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Affiner la recherche Interroger des sources externesRegional ionospheric corrections for high accuracy GNSS positioning / Tam Dao in Remote sensing, vol 14 n° 10 (May-2 2022)
Titre : Regional ionospheric corrections for high accuracy GNSS positioning Type de document : Article/Communication Auteurs : Tam Dao, Auteur ; Ken Harima, Auteur ; Brett Anthony Carter, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 2463 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] Australie
[Termes IGN] Continuously Operating Reference Station network
[Termes IGN] correction ionosphérique
[Termes IGN] modèle ionosphérique
[Termes IGN] positionnement par GNSS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] retard ionosphèriqueRésumé : (auteur) Centimetre-level accurate ionospheric corrections are required for a high accuracy and rapid convergence of Precise Point Positioning (PPP) GNSS positioning solutions. This research aims to evaluate the accuracy of a local/regional ionospheric delay model using a linear interpolation method across Australia. The accuracy of the ionospheric corrections is assessed as a function of both different latitudinal regions and the number and spatial density of GNSS Continuously Operating Reference Stations (CORSs). Our research shows that, for a local region of 5° latitude ×10° longitude in mid-latitude regions of Australia (~30° to 40°S) with approximately 15 CORS stations, ionospheric corrections with an accuracy of 5 cm can be obtained. In Victoria and New South Wales, where dense CORS networks exist (nominal spacing of ~100 km), the average ionospheric corrections accuracy can reach 2 cm. For sparse networks (nominal spacing of >200 km) at lower latitudes, the average accuracy of the ionospheric corrections is within the range of 8 to 15 cm; significant variations in the ionospheric errors of some specific satellite observations during certain periods were also found. In some regions such as Central Australia, where there are a limited number of CORSs, this model was impossible to use. On average, centimetre-level accurate ionospheric corrections can be achieved if there are sufficiently dense (i.e., nominal spacing of approximately 200 km) GNSS CORS networks in the region of interest. Based on the current availability of GNSS stations across Australia, we propose a set of 15 regions of different ionospheric delay accuracies with extents of 5° latitude ×10° longitude covering continental Australia. Numéro de notice : A2022-400 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.3390/rs14102463 Date de publication en ligne : 20/05/2022 En ligne : https://doi.org/10.3390/rs14102463 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100703
in Remote sensing > vol 14 n° 10 (May-2 2022) . - n° 2463[article]
Titre : Comparison of atmospheric mass density models using a new data source: COSMIC satellite ephemerides Type de document : Article/Communication Auteurs : Yang Yang, Auteur ; Ronald Maj, Auteur ; Changyong He Année de publication : 2022 Projets : 2-Pas d'info accessible - article non ouvert / Article en page(s) : pp 6 - 22 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] atmosphère terrestre
[Termes IGN] éphémérides de satellite
[Termes IGN] International Reference Ionosphere
[Termes IGN] masse d'air
[Termes IGN] modèle atmosphérique
[Termes IGN] orbite basse
[Termes IGN] teneur totale en électronsRésumé : (auteur) Atmospheric mass density (AMD) plays a vital role in the drag calculation for space objects in low Earth orbit. Many empirical AMD models have been developed and used for orbit prediction and efforts continue to improve their accuracy in forecasting high-altitude atmospheric conditions. Previous studies have assessed these models at the height of 200 km to 600 km. In this paper, four state-of-the-art AMD models, i.e., MSISE90, MSISE00, JB2008 and DTM2013 are assessed for their orbit prediction (OP) capabilities by using a new data source of COSMIC satellite ephemerides at an orbital height of ~800 km, where the contribution of ions in the total AMD is more significant. A new testing model was developed by accounting for ion contribution based on the International Reference Ionosphere 2016 model, including many more ion species that are not accounted for in other AMD models. In the assessment, two periods of forty days were chosen in 2014-2015 and 2018-2019, representing solar maximum and minimum periods, respectively, to assess four existing AMD models and the proposed model. Thorough analyses were conducted to compare OP results using different AMD models with