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Stochastic models in the DORIS position time series : estimates for IDS contribution to ITRF2014 / Anna Klos in Journal of geodesy, vol 92 n° 7 (July 2018)  

Public [article]  inJournal of geodesy > vol 92 n° 7 (July 2018) . - pp 743 - 763 Titre : Stochastic models in the DORIS position time series : estimates for IDS contribution to ITRF2014 Type de document : Article/Communication Auteurs : Anna Klos, Auteur ; Janusz Bogusz, Auteur ; Guilhem Moreaux, Auteur Année de publication : 2018 Article en page(s) : pp 743 - 763 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] données DORIS [Termes IGN] International Terrestrial Reference Frame [Termes IGN] modèle stochastique [Termes IGN] série temporelle Résumé : (Auteur) This paper focuses on the investigation of the deterministic and stochastic parts of the Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) weekly time series aligned to the newest release of ITRF2014. A set of 90 stations was divided into three groups depending on when the data were collected at an individual station. To reliably describe the DORIS time series, we employed a mathematical model that included the long-term nonlinear signal, linear trend, seasonal oscillations and a stochastic part, all being estimated with maximum likelihood estimation. We proved that the values of the parameters delivered for DORIS data are strictly correlated with the time span of the observations. The quality of the most recent data has significantly improved. Not only did the seasonal amplitudes decrease over the years, but also, and most importantly, the noise level and its type changed significantly. Among several tested models, the power-law process may be chosen as the preferred one for most of the DORIS data. Moreover, the preferred noise model has changed through the years from an autoregressive process to pure power-law noise with few stations characterised by a positive spectral index. For the latest observations, the medians of the velocity errors were equal to 0.3, 0.3 and 0.4 mm/year, respectively, for the North, East and Up components. In the best cases, a velocity uncertainty of DORIS sites of 0.1 mm/year is achievable when the appropriate coloured noise model is taken into consideration. Numéro de notice : A2018-454 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1092-0 Date de publication en ligne : 30/11/2017 En ligne : https://doi.org/10.1007/s00190-017-1092-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91045 [article]

Homogeneizing GPS integrated water vapour time series: methodology and benchmarking the algorithms on synthetic datasets / Roeland Van Malderen (2017)    

Public Titre : Homogeneizing GPS integrated water vapour time series: methodology and benchmarking the algorithms on synthetic datasets Type de document : Article/Communication Auteurs : Roeland Van Malderen, Auteur ; Eric Pottiaux, Auteur ; Anna Klos, Auteur ; Olivier Bock , Auteur ; Janusz Bogusz, Auteur ; Barbara Chimani, Auteur ; Michal Elias, Auteur ; et al., Auteur Editeur : Genève : Organisation Météorologique Mondiale OMM / World Meteorological Organization WMO Année de publication : 2017 Collection : WCDMP series num. 85 Conférence : HQCD & SITCM 2017, 9th seminar for Homogenization and Quality control in Climatological Databases and 4th Conference on Spatial Interpolation Techniques in Climatology and Meteorology 03/04/2017 07/04/2017 Budapest Bulgarie Importance : pp 102 - 114 Format : 21 x 30 cm Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] données hétérogènes [Termes IGN] homogénéisation [Termes IGN] jeu de données [Termes IGN] jeu de données localisées [Termes IGN] surveillance météorologique [Termes IGN] teneur intégrée en vapeur d'eau Résumé : (auteur) [motivation] Within the COST Action ES1206 “Advanced Global Navigation Satellite Systems tropospheric products for monitoring severe weather events and climate” (GNSS4SWEC), there was a clear interest and need to homogenize Integrated Water Vapour (IWV) datasets retrieved from Global Navigation Satellite System (GNSS) observations, by correcting (artificial) breakpoints due to e.g. instrumental changes. Based on the results of an inquiry, a homogenization activity was started within Working Group 3 (”Use of GNSS tropospheric products for climate monitoring”), targeting the following objectives: (i) select one or two long-term reference datasets, (ii) apply different homogenization algorithms on these reference datasets, and build up a list of commonly identified inhomogeneities based on statistical detection and metadata information, and (iii) come up with an homogenized version of the reference dataset that can be re-used to study climate trends and time variability by the entire community. Numéro de notice : C2017-047 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : sans En ligne : https://repositorio.aemet.es/bitstream/20.500.11765/8393/1/Homogenizing_Guijarro [...] Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91941

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On the significance of periodic signals in noise analysis of GPS station coordinates time series / Janusz Bogusz in GPS solutions, vol 20 n° 4 (October 2016)  

