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Auteur Manuela Seitz |
Documents disponibles écrits par cet auteur (7)
Ajouter le résultat dans votre panier Affiner la recherche Interroger des sources externesBenefits of non-tidal loading applied at distinct levels in VLBI analysis / Matthias Glomsda in Journal of geodesy, vol 94 n° 9 (September 2020)
Titre : Benefits of non-tidal loading applied at distinct levels in VLBI analysis Type de document : Article/Communication Auteurs : Matthias Glomsda, Auteur ; Mathis Blossfeld, Auteur ; Manuela Seitz, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : n° 90 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données ITGB
[Termes IGN] effet de charge
[Termes IGN] interférométrie à très grande base
[Termes IGN] pesanteur hors marée
[Termes IGN] retard troposphérique
[Termes IGN] série temporelle
[Termes IGN] surcharge hydrologique
[Termes IGN] surcharge océanique
[Termes IGN] transformation de HelmertRésumé : (auteur) In the analysis of very long baseline interferometry (VLBI) observations, many geophysical models are used for correcting the theoretical signal delay. In addition to the conventional models described by Petit and Luzum (eds) (IERS Conventions, 2010), we are applying different parts of non-tidal site loading, namely the atmospheric, oceanic, and hydrological ones. To investigate their individual contributions, these parts are considered both separately and combined to a total loading. The application of the corresponding site displacements is performed at two distinct levels of the geodetic parameter estimation process (observation and normal equation level), which turn out to give very similar results in many cases. To validate our findings internally, the site displacements are provided by two different data centres: the Earth-System-Modelling group at the Deutsches GeoForschungsZentrum in Potsdam (ESMGFZ, see Dill and Dobslaw, J Geophys Res Solid Earth, 2013. https://doi.org/10.1002/jgrb.50353ISTEX)] and the International Mass Loading Service [IMLS, see Petrov (The international mass loading service, 2015)]. We show that considering non-tidal loading is actually useful for mitigating systematic effects in the VLBI results, like annual signals in the station height time series. If the sum of all non-tidal loading parts is considered, the WRMS of the station heights and baseline lengths is reduced in 80–90% of all cases, and the relative improvement is about −3.5% on average. The main differences between our chosen providers originate from hydrological loading. Numéro de notice : A2020-540 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01418-z Date de publication en ligne : 31/08/2020 En ligne : https://doi.org/10.1007/s00190-020-01418-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95741
in Journal of geodesy > vol 94 n° 9 (September 2020) . - n° 90[article]
Titre : Influence of subdaily model for polar motion on the estimated GPS satellite orbits Type de document : Article/Communication Auteurs : Natalia Panafidina, Auteur ; Urs Hugentobler, Auteur ; Manuela Seitz, Auteur Année de publication : 2019 Article en page(s) : pp 229 - 240 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse diachronique
[Termes IGN] élément orbital
[Termes IGN] erreur systématique
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] marée océanique
[Termes IGN] mouvement du géocentre
[Termes IGN] mouvement du pôle
[Termes IGN] orbite
[Termes IGN] positionnement par GPS
[Termes IGN] rotation de la Terre
[Termes IGN] satellite GPS
[Termes IGN] traitement du signalRésumé : (auteur) In this contribution, it is shown that GPS orbits are able to absorb some diurnal signals in polar motion. The arising implications for the influence of the subdaily pole model on GPS solutions are discussed. Two signals in polar motion can be absorbed by GPS orbits: a retrograde signal with a period of a sidereal day (23 h 56 min 4 s) and a prograde signal with a period matching the revolution period of the GPS satellites in the terrestrial reference frame (23 h 55 min 56 s). We show that the retrograde signal contributes to the absolute orientation of the orbital planes in space and the prograde signal, due to coincidence of its period with the period of revolution of the GPS satellites, contributes to the position of the geocenter for each individual satellite. It is known from previous studies that there are systematic differences between orbital parameters from GPS solutions computed with different subdaily pole models. We show in this paper that this behavior can be explained by the absorption effects in 1-day GPS orbits. Diurnal signals cannot be spectrally separated over a time interval of 1 day. Adjustment of any diurnal prograde or retrograde signal to a subdaily pole time series given by a subdaily model over 24 h will lead to an estimated signal with a nonzero amplitude. Thus, any subdaily pole model used in the processing of space geodetic observations contains a part which corresponds numerically to the discussed prograde signal and a part which corresponds to the retrograde diurnal signal. Different pole models show different amplitudes of the diurnal signals which will be absorbed by the orbits. As a result, GPS orbits computed with different subdaily pole models have systematically different orientation and position in space. Using 1-day GPS solutions over a time span of 13 years (1994–2007), we show that the systematic variations in orbit position and orientation caused by individual tidal terms in polar motion can be well predicted and explained by the suggested mechanism. Numéro de notice : A2019-080 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1153-z Date de publication en ligne : 24/05/2018 En ligne : https://doi.org/10.1007/s00190-018-1153-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92198
