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An inter-comparison of zenith tropospheric delays derived from DORIS and GPS data / Olivier Bock in Advances in space research, vol 46 n° 12 (15/12/2010)
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Titre : An inter-comparison of zenith tropospheric delays derived from DORIS and GPS data Type de document : Article/Communication Auteurs : Olivier Bock , Auteur ; Pascal Willis , Auteur ; Maïté Lacarra, Auteur ; Pierre Bosser , Auteur Année de publication : 2010 Article en page(s) : pp 1648 - 1660 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] analyse diachronique
[Termes IGN] antenne GPS
[Termes IGN] données DORIS
[Termes IGN] données GPS
[Termes IGN] erreur systématique
[Termes IGN] propagation troposphérique
[Termes IGN] station DORIS
[Termes IGN] station GPS
[Termes IGN] traitement du signal
[Termes IGN] variabilitéRésumé : (Auteur) Doppler Orbitography Radiopositioning Integrated by Satellite (DORIS) and Global Positioning System (GPS) techniques are similarly affected by propagation delays in the neutral atmosphere (troposphere) and hence make use of similar data processing strategies for reducing this effect. We compare Zenith Tropospheric Delays (ZTDs) estimated from 52 DORIS and GPS station pairs co-located at 35 sites over the 2005–2008 period. We find an overall systematic negative mean bias of -4 mm and a median bias of -2 mm, with a large site-to-site scatter and especially stronger biases over South America, potentially linked to remaining problems related to the South Atlantic Anomaly (SAA) in the current DORIS data processing. The standard deviation of ZTD differences is in the range 4–12 mm over the globe (8 mm on average), with larger values located in the southern hemisphere. The spatial variability of differences is consistent with previous work but remains largely unexplained. DORIS is shown to be much less sensitive to instrumental changes than GPS (only the switch from Alcatel to Starec antenna at Toulouse is detected as an offset of -4 mm in the ZTD time series). On the opposite, discontinuities and spurious annual signals are found in the GPS ZTD solutions. A discontinuity of +5 mm is found on 5 November 2006, linked to the switch from relative to absolute GPS antenna models used in the data processing. The use of modified GPS antennas (e.g. at GODE) or improved antenna models is shown to reduce the spurious annual signal (e.g. from 5 mm to 2 mm at METS). Overall, the agreement between both techniques is good, though DORIS shows a significantly larger random scatter. The high stability and good spatial and temporal coverage make DORIS a potential candidate technique for meteorology and climate studies as long as reasonable time averaging can be applied (e.g. differences are reduced from 8.6 to 2.4 mm with 5-day averages) and no real-time application is considered. This technique could be considered as a potential contributor to Global Geodetic Observing System (GGOS) for climatology. Numéro de notice : A2010-568 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2010.05.018 Date de publication en ligne : 21/05/2010 En ligne : https://doi.org/10.1016/j.asr.2010.05.018 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30760
in Advances in space research > vol 46 n° 12 (15/12/2010) . - pp 1648 - 1660[article]Analysis of the DORIS contributions to ITRF2008 / Detlef Angermann in Advances in space research, vol 46 n° 12 (15/12/2010)
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Titre : Analysis of the DORIS contributions to ITRF2008 Type de document : Article/Communication Auteurs : Detlef Angermann, Auteur ; Manuela Seitz, Auteur ; Hermann Drewes, Auteur Année de publication : 2010 Article en page(s) : pp 1633 - 1647 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] données DORIS
[Termes IGN] International DORIS Service
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] positionnement par DORIS
[Termes IGN] série temporelle
