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Automated estimation and tools to extract positions, velocities, breaks, and seasonal terms from daily GNSS measurements: illuminating nonlinear Salton Trough deformation / Michael B. Heflin in Earth and space science, vol 7 n° 7 (July 2020)  

Public [article]  inEarth and space science > vol 7 n° 7 (July 2020) . - 10 p. Titre : Automated estimation and tools to extract positions, velocities, breaks, and seasonal terms from daily GNSS measurements: illuminating nonlinear Salton Trough deformation Type de document : Article/Communication Auteurs : Michael B. Heflin, Auteur ; Andrea Donnellan, Auteur ; Jay Parker, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : 10 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] Californie (Etats-Unis) [Termes IGN] chaîne de traitement [Termes IGN] champ de vitesse [Termes IGN] déformation horizontale de la croute terrestre [Termes IGN] données GNSS [Termes IGN] dorsale [Termes IGN] faille géologique [Termes IGN] modèle géologique [Termes IGN] positionnement par GNSS [Termes IGN] série temporelle [Termes IGN] sismologie [Termes IGN] station GPS [Termes IGN] valeur aberrante [Termes IGN] variation saisonnière Résumé : (auteur) This paper describes the methods used to estimate positions, velocities, breaks, and seasonalterms from daily Global Navigation Satellite System (GNSS) measurements. Break detection and outlierremoval have been automated so that decades of daily measurements from thousands of stations can beprocessed in a few hours. New measurements are added, and parameters are updated every week. Modelparameters allow separation of interseismic, annual, coseismic, and postseismic signals. Tools availablethrough GeoGateway (http://geo-gateway.org) allow rapid visualization and analysis of these terms forresults that can be subsetted in time or space. Results show highly variable and nonlinear motion for GPSstations in southern California. The variable motion is related to seasonal motions, distributed tectonicmotion, earthquakes, and postseismic motions that can continue for years. In some areas results suggest thatadditional processes are responsible for the observed motions. In general, following earthquakes, stationsreturn to their longterm motions after 2–3 years, though some exceptions occur. The use of the tools showsnonlinear motion in the Salton Trough of southern California related to the 2010 M7.2 El MayorCucapahearthquake, 2012 Brawley earthquake swarm, and a creep event on the Superstition Hills fault in 2017. Numéro de notice : A2020-446 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2019EA000644 Date de publication en ligne : 18/05/2020 En ligne : https://doi.org/10.1029/2019EA000644 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95516 [article]

Web services for dynamic coloring of UAVSAR images / Jun Wang in Pure and applied geophysics, vol 172 n° 8 (August 2015)  

Public [article]  inPure and applied geophysics > vol 172 n° 8 (August 2015) . - pp 2325 - 2332 Titre : Web services for dynamic coloring of UAVSAR images Type de document : Article/Communication Auteurs : Jun Wang, Auteur ; Marlon Pierce, Auteur ; Andrea Donnellan, Auteur ; Jay Parker, Auteur Année de publication : 2015 Article en page(s) : pp 2325 - 2332 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web [Termes IGN] carte thématique [Termes IGN] cartographie à la volée [Termes IGN] couleur à l'écran [Termes IGN] déformation de la croute terrestre [Termes IGN] drone [Termes IGN] image radar moirée [Termes IGN] interface web [Termes IGN] polarimétrie radar [Termes IGN] séisme [Termes IGN] service web géographique Résumé : (auteur) QuakeSim has implemented a service-based Geographic Information System to enable users to access large amounts of Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) data through an online interface. The QuakeSim Interferometric Synthetic Aperture Radar (InSAR) profile tool calculates radar-observed displacement (from an unwrapped interferogram product) along user-specified lines. Pre-rendered thumbnails with InSAR fringe patterns are used to display interferogram and unwrapped phase images on a Google Map in the InSAR profile tool. One challenge with this tool lies in the user visually identifying regions of interest when drawing the profile line. This requires that the user correctly interpret the InSAR imagery, which currently uses fringe patterns. The mapping between pixel color and pixel value is not a one-to-one relationship from the InSAR fringe pattern, and it causes difficulty in understanding general displacement information for QuakeSim users. The goal of this work is to generate color maps that directly reflect the pixel values (displacement) as an addition to the pre-rendered images. Because of an extremely uneven distribution of pixel values on an InSAR image, a histogram-based, nonlinear color template generation algorithm is currently under development. A web service enables on-the-fly coloring of UAVSAR images with dynamically generated color templates. Numéro de notice : A2015-493 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/IMAGERIE Nature : Article DOI : 10.1007/s00024-014-0941-5 Date de publication en ligne : 26/10/2014 En ligne : https://doi.org/10.1007/s00024-014-0941-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77288 [article]

KALREF, a Kalman filter and time series approach to the International Terrestrial Reference Frame realization / Xiaoping Wu in Journal of geophysical research : Solid Earth, vol 120 n° 5 (May 2015)    

Public [article]  inJournal of geophysical research : Solid Earth > vol 120 n° 5 (May 2015) . - pp 3775 - 3802 Titre : KALREF, a Kalman filter and time series approach to the International Terrestrial Reference Frame realization Type de document : Article/Communication Auteurs : Xiaoping Wu, Auteur ; Claudio Abbondanza, Auteur ; Zuheir Altamimi , Auteur ; T.M. Chin, Auteur ; Xavier Collilieux , Auteur ; Richard S. Gross, Auteur ; Michael B. Heflin, Auteur ; Yan Jiang, Auteur ; Jay Parker, Auteur Année de publication : 2015 Article en page(s) : pp 3775 - 3802 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] filtre de Kalman [Termes IGN] International Terrestrial Reference Frame [Termes IGN] point de liaison (géodésie) [Termes IGN] série temporelle [Termes IGN] vitesse Résumé : (auteur) The current International Terrestrial Reference Frame is based on a piecewise linear site motion model and realized by reference epoch coordinates and velocities for a global set of stations. Although linear motions due to tectonic plates and glacial isostatic adjustment dominate geodetic signals, at today's millimeter precisions, nonlinear motions due to earthquakes, volcanic activities, ice mass losses, sea level rise, hydrological changes, and other processes become significant. Monitoring these (sometimes rapid) changes desires consistent and precise realization of the terrestrial reference frame (TRF) quasi-instantaneously. Here, we use a Kalman filter and smoother approach to combine time series from four space geodetic techniques to realize an experimental TRF through weekly time series of geocentric coordinates. In addition to secular, periodic, and stochastic components for station coordinates, the Kalman filter state variables also include daily Earth orientation parameters and transformation parameters from input data frames to the combined TRF. Local tie measurements among colocated stations are used at their known or nominal epochs of observation, with comotion constraints applied to almost all colocated stations. The filter/smoother approach unifies different geodetic time series in a single geocentric frame. Fragmented and multitechnique tracking records at colocation sites are bridged together to form longer and coherent motion time series. While the time series approach to TRF reflects the reality of a changing Earth more closely than the linear approximation model, the filter/smoother is computationally powerful and flexible to facilitate incorporation of other data types and more advanced characterization of stochastic behavior of geodetic time series. Numéro de notice : A2015--006 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Autre URL associée : http://onlinelibrary.wiley.com/doi/10.1002/2014JB011622 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/2014JB011622 Date de publication en ligne : 07/04/2015 En ligne : http://dx.doi.org/10.1002/2014JB011622 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80479 [article]

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