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Estimating horizontal tropospheric gradients in DORIS data processing: preliminary results / Pascal Willis (2012)
Titre : Estimating horizontal tropospheric gradients in DORIS data processing: preliminary results Type de document : Article/Communication Auteurs : Pascal Willis , Auteur ; Yoaz E. Bar-Sever, Auteur ; Olivier Bock , Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2012 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 136 Conférence : IAG 2009 Symposium, Geodesy for Planet Earth 31/08/2009 04/09/2009 Buenos Aires Argentine Proceedings Springer Importance : pp 1013 - 1019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données DORIS
[Termes IGN] gradient de troposphère
[Termes IGN] orbitographie
[Termes IGN] positionnement ponctuel précis
[Termes IGN] retard troposphériqueRésumé : (auteur) Estimating horizontal tropospheric gradients is a common practice in VLBI and GPS data analyses. We investigate here the possibility to do the same for DORIS. We reprocessed all 2007 DORIS data for all satellites, using exactly the same strategy as the latest ignwd08 solution (Willis et al., Adv Space Res 45(12):1470–1480, 2010) but adding two new parameters per day to account for any asymmetry of the tropospheric delays. When averaged over the full year the DORIS north gradient estimates show a significant correlation with GPS estimates at 33 co-located sites. The east gradient is loosely determined with DORIS due to the north-south orientation of the satellites passes in 2007. Typical values are below 1 mm and North component shows a latitude dependency, negative values in the Northern hemisphere and positive values in the Southern hemisphere. The stacking of DORIS station weekly coordinates provides a more realistic value for a factor of unit weight when done using gradient estimation. Station coordinates also indicate a small improvement in internal consistency when compared to a 1-year position and velocity solution without estimating gradients. The DORIS-derived tropospheric gradients may still absorb other types of un-modeled errors, but estimation of such parameters should be investigated in more detail before reprocessing the entire DORIS data set in view of the next ITRF realization, following ITRF2008. Numéro de notice : C2009-034 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-20338-1_127 Date de publication en ligne : 26/07/2011 En ligne : https://doi.org/10.1007/978-3-642-20338-1_127 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91512 Flexible dataset combination and modelling by domain decomposition approaches / Isabelle Panet (2012)
Titre : Flexible dataset combination and modelling by domain decomposition approaches Type de document : Article/Communication Auteurs : Isabelle Panet , Auteur ; Yuki Kuroishi, Auteur ; Matthias Holschneider, Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2012 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 137 Projets : 2-Pas d'info accessible - article non ouvert / Conférence : IAG 2009, 7th Hotine-Marussi Symposium on Mathematical Geodesy 06/06/2009 10/06/2009 Rome Italie Proceedings Springer Importance : pp 67 - 73 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] compensation par moindres carrés
[Termes IGN] erreur systématique
[Termes IGN] filtrage du bruit
[Termes IGN] Japon
[Termes IGN] modèle de géopotentiel
[Termes IGN] modèle de géopotentiel local
[Termes IGN] ondelette
[Termes IGN] ondelette d'Abel-Poisson
[Termes IGN] transformation en ondelettesRésumé : (auteur) For geodetic and geophysical purposes, such as geoid determination or the study of the Earth’s structure, heterogeneous gravity datasets of various origins need to be combined over an area of interest, in order to derive a local gravity model at the highest possible resolution. The quality of the obtained gravity model strongly depends on the use of appropriate noise models for the different datasets in the combination process. In addition to random errors, those datasets are indeed often affected by systematic biases and correlated errors. Here we show how wavelets can be used to realize such combination in a flexible and economic way, and how the use of domain decomposition approaches allows to recalibrate the noise models in different wavebands and for different areas. We represent the gravity potential as a linear combination of Poisson multipole wavelets (Holschneider et al. 2003). We compute the wavelet model of the gravity field by regularized least-squares adjustment of the datasets. To solve the normal system, we apply the Schwarz iterative algorithms, based on a domain decomposition of the models space. Hierarchical scale subdomains are defined as subsets of wavelets at different scales, and for each scale, block subdomains are defined based on spatial splittings of the area. In the computation process, the data weights can be refined for each subdomain, allowing to take into account the effect of correlated noises in a simple way. Similarly, the weight of the regularization can be recalibrated for each subdomain, introducing non-stationarity in the a priori assumption of smoothness of the gravity field. We show and discuss examples of application of this method for regional gravity field modelling over a test area in Japan. Numéro de notice : C2009-035 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-22078-4_10 Date de publication en ligne : 18/11/2011 En ligne : https://doi.org/10.1007/978-3-642-22078-4_10 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91642 Improved GPS data analysis strategy for tide gauge benchmark monitoring / Alvaro Santamaria Gomez (2012)
Titre : Improved GPS data analysis strategy for tide gauge benchmark monitoring Type de document : Article/Communication Auteurs : Alvaro Santamaria Gomez, Auteur ; Marie-Noëlle Bouin , Auteur ; Guy Wöppelmann , Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2012 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 136 Conférence : IAG 2009 Symposium, Geodesy for Planet Earth 31/08/2009 04/09/2009 Buenos Aires Argentine Proceedings Springer Importance : pp 11 - 18 Format : 16 x 24 cm Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] International GNSS Service
