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The relation between degree-2160 spectral models of Earth’s gravitational and topographic potential : a guide on global correlation measures and their dependency on approximation effects / Christian Hirt in Journal of geodesy, vol 91 n° 10 (October 2017)
[article]
Titre : The relation between degree-2160 spectral models of Earth’s gravitational and topographic potential : a guide on global correlation measures and their dependency on approximation effects Type de document : Article/Communication Auteurs : Christian Hirt, Auteur ; Moritz Rexer, Auteur ; Sten Claessens, Auteur ; Reiner Rummel, Auteur Année de publication : 2017 Article en page(s) : pp 1179 – 1205 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] corrélation
[Termes IGN] Earth Gravity Model 2008
[Termes IGN] erreur systématique
[Termes IGN] modèle de géopotentiel
[Termes IGN] potentiel de pesanteur terrestreRésumé : (Auteur) Comparisons between high-degree models of the Earth’s topographic and gravitational potential may give insight into the quality and resolution of the source data sets, provide feedback on the modelling techniques and help to better understand the gravity field composition. Degree correlations (cross-correlation coefficients) or reduction rates (quantifying the amount of topographic signal contained in the gravitational potential) are indicators used in a number of contemporary studies. However, depending on the modelling techniques and underlying levels of approximation, the correlation at high degrees may vary significantly, as do the conclusions drawn. The present paper addresses this problem by attempting to provide a guide on global correlation measures with particular emphasis on approximation effects and variants of topographic potential modelling. We investigate and discuss the impact of different effects (e.g., truncation of series expansions of the topographic potential, mass compression, ellipsoidal versus spherical approximation, ellipsoidal harmonic coefficient versus spherical harmonic coefficient (SHC) representation) on correlation measures. Our study demonstrates that the correlation coefficients are realistic only when the model’s harmonic coefficients of a given degree are largely independent of the coefficients of other degrees, permitting degree-wise evaluations. This is the case, e.g., when both models are represented in terms of SHCs and spherical approximation (i.e. spherical arrangement of field-generating masses). Alternatively, a representation in ellipsoidal harmonics can be combined with ellipsoidal approximation. The usual ellipsoidal approximation level (i.e. ellipsoidal mass arrangement) is shown to bias correlation coefficients when SHCs are used. Importantly, gravity models from the International Centre for Global Earth Models (ICGEM) are inherently based on this approximation level. A transformation is presented that enables a transformation of ICGEM geopotential models from ellipsoidal to spherical approximation. The transformation is applied to generate a spherical transform of EGM2008 (sphEGM2008) that can meaningfully be correlated degree-wise with the topographic potential. We exploit this new technique and compare a number of models of topographic potential constituents (e.g., potential implied by land topography, ocean water masses) based on the Earth2014 global relief model and a mass-layer forward modelling technique with sphEGM2008. Different to previous findings, our results show very significant short-scale correlation between Earth’s gravitational potential and the potential generated by Earth’s land topography (correlation +0.92, and 60% of EGM2008 signals are delivered through the forward modelling). Our tests reveal that the potential generated by Earth’s oceans water masses is largely unrelated to the geopotential at short scales, suggesting that altimetry-derived gravity and/or bathymetric data sets are significantly underpowered at 5 arc-min scales. We further decompose the topographic potential into the Bouguer shell and terrain correction and show that they are responsible for about 20 and 25% of EGM2008 short-scale signals, respectively. As a general conclusion, the paper shows the importance of using compatible models in topographic/gravitational potential comparisons and recommends the use of SHCs together with spherical approximation or EHCs with ellipsoidal approximation in order to avoid biases in the correlation measures. Numéro de notice : A2017-541 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1016-z En ligne : https://doi.org/10.1007/s00190-017-1016-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86596
in Journal of geodesy > vol 91 n° 10 (October 2017) . - pp 1179 – 1205[article]Multi-dimensional and multi-temporal motion estimation of a beam surface during dynamic testing using low-frame rate digital cameras / I. Detchev in Applied geomatics, vol 9 n° 3 (September 2017)
[article]
Titre : Multi-dimensional and multi-temporal motion estimation of a beam surface during dynamic testing using low-frame rate digital cameras Type de document : Article/Communication Auteurs : I. Detchev, Auteur ; Derek Litchi, Auteur ; Ayman Habib, Auteur ; Mamdouh El-Badry, Auteur Année de publication : 2017 Article en page(s) : pp 127 - 141 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] ajustement de paramètres