in Journal of geodesy > vol 93 n° 2 (February 2019) . - pp 229 - 240[article]
Titre : Consistent realization of celestial and terrestrial reference frames Type de document : Article/Communication Auteurs : Younghee Kwak, Auteur ; Mathis Blossfeld, Auteur ; Ralf Schmid, Auteur ; Detlef Angermann, Auteur ; Michael Gerstl, Auteur ; Manuela Seitz, Auteur Année de publication : 2018 Article en page(s) : pp 1047 - 1061 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] cohérence des données
[Termes IGN] erreur systématique inter-systèmes
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] paramètres d'orientation de la Terre
[Termes IGN] point de liaison (géodésie)
[Termes IGN] système de référence célesteRésumé : (Auteur) The Celestial Reference System (CRS) is currently realized only by Very Long Baseline Interferometry (VLBI) because it is the space geodetic technique that enables observations in that frame. In contrast, the Terrestrial Reference System (TRS) is realized by means of the combination of four space geodetic techniques: Global Navigation Satellite System (GNSS), VLBI, Satellite Laser Ranging (SLR), and Doppler Orbitography and Radiopositioning Integrated by Satellite. The Earth orientation parameters (EOP) are the link between the two types of systems, CRS and TRS. The EOP series of the International Earth Rotation and Reference Systems Service were combined of specifically selected series from various analysis centers. Other EOP series were generated by a simultaneous estimation together with the TRF while the CRF was fixed. Those computation approaches entail inherent inconsistencies between TRF, EOP, and CRF, also because the input data sets are different. A combined normal equation (NEQ) system, which consists of all the parameters, i.e., TRF, EOP, and CRF, would overcome such an inconsistency. In this paper, we simultaneously estimate TRF, EOP, and CRF from an inter-technique combined NEQ using the latest GNSS, VLBI, and SLR data (2005–2015). The results show that the selection of local ties is most critical to the TRF. The combination of pole coordinates is beneficial for the CRF, whereas the combination of ΔUT1 results in clear rotations of the estimated CRF. However, the standard deviations of the EOP and the CRF improve by the inter-technique combination which indicates the benefits of a common estimation of all parameters. It became evident that the common determination of TRF, EOP, and CRF systematically influences future ICRF computations at the level of several μas. Moreover, the CRF is influenced by up to 50 μas if the station coordinates and EOP are dominated by the satellite techniques. Numéro de notice : A2018-458 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1130-6 Date de publication en ligne : 12/03/2018 En ligne : https://doi.org/10.1007/s00190-018-1130-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91055
in Journal of geodesy > vol 92 n° 9 (September 2018) . - pp 1047 - 1061[article]
Titre : The 2008 DGFI realization of the ITRS: DTRF2008 Type de document : Article/Communication Auteurs : Manuela Seitz, Auteur ; Detlef Angermann, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 1097 - 1123 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] Institut national de l'information géographique et forestière (France)
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] International Terrestrial Reference System
[Termes IGN] station permanente
[Termes IGN] système de positionnement par satellitesRésumé : (Auteur) A new realization of the International Terrestrial System was computed at the ITRS Combination Centre at DGFI as a contribution to ITRF2008. The solution is labelled DTRF2008. In the same way as in the DGFI computation for ITRF2005 it is based on either normal equation systems or estimated parameters derived from VLBI, SLR, GPS and DORIS observations by weekly or session-wise processing. The parameter space of the ITRS realization comprises station positions and velocities and daily resolved Earth Orientation Parameters (EOP), whereby for the first time also nutation parameters are included. The advantage of starting from time series of input data is that the temporal behaviour of geophysical parameters can be investigated to decide whether the parameters can contribute to the datum realization of the ITRF. In the same way, a standardized analysis of station position time series can be performed