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On the importance of accurately ray-traced troposphere corrections for interferometric SAR data / T. Hobiger in Journal of geodesy, vol 84 n° 9 (September 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 9 (September 2010) . - pp 537 - 546 Titre : On the importance of accurately ray-traced troposphere corrections for interferometric SAR data Type de document : Article/Communication Auteurs : T. Hobiger, Auteur ; S. Kinoshita, Auteur ; S. Shimizu, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 537 - 546 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] correction troposphérique [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] lancer de rayons [Termes IGN] modèle atmosphérique [Termes IGN] propagation troposphérique Résumé : (Auteur) Numerical weather models offer the possibility to compute corrections for a variety of space geodetic applications, including remote sensing techniques like interferometric SAR. Due to the computational complexity, exact ray-tracing is avoided in many cases and mapping approaches are applied to transform vertically integrated delay corrections into slant direction. Such an approach works well as long as lateral atmospheric gradients are small enough to be neglected. But since such an approximation holds only for very rare cases it is investigated how horizontal gradients of different atmospheric constituents can evoke errors caused by the mapping strategy. Moreover, it is discussed how sudden changes of wet refractivity can easily lead to millimeter order biases when simplified methods are applied instead of ray-tracing. By an example, based on real InSAR data, the differences of the various troposphere correction schemes are evaluated and it is shown how the interpretation of the geophysical signals can be affected. In addition, it is studied to which extend troposphere noise can be reduced by applying the exact ray-tracing solution. Numéro de notice : A2010-414 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0393-3 Date de publication en ligne : 11/06/2010 En ligne : https://doi.org/10.1007/s00190-010-0393-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30607 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2010091	SL	Revue	Centre de documentation	Revues en salle	Disponible

Asymmetric tropospheric delays from numerical weather models for UT1 determination from VLBI Intensive sessions on the baseline Wettzell–Tsukuba / Johannes Böhm in Journal of geodesy, vol 84 n° 5 (May 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 5 (May 2010) . - pp 319 - 325 Titre : Asymmetric tropospheric delays from numerical weather models for UT1 determination from VLBI Intensive sessions on the baseline Wettzell–Tsukuba Type de document : Article/Communication Auteurs : Johannes Böhm , Auteur ; T. Hobiger, Auteur ; R. Ichikawa, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 319 - 325 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] interférométrie à très grande base [Termes IGN] Japon [Termes IGN] ligne de base [Termes IGN] modèle atmosphérique [Termes IGN] propagation troposphérique [Termes IGN] temps universel [Termes IGN] Wettzell Résumé : (Auteur) One-baseline 1-h Very Long Baseline Interferometry (VLBI) Intensive sessions are carried out every day to determine Universal Time (UT1). Azimuthal asymmetry of tropospheric delays around the stations is usually ignored and not estimated because of the small number of observations. In this study we use external information about the asymmetry for the Intensive sessions between Tsukuba (Japan) and Wettzell (Germany), which are carried out on Saturdays and Sundays (1) from direct ray-tracing for each observation at Tsukuba and (2) in the form of linear horizontal north and east gradients every 6 h at both stations. The change of the UT1 estimates is at the 10 us level with maximum differences of up to 50 us, which is clearly above the formal uncertainties of the UT1 estimates (between 5 and 20 us). Spectral analysis reveals that delays from direct ray-tracing for the station Tsukuba add significant power at short periods (1–2 weeks) w.r.t. the state-of-the-art approach, and comparisons with length-of-day (LOD) estimates from Global Positioning System (GPS) indicate that these ray-traced delays slightly improve the UT1 estimates from Intensive sessions. Numéro de notice : A2010-184 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0370-x Date de publication en ligne : 05/03/2010 En ligne : https://doi.org/10.1007/s00190-010-0370-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30379 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2010051	SL	Revue	Centre de documentation	Revues en salle	Disponible