelle
[Termes descripteurs IGN] SPOT
[Termes descripteurs IGN] station DORIS
[Termes descripteurs IGN] TOPEX-Poseidon
[Termes descripteurs IGN] traitement du signalRésumé : (Auteur) The noise spectrum in DORIS ground-station motion is investigated by means of the Allan variance method applied to the decomposition of the 3D signal into its principal components in the time domain. Sets of weekly position time-series from 1994 to 2005 derived by three IDS Analysis Centres (IGN-JPL, INASAN, and LEGOS-CLS) for 119 stations at 69 sites are considered. The observing satellites are SPOT-2, SPOT-3, SPOT-4, and SPOT-5, TOPEX/Poseidon, and ENVISAT. Annual and semi-annual perturbations, as well as the 117.3-day term associated with the TOPEX/Poseidon orbit, are found at most stations. Their amplitudes reach up to 19.3, 23.7, and 13.3 mm, respectively, for the three analysis centres (ACs). When corrected for these components and a linear drift, the time-series dominantly show white noise (WN) at the 10-45mm level the noise level is the highest in the East direction, probably in connection with the high orbit inclinations. The noise level is minimum for the high latitude stations, mostly and intensively observed by the SPOT satellites, and the determination of the noise type is unclear; longer observation spans would be needed to decide between interannual variations and flicker noise. The improvement in positioning due to the DORIS constellation extension from three to five satellites in 2002, and the network rejuvenation program initiated in 2000, results in a decrease of the noise level by a factor of 1.7 in a WN context, both before and after the changes. One example of the benefit of studying the signal in the time eigenspace domain is the detection of anomalously large WN in the East direction for station HBKB (Hartebeesthoek, Africa) that masks the above-mentioned improvement. Studying the projection on the local frame of the second and third time-eigenspace components, a noise excess is detected in the North direction for some of the ACs. Station stability derived from our time-series analysis confirms, in general, the expected performance based on the careful technical review of the station components (antenna, pillar, etc.). The respective merits of our noise qualification method, based on direct time-series analysis in the time-eigenspace domain without any a priori statistical model, in comparison with other methods, such as the selection of a mixed-noise model by maximum likelihood estimation, are discussed. Copyright Springer Numéro de notice : A2006-535 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0088-y En ligne : https://doi.org/10.1007/s00190-006-0088-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28258
in Journal of geodesy > vol 80 n° 8-11 (November 2006) . - pp 541 - 565[article]Réservation
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Titre : Geocentre motion measured with DORIS and SLR, and predicted by geophysical models Type de document : Article/Communication Auteurs : Martine Feissel-Vernier, Auteur ; Karine Le Bail Année de publication : 2006 Article en page(s) : pp 637 - 648 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes descripteurs IGN] données TLS (télémétrie)
[Termes descripteurs IGN] géocentre
[Termes descripteurs IGN] géophysique interne
[Termes descripteurs IGN] positionnement par DORISRésumé : (Auteur) Geocentre motion signals measured by satellite geodesy and those predicted from the observed mass redistribution in the ocean, atmosphere and terrestrial waters over 1993.1–2003.0 are analysed and compared under two viewpoints: the amplitudes and phases of the seasonal components, and the spectral signature of the non-seasonal components. The geodetic signals partly match the geophysical variations in the seasonal band, with possible remaining annual and semi-annual errors in both techniques, at the millimetre level in the equatorial plane for Satellite laser ranging (SLR) and Doppler Orbitography and radiopositioning integrated on Satellite (DORIS), and at the centimetre level in T z (Z-axis translation) for DORIS. Unlike SLR, the DORIS annual signatures in all three geocentre components have strongly varying amplitudes after 1996. The amplitude of the annual geophysical signal in T y is slowly growing with time. All three geophysical fluids contribute to this effect. The magnitude of the geophysically derived long-term geocentre motion is of the same magnitude in the T x , T y and T z directions, with a 0.5–1.0 mm Allan standard deviation for the 1-year sampling time, while the geodetic values are 2 mm in the equatorial plane for both SLR and DORIS, 4 mm for SLR and 9 mm for DORIS in the T z direction. The mismatch of the geodetic signal with the geophysical one in the inter-annual band is suggested to be due partly to excessive geodetic noise and partly to underestimated geophysical signal. Numéro de notice : A2006-648 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0079-z En ligne : https://doi.org/10.1007/s00190-006-0079-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31334
in Journal of geodesy > vol 80 n° 8-11 (November 2006) . - pp 637 - 648[article]Réservation
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