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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)  

Public [article]  inJournal of geodesy > vol 95 n° 7 (July 2021) . - n° 77 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] tomographie Résumé : (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 [article]

An improved constrained simultaneous iterative reconstruction technique for ionospheric tomography / Yi Bin Yao in GPS solutions, Vol 24 n° 3 (July 2020)  

Public [article]  inGPS solutions > Vol 24 n° 3 (July 2020) Titre : An improved constrained simultaneous iterative reconstruction technique for ionospheric tomography Type de document : Article/Communication Auteurs : Yi Bin Yao, Auteur ; Changzhi Zhai, Auteur ; Jian Kong, Auteur ; et al., Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] données GNSS [Termes IGN] interpolation [Termes IGN] modèle ionosphérique [Termes IGN] reconstruction 3D [Termes IGN] teneur totale en électrons [Termes IGN] tomographie [Termes IGN] voxel Résumé : (auteur) Global Navigation Satellite System (GNSS) is now widely used for continuous ionospheric observations. Three-dimensional computerized ionospheric tomography (3DCIT) is an important tool for the reconstruction of electron density distributions in the ionosphere through effective use of the GNSS data. More specifically, the 3DCIT technique is able to resolve the three-dimensional electron density distributions over the reconstructed area based on the GNSS slant total electron content (STEC) observations. We present an Improved Constrained Simultaneous Iterative Reconstruction Technique (ICSIRT) algorithm that differs from the traditional ionospheric tomography methods in 3 ways. First, the ICSIRT computes the electron density corrections based on the product of the intercept and electron density within voxels so that the assignment of corrections at different heights becomes more reasonable. Second, an Inverse Distance Weighted (IDW) interpolation is used to restrict the electron density values in the voxels not traversed by GNSS rays, thereby ensuring the smoothness of the reconstructed region. Also, to improve the reconstruction accuracy around the HmF2 (the peak height of the F2 layer) altitude, a multiresolution grid is adopted in the vertical direction, with a 10-km resolution from 200 to 420 km and a 50-km resolution at other altitudes. The new algorithm has been applied to the GNSS data over the European and North American regions in different case studies that involve different seasonal conditions as well as a major storm. In the European region experiment, reconstruction results show that the new ICSIRT algorithm can effectively improve the reconstruction of the GNSS data. The electron density profiles retrieved from ICSIRT are much closer to the ionosonde observations than those from its predecessor, namely, the Constrained Simultaneous Iteration Reconstruction Technique (CSIRT). The reconstruction accuracy is significantly improved. In the North American region experiment, the electron density profiles in ICSIRT results show better agreement with incoherent scatter radar observations than CSIRT, even for the topside profiles. Numéro de notice : A2020-227 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-00981-4 Date de publication en ligne : 18/04/2020 En ligne : https://doi.org/10.1007/s10291-020-00981-4 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94958 [article]