precise reference ephemerides of COSMIC satellites and based on various space weather indices. It is shown that the proposed model outperforms all other AMD models in terms of OP errors during the solar maximum period. During solar minimum, the drag acceleration is relatively small for COSMIC satellites. Assessment of all AMD models in the orbit prediction process tends to be contaminated by the remaining uncertainty sources, such as solar radiation pressure. Numéro de notice : A2022-070 Affiliation des auteurs : ENSG+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/MAES.2021.3125101 Date de publication en ligne : 20/12/2021 En ligne : https://doi.org/10.1109/MAES.2021.3125101 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99376
in IEEE Aerospace and Electronic Systems Magazine > vol 37 n° 2 (February 2022) . - pp 6 - 22[article]
Titre : Comparison of atmospheric mass density models using a new data source: COSMIC satellite ephemerides Type de document : Article/Communication Auteurs : Yang Yang, Auteur ; Ronald Maj, Auteur ; Changyong He Editeur : Washington DC [Etats-Unis] : Earth and Space Science Open Archive ESSOAr Année de publication : 2020 Note générale : bibliographie
Submitted to Space WeatherLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] atmosphère terrestre
[Termes IGN] éphémérides de satellite
[Termes IGN] International Reference Ionosphere
[Termes IGN] masse d'air
[Termes IGN] modèle atmosphérique
[Termes IGN] orbite basseRésumé : (auteur) Atmospheric mass density (AMD) plays a vital role in the drag calculation for space objects in low Earth orbit (LEO). Many empirical AMD models have been developed and used for orbit prediction and efforts continue to improve their accuracy in forecasting high-altitude atmospheric conditions. Previous studies have assessed these models at the height of 200 km to 600 km. A new empirical AMD model, dubbed as the SERC model, was developed by accounting for ion contribution based on the International Reference Ionosphere 2016 model, including many more ions that are not accounted for in other AMD models. This new model has been assessed in orbit prediction by using a new data source of COSMIC satellite ephemerides at the height of 800 km, where the contribution of ions in the total AMD is more significant. More specifically, two periods of forty days were chosen in 2014--2015 and 2018--2019, representing the solar maximum and minimum periods, respectively, to assess the SERC model and four other state-of-the-art AMD models. Thorough analyses were conducted to compare OP results using different AMD models with precise reference ephemerides of COSMIC satellites and based on various space weather indices. It is indicated that the SERC model outperforms all other AMD models in terms of OP errors during the solar maximum period and yields comparable OP results during the solar minimum period. Numéro de notice : P2020-001 Affiliation des auteurs : ENSG+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Preprint nature-HAL : Préprint DOI : 10.1002/essoar.10502170.1 Date de publication en ligne : 09/02/2020 En ligne : https://doi.org/10.1002/essoar.10502170.1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97632
Titre : Impact of thermospheric mass density on the orbit prediction of LEO satellites Type de document : Article/Communication Auteurs : Changyong He Année de publication : 2020 Projets : 1-Pas de projet / Article en page(s) : n° e2019SW002336 Note générale : bibliographie
This study was supported by the Cooperative Research Centre for Space Environment Management (SERCLimited) through the Australian Government's Cooperative Research Centre Programme and partially supported by the National Natural Science Foundation of China (41874040) and the CUMT Independent Innovation Project of “Double-First Class” Construction (2018ZZCX08)Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales
[Termes IGN] masse d'air
[Termes IGN] orbite basse
