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Comparison of atmospheric mass density models using a new data source: COSMIC satellite ephemerides / Yang Yang (2020)  

Public contenu dans Earth and Space Science Open Archive ESSOAr / American Geophysical Union (2019)   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 , Auteur ; Robert Norman, Auteur ; Emma Kerr, Auteur ; Brett Anthony Carter, Auteur ; Julie Louise Currie, Auteur ; Steve Gower, Auteur Editeur : Washington DC [Etats-Unis] : Earth and Space Science Open Archive ESSOAr Année de publication : 2020 Note générale : bibliographie Submitted to Space Weather Langues : Anglais (eng) Descripteur : [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 Résumé : (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

Evaluation of the IRI-2016 and NeQuick electron content specification by COSMIC GPS radio occultation, ground-based GPS and Jason-2 joint altimeter/GPS observations / Iurii Cherniak in Advances in space research, vol 63 n° 6 (15 March 2019)  

Public [article]  inAdvances in space research > vol 63 n° 6 (15 March 2019) . - pp 1845 - 1859 Titre : Evaluation of the IRI-2016 and NeQuick electron content specification by COSMIC GPS radio occultation, ground-based GPS and Jason-2 joint altimeter/GPS observations Type de document : Article/Communication Auteurs : Iurii Cherniak, Auteur ; Irina Zakharenkova, Auteur Année de publication : 2019 Article en page(s) : pp 1845 - 1859 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] données altimétriques [Termes IGN] données GPS [Termes IGN] données Jason [Termes IGN] International Reference Ionosphere [Termes IGN] modèle ionosphérique [Termes IGN] plasmasphère [Termes IGN] teneur totale en électrons [Termes IGN] variation diurne Résumé : (Auteur) We examined performance of two empirical profile-based ionospheric models, namely IRI-2016 and NeQuick-2, in electron content (EC) and total electron content (TEC) representation for different seasons and levels of solar activity. We derived and analyzed EC estimates in several representative altitudinal intervals for the ionosphere and the plasmasphere from the COSMIC GPS radio occultation, ground-based GPS and Jason-2 joint altimeter/GPS observations. It allows us to estimate a quantitative impact of the ionospheric electron density profiles formulation in several altitudinal intervals and to examine the source of the model-data discrepancies of the EC specification from the bottom-side ionosphere towards the GPS orbit altitudes. The most pronounced model-data differences were found at the low latitude region as related to the equatorial ionization anomaly appearance. Both the IRI-2016 and NeQuick-2 models tend to overestimate the daytime ionospheric EC and TEC at low latitudes during all seasons of low solar activity. On the contrary, during high solar activity the model results underestimated the EC/TEC observations at low latitudes. We found that both models underestimated the EC for the topside ionosphere and plasmasphere regions for all levels of solar activity. For low solar activity, the underestimated EC from the topside ionosphere and plasmasphere can compensate the overestimation of the ionospheric EC and, consequently, can slightly decrease the resulted model overestimation of the ground-based TEC. For high solar activity, the underestimated EC from the topside ionosphere and plasmasphere leads to a strengthening of the model underestimation of the ground-based TEC values. We demonstrated that the major source of the model-data discrepancies in the EC/TEC domain comes from the topside ionosphere/plasmasphere system. Numéro de notice : A2019-171 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2018.10.036 date de publication en ligne : 02/11/2018 En ligne : https://doi.org/10.1016/j.asr.2018.10.036 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92622 [article]

Determination of the ionospheric foF2 using a stand-alone GPS receiver / Dudy D Wijaya in Journal of geodesy, vol 91 n° 9 (September 2017)  

