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Termes IGN > sciences naturelles > sciences de la Terre et de l'univers > géosciences > géophysique interne > géodésie > géodésie physique > orientation de la Terre
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A global terrestrial reference frame from simulated VLBI and SLR data in view of GGOS / Susanne Glaser in Journal of geodesy, vol 91 n° 7 (July 2017)
[article]
Titre : A global terrestrial reference frame from simulated VLBI and SLR data in view of GGOS Type de document : Article/Communication Auteurs : Susanne Glaser, Auteur ; Rolf König, Auteur ; Dimitrios Ampatzidis, Auteur ; Tobias Nilsson, Auteur ; Robert Heinkelmann, Auteur ; Frank Flechtner, Auteur ; Harald Schuh, Auteur Année de publication : 2017 Article en page(s) : pp 723 - 733 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données ITGB
[Termes IGN] données TLS (télémétrie)
[Termes IGN] Global Geodetic Observing System
[Termes IGN] paramètres d'orientation de la Terre
[Termes IGN] point de liaison (géodésie)
[Termes IGN] repère de référence
[Termes IGN] simulationRésumé : (Auteur) In this study, we assess the impact of two combination strategies, namely local ties (LT) and global ties (GT), on the datum realization of Global Terrestrial Reference Frames in view of the Global Geodetic Observing System requiring 1 mm-accuracy. Simulated Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) data over a 7 year time span was used. The LT results show that the geodetic datum can be best transferred if the precision of the LT is at least 1 mm. Investigating different numbers of LT, the lack of co-located sites on the southern hemisphere is evidenced by differences of 9 mm in translation and rotation compared to the solution using all available LT. For the GT, the combination applying all Earth rotation parameters (ERP), such as pole coordinates and UT1-UTC, indicates that the rotation around the Z axis cannot be adequately transferred from VLBI to SLR within the combination. Applying exclusively the pole coordinates as GT, we show that the datum can be transferred with mm-accuracy within the combination. Furthermore, adding artificial stations in Tahiti and Nigeria to the current VLBI network results in an improvement in station positions by 13 and 12%, respectively, and in ERP by 17 and 11%, respectively. Extending to every day VLBI observations leads to 65% better ERP estimates compared to usual twice-weekly VLBI observations. Numéro de notice : A2017-295 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1021-2 En ligne : http://doi.org/10.1007/s00190-017-1021-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85330
in Journal of geodesy > vol 91 n° 7 (July 2017) . - pp 723 - 733[article]The extension of the parametrization of the radio source coordinates in geodetic VLBI and its impact on the time series analysis / Maria Karbon in Journal of geodesy, vol 91 n° 7 (July 2017)
[article]
Titre : The extension of the parametrization of the radio source coordinates in geodetic VLBI and its impact on the time series analysis Type de document : Article/Communication Auteurs : Maria Karbon, Auteur ; Robert Heinkelmann, Auteur ; Julian Mora-Diaz, Auteur ; Minghui Xu, Auteur ; Tobias Nilsson, Auteur ; Harald Schuh, Auteur Année de publication : 2017 Article en page(s) : pp 755 - 765 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données ITGB
[Termes IGN] fonction spline
[Termes IGN] interférométrie à très grande base
[Termes IGN] paramètres d'orientation de la Terre
[Termes IGN] régression multivariée par spline adaptative
[Termes IGN] repère de référence céleste
[Termes IGN] série temporelleRésumé : (Auteur) The radio sources within the most recent celestial reference frame (CRF) catalog ICRF2 are represented by a single, time-invariant coordinate pair. The datum sources were chosen mainly according to certain statistical properties of their position time series. Yet, such statistics are not applicable unconditionally, and also ambiguous. However, ignoring systematics in the source positions of the datum sources inevitably leads to a degradation of the quality of the frame and, therefore, also of the derived quantities such as the Earth orientation parameters. One possible approach to overcome these deficiencies is to extend the parametrization of the source positions, similarly to what is done for the station positions. We decided to use the multivariate adaptive regression splines