[Termes IGN] station DORISRésumé : (Auteur) In its function as an ITRS Combination Centre, DGFI is in charge with the computation of an ITRF2008 solution. The computation methodology of DGFI is based on the combination of datum-free normal equations (weekly or session data sets, respectively) of station positions and Earth orientation parameters (EOP) from the geodetic space techniques DORIS, GPS, SLR and VLBI. In this paper we focus on the DORIS part within the ITRF2008 computations. We present results obtained from the analysis of the DORIS time series for station positions, network translation and scale parameters, as well as for the terrestrial pole coordinates. The submissions to ITRF2008 benefit from improved analysis strategies of the seven contributing IDS analysis centres and from a combination of the weekly solutions of station positions and polar motion. The results show an improvement by a factor of two compared to past DORIS data submitted to ITRF2005, which has been evaluated by investigating the repeatabilities of position time series. The DORIS position time series were analysed w.r.t. discontinuities and other non-linear effects such as seasonal variations. About 40 discontinuities have been identified which have been compared with the results of an earlier study. Within the inter-technique combination we focus on the DORIS contribution to the integration of the different space geodetic observations and on a comparison of the geodetic local ties with the space geodetic solutions. Results are given for the 41 co-location sites between DORIS and GPS. Numéro de notice : A2010-567 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2010.07.018 En ligne : https://doi.org/10.1016/j.asr.2010.07.018 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30759
in Advances in space research > vol 46 n° 12 (15/12/2010) . - pp 1633 - 1647[article]DORIS/Jason-2: Better than 10 cm on-board orbits available for near-real-time altimetry / Christian Jayles in Advances in space research, vol 46 n° 12 (15/12/2010)
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Titre : DORIS/Jason-2: Better than 10 cm on-board orbits available for near-real-time altimetry Type de document : Article/Communication Auteurs : Christian Jayles, Auteur ; J.P. Chauveau, Auteur ; F. Rozo, Auteur Année de publication : 2010 Article en page(s) : pp 1497 - 1512 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales
[Termes IGN] altimétrie
[Termes IGN] DIODE (détermination d'orbite)
[Termes IGN] données DORIS
[Termes IGN] Jason
[Termes IGN] orbitographie
[Termes IGN] précision centimétrique
[Termes IGN] temps réel
[Termes IGN] trajectographie par DORISRésumé : (Auteur) DIODE (DORIS Immediate Orbit on-board Determination) is a real-time on-board orbit determination software, embedded in the DORIS receiver. The purpose of this paper is to focus on DIODE performances. After a description of the recent DORIS evolutions, we detail how compliance with specifications are verified during extensive ground tests before the launch, then during the in-flight commissioning phase just after the launch, and how well they are met in the routine phase and today. Future improvements are also discussed for Jason-2 as well as for the next missions. The complete DORIS ground validation using DORIS simulator and new DORIS test equipments has shown prior to the Jason-2 flight that every functional requirement was fulfilled, and also that better than 10 cm real-time DIODE orbits would be achieved on-board Jason-2. The first year of Jason-2 confirmed this, and after correction of a slowly evolving polar motion error at the end of the commissioning phase, the DIODE on-board orbits are indeed better than the 10 cm specification: in the beginning of the routine phase, the discrepancy was already 7.7 cm Root-Mean-Square (RMS) in the radial component as compared to the final Precise Orbit Ephemerides (POE) orbit. Since the first day of Jason-2 cycle 1, the real-time DIODE orbits have been delivered in the altimetry fast delivery products. Their accuracy and their 100% availability make them a key input to fairly precise Near-Real-Time Altimetry processing. Time-tagging is at the microsecond level. In parallel, a few corrections (quaternion problem) and improvements have been gathered in an enhanced version of DIODE, which is already implemented and validated. With this new version, a 5 cm radial accuracy is achieved during ground validation over more than Jason-2 first year (cycles 1–43, from July 12th, 2008 to September 11th, 2009). The Seattle Ocean Surface Topography Science Team Meeting (OSTST) has recommended an upload of this v4.02 version on-board Jason-2 in order to take benefit from more accurate real-time orbits. For the future, perhaps the most important point of this work is that a 9 mm consistency is observed on-ground between simulated and adjusted orbits, proving that the DORIS measurement is very precisely and properly modelled in the DIODE navigation software. This implies that improvement of DIODE accuracy is still possible and should be driven by enhancement of the physical models: forces and perturbations of the satellite movement, Radio/Frequency phenomena perturbing measurements. A 2-cm accuracy is possible with future versions, if analysis and model improvements continue to progress. Numéro de notice : A2010-563 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2010.04.030 En ligne : https://doi.org/10.1016/j.asr.2010.04.030 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30755
