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Estimation of code observation-specific biases (OSBs) for the modernized multi-frequency and multi-GNSS signals: an undifferenced and uncombined approach / Teng Liu in Journal of geodesy, vol 95 n° 8 (August 2021)
[article]
Titre : Estimation of code observation-specific biases (OSBs) for the modernized multi-frequency and multi-GNSS signals: an undifferenced and uncombined approach Type de document : Article/Communication Auteurs : Teng Liu, Auteur ; Baocheng Zhang, Auteur Année de publication : 2021 Article en page(s) : n° 97 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] code GNSS
[Termes IGN] combinaison linéaire
[Termes IGN] erreur systématique de code différentiel
[Termes IGN] fréquence multiple
[Termes IGN] phase GNSS
[Termes IGN] retard ionosphèrique
[Termes IGN] signal GNSS
[Termes IGN] teneur verticale totale en électrons
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) For a long time, code biases of global navigation satellite system (GNSSs) have been parameterized and presented in the differential mode, namely the commonly-known differential code biases (DCB). However, with the continuous modernization of the existing constellations and rapid developments of the new systems, various new frequencies and types of GNSS signals are emerging, which makes the traditional DCB mode less flexible and efficient to handle the new situations and challenges. Recently, code biases in observation-specific representation, which finally provides observation-specific biases (OSBs), turns out to be a good solution and is gradually accepted by the GNSS community, though existing products are generated based on routine procedures and few studies concentrate on the new methods. In view of it, this study aims to propose a rigorous, flexible and efficient approach of OSB estimation for the modernized multi-frequency and, multi-GNSS signals. To achieve this, instead of being-based on linear combinations of raw observations in the existing literature, an extended multi-frequency geometry-free model is first established based on undifferenced and uncombined observations, which can adapt to observations of arbitrary frequencies and types in a compatible and flexible way and is used to extract the various types of linear combinations of the interested OSBs. Then, regarding the previously-obtained linear combinations as virtual observables after station-based ionosphere modeling, all OSB parameters are setup and estimated in a single normal equation, during which a clear identification and elimination of the rank deficiencies in the linear system is carefully conducted by introducing different types of constraints. The proposed new method is validated with one month of real data to generate totally 32 types of OSBs for GPS, GLONASS, Galileo, BeiDou, and QZSS. The estimated OSBs are compared with existing OSB and DCB products from other agencies. Results indicate that the proposed method can be used as a flexible and precise method for full-constellation and full-type OSB estimation. Numéro de notice : A2021-584 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01549-x Date de publication en ligne : 12/08/2021 En ligne : https://doi.org/10.1007/s00190-021-01549-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98199
in Journal of geodesy > vol 95 n° 8 (August 2021) . - n° 97[article]Atmospheric correction to passive microwave brightness temperature in snow cover mapping over china / Yubao Qiu in IEEE Transactions on geoscience and remote sensing, vol 59 n° 8 (August 2021)
[article]
Titre : Atmospheric correction to passive microwave brightness temperature in snow cover mapping over china Type de document : Article/Communication Auteurs : Yubao Qiu, Auteur ; Lijuan Shi, Auteur ; Juha Lemmetyinen, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 6482 - 6495 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] capteur passif
[Termes IGN] Chine
[Termes IGN] correction atmosphérique
[Termes IGN] image NOAA
[Termes IGN] image SSMIS
[Termes IGN] image Terra-MODIS
[Termes IGN] manteau neigeux
[Termes IGN] modèle atmosphérique
[Termes IGN] neige
[Termes IGN] série temporelle
[Termes IGN] télédétection en hyperfréquence
[Termes IGN] température de luminance
[Termes IGN] teneur en vapeur d'eauRésumé : (auteur) Variable atmospheric conditions are typically ignored in the retrieval of geophysical parameters of the Earth’s surface when using spaceborne passive microwave observations. However, high frequencies, for example, 91.7 GHz, are sensitive to variable atmospheric absorption, even in winter’s dry conditions. In this article, the influence of variable atmospheric absorption on snow cover extent (SCE) mapping was quantitatively investigated. A physical method was derived to enable atmospheric correction for variable atmospheric conditions. The total column precipitable water vapor (TPWV) from Moderate Resolution Imaging Spectroradiometer (MODIS) was parametrized into transmittances in this correction method. The corrected brightness temperature at 19 and 91.7 GHz from the Special Sensor Microwave Imager Sounder (SSMIS) was applied to the threshold algorithm for snow mapping over China. Compared with the Interactive Multisensor Snow and Ice Mapping System (IMS) data in winter from 2012 to 2013, for Qinghai–Tibet plateau (QTP), a significant improvement after correction was obtained from February to March over ephemeral and shallow snow, where the largest daily improvement of accuracy is up to 20%. The accuracy (incl. precision, recall, and F1 index) improved on average is from 0.77 (0.60, 0.68, and 0.63) to 0.79 (0.69, 0.7, and 0.68) over the full winter time from December to March. Over forest-rich Northeast China, where snow in winter is thicker, small improvement was observed at the onset of the snow season and over snow margin area. It was evidenced that high frequency is a promising way of snow cover mapping with the proposed atmospheric correction method. Numéro de notice : A2021-630 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2020.3031837 Date de publication en ligne : 02/11/2020 En ligne : https://doi.org/10.1109/TGRS.2020.3031837 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98279