Public [article]  inGPS solutions > vol 20 n° 4 (October 2016) . - pp 655 - 664 Titre : On the significance of periodic signals in noise analysis of GPS station coordinates time series Type de document : Article/Communication Auteurs : Janusz Bogusz, Auteur ; Anna Klos, Auteur Année de publication : 2016 Article en page(s) : pp 655 - 664 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] analyse diachronique [Termes IGN] bruit (théorie du signal) [Termes IGN] coordonnées cartésiennes géocentriques [Termes IGN] GIPSY-OASIS [Termes IGN] positionnement ponctuel précis [Termes IGN] série temporelle [Termes IGN] signal GPS [Termes IGN] station GPS [Termes IGN] variation saisonnière [Termes IGN] vitesse Résumé : (Auteur) Each of the GPS-derived time series consists of the deterministic (functional) and stochastic part. We propose that the deterministic part includes all periodicities from 1st to 9th harmonics of residual Chandler, tropical and draconitic periods and compare it with commonly used calculations of the annual and semi-annual tropical curve. Then, we address the issues of whether all residual periodicities, as proposed here, need to be taken into consideration when performing noise analysis. We use the position time series from 180 International GNSS Service stations obtained at the Jet Propulsion Laboratory using the GIPSY-OASIS software in a Precise Point Positioning mode. The longest series has 22.1 years of GPS daily solutions. The spectral indices range from –0.12 to –0.92, while the median values of “global” spectral indices are equal to: –0.41 ± 0.15, –0.38 ± 0.12 and –0.33 ± 0.18 for North, East and Up components, respectively. All non-modelled geophysical processes or non-included artificial effects in time series lead to an underestimation of errors of velocities, but also to changes in the velocity values themselves. The proposed assumption of seasonals subtraction caused the Akaike information criterion values to show a decrease in the median value of 30 %, which in fact means that all the seasonals mentioned here must be taken into account when analyzing noises. Finally, we noticed that there are some of the GPS stations that improved their velocity uncertainty even of 56 %. Numéro de notice : A2016--027 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0478-9 En ligne : http://dx.doi.org/10.1007/s10291-015-0478-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83929 [article]

Towards reliable velocities of permanent GNSS stations / Janusz Bogusz in Reports on geodesy and geoinformatics, vol 100 (May 2016)  

Public [article]  inReports on geodesy and geoinformatics > vol 100 (May 2016) . - pp 17 - 26 Titre : Towards reliable velocities of permanent GNSS stations Type de document : Article/Communication Auteurs : Janusz Bogusz, Auteur ; Anna Klos, Auteur ; Marta Gruszczynska, Auteur ; Maciej Gruszczynski, Auteur Année de publication : 2016 Article en page(s) : pp 17 - 26 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse de spectre singulier [Termes IGN] analyse en composantes principales [Termes IGN] bruit (théorie du signal) [Termes IGN] coordonnées GNSS [Termes IGN] série temporelle [Termes IGN] station permanente [Termes IGN] vitesse [Vedettes matières IGN] Traitement de données GNSS Résumé : (Auteur) In the modern geodesy the role of the permanent station is growing constantly. The proper treatment of the time series from such station lead to the determination of the reliable velocities. In this paper we focused on some pre-analysis as well as analysis issues, which have to be performed upon the time series of the North, East and Up components and showed the best, in our opinion, methods of determination of periodicities (by means of Singular Spectrum Analysis) and spatio-temporal correlations (Principal Component Analysis), that still exist in the time series despite modelling. Finally, the velocities of the selected European permanent stations with the associated errors determined following power-law assumption in the stochastic part is presented. In this paper we preliminary discuss methods for collecting raster data in a geodatabase by processing open multi-temporal and multi-scale satellite data aimed at retrieving indicators for land degradation phenomenon (i.e. land cover/land use analysis, vegetation indices, trend analysis, etc.). Then we describe a methodology for designing a WebGIS framework in order to disseminate information through maps for territory monitoring. Basic WebGIS functions were extended with the help of POSTGIS database and OpenLayers libraries. Geoserver was customized to set up and enhance the website functions developing various advanced queries using PostgreSQL and innovative tools to carry out efficiently multi-layer overlay analysis. The end-product is a simple system that provides the opportunity not only to consult interactively but also download processed remote sensing data. Numéro de notice : A2016-645 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/rgg-2016-0003 En ligne : http://dx.doi.org/10.1515/rgg-2016-0003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81851 [article]

Earth rotation and geodynamics / Janusz Bogusz in Geodesy and cartography, vol 64 n° 2 (December 2015)  

Public [article]  inGeodesy and cartography > vol 64 n° 2 (December 2015) . - pp 201 - 242 Titre : Earth rotation and geodynamics Type de document : Article/Communication Auteurs : Janusz Bogusz, Auteur ; Alexander Brzezinski, Auteur ; Wieslaw Kosek, Auteur ; Jolanta Nastula, Auteur Année de publication : 2015 Article en page(s) : pp 201 - 242 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] champ géomagnétique [Termes IGN] géodynamique [Termes IGN] marée terrestre [Termes IGN] Pologne [Termes IGN] positionnement par GNSS [Termes IGN] positionnement par télémétrie laser sur satellite [Termes IGN] rotation de la Terre Résumé : (auteur) This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals with monitoring of geodynamic phenomena. It contains analysis of geodynamic networks of local, and regional scale using space (GNSS and SLR) techniques, Earth tides monitoring with gravimeters and water-tube hydrostatic clinometer, and the determination of secular variation of the Earth’ magnetic field. Numéro de notice : A2015--018 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/geocart-2015-0013 En ligne : http://dx.doi.org/10.1515/geocart-2015-0013 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80814 [article]

Irregular variations in GPS time series by probability and noise analysis / Anna Klos in Survey review, vol 47 n° 342 (May 2015)  

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Spatio-temporal filtering for determination of common mode error in regional GNSS networks / Janusz Bogusz in Open geosciences, vol 7 n° 1 (January 2015)  

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