Public [article]  inJournal of geodesy > vol 91 n° 9 (September 2017) . - pp 1117 – 1133 Titre : Determination of the ionospheric foF2 using a stand-alone GPS receiver Type de document : Article/Communication Auteurs : Dudy D Wijaya, Auteur ; Haris Haralambous, Auteur ; Christina Oikonomou, Auteur ; Wedyanto Kuntjoro, Auteur Année de publication : 2017 Article en page(s) : pp 1117 – 1133 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] filtre de Kalman [Termes IGN] gradient ionosphèrique [Termes IGN] International Reference Ionosphere [Termes IGN] ionosphère [Termes IGN] récepteur GPS [Termes IGN] sonde spatiale [Termes IGN] teneur totale en électrons Résumé : (auteur) The critical frequency of ionospheric F2 layer (foF2) is a measure of the highest frequency of radio signal that may be reflected back by the F2 layer, and it is associated with ionospheric peak electron density in the F2 layer. Accurate long-term foF2 variations are usually derived from ionosonde observations. In this paper, we propose a new method to observe foF2 using a stand-alone global positioning system (GPS) receiver. The proposed method relies on the mathematical equation that relates foF2 to GPS observations. The equation is then implemented in the Kalman filter algorithm to estimate foF2 at every epoch of the observation (30-s rate). Unlike existing methods, the proposed method does not require any additional information from ionosonde observations and does not require any network of GPS receivers. It only requires as inputs the ionospheric scale height and the modeled plasmaspheric electron content, which practically can be derived from any existing ionospheric/plasmaspheric model. We applied the proposed method to estimate long-term variations of foF2 at three GPS stations located at the northern hemisphere (NICO, Cyprus), the southern hemisphere (STR1, Australia) and the south pole (SYOG, Antarctic). To assess the performance of the proposed method, we then compared the results against those derived by ionosonde observations and the International Reference Ionosphere (IRI) 2012 model. We found that, during the period of high solar activity (2011–2012), the values of absolute mean bias between foF2 derived by the proposed method and ionosonde observations are in the range of 0.2–0.5 MHz, while those during the period of low solar activity (2009–2010) are in the range of 0.05–0.15 MHz. Furthermore, the root-mean-square-error (RMSE) values during high and low solar activities are in the range of 0.8–0.9 MHz and of 0.6–0.7 MHz, respectively. We also noticed that the values of absolute mean bias and RMSE between foF2 derived by the proposed method and the IRI-2012 model are slightly larger than those between the proposed method and ionosonde observations. These results demonstrate that the proposed method can estimate foF2 with a comparable accuracy. Since the proposed method can estimate foF2 at every epoch of the observation, it therefore has promising applications for investigating various scales (from small to large) of foF2 irregularities. Numéro de notice : A2017-481 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : https://doi.org/10.1007/s00190-017-1013-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86412 [article]

Performance evaluation of ionospheric time delay forecasting models using GPS observations at a low-latitude station / G. Sivavaraprasad in Advances in space research, vol 60 n° 2 (15 July 2017)  

Public [article]  inAdvances in space research > vol 60 n° 2 (15 July 2017) . - pp 475 - 490 Titre : Performance evaluation of ionospheric time delay forecasting models using GPS observations at a low-latitude station Type de document : Article/Communication Auteurs : G. Sivavaraprasad, Auteur ; D. Venkata Ratman, Auteur Année de publication : 2017 Article en page(s) : pp 475 - 490 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] données GPS [Termes IGN] données météorologiques [Termes IGN] Inde [Termes IGN] International Reference Ionosphere [Termes IGN] latitude [Termes IGN] modèle de simulation [Termes IGN] modèle ionosphérique [Termes IGN] retard ionosphèrique [Termes IGN] teneur totale en électrons [Termes IGN] teneur verticale totale en électrons [Termes IGN] test de performance [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) Ionospheric delay is one of the major atmospheric effects on the performance of satellite-based radio navigation systems. It limits the accuracy and availability of Global Positioning System (GPS) measurements, related to critical societal and safety applications. The temporal and spatial gradients of ionospheric total electron content (TEC) are driven by several unknown priori geophysical conditions and solar-terrestrial phenomena. Thereby, the prediction of ionospheric delay is challenging especially over Indian sub-continent. Therefore, an appropriate short/long-term ionospheric delay forecasting model is necessary. Hence, the intent of this paper is to forecast ionospheric delays by considering day to day, monthly and seasonal ionospheric TEC variations. GPS-TEC data (January 2013–December 2013) is extracted from a multi frequency GPS receiver established at K L University, Vaddeswaram, Guntur station (geographic: 16.37°N, 80.37°E; geomagnetic: 7.44°N, 153.75°E), India. An evaluation, in terms of forecasting capabilities, of three ionospheric time delay models – an Auto Regressive Moving Average (ARMA) model, Auto Regressive Integrated Moving Average (ARIMA) model, and a Holt-Winter's model is presented. The performances of these models are evaluated through error measurement analysis during both geomagnetic quiet and disturbed days. It is found that, ARMA model is effectively forecasting the ionospheric delay with an accuracy of 82–94%, which is 10% more superior to ARIMA and Holt-Winter’s models. Moreover, the modeled VTEC derived from International Reference Ionosphere, IRI (IRI-2012) model and new global TEC model, Neustrelitz TEC Model (NTCM-GL) have compared with forecasted VTEC values of ARMA, ARIMA and Holt-Winter’s models during geomagnetic quiet days. The forecast results are indicating that ARMA model would be useful to set up an early warning system for ionospheric disturbances at low latitude regions. Numéro de notice : A2017-252 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2017.01.031 date de publication en ligne : 30/01/2017 En ligne : https://doi.org/10.1016/j.asr.2017.01.031 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85254 [article]