in IEEE Transactions on geoscience and remote sensing > vol 59 n° 8 (August 2021) . - pp 6482 - 6495[article]Ordered subsets-constrained ART algorithm for ionospheric tomography by combining VTEC data / Dunyong Zheng in IEEE Transactions on geoscience and remote sensing, vol 59 n° 8 (August 2021)
[article]
Titre : Ordered subsets-constrained ART algorithm for ionospheric tomography by combining VTEC data Type de document : Article/Communication Auteurs : Dunyong Zheng, Auteur ; Yibin Yao, Auteur ; Wenfeng Nie, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 7051 - 7061 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] données GNSS
[Termes IGN] modèle ionosphérique
[Termes IGN] teneur totale en électrons
[Termes IGN] teneur verticale totale en électrons
[Termes IGN] tomographie par GPSRésumé : (auteur) Computerized ionospheric tomography is an important technique for ionosphere investigation. However, it is an ill-posed problem owing to an insufficient amount of available data, because of which the distributions of ionospheric electron density (IED) cannot be reconstructed accurately. In light of this, the ordered subsets-constrained algebraic reconstruction technique (OS_CART) is developed here using vertical total electron content (VTEC) data to solve this problem, where the VTEC derived from the slant total electron content (STEC) of Global Navigation Satellite System (GNSS) signal paths is used to compensate for the lack of data provided by GNSS observations in inversion regions, and the OS_CART is also used to improve the spatial resolution and inversion efficiency. The proposed method was validated by conducting numerical experiments using GNSS and independent ionosonde data in both quiescent and disturbed ionospheric conditions. In contrast to classical methods of ionospheric tomography, the proposed method exhibited significantly higher reconstruction accuracy. While delivering a comparable accuracy to that of traditional methods in terms of self-consistency validation using STEC data and without overfitting, the proposed method yielded a more than 90% improvement over the self-consistency validation using VTEC data. In addition, a better daily description of the ionosphere was obtained using the proposed method, where an increase in the peak height and irregular changes to the IED, associated with variations in the number of epochs and the occurrence of magnetic storms, were observed. Overall, the results reveal that the proposed method is a useful tool for research on space weather. Numéro de notice : A2021-634 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2020.3029819 Date de publication en ligne : 28/10/2020 En ligne : https://doi.org/10.1109/TGRS.2020.3029819 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98297
in IEEE Transactions on geoscience and remote sensing > vol 59 n° 8 (August 2021) . - pp 7051 - 7061[article]GPS satellite differential code bias estimation with current eleven low earth orbit satellites / Xingxing Li in Journal of geodesy, vol 95 n° 7 (July 2021)
[article]
Titre : GPS satellite differential code bias estimation with current eleven low earth orbit satellites Type de document : Article/Communication Auteurs : Xingxing Li, Auteur ; Wei Zhang, Auteur ; Keke Zhang, Auteur Année de publication : 2021 Article en page(s) : n° 76 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] erreur systématique de code différentiel
[Termes IGN] orbite basse
[Termes IGN] précision de l'estimation
[Termes IGN] récepteur GPS
[Termes IGN] teneur verticale totale en électrons
[Termes IGN] trajet multipleRésumé : (auteur) Many low earth orbit (LEO) missions have been launched recently for different geoscience studying purposes such as ionosphere detecting and gravity recovering. The onboard observations from LEO satellites provide us a great opportunity to estimate the differential code bias (DCB) which is vital for precise applications of global navigation satellites system. This paper mainly focuses on the contribution of multi-LEO combination to the DCB estimation using onboard data collected by current eleven LEO satellites from day of year (DOY) 061, 2018 to DOY 120, 2018. The single-LEO solutions with different LEO and multi-LEO solutions with different LEO subsets are compared and analyzed in detail to fully exploit the potential of LEO onboard observations in the DCB estimation. We also evaluate and discuss the vertical total electron content (VTEC) results and posterior residuals to validate the estimation accuracy. Our results show that the average DCB standard deviation (STD) values are within 0.140 ns for all eleven single-LEO solutions with the best stability of 0.082 ns for Swarm-B solution. The evaluation of multi-LEO solutions indicates that with the increase in LEO satellites, the GPS DCB stability gets improved gradually. The 9-LEO solution can achieve the stability with STD value of 0.051 ns, better than that of DCB products from the German Aerospace Center (DLR) (0.055 ns) but slightly