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A breakpoint detection in the mean model with heterogeneous variance on fixed time-intervals / Olivier Bock in Statistics and Computing, vol 29 n° 1 (February 2020)  

Public [article]  inStatistics and Computing > vol 29 n° 1 (February 2020) . - pp 1 - 13 Titre : A breakpoint detection in the mean model with heterogeneous variance on fixed time-intervals Type de document : Article/Communication Auteurs : Olivier Bock , Auteur ; Xavier Collilieux , Auteur ; François Guillamon, Auteur ; Emilie Lebarbier, Auteur ; Claire Pascal, Auteur Année de publication : 2020 Projets : 1-Pas de projet / Article en page(s) : pp 1 - 13 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Statistiques [Termes descripteurs IGN] analyse de variance [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] inférence statistique [Termes descripteurs IGN] méthode robuste [Termes descripteurs IGN] points de rupture [Termes descripteurs IGN] processus gaussien [Termes descripteurs IGN] segmentation [Termes descripteurs IGN] série temporelle [Termes descripteurs IGN] variabilité Résumé : (Auteur) This work is motivated by an application for the homogenization of global navigation satellite system (GNSS)-derived integrated water vapour series. Indeed, these series are affected by abrupt changes due to equipment changes or environmental effects. The detection and correction of the series from these changes are a crucial step before any use for climate studies. In addition to these abrupt changes, it has been observed in the series a non-stationary of the variability. We propose in this paper a new segmentation model that is a breakpoint detection in the mean model of a Gaussian process with heterogeneous variance on known time intervals. In this segmentation case, the dynamic programming algorithm used classically to infer the breakpoints cannot be applied anymore. We propose a procedure in two steps: we first estimate robustly the variances and then apply the classical inference by plugging these estimators. The performance of our proposed procedure is assessed through simulation experiments. An application to real GNSS data is presented. Numéro de notice : A2020-368 Thématique : MATHEMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s11222-019-09853-5 date de publication en ligne : 03/05/2019 En ligne : https://doi.org/10.1007/s11222-019-09853-5 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92571 [article]

Advanced GNSS tropospheric products for monitoring severe weather events and climate, ch. 5. Use of GNSS Tropospheric Products for Climate Monitoring (Working Group 3) / Olivier Bock (2020)  

Public contenu dans Advanced GNSS tropospheric products for monitoring severe weather events and climate / Jonathan Jones (2020)   Titre de série : Advanced GNSS tropospheric products for monitoring severe weather events and climate, ch. 5 Titre : Use of GNSS Tropospheric Products for Climate Monitoring (Working Group 3) Type de document : Chapitre/Contribution Auteurs : Olivier Bock , Auteur ; Rosa Pacione, Auteur ; F. Ahmed, Auteur ; et al., Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2020 Projets : GNSS4SWEC / Importance : pp 267 - 402 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] format SINEX [Termes descripteurs IGN] propagation troposphérique [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] série temporelle [Termes descripteurs IGN] surveillance météorologique [Termes descripteurs IGN] teneur intégrée en vapeur d'eau Résumé : (Auteur) There has been growing interest in recent years in the use of homogeneously reprocessed ground-based GNSS, VLBI, and DORIS measurements for climate applications. Existing datasets are reviewed and the sensitivity of tropospheric estimates to the processing details is discussed. The uncertainty in the derived IWV estimates and linear trends is around 1 kg m−2 RMS and ± 0.3 kg m−2 per decade, respectively. Standardized methods for ZTD outlier detection and IWV conversion are proposed. The homogeneity of final time series is limited however by changes in the stations equipment and environment. Various homogenization algorithms have been evaluated based on a synthetic benchmark dataset. The uncertainty of trends estimated from the homogenized times series is estimated to ±0.5 kg m−2 per decade. Reprocessed GNSS IWV data are analysed along with satellites data, reanalyses and global and regional climate model simulations. A selection of global and regional reprocessed GNSS datasets and ERA-interim reanalysis are made available through the GOP-TropDB tropospheric database and online service. A new tropo SINEX format, providing new features and simplifications, was developed and it is going to be adopted by all the IAG services. Numéro de notice : H2020-001 Thématique : POSITIONNEMENT Nature : Chapître / contribution nature-HAL : ChOuvrScient DOI : 10.1007/978-3-030-13901-8_5 date de publication en ligne : 14/09/2019 En ligne : https://doi.org/10.1007/978-3-030-13901-8_5 Format de la ressource électronique : URL chapitre Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94504

Advanced GNSS tropospheric products for monitoring severe weather events and climate / Jonathan Jones (2020)  

