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High-frequency Earth rotation variations deduced from altimetry-based ocean tides / Matthias Madzak in Journal of geodesy, vol 90 n° 11 (November 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 11 (November 2016) . - pp 1237 - 1253 Titre : High-frequency Earth rotation variations deduced from altimetry-based ocean tides Type de document : Article/Communication Auteurs : Matthias Madzak, Auteur ; Michael Schindelegger, Auteur ; Johannes Böhm , Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 1237 - 1253 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] altimétrie satellitaire par radar [Termes IGN] géodésie dynamique [Termes IGN] marée océanique [Termes IGN] rotation de la Terre Résumé : (Auteur) A model of diurnal and semi-diurnal variations in Earth rotation parameters (ERP) is constructed based on altimetry-measured tidal heights from a multi-mission empirical ocean tide solution. Barotropic currents contributing to relative angular momentum changes are estimated for nine major tides in a global inversion algorithm that solves the two-dimensional momentum equations on a regular 0.5∘ grid with a heavily weighted continuity constraint. The influence of 19 minor tides is accounted for by linear admittance interpolation of ocean tidal angular momentum, although the assumption of smooth admittance variations with frequency appears to be a doubtful concept for semi-diurnal mass terms in particular. A validation of the newly derived model based on post-fit corrections to polar motion and universal time (ΔUT1) from the analysis of Very Long Baseline Interferometry (VLBI) observations shows a variance reduction for semi-diurnal ΔUT1 residuals that is significant at the 0.05 level with respect to the conventional ERP model. Improvements are also evident for the explicitly modeled K1, Q1, and K2 tides in individual ERP components, but large residuals of more than 15 μas remain at the principal lunar frequencies of O1 and M2. We attribute these shortcomings to uncertainties in the inverted relative angular momentum changes and, to a minor extent, to violation of mass conservation in the empirical ocean tide solution. Further dedicated hydrodynamic modeling efforts of these anomalous constituents are required to meet the accuracy standards of modern space geodesy. Numéro de notice : A2016-800 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0919-4 En ligne : http://dx.doi.org/10.1007/s00190-016-0919-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82581 [article]

Development of an improved empirical model for slant delays in the troposphere (GPT2w) / Johannes Böhm in GPS solutions, vol 19 n° 3 (July 2015)    

Public [article]  inGPS solutions > vol 19 n° 3 (July 2015) . - pp 433 - 441 Titre : Development of an improved empirical model for slant delays in the troposphere (GPT2w) Type de document : Article/Communication Auteurs : Johannes Böhm , Auteur ; Gregor Möller, Auteur ; Michael Schindelegger, Auteur ; Grégory Pain, Auteur ; Robert Weber, Auteur Année de publication : 2015 Article en page(s) : pp 433 - 441 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] coordonnées GNSS [Termes IGN] erreur systématique [Termes IGN] modèle empirique [Termes IGN] retard troposphérique [Termes IGN] station permanente [Termes IGN] teneur en vapeur d'eau Résumé : (Auteur) Global pressure and temperature 2 wet (GPT2w) is an empirical troposphere delay model providing the mean values plus annual and semiannual amplitudes of pressure, temperature and its lapse rate, water vapor pressure and its decrease factor, weighted mean temperature, as well as hydrostatic and wet mapping function coefficients of the Vienna mapping function 1. All climatological parameters have been derived consistently from monthly mean pressure level data of ERA-Interim fields (European Centre for Medium-Range Weather Forecasts Re-Analysis) with a horizontal resolution of 1°, and the model is suitable to calculate slant hydrostatic and wet delays down to 3° elevation at sites in the vicinity of the earth surface using the date and approximate station coordinates as input. The wet delay estimation builds upon gridded values of the water vapor pressure, the weighted mean temperature, and the water vapor decrease factor, with the latter being tuned to ray-traced zenith wet delays. Comparisons with zenith delays at 341 globally distributed global navigation satellite systems stations show that the mean bias over all stations is below 1 mm and the mean standard deviation is about 3.6 cm. The GPT2w model with the gridded input file is provided at. Numéro de notice : A2015--112 Affiliation des auteurs : ENSG+Ext (2012-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-014-0403-7 Date de publication en ligne : 26/08/2014 En ligne : https://doi.org/10.1007/s10291-014-0403-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90646 [article]

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