[Termes IGN] orbitographieRésumé : (auteur) Many thermospheric mass density (TMD) variations have been recognized in observations and physical simulations; however, their impact on the low‐Earth‐orbit satellites has not been fully evaluated. The present study investigates the quantitative impact of periodic spatiotemporal TMD variations modulated by the empirical DTM2013 model. Also considered are two small‐scale variations, that is, the equatorial mass anomaly and the midnight density maximum, which are reproduced by the Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model. This investigation is performed through a 1‐day orbit prediction (OP) simulation for a 400‐km circular orbit. The results show that the impact of TMD variations during solar maximum is 1 order of magnitude larger than that during solar minimum. The dominant impact has been found in the along‐track direction. Semiannual and semidiurnal variations in TMD exert the most significant impact on OP among the intra‐annual and intradiurnal variations, respectively. The zero mean periodic variations in TMD may not significantly affect the predicted orbit but increase the orbital uncertainty if their periods are shorter than the time span of OP. Additionally, the equatorial mass anomaly creates a mean orbit difference of 50 m (5 m) with a standard deviation of 30 m (3 m) in 1‐day OP during high (low) solar activity. The midnight density maximum exhibits a stronger impact in the order of 150±30 and 15±6 m during solar maximum and solar minimum, respectively. This study makes clear that careful selection of TMD variations is of great importance to balance the trade‐off between efficiency and accuracy in OP problems. Numéro de notice : A2020-467 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2019SW002336 Date de publication en ligne : 06/11/2019 En ligne : https://doi.org/10.1029/2019SW002336 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95553
in Space weather > vol 18 n° 1 (January 2020) . - n° e2019SW002336[article]
Titre : Helmert-VCE-aided fast-WTLS approach for global ionospheric VTEC modelling using data from GNSS, satellite altimetry and radio occultation Type de document : Article/Communication Auteurs : Andong Hu, Auteur ; Zishen Li, Auteur ; Brett Anthony Carter, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 877 - 888 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] carte ionosphérique mondiale
[Termes IGN] données altimétriques
[Termes IGN] données GNSS
[Termes IGN] méthode des moindres carrés
[Termes IGN] modèle ionosphérique
[Termes IGN] occultation du signal
[Termes IGN] pondération
[Termes IGN] retard ionosphèrique
[Termes IGN] teneur verticale totale en électrons
[Termes IGN] varianceRésumé : (auteur) Vertical total electron content (VTEC) global ionospheric maps (GIM) are commonly used to correct the ionospheric delay of global navigation satellite system (GNSS) signals for single-frequency positioning and other ionospheric studies. The measurements observed by inhomogeneously distributed ground reference stations are the only data used to generate the GIMs. Thus the accuracy of the GIMs over ocean and polar regions is relatively poor due to the lack of measurements over these regions. In this study, space-borne VTECs obtained from ocean-altimetry and GNSS radio occultation measurements are incorporated into the modelling process. Since the three types of VTEC data have different qualities, the weight for each type of data is determined using the Helmert-variance component estimation (Helmert-VCE) method. In addition, unlike the traditional weighted least squares (WLS) estimation method in which the design matrix of observation equations is fixed, in this study, the design matrix, especially those elements in design matrix that are derived from the coordinates of either tangent point or ionospheric pierce point, are considered to be inaccurate. Thus they are adjusted together with the unknown coefficient parameters of the fitting model using the fast-weighted total least squares (fast-WTLS) technique. The proposed approach, named Helmert-WTLS, was tested using the data in the period of day of year (DOY) 217–224, 2016 and validated using GIMs produced by the research team for ionosphere and precise positioning based on BDS/GNSS (GIPP) at the Academy of Opto-Electronics, Chinese Academy of Sciences (CAS). Comparison results showed that the GIMs (with a 2 h temporal resolution) generated using the new approach can improve the determination of ionospheric TEC by 0.28 TEC units (TECU) over those from the Helmert-VCE-aided WLS approach (w.r.t CAS references, respectively) and by 1.61 TECU better than those from WLS, in terms of the mean of all root-mean-squares errors of all 2 h time slots in the 8-day testing period. In addition, in comparison with out-of-sample Jason-3 observations, results from the proposed method also outperformed Helmert-VCE-aided WLS, CAS and CODE models by 1.5, 2.4 and 2.4 TECU, respectively. Numéro de notice : A2019-352 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1210-7 Date de publication en ligne : 14/11/2018 En ligne : https://doi.org/10.1007/s00190-018-1210-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93398
in Journal of geodesy > vol 93 n°6 (June 2019) . - pp 877 - 888[article]