[Termes IGN] caméra numérique
[Termes IGN] déviation de la verticale
[Termes IGN] méthode des moindres carrés
[Termes IGN] photogrammétrie métrologiqueRésumé : (Auteur) The combination of digital close-range photogrammetric systems and image processing techniques has been employed in structural health monitoring applications for more than 10 years. The use of off-the-shelf entry level digital single-lens reflex cameras has lately become a suitable choice even for applications requiring sub-millimetre- level precision especially when the involved devices need to be inexpensive. The drawback of such low-cost cameras is in the trade-off between spatial resolution, frame rate, and burst rate—at the highest available spatial resolution, a high frame rate is either not possible or it has a low burst rate. This may be problematic when monitoring a structural component during a dynamic/fatigue test. In order to estimate specimen motion in such a situation, this paper proposes an innovative sinusoidal fitting based on a least squares adjustment. This method simultaneously processes multiple bursts of data in order to synthetically increase the sampling frequency of the system. The input data for the adjustment comes from a full surface modelling procedure based on a newly proposed generalized 3D polynomial. The experimental results include a beam deformation test performed in a structures laboratory. The new sinusoidal fitting method effectively increased the system temporal resolution three-fold, which improved the precision of the derived parameters with up to two orders of magnitude. The root mean square error of the residuals were as good as 26 μm, and the one of the estimated amplitudes from the photogrammetric system versus a set of laser transducers used as control was as small as 43 μm. Numéro de notice : A2017-595 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1007/s12518-017-0184-0 Date de publication en ligne : 10/04/2017 En ligne : https://doi.org/10.1007/s12518-017-0184-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86803
in Applied geomatics > vol 9 n° 3 (September 2017) . - pp 127 - 141[article]TotalStation/GNSS/EGM integrated geocentric positioning method / Edward Osada in Survey review, vol 49 n° 354 (September 2017)
[article]
Titre : TotalStation/GNSS/EGM integrated geocentric positioning method Type de document : Article/Communication Auteurs : Edward Osada, Auteur ; M. Owczarek-Wesołowska, Auteur ; M. Ficner, Auteur ; G. Kurpiński, Auteur Année de publication : 2017 Article en page(s) : pp 206 - 211 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] coordonnées cartésiennes géocentriques
[Termes IGN] déviation de la verticale
[Termes IGN] Earth Gravity Model 2008
[Termes IGN] ellipsoïde GRS 1980
[Termes IGN] modélisation 3D
[Termes IGN] positionnement par GNSS
[Termes IGN] tachéomètre électroniqueRésumé : (Auteur) In this study, we have investigated the use of the plumb line direction from Global Gravity Earth Model EGM2008 in the 3D integrated TotalStation/GNSS positioning. Our study shows that measurements along a total station traverse provides more accurate positioning results if the vertical deflection of plumb line is retrieved from EGM2008, than positioning with unknown deflection. The use of EGM2008 model improves the 3D coordinates accuracy to the level of precise GNSS measurements, while lack of this data introduce spatial displacements of the measured points, up to 26 cm. Hence our method can be useful for building precise 3D models of terrestrial objects in the GRS80 geocentric coordinate system. Numéro de notice : A2017-546 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2016.1151969 En ligne : https://doi.org/10.1080/00396265.2016.1151969 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86601
in Survey review > vol 49 n° 354 (September 2017) . - pp 206 - 211[article]Analysis of decade-long time series of GPS-based polar motion estimates at 15-min temporal resolution / Aurore E. Sibois in Journal of geodesy, vol 91 n° 8 (August 2017)
[article]
Titre : Analysis of decade-long time series of GPS-based polar motion estimates at 15-min temporal resolution Type de document : Article/Communication Auteurs : Aurore E. Sibois, Auteur ; Shailen Desai, Auteur ; Willy I. Bertiger, Auteur ; Bruce J. Haines, Auteur Année de publication : 2017 Article en page(s) : pp 965–983 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse diachronique
[Termes IGN] marée océanique
[Termes IGN] mouvement du pôle
[Termes IGN] nutation
[Termes IGN] pôle
[Termes IGN] positionnement par GPS