in Advances in space research > vol 46 n° 12 (15/12/2010) . - pp 1497 - 1512[article]IDS contribution to ITRF2008 / Jean-Jacques Valette in Advances in space research, vol 46 n° 12 (15/12/2010)
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Titre : IDS contribution to ITRF2008 Type de document : Article/Communication Auteurs : Jean-Jacques Valette, Auteur ; Franck G. Lemoine, Auteur ; Pascale Ferrage, Auteur ; Philippe Yaya, Auteur ; Zuheir Altamimi , Auteur ; Pascal Willis , Auteur ; Laurent Soudarin, Auteur Année de publication : 2010 Article en page(s) : pp 1614 - 1632 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse diachronique
[Termes IGN] correction troposphérique
[Termes IGN] données DORIS
[Termes IGN] DORIS
[Termes IGN] géocentre
[Termes IGN] International DORIS Service
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] modèle de géopotentiel
[Termes IGN] orbitographie
[Termes IGN] orientation de la TerreRésumé : (Auteur) For the first time, the International DORIS Service (IDS) has produced a technique level combination based on the contributions of seven analysis centers (ACs), including the European Space Operations Center (ESOC), Geodetic Observatory Pecny (GOP), Geoscience Australia (GAU), the NASA Goddard Space Flight Center (GSFC), the Institut Géographique National (IGN), the Institute of Astronomy, Russian Academy of Sciences (INASAN, named as INA), and CNES/CLS (named as LCA). The ACs used five different software packages to process the DORIS data from 1992 to 2008, including NAPEOS (ESA), Bernese (GOP), GEODYN (GAU, GSC), GIPSY/OASIS (INA), and GINS (LCA). The data from seven DORIS satellites, TOPEX/Poseidon, SPOT-2, SPOT-3, SPOT-4, SPOT-5, Envisat and Jason-1 were processed and all the analysis centers produced weekly SINEX files in either variance–covariance or normal equation format. The processing by the analysis centers used the latest GRACE-derived gravity models, forward modelling of atmospheric gravity, updates to the radiation pressure modelling to improve the DORIS geocenter solutions, denser parameterization of empirically determined drag coefficients to improve station and EOP solutions, especially near the solar maximum in 2001–2002, updated troposphere mapping functions, and an ITRF2005-derived station set for orbit determination, DPOD2005. The CATREF software was used to process the weekly AC solutions, and produce three iterations of an IDS global weekly combination. Between the development of the initial solution IDS-1, and the final solution, IDS-3, the ACs improved their analysis strategies and submitted updated solutions to eliminate troposphere-derived biases in the solution scale, to reduce drag-related degradations in station positioning, and to refine the estimation strategy to improve the combination geocenter solution. An analysis of the frequency content of the individual AC geocenter and scale solutions was used as the basis to define the scale and geocenter of the IDS-3 combination. The final IDS-3 combination has an internal position consistency (WRMS) that is 15 to 20 mm before 2002 and 8 to 10 mm after 2002, when 4 or 5 satellites contribute to the weekly solutions. The final IDS-3 combination includes solutions for 130 DORIS stations on 67 different sites of which 35 have occupations over 16 years (1993.0–2009.0). The EOPs from the IDS-3 combination were compared with the IERS 05 C04 time series and the RMS agreement was 0.24 mas and 0.35 mas for the X and Y components of polar motion. The comparison to ITRF2005 in station position shows an agreement of 6 to 8 mm RMS in horizontal and 10.3 mm in height. The RMS comparison to ITRF2005 in station velocity is at 1.8 mm/year on the East component, to 1.2 mm/year in North component and 1.6 mm/year in height. Numéro de notice : A2010-566 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2010.05.029 Date de publication en ligne : 02/06/2010 En ligne : https://doi.org/10.1016/j.asr.2010.05.029 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30758