algorithm to parametrize the source coordinates. It allows a great deal of automation, by combining recursive partitioning and spline fitting in an optimal way. The algorithm finds the ideal knot positions for the splines and, thus, the best number of polynomial pieces to fit the data autonomously. With that we can correct the ICRF2 a priori coordinates for our analysis and eliminate the systematics in the position estimates. This allows us to introduce also special handling sources into the datum definition, leading to on average 30 % more sources in the datum. We find that not only the CPO can be improved by more than 10 % due to the improved geometry, but also the station positions, especially in the early years of VLBI, can benefit greatly. Numéro de notice : A2017-296 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0954-1 En ligne : http://doi.org/10.1007/s00190-016-0954-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85331
in Journal of geodesy > vol 91 n° 7 (July 2017) . - pp 755 - 765[article]Multivariate analysis of GPS position time series of JPL second reprocessing campaign / Ali Reza Amiri-Simkooei in Journal of geodesy, vol 91 n° 6 (June 2017)
[article]
Titre : Multivariate analysis of GPS position time series of JPL second reprocessing campaign Type de document : Article/Communication Auteurs : Ali Reza Amiri-Simkooei, Auteur ; T.H. Mohammadloo, Auteur ; Donald F. Argus, Auteur Année de publication : 2017 Article en page(s) : pp 685 - 704 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse multivariée
[Termes IGN] bruit blanc
[Termes IGN] bruit rose
[Termes IGN] campagne GPS
[Termes IGN] centre de phase
[Termes IGN] coordonnées GPS
[Termes IGN] série temporelle
[Termes IGN] terme de Chandler
[Vedettes matières IGN] Traitement de données GNSSRésumé : (Auteur) The second reprocessing of all GPS data gathered by the Analysis Centers of IGS was conducted in late 2013 using the latest models and methodologies. Improved models of antenna phase center variations and solar radiation pressure in JPL’s reanalysis are expected to significantly reduce errors. In an earlier work, JPL estimates of position time series, termed first reprocessing campaign, were examined in terms of their spatial and temporal correlation, power spectra, and draconitic signal. Similar analyses are applied to GPS time series at 89 and 66 sites of the second reanalysis with the time span of 7 and 21 years, respectively, to study possible improvements. Our results indicate that the spatial correlations are reduced on average by a factor of 1.25. While the white and flicker noise amplitudes for all components are reduced by 29–56 %, the random walk amplitude is enlarged. The white, flicker, and random walk noise amount to rate errors of, respectively, 0.01, 0.12, and 0.09 mm/yr in the horizontal and 0.04, 0.41 and 0.3 mm/yr in the vertical. Signals reported previously, such as those with periods of 13.63, 14.76, 5.5, and 351.4 / n for n=1,2,…,8 days, are identified in multivariate spectra of both data sets. The oscillation of the draconitic signal is reduced by factors of 1.87, 1.87, and 1.68 in the east, north and up components, respectively. Two other signals with Chandlerian period and a period of 380 days can also be detected. Numéro de notice : A2017-297 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0991-9 En ligne : http://dx.doi.org/10.1007/s00190-016-0991-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85328
in Journal of geodesy > vol 91 n° 6 (June 2017) . - pp 685 - 704[article]GRACE era variability in the Earth's oblateness: a comparison of estimates from six different sources / Thierry Meyrath in Geophysical journal international, vol 208 n° 2 (February 2017)
[article]
Titre : GRACE era variability in the Earth's oblateness: a comparison of estimates from six different sources Type de document : Article/Communication Auteurs : Thierry Meyrath, Auteur ; Paul Rebischung , Auteur ; Tonie M. van Dam, Auteur Année de publication : 2017 Projets : 1-Pas de projet / Article en page(s) : pp 1126 - 1138 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] données GRACE
[Termes IGN] données TLS (télémétrie)
[Termes IGN] gravimétrie spatiale
[Termes IGN] longueur du jour
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] rotation de la Terre
