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MIDAS robust trend estimator for accurate GPS station velocities without step detection / Geoffrey Blewitt in Journal of geophysical research : Solid Earth, vol 121 n° 3 (March 2016)
[article]
Titre : MIDAS robust trend estimator for accurate GPS station velocities without step detection Type de document : Article/Communication Auteurs : Geoffrey Blewitt, Auteur ; Corné Kremer, Auteur ; William C. Hammond, Auteur ; Julien Gazeaux , Auteur Année de publication : 2016 Article en page(s) : pp 2054 - 2068 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] Amérique du nord
[Termes IGN] coordonnées GPS
[Termes IGN] estimateur
[Termes IGN] méthode robuste
[Termes IGN] série temporelle
[Termes IGN] station GPS
[Termes IGN] valeur aberrante
[Termes IGN] vitesseRésumé : (auteur) Automatic estimation of velocities from GPS coordinate time series is becoming required to cope with the exponentially increasing flood of available data, but problems detectable to the human eye are often overlooked. This motivates us to find an automatic and accurate estimator of trend that is resistant to common problems such as step discontinuities, outliers, seasonality, skewness, and heteroscedasticity. Developed here, Median Interannual Difference Adjusted for Skewness (MIDAS) is a variant of the Theil‐Sen median trend estimator, for which the ordinary version is the median of slopes vij = (xj–xi)/(tj–ti) computed between all data pairs i > j. For normally distributed data, Theil‐Sen and least squares trend estimates are statistically identical, but unlike least squares, Theil‐Sen is resistant to undetected data problems. To mitigate both seasonality and step discontinuities, MIDAS selects data pairs separated by 1 year. This condition is relaxed for time series with gaps so that all data are used. Slopes from data pairs spanning a step function produce one‐sided outliers that can bias the median. To reduce bias, MIDAS removes outliers and recomputes the median. MIDAS also computes a robust and realistic estimate of trend uncertainty. Statistical tests using GPS data in the rigid North American plate interior show ±0.23 mm/yr root‐mean‐square (RMS) accuracy in horizontal velocity. In blind tests using synthetic data, MIDAS velocities have an RMS accuracy of ±0.33 mm/yr horizontal, ±1.1 mm/yr up, with a 5th percentile range smaller than all 20 automatic estimators tested. Considering its general nature, MIDAS has the potential for broader application in the geosciences. Numéro de notice : A2016--176 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/2015JB012552 Date de publication en ligne : 12/02/2016 En ligne : https://doi.org/10.1002/2015JB012552 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91799
in Journal of geophysical research : Solid Earth > vol 121 n° 3 (March 2016) . - pp 2054 - 2068[article]Documents numériques
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MIDAS robust trend estimator ... - pdf éditeurAdobe Acrobat PDF Understanding sea-level rise and variability, ch 9. Geodetic observations and global reference frame contributions to understanding sea-level rise and variability / Geoffrey Blewitt (2010)
Titre de série : Understanding sea-level rise and variability, ch 9 Titre : Geodetic observations and global reference frame contributions to understanding sea-level rise and variability Type de document : Chapitre/Contribution Auteurs : Geoffrey Blewitt, Auteur ; Zuheir Altamimi , Auteur ; James Davis, Auteur ; et al., Auteur Editeur : New York, Londres, Hoboken (New Jersey), ... : John Wiley & Sons Année de publication : 2010 Importance : pp 256 - 284 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] coordonnées cartésiennes géocentriques
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] montée du niveau de la mer
[Termes IGN] variabilitéRésumé : (auteur) This chapter contains sections titled: -Introduction, -Global and Regional Reference Systems, -Linking GPS to Tide Gauges and Tide-Gauge Benchmarks, -Recommendations for Geodetic Observations. Numéro de notice : H2010-017 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Chapître / contribution nature-HAL : ChOuvrScient DOI : 10.1002/9781444323276.ch9 Date de publication en ligne : 05/07/2010 En ligne : https://doi.org/10.1002/9781444323276.ch9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102044 Mapping Dilution of Precision (MDOP) and map-matched GPS / Geoffrey Blewitt in International journal of geographical information science IJGIS, vol 16 n° 1 (january 2002)
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Titre : Mapping Dilution of Precision (MDOP) and map-matched GPS Type de document : Article/Communication Auteurs : Geoffrey Blewitt, Auteur ; Georges E. Taylor, Auteur Année de publication : 2002 Article en page(s) : pp 55 - 67 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] affaiblissement géométrique de la précision
[Termes IGN] appariement de cartes
[Termes IGN] correction
[Termes IGN] erreur de positionnement
[Termes IGN] GPS assisté pour la navigation (technologies)
[Termes IGN] GPS en mode différentiel
[Termes IGN] méthode des moindres carrés
[Termes IGN] navigation automobile
[Termes IGN] positionnement différentiel