in Advances in space research > vol 46 n° 12 (15/12/2010) . - pp 1614 - 1632[article]Refining DORIS atmospheric drag estimation in preparation of ITRF2008 / Marie-Line Gobinddass in Advances in space research, vol 46 n° 12 (15/12/2010)
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Titre : Refining DORIS atmospheric drag estimation in preparation of ITRF2008 Type de document : Article/Communication Auteurs : Marie-Line Gobinddass , Auteur ; Pascal Willis , Auteur ; Michel Menvielle, Auteur ; Michel Diament , Auteur Année de publication : 2010 Article en page(s) : pp 1566 - 1577 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] champ géomagnétique
[Termes IGN] données DORIS
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] modèle atmosphérique
[Termes IGN] mouvement du pôle
[Termes IGN] série temporelle
[Termes IGN] traitement du signalRésumé : (Auteur) In preparation of ITRF2008, all geodetic technique services (VLBI, SLR, GPS and DORIS) are generating new solutions based on combination of individual analysis centers solutions. These data reprocessing are based on a selection of models, parameterization and estimation strategy unique to each analysis center and to each technique. While a good agreement can be found for models between groups, thanks to the existence of the IERS conventions, a great diversity still exist for parameter estimation, allowing possible future improvements in this direction. The goal of this study is to focus on the atmospheric drag estimation used to generate the new DORIS/IGN ignwd08 time series prepared for ITRF2008. We develop here a method to inter-compare different processing strategies. In a first step, by analyzing single-satellite solutions for a few weeks of data but for a large number of possible analysis strategies, we demonstrate that estimating drag coefficient more frequently (typically every 1–2 h instead of previously every 4–8 h) for the lowest DORIS satellites (SPOTs and Envisat) provides better geodetic results for station coordinates and polar motion. This new processing strategy also solved earlier problem found when processing DORIS data during intense geomagnetic events, such as geomagnetic storms. Differences between drag estimation strategies can mostly be found during these few specific periods of extreme geomagnetic activity (few days per year). In such a case, when drag coefficient is only estimated every 6 h or less often for single-satellite solution, a significant degradation in station coordinate accuracy can be observed (120 mm vs. 20 mm) and significant biases arose in polar motion estimation (5 mas vs. 0.3 mas). In a second step, we reprocessed a full year of DORIS data (2003) in a standard multi-satellite mode. We were able to provide statistics on a more reliable data set and to strengthen these conclusions. Our proposed DORIS analysis is easy to implement in all software packages and is now already used by several analysis centers of the International DORIS Service (IDS) when submitting reprocessed solutions for ITRF2008. Numéro de notice : A2010-565 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2010.04.004 Date de publication en ligne : 09/04/2010 En ligne : https://doi.org/10.1016/j.asr.2010.04.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30757
in Advances in space research > vol 46 n° 12 (15/12/2010) . - pp 1566 - 1577[article]Towards development of a consistent orbit series for TOPEX, Jason-1, and Jason-2 / Franck G. Lemoine in Advances in space research, vol 46 n° 12 (15/12/2010)PermalinkContributions of the French Institut Géographique National (IGN) to the International DORIS Service / Pascal Willis in Advances in space research, vol 45 n° 12 (15/06/2010)PermalinkGSFC DORIS contribution to ITRF2008 / Karine Le Bail in Advances in space research, vol 45 n° 12 (15/06/2010)PermalinkQuality assessment of the IDS contribution to ITRF2008 / Zuheir Altamimi in Advances in space research, vol 45 n° 12 (15/06/2010)PermalinkThe crustal dynamics data information system: a resource to support scientific analysis using space geodesy / Carey E. Noll in Advances in space research, vol 45 n° 12 (15/06/2010)PermalinkThe international DORIS service (IDS): toward maturity / Pascal Willis in Advances in space research, vol 45 n° 12 (15/06/2010)PermalinkVertical crustalmotion derived from satellite altimetry and tide gauges, and comparisons with DORIS measurements / R. Ray in Advances in space research, vol 45 n° 12 (15/06/2010)PermalinkEtude des erreurs systématiques liées à la détermination du géocentre par les mesures DORIS / Marie-Line Gobinddass (2010)PermalinkPermalinkPermalink