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Evaluation of methods for connecting InSAR to a terrestrial reference frame in the Latrobe Valley, Australia / P.J. Johnston in Journal of geodesy, vol 95 n° 10 (October 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 10 (October 2021) . - n° 115 Titre : Evaluation of methods for connecting InSAR to a terrestrial reference frame in the Latrobe Valley, Australia Type de document : Article/Communication Auteurs : P.J. Johnston, Auteur ; M. S. Filmer, Auteur ; Thomas Fuhrmann, Auteur Année de publication : 2021 Article en page(s) : n° 115 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] Australian Geodetic Datum [Termes IGN] Australie [Termes IGN] Continuously Operating Reference Station network [Termes IGN] image Sentinel-SAR [Termes IGN] incertitude de mesurage [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] International Terrestrial Reference Frame [Termes IGN] littoral [Termes IGN] propagation d'erreur [Termes IGN] réseau géodésique permanent [Termes IGN] station GNSS [Termes IGN] subsidence Résumé : (auteur) Deformation measurements from satellite-borne synthetic aperture radar interferometry (InSAR) are usually measured relative to an arbitrary reference point (RP) of assumed stability over time. For InSAR rates to be reliably interpreted as uplift or subsidence, they must be connected to a defined Earth-centred terrestrial reference frame (TRF), usually made through GNSS continuously operating reference stations (CORS). We adapt and compare three methods of TRF connection proposed by different studies which we term the single CORS RP (SCRP), plane-fit multiple CORS (PFMC), and the multiple CORS RP (MCRP). We generalise equations for these methods, and importantly, develop equations to propagate InSAR and GNSS uncertainties through the transformation process. This is significant, because it is important to not only estimate the InSAR uncertainties, but also to account for the uncertainties that are introduced when connecting to the CORS so as to better inform our interpretation of the deformation field and the limitation of the measurements. We then test these methods using Sentinel-1 data in the Latrobe Valley, Australia. These results indicate that differences among the three TRF connection methods may be greater than their estimated uncertainties. MCRP appears the most reliable method, although it may be limited in large study areas with sparse CORS due to long wavelength InSAR errors and that gaps and/or steps may appear at the spatial limit from the CORS. SCRP relies on the quality of the single CORS connection, but can be validated by unconnected CORS in the study area. The PFMC method is suited to larger areas undergoing slow, constant deformation covering large spatial extents where there are evenly distributed CORS across the study area. Selecting an optimal method of TRF connection is dependent on local site conditions, CORS network geometry and the characteristics of the deformation field. Hence, the choice of TRF connection method should be carefully considered, because different methods may result in significantly different transformed deformation rates. We confirm slow subsidence across the Latrobe Valley relative to the vertical component of the ITRF2014, with localised high subsidence rates near open cut mining activities. Subsidence of ~ -6 mm/year is observed in the adjacent coastal region which may exacerbate relative sea level rise along the coastline, increasing future risks of coastal inundation. Numéro de notice : A2021-749 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s00190-021-01560-2 Date de publication en ligne : 08/10/2021 En ligne : https://doi.org/10.1007/s00190-021-01560-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98730 [article]

Generating statistically robust multipath stacking maps using congruent cells / Thomas Fuhrmann in GPS solutions, vol 19 n° 1 (January 2015)  

Public [article]  inGPS solutions > vol 19 n° 1 (January 2015) . - pp 83 - 92 Titre : Generating statistically robust multipath stacking maps using congruent cells Type de document : Article/Communication Auteurs : Thomas Fuhrmann, Auteur ; Xiaoguang Luo, Auteur ; Andreas Knöpfler, Auteur ; Michael Mayer, Auteur Année de publication : 2015 Article en page(s) : pp 83 - 92 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] congruence [Termes IGN] correction du trajet multiple [Termes IGN] résidu [Termes IGN] superposition [Termes IGN] trajet multiple [Termes IGN] valeur aberrante Résumé : (auteur) Multipath effects caused by reflections in the near-field and far-field of a GNSS antenna represent a major error source in static and kinematic GNSS positioning applications. Since these effects are strongly site-specific, a generally valid and practicable analytical multipath model is still lacking. In contrast, using GNSS carrier phase observation residuals, the multipath stacking (MPS) methods are able to take site-specific conditions into account. We propose an advanced approach to performing residual-based MPS in the space domain. Being superior to most conventional attempts in which stacking cells have a fixed azimuthal resolution, our suggested method makes use of congruent cells and rigorous statistical assessments in terms of outlier detection and significance evaluation of the stacked values. The advanced stacking approach is applied to representative phase residuals from static precise point positioning. The results show that the use of congruent cells allows for MPS at high elevation angles and with a fine spatial resolution. Applying the resulting MPS maps at the residual level, both near-field and far-field effects at high and low elevation angles, respectively, can be significantly mitigated. In comparison with the conventional approach, the advanced one enables a larger reduction of about 20 % in the SD of residuals. Numéro de notice : A2015-205 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0367-7 Date de publication en ligne : 23/02/2014 En ligne : https://doi.org/10.1007/s10291-014-0367-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76018 [article]