[Termes IGN] série temporelleRésumé : (auteur) We study fluctuations in the degree-2 zonal spherical harmonic coefficient of the Earth's gravity potential, C20, over the period 2003–2015. This coefficient is related to the Earth's oblateness and studying its temporal variations, ΔC20, can be used to monitor large-scale mass movements between high and low latitude regions. We examine ΔC20 inferred from six different sources, including satellite laser ranging (SLR), GRACE and global geophysical fluids models. We further include estimates that we derive from measured variations in the length-of-day (LOD), from the inversion of global crustal displacements as measured by GPS, as well as from the combination of GRACE and the output of an ocean model as described by Sun et al. We apply a sequence of trend and seasonal moving average filters to the different time-series in order to decompose them into an interannual, a seasonal and an intraseasonal component. We then perform a comparison analysis for each component, and we further estimate the noise level contained in the different series using an extended version of the three-cornered-hat method. For the seasonal component, we generally obtain a very good agreement between the different sources, and except for the LOD-derived series, we find that over 90 per cent of the variance in the seasonal components can be explained by the sum of an annual and semiannual oscillation of constant amplitudes and phases, indicating that the seasonal pattern is stable over the considered time period. High consistency between the different estimates is also observed for the intraseasonal component, except for the solution from GRACE, which is known to be affected by a strong tide-like alias with a period of about 161 d. Estimated interannual components from the different sources are generally in agreement with each other, although estimates from GRACE and LOD present some discrepancies. Slight deviations are further observed for the estimate from the geophysical models, likely to be related to the omission of polar ice and groundwater changes in the model combination we use. On the other hand, these processes do not seem to play an important role at seasonal and shorter timescales, as the sum of modelled atmospheric, oceanic and hydrological effects effectively explains the observed C20 variations at those scales. We generally obtain very good results for the solution from SLR, and we confirm that this well-established technique accurately tracks changes in C20. Good agreement is further observed for the estimate from the GPS inversion, showing that this indirect method is successful in capturing fluctuations in C20 on scales ranging from intra- to interannual. Obtaining accurate estimates from LOD, however, remains a challenging task and more reliable models of atmospheric wind fields are needed in order to obtain high-quality ΔC20, in particular at the seasonal scale. The combination of GRACE data and the output of an ocean model appears to be a promising approach, particularly since corresponding ΔC20 is not affected by tide-like aliases, and generally gives better results than the solution from GRACE, which still seems to be of rather poor quality. Numéro de notice : A2017-863 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/gji/ggw441 Date de publication en ligne : 24/11/2016 En ligne : https://doi.org/10.1093/gji/ggw441 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89852
in Geophysical journal international > vol 208 n° 2 (February 2017) . - pp 1126 - 1138[article]On the consistency of the current conventional EOP series and the celestial and terrestrial reference frames / Santiago Belda in Journal of geodesy, vol 91 n° 2 (February 2017)
[article]
Titre : On the consistency of the current conventional EOP series and the celestial and terrestrial reference frames Type de document : Article/Communication Auteurs : Santiago Belda, Auteur ; Robert Heinkelmann, Auteur ; José M. Ferrándiz,, Auteur ; Tobias Nilsson, Auteur Année de publication : 2017 Article en page(s) : pp 135 - 149 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] erreur systématique
[Termes IGN] interférométrie à très grande base
[Termes IGN] International Earth Rotation Service
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] orientation de la Terre
[Termes IGN] repère de référence céleste
[Termes IGN] rotation de la Terre