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] niveau de la merRésumé : (auteur) The University of La Rochelle (ULR) TIGA Analysis Center (TAC) completed a new global reprocessed solution spanning 13 years with more than 300 GPS permanent stations, 216 of them being co-located with tide gauges. A state-of-the-art GPS processing strategy was applied, in particular, the station sub-networks used in the daily processing were optimally built. Station vertical velocities were estimated in the ITRF2005 reference frame by stacking the weekly position estimates. Outliers, offsets and discontinuities in time series were carefully examined. Vertical velocities uncertainties were assessed in a realistic way by analysing the type and amplitude of the noise content in the residual position time series. The comparison shows that the velocity uncertainties have been reduced by a factor of 2 with respect to previous ULR solutions. The analysis of this solution and its by-products shows the high geodetic quality achieved in terms of homogeneity, precision and consistency with respect to other top-level geodetic solutions. Numéro de notice : C2009-059 Affiliation des auteurs : LAREG (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-20338-1_2 En ligne : https://doi.org/10.1007/978-3-642-20338-1_2 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101475 Ocean Loading in Brittany, Northwest France: Impact of the GPS Analysis Strategy / Joëlle Nicolas (2012)
Titre : Ocean Loading in Brittany, Northwest France: Impact of the GPS Analysis Strategy Type de document : Article/Communication Auteurs : Joëlle Nicolas, Auteur ; Stéphane Durand, Auteur ; Mathilde Vergnolle, Auteur ; Laurent Morel, Auteur ; Stavros A. Melachroinos, Auteur ; Marie-Noëlle Bouin , Auteur ; François Fund, Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2012 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 137 Conférence : IAG 2009, 7th Hotine-Marussi Symposium on Mathematical Geodesy 06/06/2009 10/06/2009 Rome Italie Proceedings Springer Importance : pp 367 - 372 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse comparative
[Termes IGN] Bernese
[Termes IGN] GAMIT
[Termes IGN] GINS
[Termes IGN] GIPSY-OASIS
[Termes IGN] surcharge océaniqueRésumé : (auteur) In this contribution, we analyze the impact of different GPS processing strategies on ocean tide loading estimation. We use continuous GPS data acquired during a 4-month campaign performed in 2004 in Brittany, Northwest France. Since the expected geodynamical signal in the estimated positions is exceeding the typical GPS data analysis noise, this data set can be used to compare the results obtained with different analysis software packages. Moreover, in this specific case we need short sub-daily solutions to study short-period signals instead of classical 24 h-solutions. The GPS capability for measuring 3D ocean tide loading deformation has already been assessed, but since we are looking for the finest signal as the one induced by the shallow water constituents, it is essential to be sure that the position time series represent a geodynamical signal and are not biased by the data processing strategy used. To analyze the possible effect of the methodology used on the geodynamical results, we compare different solutions computed with different strategies (Double Differencing and Precise Point Positioning) with various GPS analysis software packages (Bernese, GAMIT, GINS, and GIPSY/OASIS). We show that the different solution consistency is at the level of 1–3 mm. We also show that the data processing strategy has a mean effect of about 10–20% of the ocean tide loading signal amplitude. Numéro de notice : C2009-001 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-22078-4_55 Date de publication en ligne : 18/10/2011 En ligne : https://doi.org/10.1007/978-3-642-22078-4_55 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102737 Recent improvements in DORIS data processing at IGN in view of ITRF2008, the IGNWD08 Solution / Pascal Willis (2012)
Titre : Recent improvements in DORIS data processing at IGN in view of ITRF2008, the IGNWD08 Solution Type de document : Article/Communication Auteurs : Pascal Willis , Auteur ; Marie-Line Gobinddass , Auteur ; Bruno Garayt , Auteur ; Hervé Fagard, Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2012 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 136 Conférence : IAG 2009 Symposium, Geodesy for Planet Earth 31/08/2009 04/09/2009 Buenos Aires Argentine Proceedings Springer Importance : pp 43 - 49 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] chaîne de traitement
[Termes IGN] données DORIS
[Termes IGN] Institut géographique national (France)
[Termes IGN] International Terrestrial Reference FrameRésumé : (auteur) In preparation for the computation of ITRF2008, the DORIS IGN analysis center has undertaken the task of a complete reprocessing of all DORIS data from 1993.0 to 2009.0, using all available DORIS data as well as the most recent models and estimation strategies. We provide here a detailed description of the major improvements recently made in the DORIS data processing, mainly in terms of solar radiation pressure, atmospheric drag, gravity field, and tropospheric correction. We address here the impact of the new IGN time series (ignwd08) on geodetic products using comparison to the previous IGN solutions (ignwd04). In particular, previous artifacts, such as 118-day or 1-year periodic errors in the TZ-geocenter solution or in the vertical component of high latitude DORIS tracking stations, have now disappeared, leading to more precise and reliable time series of DORIS station coordinates. Finally, possible future improvements are discussed proposing new investigations for the future. Numéro de notice : C2009-031 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-20338-1_6 Date de publication en ligne : 26/07/2011 En ligne : https://doi.org/10.1007/978-3-642-20338-1_6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91513 PermalinkPermalinkAssessment of a numerical method for computing the spherical harmonic coefficients of the gravitational potential of a constant density polyhedron / Olivier Jamet (2010)PermalinkGravity, Geoid and Earth Observation, IAG Commission 2 Gravity Field, Chania, Crete, Greece, 23-27 June 2008 / Stelios Mertikas (2010)PermalinkPermalinkPermalinkImpact of the network effect on the origin and scale: case study of Satellite Laser Ranging / Xavier Collilieux (2009)PermalinkPermalinkPermalinkPermalink