Ionospheric error contribution to GNSS single-frequency navigation at the 2014 solar maximum / Raul Orus Perez in Journal of geodesy, vol 91 n° 4 (April 2017)  

Public [article]  inJournal of geodesy > vol 91 n° 4 (April 2017) . - pp 397 - 407 Titre : Ionospheric error contribution to GNSS single-frequency navigation at the 2014 solar maximum Type de document : Article/Communication Auteurs : Raul Orus Perez, Auteur Année de publication : 2017 Article en page(s) : pp 397 - 407 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] correction ionosphérique [Termes IGN] éruption solaire [Termes IGN] International GNSS Service [Termes IGN] International Reference Ionosphere [Termes IGN] modèle ionosphérique [Termes IGN] récepteur bifréquence [Termes IGN] récepteur monofréquence [Termes IGN] retard ionosphèrique [Termes IGN] signal Galileo [Termes IGN] signal GPS [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) For single-frequency users of the global satellite navigation system (GNSS), one of the main error contributors is the ionospheric delay, which impacts the received signals. As is well-known, GPS and Galileo transmit global models to correct the ionospheric delay, while the international GNSS service (IGS) computes precise post-process global ionospheric maps (GIM) that are considered reference ionospheres. Moreover, accurate ionospheric maps have been recently introduced, which allow for the fast convergence of the real-time precise point position (PPP) globally. Therefore, testing of the ionospheric models is a key issue for code-based single-frequency users, which constitute the main user segment. Therefore, the testing proposed in this paper is straightforward and uses the PPP modeling applied to single- and dual-frequency code observations worldwide for 2014. The usage of PPP modeling allows us to quantify—for dual-frequency users—the degradation of the navigation solutions caused by noise and multipath with respect to the different ionospheric modeling solutions, and allows us, in turn, to obtain an independent assessment of the ionospheric models. Compared to the dual-frequency solutions, the GPS and Galileo ionospheric models present worse global performance, with horizontal root mean square (RMS) differences of 1.04 and 0.49 m and vertical RMS differences of 0.83 and 0.40 m, respectively. While very precise global ionospheric models can improve the dual-frequency solution globally, resulting in a horizontal RMS difference of 0.60 m and a vertical RMS difference of 0.74 m, they exhibit a strong dependence on the geographical location and ionospheric activity. Numéro de notice : A2017-106 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://dx.doi.org/10.1007/s00190-016-0971-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84496 [article]

Ionospheric tomography using GNSS: multiplicative algebraic reconstruction technique applied to the area of Brazil / Fabricio Dos Santos Prol in GPS solutions, vol 20 n° 4 (October 2016)  

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A new computerized ionosphere tomography model using the mapping function and an application to the study of seismic-ionosphere disturbance / Jian Kong in Journal of geodesy, vol 90 n° 8 (August 2016)  

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Modeling of ionosphere time series using wavelet neural networks (case study: N-W of Iran) / Mir Reza Ghaffari Razin in Advances in space research, vol 58 n° 1 (July 2016)  

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Characterization of ionospheric variability in TEC using EOF and wavelets over low-latitude GNSS stations / J.R.K. Kumar Dabbakuti in Advances in space research, vol 57 n° 12 (June 2016)  

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A technique for routinely updating the ITU-R database using radio occultation electron density profiles / Claudio Brunini in Journal of geodesy, vol 87 n° 9 (September 2013)  

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The international reference ionosphere today and in the future / Dieter Bilitza in Journal of geodesy, vol 85 n° 12 (December 2011)  

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Validation of international reference ionosphere models using in situ measurements from GRACE K-band ranging system and CHAMP planar Langmuir probe / C. Lee in Journal of geodesy, vol 85 n° 12 (December 2011)  

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vol 85 n° 12 - December 2011 - Special issue : Ionosphere (Bulletin de Journal of geodesy) / M. Schmidt  

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