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Comparison of total water vapour content in the Arctic derived from GNSS, AIRS, MODIS and SCIAMACHY / Dunya Alraddawi in Atmospheric measurement techniques, vol 11 n° 5 (May 2018)
[article]
Titre : Comparison of total water vapour content in the Arctic derived from GNSS, AIRS, MODIS and SCIAMACHY Type de document : Article/Communication Auteurs : Dunya Alraddawi, Auteur ; Alain Sarkissian, Auteur ; Philippe Keckhut, Auteur ; Olivier Bock , Auteur ; Stefan Noël, Auteur ; Slimane Bekki, Auteur ; Abdanour Irbah, Auteur ; Mustapha Meftah, Auteur ; Chantal Claud, Auteur Année de publication : 2018 Projets : GNSS4SWEC / , VEGAN / Bock, Olivier Article en page(s) : pp 2949 - 2965 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] Arctique
[Termes IGN] Atmospheric Infrared Sounder
[Termes IGN] données GNSS
[Termes IGN] données météorologiques
[Termes IGN] erreur systématique
[Termes IGN] image Aqua-MODIS
[Termes IGN] image Terra-MODIS
[Termes IGN] nébulosité
[Termes IGN] série temporelle
[Termes IGN] teneur en vapeur d'eauRésumé : (auteur) Atmospheric water vapour plays a key role in the Arctic radiation budget, hydrological cycle and hence climate, but its measurement with high accuracy remains an important challenge. Total column water vapour (TCWV) datasets derived from ground-based GNSS measurements are used to assess the quality of different existing satellite TCWV datasets, namely from the Moderate Resolution Imaging Spectroradiometer (MODIS), the Atmospheric Infrared Sounder (AIRS) and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The comparisons between GNSS and satellite data are carried out for three reference Arctic observation sites (Sodankylä, Ny-Ålesund and Thule) where long homogeneous GNSS time series of more than a decade (2001–2014) are available. We select hourly GNSS data that are coincident with overpasses of the different satellites over the three sites and then average them into monthly means that are compared with monthly mean satellite products for different seasons. The agreement between GNSS and satellite time series is generally within 5 % at all sites for most conditions. The weakest correlations are found during summer. Among all the satellite data, AIRS shows the best agreement with GNSS time series, though AIRS TCWV is often slightly too high in drier atmospheres (i.e. high-latitude stations during autumn and winter). SCIAMACHY TCWV data are generally drier than GNSS measurements at all the stations during the summer. This study suggests that these biases are associated with cloud cover, especially at Ny-Ålesund and Thule. The dry biases of MODIS and SCIAMACHY observations are most pronounced at Sodankylä during the snow season (from October to March). Regarding SCIAMACHY, this bias is possibly linked to the fact that the SCIAMACHY TCWV retrieval does not take accurately into account the variations in surface albedo, notably in the presence of snow with a nearby canopy as in Sodankylä. The MODIS bias at Sodankylä is found to be correlated with cloud cover fraction and is also expected to be affected by other atmospheric or surface albedo changes linked for instance to the presence of forests or anthropogenic emissions. Overall, the results point out that a better estimation of seasonally dependent surface albedo and a better consideration of vertically resolved cloud cover are recommended if biases in satellite measurements are to be reduced in the polar regions. Numéro de notice : A2018-240 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/amt-11-2949-2018 Date de publication en ligne : 18/05/2018 En ligne : https://doi.org/10.5194/amt-11-2949-2018 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90215
in Atmospheric measurement techniques > vol 11 n° 5 (May 2018) . - pp 2949 - 2965[article]Carrier phase bias estimation of geometry-free linear combination of GNSS signals for ionospheric TEC modeling / Anna Krypiak-Gregorczyk in GPS solutions, vol 22 n° 2 (April 2018)
[article]
Titre : Carrier phase bias estimation of geometry-free linear combination of GNSS signals for ionospheric TEC modeling Type de document : Article/Communication Auteurs : Anna Krypiak-Gregorczyk, Auteur ; Pawel Wielgosz, Auteur Année de publication : 2018 Article en page(s) : pp 22 - 45 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] combinaison linéaire
[Termes IGN] erreur systématique
[Termes IGN] modèle ionosphérique
[Termes IGN] phase
[Termes IGN] positionnement par GNSS
[Termes IGN] retard ionosphèrique
[Termes IGN] signal GNSS
[Termes IGN] teneur totale en électrons