Public Titre : Advanced GNSS tropospheric products for monitoring severe weather events and climate : COST action ES1206 final action dissemination report Type de document : Actes de congrès Auteurs : Jonathan Jones, Editeur scientifique ; Guergana Guerova, Editeur scientifique ; Jan Douša, Editeur scientifique ; Galina Dick, Editeur scientifique ; Siebren de Haan, Editeur scientifique ; Eric Pottiaux, Editeur scientifique ; Olivier Bock , Editeur scientifique ; Rosa Pacione, Editeur scientifique ; Roeland Van Malderen, Editeur scientifique Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2020 Projets : GNSS4SWEC / Importance : 563 p. ISBN/ISSN/EAN : 978-3-030-13901-8 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] changement climatique [Termes descripteurs IGN] climat terrestre [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] données météorologiques [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] propagation troposphérique [Termes descripteurs IGN] surveillance météorologique [Termes descripteurs IGN] vapeur d'eau Résumé : (Editeur) [Introduction] The book (COST Action Final report) summarises the proceedings from COST Action ES1206. COST Action ES1206, Advanced GNSS Tropospheric Products for Severe Weather Events and Climate (GNSS4SWEC), was a 4-year project, running from 2013 to 2017, which coordinated new and improved capabilities from concurrent developments in GNSS, meteorological and climate communities. For the first time, the synergy of multi-GNSS constellations was used to develop new, more advanced tropospheric products, exploiting the full potential of multi-GNSS on a wide range of temporal and spatial scales - from real-time products monitoring and forecasting severe weather, to the highest quality post-processed products suitable for climate research. The Action also promoted the use of meteorological data as an input to real-time GNSS positioning, navigation, and timing services and has stimulated knowledge and data transfer throughout Europe and beyond. Note de contenu : - Front Matter - General Background - Advanced GNSS Processing Techniques (Working Group 1) - Use of GNSS Tropospheric Products for High-Resolution, Rapid-Update NWP and Severe Weather Forecasting (Working Group 2) - Use of GNSS Tropospheric Products for Climate Monitoring (Working Group 3) - National Status Reports - STSM Reports - Back Matter Numéro de notice : 26248 Thématique : POSITIONNEMENT Nature : Actes nature-HAL : DirectOuvrColl/Actes DOI : 10.1007/978-3-030-13901-8 date de publication en ligne : 14/09/2019 En ligne : https://doi.org/10.1007/978-3-030-13901-8 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94503

Contient

• Advanced GNSS tropospheric products for monitoring severe weather events and climate, ch. 5. Use of GNSS Tropospheric Products for Climate Monitoring (Working Group 3) / Olivier Bock (2020)  

A new segmentation method for the homogenisation of GNSS-derived IWV time-series / A. Quarello (2020)  

Public contenu dans ArXiv / Université Cornell (Etats-Unis) (1991)   Titre : A new segmentation method for the homogenisation of GNSS-derived IWV time-series Type de document : Article/Communication Auteurs : A. Quarello, Auteur ; Olivier Bock , Auteur ; Emilie Lebarbier, Auteur Editeur : Ithaca [New York - Etats-Unis] : ArXiv - Université Cornell Année de publication : 2020 Importance : 25 p. Format : 21 x 30 cm Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] algorithme d'homogénéisation [Termes descripteurs IGN] analyse de variance [Termes descripteurs IGN] changement climatique [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] estimateur [Termes descripteurs IGN] inférence [Termes descripteurs IGN] itération [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] programmation dynamique [Termes descripteurs IGN] série temporelle [Termes descripteurs IGN] surveillance météorologique [Termes descripteurs IGN] teneur intégrée en vapeur d'eau [Termes descripteurs IGN] variation saisonnière Résumé : (auteur) Homogenization is an important and crucial step to improve the usage of observational data for climate analysis. This work is motivated by the analysis of long series of GNSS Integrated Water Vapour (IWV) data which have not yet been used in this context. This paper proposes a novel segmentation method that integrates a periodic bias and a heterogeneous, monthly varying, variance. The method consists in estimating first the variance using a robust estimator and then estimating the segmentation and periodic bias iteratively. This strategy allows for the use of the dynamic programming algorithm that remains the most efficient exact algorithm to estimate the change-point positions. The statistical performance of the method is assessed through numerical experiments. An application to a real data set of 120 global GNSS stations is presented. The method is implemented in the R package GNSSseg that will be available on the CRAN. Numéro de notice : P2020-005 Thématique : POSITIONNEMENT Nature : Article nature-HAL : Préprint DOI : sans En ligne : https://arxiv.org/pdf/2005.04683.pdf Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95078

Consistency and representativeness of integrated water vapour from ground-based GPS observations and ERA-Interim reanalysis / Olivier Bock in Atmospheric chemistry and physics, vol 19 n° 14 (July 2019)  