worse than that of DCB products from the Chinese Academy of Sciences (CAS) (0.048 ns). The results suggest that the GPS DCB stability based on the onboard observations of nine LEO satellites can be comparable to the ground-based solution derived from a global ground network with hundreds of stations. The LEO space-borne receiver DCB results illustrate that the inclusion of more LEO satellites can contribute to the stability improvement of receiver DCB. In addition, the VTEC estimation can benefit from the joint processing of multiple LEO observations and achieves a noticeable reduction in the percentage of negative VTEC values. Our results also reveal that the spherical symmetry ionosphere assumption might cause accuracy degradation in the DCB estimation at low latitudes. Numéro de notice : A2021-517 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01536-2 Date de publication en ligne : 22/06/2021 En ligne : https://doi.org/10.1007/s00190-021-01536-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97939
in Journal of geodesy > vol 95 n° 7 (July 2021) . - n° 76[article]Three-dimensional reconstruction of seismo-traveling ionospheric disturbances after March 11, 2011, Japan Tohoku earthquake / Changzhi Zhai in Journal of geodesy, vol 95 n° 7 (July 2021)
[article]
Titre : Three-dimensional reconstruction of seismo-traveling ionospheric disturbances after March 11, 2011, Japan Tohoku earthquake Type de document : Article/Communication Auteurs : Changzhi Zhai, Auteur ; Yibin Yao, Auteur ; Jian Kong, Auteur Année de publication : 2021 Article en page(s) : n° 77 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] diffusion de Rayleigh
[Termes IGN] GeoNet
[Termes IGN] modèle ionosphérique
[Termes IGN] onde acoustique
[Termes IGN] perturbation ionosphérique
[Termes IGN] reconstruction 3D
[Termes IGN] séisme
[Termes IGN] signal GPS
[Termes IGN] teneur totale en électrons
[Termes IGN] Tohoku (Japon)
[Termes IGN] tomographieRésumé : (auteur) The electron density structures of the seismo-traveling ionospheric disturbances (STIDs) during the Tohoku earthquake are reconstructed by applying the three-dimensional computerized ionospheric tomography (3DCIT) technique with a 30-s time resolution for the first time. The vertical distribution of 3DCIT results is consistent with the constellation observing system for meteorology, ionosphere and climate (COSMIC) observations. The horizontal speeds of STIDs at different altitudes are estimated, and the three types of STIDs related to Rayleigh waves, acoustic waves and gravity waves are identified by their propagation characters. The magnitude of STIDs related to Rayleigh waves decreased with altitude, and there was no significant difference between the speeds (~ 2500 m/s) at different altitudes. The STIDs caused by acoustic waves traveled faster at 300 km altitude (~ 666–724 m/s) than at 150 km altitude (~ 500–550 m/s). From 150 to 250 km altitudes, in the STIDs induced by gravity waves, the magnitude of positive and negative wave fronts showed the opposite trend. The speed at 300 km altitude (~ 332 m/s) was slightly larger than at 150 km altitude (~ 310 m/s). The Rayleigh waves related STIDs showed a conic-like geometry, whereas the acoustic waves and gravity waves induced STIDs showed inverted conic-like geometries. The possible propagation mechanisms of different types of STIDs are also discussed. Numéro de notice : A2021-524 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01533-5 Date de publication en ligne : 23/06/2021 En ligne : https://doi.org/10.1007/s00190-021-01533-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97961
in Journal of geodesy > vol 95 n° 7 (July 2021) . - n° 77[article]Comparison of polar ionospheric behavior at Arctic and Antarctic regions for improved satellite-based positioning / Arun Kumar Singh in Journal of applied geodesy, vol 15 n° 3 (July 2021)PermalinkIonospheric irregularity layer height and thickness estimation with a GNSS receiver array / Seebany Datta-Barua in IEEE Transactions on geoscience and remote sensing, Vol 59 n° 7 (July 2021)PermalinkAdaptive regularization method for 3-D GNSS ionospheric tomography based on the U-curve / Jun Tang in IEEE Transactions on geoscience and remote sensing, vol 59 n° 6 (June 2021)PermalinkGNSS-based statistical analysis of ionospheric anomalies during typhoon landings in Taiwan/Japan / Hai Peng in IEEE Transactions on geoscience and remote sensing, vol 59 n° 6 (June 2021)PermalinkMulti-GNSS PPP/INS tightly coupled integration with atmospheric augmentation and its application in urban vehicle navigation / Shengfeng Gu in Journal of geodesy, vol 95 n° 6 (June 2021)PermalinkAn improved computerized ionospheric tomography model fusing 3-D multisource ionospheric data enabled quantifying the evolution of magnetic storm / Jian Kong in IEEE Transactions on geoscience and remote sensing, vol 59 n° 5 (May 2021)PermalinkObservable quality assessment of broadband very long baseline interferometry system / Ming H. Xu in Journal of geodesy, vol 95 n° 5 (May 2021)PermalinkCloud detection from paired CrIS water vapor and CO₂ channels using machine learning techniques / Miao Tian in IEEE Transactions on geoscience and remote sensing, vol 59 n° 4 (April 2021)PermalinkApplication of a multi-layer artificial neural network in a 3-D global electron density model using the long-term observations of COSMIC, Fengyun-3C, and Digisonde / Li Wang in Space weather, vol 19 n° 3 (March 2021)PermalinkIntegrity investigation of global ionospheric TEC maps for high-precision positioning / Jiaojiao Zhao in Journal of geodesy, vol 95 n° 3 (March 2021)Permalink