[Vedettes matières IGN] Traitement de données GNSSRésumé : (Auteur) The ionosphere can be modeled and studied using multi-frequency GNSS signals and their geometry-free linear combination. Therefore, a number of GNSS-derived ionospheric models have been developed and applied in a broad range of applications. However, due to the complexity of estimating the carrier phase ambiguities, most of these models are based on low-accuracy carrier phase smoothed pseudorange data. This, in turn, critically limits their accuracy and applicability. Therefore, we present a new methodology of estimating the phase bias of the scaled L1 and L2 carrier phase difference which is a function of the ambiguities, the ionospheric delay, and hardware delays. This methodology is suitable for ionospheric modeling at regional and continental scales. In addition, we present its evaluation under varying ionospheric conditions. The test results show that the carrier phase bias of geometry-free linear combination can be estimated with a very high accuracy, which consequently allows for calculating ionospheric TEC with the uncertainty lower than 1.0 TECU. This high accuracy makes the resulting ionosphere model suitable for improving GNSS positioning for high-precision applications in geosciences. Numéro de notice : A2018-160 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-018-0711-4 Date de publication en ligne : 16/02/2018 En ligne : https://doi.org/10.1007/s10291-018-0711-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89783
in GPS solutions > vol 22 n° 2 (April 2018) . - pp 22 - 45[article]Joint estimation of vertical total electron content (VTEC) and satellite differential code biases (SDCBs) using low-cost receivers / Baocheng Zhang in Journal of geodesy, vol 92 n° 4 (April 2018)
[article]
Titre : Joint estimation of vertical total electron content (VTEC) and satellite differential code biases (SDCBs) using low-cost receivers Type de document : Article/Communication Auteurs : Baocheng Zhang, Auteur ; Peter J.G. Teunissen, Auteur ; Yunbin Yuan, Auteur ; Hongxing Zhang, Auteur ; Min Li, Auteur Année de publication : 2018 Article en page(s) : pp 401 - 413 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] erreur systématique
[Termes IGN] modèle ionosphérique
[Termes IGN] positionnement ponctuel précis
[Termes IGN] propagation ionosphérique
[Termes IGN] récepteur GNSS
[Termes IGN] récepteur monofréquence
[Termes IGN] série temporelle
[Termes IGN] teneur verticale totale en électronsRésumé : (Auteur) Vertical total electron content (VTEC) parameters estimated using global navigation satellite system (GNSS) data are of great interest for ionosphere sensing. Satellite differential code biases (SDCBs) account for one source of error which, if left uncorrected, can deteriorate performance of positioning, timing and other applications. The customary approach to estimate VTEC along with SDCBs from dual-frequency GNSS data, hereinafter referred to as DF approach, consists of two sequential steps. The first step seeks to retrieve ionospheric observables through the carrier-to-code leveling technique. This observable, related to the slant total electron content (STEC) along the satellite–receiver line-of-sight, is biased also by the SDCBs and the receiver differential code biases (RDCBs). By means of thin-layer ionospheric model, in the second step one is able to isolate the VTEC, the SDCBs and the RDCBs from the ionospheric observables. In this work, we present a single-frequency (SF) approach, enabling the joint estimation of VTEC and SDCBs using low-cost receivers; this approach is also based on two steps and it differs from the DF approach only in the first step, where we turn to the precise point positioning technique to retrieve from the single-frequency GNSS data the ionospheric observables, interpreted as the combination of the STEC, the SDCBs and the biased receiver clocks at the pivot epoch. Our numerical analyses clarify how SF approach performs when being applied to GPS L1 data collected by a single receiver under both calm and disturbed ionospheric conditions. The daily time series of zenith VTEC estimates has an accuracy ranging from a few tenths of a TEC unit (TECU) to approximately 2 TECU. For 73–96% of GPS satellites in view, the daily estimates of SDCBs do not deviate, in absolute value, more than 1 ns from their ground truth values published by the Centre for Orbit Determination in Europe. Numéro de notice : A2018-062 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1071-5 Date de publication en ligne : 05/10/2017 En ligne : https://doi.org/10.1007/s00190-017-1071-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89398
in Journal of geodesy > vol 92 n° 4 (April 2018) . - pp 401 - 413[article]Toward a global horizontal and vertical elastic load deformation model derived from GRACE and GNSS station position time series / Kristel Chanard in Journal of geophysical research : Solid Earth, vol 123 n° 4 (April 2018)
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Titre : Toward a global horizontal and vertical elastic load deformation model derived from GRACE and GNSS station position time series Type de document : Article/Communication Auteurs : Kristel Chanard , Auteur ; Luce Fleitout, Auteur ; Eric Calais, Auteur ; Paul Rebischung , Auteur ; Jean-Philippe Avouac, Auteur Année de publication : 2018 Projets : 3-projet - voir note / Bock, Olivier Article en page(s) : pp 3225 - 3237 Note générale : bibliographie
