Détail de l'auteur
Auteur Pascal Willis
Commentaire :
Autorités liées :
idHAL :
pascal-willis
idRef :
autre URL :
ORCID :
Scopus :
|
Documents disponibles écrits par cet auteur (196)
Ajouter le résultat dans votre panier
Visionner les documents numériques
Affiner la recherche Interroger des sources externes
Calibration of wet tropospheric delays in GPS observation using Raman lidar measurements / Pierre Bosser (2012)
Titre : Calibration of wet tropospheric delays in GPS observation using Raman lidar measurements Type de document : Article/Communication Auteurs : Pierre Bosser , Auteur ; Christian Thom , Auteur ; Olivier Bock , Auteur ; Jacques Pelon, Auteur ; Pascal Willis , 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 795 - 800 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données GPS
[Termes IGN] données lidar
[Termes IGN] étalonnage des données
[Termes IGN] humidité de l'air
[Termes IGN] lidar Raman
[Termes IGN] retard troposphériqueRésumé : (auteur) Water vapor measurements from a Raman lidar developed conjointly by the IGN and the LATMOS/CNRS are used for documenting the water vapor heterogeneities and correcting GPS signal propagation delays in clear sky conditions. We use data from four 6 h-observing sessions during the VAPIC experiment (15 May–15 June 2004). The retrieval of zenith wet delays (ZWDs) from our Raman lidar is shown to agree well with radiosonde (0.6 ± 2.5 mm) and microwave radiometers (−6.6 ± 1.2 and 6.0 ± 3.8 mm) retrievals. ZWDs estimated from GPS data present a good consistency too (−2.0 ± 2.7 mm) but they are still shown to not represent properly the fast evolutions with high frequency variations correlation about 0.12. Part of the errors is also due to multipath and antenna phase center variations. Within this framework, methodologies for integrating of zenith lidar observations into the GPS processing are described. They include also a correction for multipath and antenna phase center variation. The best results are obtained when the lidar ZWDs are used for a priori correcting the GPS phase observations: discrepancies between lidar and GPS estimates are then reduced to −1.1 ± 1.4 mm. It is shown also that mapping function derived from the lidar vertical profiles performs nearly as well as the VMF1 mapping function. Numéro de notice : C2009-033 Affiliation des auteurs : LOEMI+Ext (1985-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-20338-1_100 Date de publication en ligne : 26/07/2011 En ligne : https://doi.org/10.1007/978-3-642-20338-1_100 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91511 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 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 Report of the IGN/JPL analysis center 2011 / Pascal Willis (2012)
Titre : Report of the IGN/JPL analysis center 2011 Type de document : Chapitre/Contribution Auteurs : Pascal Willis , Auteur ; Bruno Garayt , Auteur Editeur : Toulouse : International Doris Service, IDS Année de publication : 2012 Importance : pp 58 - 60 Langues : Anglais (eng) Numéro de notice : H2011-008 Affiliation des auteurs : LAREG (1991-2011) Nature : Chapître / contribution nature-HAL : ChRappRech DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101411 Multi-technique comparison of troposphere zenith delays and gradients during CONT08 / Kamil Teke in Journal of geodesy, vol 85 n° 7 (July 2011)
[article]
Titre : Multi-technique comparison of troposphere zenith delays and gradients during CONT08 Type de document : Article/Communication Auteurs : Kamil Teke, Auteur ; Johannes Böhm , Auteur ; Tobias Nilsson, Auteur ; Harald Schuh, Auteur ; Peter Steigenberger, Auteur ; Rolf Dach, Auteur ; Robert Heinkelmann, Auteur ; Pascal Willis , Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 395 - 413 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] données DORIS
[Termes IGN] données GPS
[Termes IGN] données ITGB
[Termes IGN] données WVR
[Termes IGN] gradient de troposphère
[Termes IGN] retard troposphérique