[Termes IGN] série temporelleRésumé : (Auteur) Precise transformation between the celestial reference frames (CRF) and terrestrial reference frames (TRF) is needed for many purposes in Earth and space sciences. According to the Global Geodetic Observing System (GGOS) recommendations, the accuracy of positions and stability of reference frames should reach 1 mm and 0.1 mm year−1, and thus, the Earth Orientation Parameters (EOP) should be estimated with similar accuracy. Different realizations of TRFs, based on the combination of solutions from four different space geodetic techniques, and CRFs, based on a single technique only (VLBI, Very Long Baseline Interferometry), might cause a slow degradation of the consistency among EOP, CRFs, and TRFs (e.g., because of differences in geometry, orientation and scale) and a misalignment of the current conventional EOP series, IERS 08 C04. We empirically assess the consistency among the conventional reference frames and EOP by analyzing the record of VLBI sessions since 1990 with varied settings to reflect the impact of changing frames or other processing strategies on the EOP estimates. Our tests show that the EOP estimates are insensitive to CRF changes, but sensitive to TRF variations and unmodeled geophysical signals at the GGOS level. The differences between the conventional IERS 08 C04 and other EOP series computed with distinct TRF settings exhibit biases and even non-negligible trends in the cases where no differential rotations should appear, e.g., a drift of about 20 μas year−1in ypol when the VLBI-only frame VTRF2008 is used. Likewise, different strategies on station position modeling originate scatters larger than 150 μas in the terrestrial pole coordinates. Numéro de notice : A2017-061 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0944-3 En ligne : http://dx.doi.org/10.1007/s00190-016-0944-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84273
in Journal of geodesy > vol 91 n° 2 (February 2017) . - pp 135 - 149[article]Les références de temps et d'espace / Claude Boucher (2017)PermalinkThe International DORIS Service contribution to the 2014 realization of the International Terrestrial Reference Frame / Guilhem Moreaux in Advances in space research, vol 58 n° 12 (15 December 2016)PermalinkComplex demodulation in monitoring earth rotation by VLBI: testing the algorithm by analysis of long periodic EOP components / Agata Wielgosz in Artificial satellites, vol 51 n° 4 (December 2016)PermalinkUltra short-term prediction of pole coordinates via combination of empirical mode decomposition and neural networks / Yu Lei in Artificial satellites, vol 51 n° 4 (December 2016)PermalinkHigh-frequency Earth rotation variations deduced from altimetry-based ocean tides / Matthias Madzak in Journal of geodesy, vol 90 n° 11 (November 2016)PermalinkTesting impact of the strategy of VLBI data analysis on the estimation of Earth Orientation Parameters and station coordinates / Agata Wielgosz in Reports on geodesy and geoinformatics, vol 101 (June 2016)PermalinkCODE’s new ultra-rapid orbit and ERP products for the IGS / Simon Lutz in GPS solutions, vol 20 n° 2 (April 2016)PermalinkImpact of the arc length on GNSS analysis results / Simon Lutz in Journal of geodesy, vol 90 n° 4 (April 2016)PermalinkElliptic polarisation of the polar motion excitation / Christian Bizouard in Journal of geodesy, vol 90 n° 2 (February 2016)PermalinkCaractérisation des signaux et des bruits des séries temporelles du géocentre et des paramètres de rotation de la Terre (EOP) / Bachir Gourine in Bulletin des sciences géographiques, n° 30 (2015 - 2016)PermalinkThe International DORIS Service (IDS) : Recent developments in preparation for ITRF2013 / Pascal Willis (2016)PermalinkTrouver le Nord / Olivier Le Carrer (2016)PermalinkEarth rotation and geodynamics / Janusz Bogusz in Geodesy and cartography, vol 64 n° 2 (December 2015)PermalinkRevisiting the pole tide for and from satellite altimetry / Shailen Desai in Journal of geodesy, vol 89 n° 12 (december 2015)PermalinkPermalinkCODE’s new solar radiation pressure model for GNSS orbit determination / Daniel Arnold in Journal of geodesy, vol 89 n° 8 (August 2015)PermalinkSeparation of atmospheric, oceanic and hydrological polar motion excitation mechanisms based on a combination of geometric and gravimetric space observations / F. Göttl in Journal of geodesy, vol 89 n° 4 (April 2015)PermalinkDetermination of precise satellite orbits and geodetic parameters using satellite laser ranging / Krzysztof Sosnica (2015)PermalinkEarth orientation parameters estimated from VLBI during the CONT11 campaign / Tobias Nilsson in Journal of geodesy, vol 88 n° 5 (May 2014)PermalinkPermalink