Public [article]  inAtmospheric chemistry and physics > vol 19 n° 14 (July 2019) . - 17 p. Titre : Consistency and representativeness of integrated water vapour from ground-based GPS observations and ERA-Interim reanalysis Type de document : Article/Communication Auteurs : Olivier Bock , Auteur ; Ana-Claudia Bernardes Parracho, Auteur Année de publication : 2019 Projets : GNSS4SWEC / Article en page(s) : 17 p. Note générale : bibliographie This work is a contribution to the European COST Action ES1206 GNSS4SWEC (GNSS for Severe Weather and Climate monitoring; http://www.cost.eu/COST_Actions/essem/ES1206, last access: 22 July 2019) aiming at the development of the global GPS network for atmospheric research and climate change monitoring. This study benefited from the IPSL mesocentre ESPRI facility, which is supported by CNRS, UPMC, Labex L-IPSL, CNES, and Ecole Polytechnique, which is funded by the ANR (grant no. ANR-10-LABX-0018) and by the European FP7 IS-ENES2 project (grant no. 312979). Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] analyse diachronique [Termes descripteurs IGN] données GPS [Termes descripteurs IGN] erreur [Termes descripteurs IGN] humidité de l'air [Termes descripteurs IGN] interpolation spatiale [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] teneur intégrée en vapeur d'eau [Termes descripteurs IGN] variation diurne [Termes descripteurs IGN] variation saisonnière Résumé : (auteur) This study examines the consistency and representativeness differences of daily integrated water vapour (IWV) data from ERA-Interim reanalysis and GPS observations at 120 global sites over a 16-year period (1995–2010). Various comparison statistics are analysed as a function of geographic, topographic, and climatic features. A small (±1 kg m−2) bias is found in the reanalysis across latitudes (moist in northern and southern midlatitudes and dry in the tropics). The standard deviation of daily IWV differences is generally below 2 kg m−2 but peaks in the northern and southern storm-track regions. In general, the larger IWV differences are explained by increased representativeness errors, when GPS observations capture some small-scale variability that is not resolved by the reanalysis. A representativeness error statistic is proposed which measures the spatiotemporal variability in the vicinity of the GPS sites, based on reanalysis data at the four surrounding grid points. It allows to predict the standard deviation of daily IWV differences with a correlation of 0.73. In general, representativeness differences can be reduced by temporal averaging and spatial interpolation from the four surrounding grid points. A small number of outlying cases (15 sites) which do not follow the general tendencies are further examined. It is found that their special topographic and climatic features strongly enhance the representativeness errors (e.g. steep topography, coastlines, and strong seasonal cycle in monsoon regions). Discarding these sites significantly improves the global ERA-Interim and GPS comparison results. The selection of sites a priori, based on the representativeness error statistic, is able to detect 11 out of the 15 sites and improve the comparison results by 20 % to 30 %. Numéro de notice : A2019-615 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/acp-19-9453-2019 date de publication en ligne : 24/07/2019 En ligne : https://doi.org/10.5194/acp-19-9453-2019 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95311 [article]

Sensitivity of GPS tropospheric estimates to mesoscale convective systems in West Africa / Samuel Nahmani in Atmospheric chemistry and physics, vol 19 n° 14 (July 2019)    

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The AROME-WMED reanalyses of the first special observation period of the Hydrological cycle in the Mediterranean experiment (HyMeX) / Nadia Fourrié in Geoscientific Model Development, vol 12 n° 7 (July 2019)  

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Impact of humidity biases on light precipitation occurrence: observations versus simulations / Sophie Bastin in Atmospheric chemistry and physics, vol 19 n° 3 (February 2019)  

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Global IWV trends and variability in atmospheric reanalyses and GPS observations / Ana-Claudia Bernardes Parracho in Atmospheric chemistry and physics, vol 18 n° 22 ([01/11/2018])  

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Multi‐scale observations of atmospheric moisture variability in relation to heavy precipitating systems in the northwestern Mediterranean during HyMeX IOP12 / Samiro Khodayar in Quarterly Journal of the Royal Meteorological Society, vol 144 n° 717 (October 2018 Part B)  

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Comparison of total water vapour content in the Arctic derived from GNSS, AIRS, MODIS and SCIAMACHY / Dunya Alraddawi in Atmospheric measurement techniques, vol 11 n° 5 (May 2018)  

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Reduction of ZTD outliers through improved GNSS data processing and screening strategies [Interactive discussion] / Katarzyna Stępniak in Atmospheric measurement techniques, vol 11 n° 3 (March 2018)  

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Bilan de l’Action COST ES1206 - GNSS4SWEC (Advanced Global Navigation Satellite Systems tropospheric products for monitoring severe weather events and climate) / Olivier Bock (2018)

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Precipitable water vapour content from ESR/SKYNET sun–sky radiometers : validation against GNSS/GPS and AERONET over three different sites in Europe / Monica Campanelli in Atmospheric measurement techniques, vol 11 n° 1 (January 2018)    

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Enhanced MODIS atmospheric total water vapour content trends in response to Arctic amplification / Dunya Alraddawi in Atmosphere, vol 8 n° 12 (December 2017)  

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