[Termes IGN] troposphèreRésumé : (Auteur) CONT08 was a 15 days campaign of continuous Very Long Baseline Interferometry (VLBI) sessions during the second half of August 2008 carried out by the International VLBI Service for Geodesy and Astrometry (IVS). In this study, VLBI estimates of troposphere zenith total delays (ZTD) and gradients during CONT08 were compared with those derived from observations with the Global Positioning System (GPS), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), and water vapor radiometers (WVR) co-located with the VLBI radio telescopes. Similar geophysical models were used for the analysis of the space geodetic data, whereas the parameterization for the least-squares adjustment of the space geodetic techniques was optimized for each technique. In addition to space geodetic techniques and WVR, ZTD and gradients from numerical weather models (NWM) were used from the European Centre for Medium-Range Weather Forecasts (ECMWF) (all sites), the Japan Meteorological Agency (JMA) and Cloud Resolving Storm Simulator (CReSS) (Tsukuba), and the High Resolution Limited Area Model (HIRLAM) (European sites). Biases, standard deviations, and correlation coefficients were computed between the troposphere estimates of the various techniques for all eleven CONT08 co-located sites. ZTD from space geodetic techniques generally agree at the sub-centimetre level during CONT08, and—as expected—the best agreement is found for intra-technique comparisons: between the Vienna VLBI Software and the combined IVS solutions as well as between the Center for Orbit Determination (CODE) solution and an IGS PPP time series; both intra-technique comparisons are with standard deviations of about 3–6 mm. The best inter space geodetic technique agreement of ZTD during CONT08 is found between the combined IVS and the IGS solutions with a mean standard deviation of about 6 mm over all sites, whereas the agreement with numerical weather models is between 6 and 20 mm. The standard deviations are generally larger at low latitude sites because of higher humidity, and the latter is also the reason why the standard deviations are larger at northern hemisphere stations during CONT08 in comparison to CONT02 which was observed in October 2002. The assessment of the troposphere gradients from the different techniques is not as clear because of different time intervals, different estimation properties, or different observables. However, the best inter-technique agreement is found between the IVS combined gradients and the GPS solutions with standard deviations between 0.2 and 0.7 mm. Numéro de notice : A2011-331 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0434-y Date de publication en ligne : 27/04/2011 En ligne : https://doi.org/10.1007/s00190-010-0434-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31110
in Journal of geodesy > vol 85 n° 7 (July 2011) . - pp 395 - 413[article]Réservation
Réserver ce documentExemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 266-2011071 RAB Revue Centre de documentation En réserve L003 Disponible Evidence for a slow subsidence of the Tahiti Island from GPS, DORIS, and combined satellite altimetry and tide gauge sea level records / Abdelali Fadil in Comptes rendus : Géoscience, vol 343 n° 5 (May 2011)PermalinkAnalyse conjointe lidar Raman-GPS pour l'estimation de la composante verticale en GPS / Pierre Bosser in Bulletin d'information scientifique et technique de l'IGN, n° 77 (avril 2011)PermalinkScientific applications of Galileo and other Global Navigation Satellite Systems (II) Preface / Pascal Willis in Advances in space research, vol 47 n° 5 (1 March 2011)PermalinkPermalinkPermalinkAn 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)PermalinkDORIS/SLR POD modeling improvements for Jason-1 and Jason-2 / Nikita P. Zelensky in Advances in space research, vol 46 n° 12 (15/12/2010)PermalinkIDS contribution to ITRF2008 / Jean-Jacques Valette in Advances in space research, vol 46 n° 12 (15/12/2010)PermalinkPreface [to DORIS: Precise orbit determination and applications to the Earth sciences] / Pascal Willis in Advances in space research, vol 46 n° 12 (15/12/2010)PermalinkRefining DORIS atmospheric drag estimation in preparation of ITRF2008 / Marie-Line Gobinddass in Advances in space research, vol 46 n° 12 (15/12/2010)Permalink
HDR en 2003