to detect and remove discontinuities. The advantage of including EOP in the ITRS realization is twofold: (1) the combination of the coordinates of the terrestrial pole—estimated from all contributing techniques—links the technique networks in two components of the orientation, leading to an improvement of consistency of the Terrestrial Reference Frame (TRF) and (2) in their capacity as parameters common to all techniques, the terrestrial pole coordinates enhance the selection of local ties as they provide a measure for the consistency of the combined frame. The computation strategy of DGFI is based on the combination of normal equation systems while at the ITRS Combination Centre at IGN solutions are combined. The two independent ITRS realizations provide the possibility to assess the accuracy of ITRF by comparison of the two frames. The accuracy evaluation was done separately for the datum parameters (origin, orientation and scale) and the network geometry. The accuracy of the datum parameters, assessed from the comparison of DTRF2008 and ITRF2008, is between 2–5 mm and 0.1–0.8 mm/year depending on the technique. The network geometry (station positions and velocities) agrees within 3.2 mm and 1.0 mm/year. A comparison of DTRF2008 and ITRF2005 provides similar results for the datum parameters, but there are larger differences for the network geometry. The internal accuracy of DTRF2008—that means the level of conservation of datum information and network geometry within the combination—was derived from comparisons with the technique-only multi-year solutions. From this an internal accuracy of 0.32 mm for the VLBI up to 3.3 mm for the DORIS part of the network is found. The internal accuracy of velocities ranges from 0.05 mm/year for VLBI to 0.83 mm/year for DORIS. The internal consistency of DTRF2008 for orientation can be derived from the analysis of the terrestrial pole coordinates. It is estimated at 1.5–2.5 mm for the GPS, VLBI and SLR parts of the network. The consistency of these three and the DORIS network part is within 6.5 mm. Numéro de notice : A2012-650 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0567-2 Date de publication en ligne : 04/05/2012 En ligne : https://doi.org/10.1007/s00190-012-0567-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32096
in Journal of geodesy > vol 86 n° 12 (December 2012) . - pp 1097 - 1123[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2012121 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : Combination of different space-geodetic observations for regional ionosphere modeling Type de document : Article/Communication Auteurs : D. Dettmering, Auteur ; M. Schmidt, Auteur ; Robert Heinkelmann, Auteur ; Manuela Seitz, Auteur Année de publication : 2011 Article en page(s) : pp 989 - 998 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse combinatoire (maths)
[Termes IGN] B-Spline
[Termes IGN] correction ionosphérique
[Termes IGN] ionosphère
[Termes IGN] modèle ionosphérique
[Termes IGN] teneur totale en électronsRésumé : (Auteur) Most of the space-geodetic observation techniques can be used for modeling the distribution of free electrons in the Earth’s ionosphere. By combining different techniques one can take advantage of their different spatial and temporal distributions as well as their different observation characteristics and sensitivities concerning ionospheric parameter estimation. The present publication introduces a procedure for multi-dimensional ionospheric modeling. The model consists of a given reference part and an unknown correction part expanded in terms of B-spline functions. This approach is used to compute regional models of Vertical Total Electron Content (VTEC) based on the International Reference Ionosphere (IRI 2007) and GPS observations from terrestrial Global Navigation Satellite System (GNSS) reference stations, radio occultation data from Low Earth Orbiters (LEOs), dual-frequency radar altimetry measurements, and data obtained by Very Long Baseline Interferometry (VLBI). The approach overcomes deficiencies in the climatological IRI model and reaches the same level of accuracy than GNSS-based VTEC maps from IGS. In areas without GNSS observations (e.g., over the oceans) radio occultations and altimetry provide valuable measurements and further improve the VTEC maps. Moreover, the approach supplies information on the offsets between different observation techniques as well as on their different sensitivity for ionosphere modeling. Altogether, the present procedure helps to derive improved ionospheric corrections (e.g., for one-frequency radar altimeters) and at the same time it improves our knowledge on the Earth’s ionosphere. Numéro de notice : A2011-504 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0423-1 Date de publication en ligne : 10/11/2011 En ligne : https://doi.org/10.1007/s00190-010-0423-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31398
in Journal of geodesy > vol 85 n° 12 (December 2011) . - pp 989 - 998[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2011121 RAB Revue Centre de documentation En réserve L003 Disponible PermalinkPermalink