[Termes IGN] série temporelleRésumé : (auteur) We present results from the generation of 10-year-long continuous time series of the Earth’s polar motion at 15-min temporal resolution using Global Positioning System ground data. From our results, we infer an overall noise level in our high-rate polar motion time series of 60 μas (RMS). However, a spectral decomposition of our estimates indicates a noise floor of 4 μas at periods shorter than 2 days, which enables recovery of diurnal and semidiurnal tidally induced polar motion. We deliberately place no constraints on retrograde diurnal polar motion despite its inherent ambiguity with long-period nutation. With this approach, we are able to resolve damped manifestations of the effects of the diurnal ocean tides on retrograde polar motion. As such, our approach is at least capable of discriminating between a historical background nutation model that excludes the effects of the diurnal ocean tides and modern models that include those effects. To assess the quality of our polar motion solution outside of the retrograde diurnal frequency band, we focus on its capability to recover tidally driven and non-tidal variations manifesting at the ultra-rapid (intra-daily) and rapid (characterized by periods ranging from 2 to 20 days) periods. We find that our best estimates of diurnal and semidiurnal tidally induced polar motion result from an approach that adopts, at the observation level, a reasonable background model of these effects. We also demonstrate that our high-rate polar motion estimates yield similar results to daily-resolved polar motion estimates, and therefore do not compromise the ability to resolve polar motion at periods of 2–20 days. Numéro de notice : A2017-462 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1001-6 En ligne : https://doi.org/10.1007/s00190-017-1001-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86408
in Journal of geodesy > vol 91 n° 8 (August 2017) . - pp 965–983[article]A global terrestrial reference frame from simulated VLBI and SLR data in view of GGOS / Susanne Glaser in Journal of geodesy, vol 91 n° 7 (July 2017)
[article]
Titre : A global terrestrial reference frame from simulated VLBI and SLR data in view of GGOS Type de document : Article/Communication Auteurs : Susanne Glaser, Auteur ; Rolf König, Auteur ; Dimitrios Ampatzidis, Auteur ; Tobias Nilsson, Auteur ; Robert Heinkelmann, Auteur ; Frank Flechtner, Auteur ; Harald Schuh, Auteur Année de publication : 2017 Article en page(s) : pp 723 - 733 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données ITGB
[Termes IGN] données TLS (télémétrie)
[Termes IGN] Global Geodetic Observing System
[Termes IGN] paramètres d'orientation de la Terre
[Termes IGN] point de liaison (géodésie)
[Termes IGN] repère de référence
[Termes IGN] simulationRésumé : (Auteur) In this study, we assess the impact of two combination strategies, namely local ties (LT) and global ties (GT), on the datum realization of Global Terrestrial Reference Frames in view of the Global Geodetic Observing System requiring 1 mm-accuracy. Simulated Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) data over a 7 year time span was used. The LT results show that the geodetic datum can be best transferred if the precision of the LT is at least 1 mm. Investigating different numbers of LT, the lack of co-located sites on the southern hemisphere is evidenced by differences of 9 mm in translation and rotation compared to the solution using all available LT. For the GT, the combination applying all Earth rotation parameters (ERP), such as pole coordinates and UT1-UTC, indicates that the rotation around the Z axis cannot be adequately transferred from VLBI to SLR within the combination. Applying exclusively the pole coordinates as GT, we show that the datum can be transferred with mm-accuracy within the combination. Furthermore, adding artificial stations in Tahiti and Nigeria to the current VLBI network results in an improvement in station positions by 13 and 12%, respectively, and in ERP by 17 and 11%, respectively. Extending to every day VLBI observations leads to 65% better ERP estimates compared to usual twice-weekly VLBI observations. Numéro de notice : A2017-295 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1021-2 En ligne : http://doi.org/10.1007/s00190-017-1021-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85330
in Journal of geodesy > vol 91 n° 7 (July 2017) . - pp 723 - 733[article]The extension of the parametrization of the radio source coordinates in geodetic VLBI and its impact on the time series analysis / Maria Karbon in Journal of geodesy, vol 91 n° 7 (July 2017)PermalinkDetermination of a high spatial resolution geopotential model using atomic clock comparisons / Guillaume Lion in Journal of geodesy, vol 91 n° 6 (June 2017)PermalinkITRF2014 plate motion model / Zuheir Altamimi in Geophysical journal international, vol 209 n° 3 (June 2017)PermalinkMultivariate analysis of GPS position time series of JPL second reprocessing campaign / Ali Reza Amiri-Simkooei in Journal of geodesy, vol 91 n° 6 (June 2017)PermalinkInverting Glacial Isostatic Adjustment signal using Bayesian framework and two linearly relaxing rheologies / Lambert Caron in Geophysical journal international, vol 209 n° 2 (May 2017)PermalinkMulti-scale modeling of Earth's gravity field in space and time / Shuo (2) Wang in Journal of geodynamics, vol 106 (May 2017)PermalinkSpace-wise approach for airborne gravity data modelling / Daniele Sampietro in Journal of geodesy, vol 91 n° 5 (May 2017)PermalinkCalcul du quasi-géoïde QGF16 et de la grille de conversion altimétrique RAF16 : état d'avancement et perspectives / François L'écu in XYZ, n° 150 (mars - mai 2017)PermalinkLe chemin vers un système de référence altimétrique global et unifié / Laura Sánchez in XYZ, n° 150 (mars - mai 2017)PermalinkDétermination pratique de modèles de géoïde et autres surfaces de référence altimétrique / Jean-Louis Carme in XYZ, n° 150 (mars - mai 2017)Permalink