[Termes IGN] véhicule automobileRésumé : (Auteur) A novel method of map matching using the Global Positioning System (GPS) has been developed which uses digital mapping and height data to augment point position computation. This method reduces the error in position, which is a sum from several sources, including signal delay due to the ionosphere and atmosphere and until recently from 'selective availability' (S/A). S/A was imposed by the US military to degrade purposefully the accuracy of GPS, but was switched off on 2 May 2000, and is to be replaced with 'regional denial capabilities in lieu of global degradation' (Interagency GPS Executive Board, 2000). Taylor et al. (2001) describe the Road Reduction Filter (RRF) in detail. RRF is a method of detecting the correct road on which a vehicle is travelling. In the work described here, the position error vector is estimated in a formal least squares procedure, as the vehicle is moving. This estimate is a map-matched correction, that provides an autonomous alternative to DGPS for in-car navigation and fleet management. In this paper, a formula is derived for 'Mapped Dilution of Precision' (MDOP), defined as the theoretical ratio of position precision using map-matched corrections to that using perfect Differential GPS (DGPS) correction. This is shown to be purely a function of route geometry, and is computed for examples of basic road shapes. MDOP is favourable unless the route has less than a few degrees curvature for several kilometres. MDOP can thus provide an objective estimate of positioning precision to a vehicle driver. Precision estimates using MDOP are shown to agree well with 'true' positioning errors determined using high precision (cm) GPS carrier phase techniques. The exact location of a vehicle on a road is essential for accurate surveying applications. These include close range photogrammetry using digital video or still cameras and the verification of digital mapping by measured (GPS and other sensors) trajectories. Numéro de notice : A2002-004 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/13658810110075996 En ligne : https://doi.org/10.1080/13658810110075996 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21921
in International journal of geographical information science IJGIS > vol 16 n° 1 (january 2002) . - pp 55 - 67[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 079-02011 RAB Revue Centre de documentation En réserve L003 Disponible A European network for sea level and coastal land level monitoring / Trevor F. Baker in Journal of Marine Systems, vol 13 n° 1-4 (October 1997)
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Titre : A European network for sea level and coastal land level monitoring Type de document : Article/Communication Auteurs : Trevor F. Baker, Auteur ; Philip L. Woodworth, Auteur ; Geoffrey Blewitt, Auteur ; Claude Boucher , Auteur ; Guy Wöppelmann , Auteur Année de publication : 1997 Article en page(s) : pp 163 - 171 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] déformation verticale de la croute terrestre
[Termes IGN] Global Ocean Observing System
[Termes IGN] marée océanique
[Termes IGN] marégraphe
[Termes IGN] niveau moyen des mers
[Termes IGN] positionnement par GPS
[Termes IGN] surveillance géologiqueRésumé : (Auteur) Recommendations have recently been made by an international working group that a global absolute sea level monitoring system should be set up over the next few years by installing permanently operating GPS receivers at 100, or thereabouts, key tide gauges around the world. After giving a brief overview of these recommendations and of the current state of global and regional tide gauge and GPS networks, we propose the formation of a strategic European network for sea level and coastal land level monitoring. This will complement the sparser 'global' monitoring system and provide a European network infrastructure with common standards. It will provide a more regional basis for sea and land level monitoring, and can be further densified in local areas which have flood defence problems. The proposed system will provide data for determining regional changes in absolute mean sea levels due to climate change, identifying areas of coastal subsidence, monitoring flow through straits, and for helping to define a unified European vertical datum. We hope to stimulate discussions between European geodesists, oceanographers and tide gauge operators, with the aim of achieving extensive support for such a network. Numéro de notice : A1997-002 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/S0924-7963(96)00118-2 Date de publication en ligne : 15/06/1998 En ligne : https://doi.org/10.1016/S0924-7963(96)00118-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33693
in Journal of Marine Systems > vol 13 n° 1-4 (October 1997) . - pp 163 - 171[article]Atmospheric pressure loading effects on global positioning system coordinate determinations / Tonie M. VanDam in Journal of geophysical research : Solid Earth, vol 99 n° 12 (10/12/1994)
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Titre : Atmospheric pressure loading effects on global positioning system coordinate determinations Type de document : Article/Communication Auteurs : Tonie M. VanDam, Auteur ; Geoffrey Blewitt, Auteur ; Michael B. Heflin, Auteur Année de publication : 1994 Article en page(s) : pp 23939 - 23950 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] coordonnées GPS
[Termes IGN] correction atmosphérique
[Termes IGN] données GPS
[Termes IGN] ligne de base
[Termes IGN] pression atmosphérique
[Termes IGN] surcharge atmosphérique
[Termes IGN] traitement de données GNSS
[Termes IGN] varianceRésumé : (Auteur) Earth deformation signals caused by atmospheric pressure loading are detected in vertical position estimates at Global Positioning System (GPS) stations. Surface displacements due to changes in atmospheric pressure account for up to 24% of the total variance in the GPS height estimates. The detected loading signals are larger at higher latitudes where pressure variations are greatest; the largest effect is observed at Fairbanks, Alaska (latitude 65°), with a signal RMS of 5 mm. Out of 19 continuously operating GPS sites (with a mean of 281 daily solutions per site), 18 show a positive correlation between the GPS vertical estimates and the modeled loading displacements. Accounting for loading reduces the variance of the vertical station positions on 12 of the 19 sites investigated. Numéro de notice : A1994-019 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1029/94JB02122 En ligne : https://doi.org/10.1029/94JB02122 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=25723
in Journal of geophysical research : Solid Earth > vol 99 n° 12 (10/12/1994) . - pp 23939 - 23950[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 194-94121 Revue Centre de documentation Indéterminé Disponible