The project was funded by NSF grant EAR 1345136, the Laboratoire de Recherche Commun “Yves Rocard” (ENS‐CEA‐CNRS), and CNRS/TOSCA grant 2925.Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] coordonnées GNSS
[Termes IGN] déformation horizontale de la croute terrestre
[Termes IGN] déformation verticale de la croute terrestre
[Termes IGN] données GRACE
[Termes IGN] Earth Gravity Model 2008
[Termes IGN] erreur systématique
[Termes IGN] harmonique sphérique
[Termes IGN] modèle de déformation tectonique
[Termes IGN] mouvement du géocentre
[Termes IGN] série temporelleRésumé : (Auteur) We model surface displacements induced by variations in continental water, atmospheric pressure, and non‐tidal oceanic loading, derived from the Gravity and Recovery Climate Experiment (GRACE) for spherical harmonic degrees two and higher. As they are not observable by GRACE, we use at first the degree‐1 spherical harmonic coefficients from (Swenson2008estimating). We compare the predicted displacements with the position time series of 689 globally distributed continuous Global Navigation Satellite System (GNSS) stations. While GNSS vertical displacements are well explained by the model at a global scale, horizontal displacements are systematically underpredicted and out‐of‐phase with GNSS station position time series. We then re‐estimate the degree‐1 deformation field from a comparison between our GRACE‐derived model, with no a priori degree‐1 loads, and the GNSS observations. We show that this approach reconciles GRACE‐derived loading displacements and GNSS station position time series at a global scale, particularly in the horizontal components. Assuming that they reflect surface loading deformation only, our degree‐1 estimates can be translated into geocenter motion time series. We also address and assess the impact of systematic errors in GNSS station position time series at the Global Positioning System (GPS) draconitic period and its harmonics on the comparison between GNSS and GRACE‐derived annual displacements. Our results confirm that surface mass redistributions observed by GRACE, combined with an elastic spherical and layered Earth model, can be used to provide first order corrections for loading deformation observed in both horizontal and vertical components of GNSS station position time series. Numéro de notice : A2018-055 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/2017JB015245 Date de publication en ligne : 21/02/2018 En ligne : https://doi.org/10.1002/2017JB015245 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89382
in Journal of geophysical research : Solid Earth > vol 123 n° 4 (April 2018) . - pp 3225 - 3237[article]Reduction of ZTD outliers through improved GNSS data processing and screening strategies [Interactive discussion] / Katarzyna Stępniak in Atmospheric measurement techniques, vol 11 n° 3 (March 2018)
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Titre : Reduction of ZTD outliers through improved GNSS data processing and screening strategies [Interactive discussion] Type de document : Article/Communication Auteurs : Katarzyna Stępniak, Auteur ; Olivier Bock , Auteur ; Pawel Wielgosz, Auteur Année de publication : 2018 Projets : 3-projet - voir note / Bock, Olivier Article en page(s) : pp 1347 - 1361 Note générale : Bibliographie
This work has been supported by Polish National Science Centre grant no. UMO-2015/19/B/ST10/02758. The study was partially carried out during Short Term Scientific Mission (STSM) in the framework of ES1206 COST Action.Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] Bernese
[Termes IGN] coordonnées GPS
[Termes IGN] double différence
[Termes IGN] erreur systématique
[Termes IGN] Pologne
[Termes IGN] réseau géodésique local
[Termes IGN] réseau géodésique permanent
[Termes IGN] retard troposphérique zénithal
[Termes IGN] série temporelle
[Termes IGN] valeur aberranteRésumé : (Auteur) Though Global Navigation Satellite System (GNSS) data processing has been significantly improved over the years, it is still commonly observed that zenith tropospheric delay (ZTD) estimates contain many outliers which are detrimental to meteorological and climatological applications. In this paper, we show that ZTD outliers in double-difference processing are mostly caused by sub-daily data gaps at reference stations, which cause disconnections of clusters of stations from the reference network and common mode biases due to the strong correlation between stations in short baselines. They can reach a few centimetres in ZTD and usually coincide with a jump in formal errors. The magnitude and sign of these biases are impossible to predict because they depend on different errors in the observations and on the geometry of the baselines. We elaborate and test a new baseline strategy which solves this problem and significantly