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Wavelet modelling of the gravity field by domain decomposition methods: an example over Japan / Isabelle Panet in Geophysical journal international, vol 184 n° 1 (January 2011)
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Titre : Wavelet modelling of the gravity field by domain decomposition methods: an example over Japan Type de document : Article/Communication Auteurs : Isabelle Panet , Auteur ; Yuki Kuroishi, Auteur ; Matthias Holschneider, Auteur
Année de publication : 2011 Article en page(s) : pp 203 - 219 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse harmonique
[Termes IGN] bruit blanc
[Termes IGN] bruit rose
[Termes IGN] harmonique sphérique
[Termes IGN] itération
[Termes IGN] Japon
[Termes IGN] modèle de géopotentiel local
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] transformation en ondelettesRésumé : (auteur) With the advent of satellite gravity, large gravity data sets of unprecedented quality at low and medium resolution become available. For local, high resolution field modelling, they need to be combined with the surface gravity data. Such models are then used for various applications, from the study of the Earth interior to the determination of oceanic currents. Here we show how to realize such a combination in a flexible way using spherical wavelets and applying a domain decomposition approach. This iterative method, based on the Schwarz algorithms, allows to split a large problem into smaller ones, and avoids the calculation of the entire normal system, which may be huge if high resolution is sought over wide areas. A subdomain is defined as the harmonic space spanned by a subset of the wavelet family. Based on the localization properties of the wavelets in space and frequency, we define hierarchical subdomains of wavelets at different scales. On each scale, blocks of subdomains are defined by using a tailored spatial splitting of the area. The data weighting and regularization are iteratively adjusted for the subdomains, which allows to handle heterogeneity in the data quality or the gravity variations. Different levels of approximations of the subdomains normals are also introduced, corresponding to building local averages of the data at different resolution levels. We first provide the theoretical background on domain decomposition methods. Then, we validate the method with synthetic data, considering two kinds of noise: white noise and coloured noise. We then apply the method to data over Japan, where we combine a satellite-based geopotential model, EIGEN-GL04S, and a local gravity model from a combination of land and marine gravity data and an altimetry-derived marine gravity model. A hybrid spherical harmonics/wavelet model of the geoid is obtained at about 15 km resolution and a corrector grid for the surface model is derived. Numéro de notice : A2011-604 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/j.1365-246X.2010.04840.x Date de publication en ligne : 01/01/2011 En ligne : https://doi.org/10.1111/j.1365-246X.2010.04840.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91678
in Geophysical journal international > vol 184 n° 1 (January 2011) . - pp 203 - 219[article]Documents numériques
en open access
Wavelet modelling of the gravity field .. - pdf éditeurAdobe Acrobat PDFWavelets and notch filtering: innovative techniques for mitigating RF interference / M. Paonni in Inside GNSS, vol 6 n° 1 (January - February 2011)
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Titre : Wavelets and notch filtering: innovative techniques for mitigating RF interference Type de document : Article/Communication Auteurs : M. Paonni, Auteur ; J. Jang, Auteur ; Bernd Eissfeller, Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : 9 p. ; pp 54 - 62 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] filtrage du signal
[Termes IGN] interférence
[Termes IGN] radiofréquence
[Termes IGN] transformation en ondelettesRésumé : (Auteur) As interest in use of GNSS for safety critical applications gains momentum, interference concerns abound. Pulsed interference and continuous wave signals can degrade the reception of GNSS signals. The authors present emerging concepts for detecting and mitigating interference by means of digital processing techniques applied in the receiver. Numéro de notice : A2011-617 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans En ligne : http://www.insidegnss.com/node/2431 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33390
in Inside GNSS > vol 6 n° 1 (January - February 2011) . - 9 p. ; pp 54 - 62[article]Réservation
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Wavelets and notch ... - pdf éditeurAdobe Acrobat PDFAn 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]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]GNSS RF Compatibility assessment: Interference among GPS, Galileo and Compass / W. Liu in GPS world, vol 21 n° 12 (December 2010)
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