reduces the number of outliers compared to the standard strategy commonly used for positioning (e.g. determination of national reference frame) in which the pre-defined network is composed of a skeleton of reference stations to which secondary stations are connected in a star-like structure. The new strategy is also shown to perform better than the widely used strategy maximizing the number of observations available in many GNSS programs. The reason is that observations are maximized before processing, whereas the final number of used observations can be dramatically lower because of data rejection (screening) during the processing. The study relies on the analysis of 1 year of GPS (Global Positioning System) data from a regional network of 136 GNSS stations processed using Bernese GNSS Software v.5.2. A post-processing screening procedure is also proposed to detect and remove a few outliers which may still remain due to short data gaps. It is based on a combination of range checks and outlier checks of ZTD and formal errors. The accuracy of the final screened GPS ZTD estimates is assessed by comparison to ERA-Interim reanalysis. Numéro de notice : A2018-065 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/amt-11-1347-2018 Date de publication en ligne : 08/03/2018 En ligne : http://dx.doi.org/10.5194/amt-11-1347-2018 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89407
in Atmospheric measurement techniques > vol 11 n° 3 (March 2018) . - pp 1347 - 1361[article]Systematic error reduction in geometric measurements based on altimetric enrichment of geographical features / Jean-François Girres in Cartographica, vol 53 n° 1 (Spring 2018)PermalinkImproving the upscaling of land cover maps by fusing uncertainty and spatial structure information / Peijun Sun in Photogrammetric Engineering & Remote Sensing, PERS, vol 84 n° 2 (February 2018)PermalinkDesign and implementation of a model predictive observer for AHRS / Jafar Keighobadi in GPS solutions, vol 22 n° 1 (January 2018)PermalinkGéo-référencement précis d'acquisition photogrammétrique de « longues » scènes d'intérieur / Truong Giang Nguyen (2018)PermalinkHeight biases of SRTM DEM related to EGM96: from a global perspective to regional practice / A. Üstün in Survey review, vol 50 n° 358 (January 2018)PermalinkA numerical test of the topographic bias / Lars E. Sjöberg in Journal of geodetic science, vol 8 n° 1 (January 2018)PermalinkOn the topographic bias and density distribution in modelling the geoid and orthometric heights / Lars E. Sjöberg in Journal of geodetic science, vol 8 n° 1 (January 2018)PermalinkA posteriori bias correction of three models used for environmental reporting / Bogdan M. Strimbu in Forestry, an international journal of forest research, vol 91 n° 1 (January 2018)PermalinkPerformance analysis of BDS/GPS precise point positioning with undifferenced ambiguity resolution / Min Wang in Advances in space research, vol 60 n° 12 (15 December 2017)PermalinkLarge-scale block adjustment without use of ground control points based on the compensation of geometric calibration for ZY-3 images / Yang Bo in ISPRS Journal of photogrammetry and remote sensing, vol 134 (December 2017)PermalinkPer-pixel bias-variance decomposition of continuous errors in data-driven geospatial modeling : A case study in environmental remote sensing / Jing Gao in ISPRS Journal of photogrammetry and remote sensing, vol 134 (December 2017)PermalinkSystematic error mitigation in multi-GNSS positioning based on semiparametric estimation / Wenkun Yu in Journal of geodesy, vol 91 n° 12 (December 2017)PermalinkTropospheric delay modelling for the EGNOS augmentation system / Kamil Kazmierski in Survey review, vol 49 n° 357 (December 2017)PermalinkIGS polar motion measurement accuracy / Jim Ray in Geodesy and Geodynamics, vol 8 n° 6 (November 2017)PermalinkIonospheric and receiver DCB-constrained multi-GNSS single-frequency PPP integrated with MEMS inertial measurements / Zhouzheng Gao in Journal of geodesy, vol 91 n° 11 (November 2017)PermalinkNonlinear bias compensation of ZiYuan-3 satellite imagery with cubic splines / Jinshan Cao in ISPRS Journal of photogrammetry and remote sensing, vol 133 (November 2017)PermalinkComputation of GPS P1–P2 differential code biases with JASON-2 / Gilles Wautelet in GPS solutions, vol 21 n° 4 (October 2017)PermalinkThe relation between degree-2160 spectral models of Earth’s gravitational and topographic potential : a guide on global correlation measures and their dependency on approximation effects / Christian Hirt in Journal of geodesy, vol 91 n° 10 (October 2017)PermalinkTree size thresholds produce biased estimates of forest biomass dynamics / Eric B. Searle in Forest ecology and management, vol 400 (15 September 2017)PermalinkRéduction de l'erreur systématique de mesure géométrique par enrichissement altimétrique des données géographiques / Jean-François Girres in Cartes & Géomatique, n° 233 (septembre - novembre 2017)Permalink