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The impact of relative and absolute GNSS positioning strategies on estimated coordinates and ZWD in the framework of meteorological applications / Alessandro Fermi in Applied geomatics, vol 11 n° 1 (March 2019)  

Public [article]  inApplied geomatics > vol 11 n° 1 (March 2019) . - pp 25 - 38 Titre : The impact of relative and absolute GNSS positioning strategies on estimated coordinates and ZWD in the framework of meteorological applications Type de document : Article/Communication Auteurs : Alessandro Fermi, Auteur ; Eugenio Realini, Auteur ; Giovanna Venuti, Auteur Année de publication : 2019 Article en page(s) : pp 25 - 38 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] coordonnées GNSS [Termes IGN] données météorologiques [Termes IGN] positionnement absolu [Termes IGN] positionnement différentiel [Termes IGN] retard troposphérique [Termes IGN] retard troposphérique zénithal [Termes IGN] teneur en vapeur d'eau Résumé : (Auteur) Since many years, the GNSS has been regarded by the meteorological community as one of the systems for atmospheric water vapour remote sensing. Time series of wet delays, estimated as by-products of accurate positioning, have been assimilated into numerical weather prediction models. However, a dedicated use the system for water vapour monitoring is still under investigation. Ad hoc dense networks have been designed and implemented to collect data at a high spatial resolution, baseline lengths lower than 10 km, with the aim of describing the high spatial and temporal variability of tropospheric water vapour. Within this framework, the paper reports a study on how the positioning strategy affects the estimated coordinates and tropospheric parameters. The study was conducted on the data collected by an experimental network of geodetic receivers, used as single or dual frequency ones. More specifically, investigations were made on the use of L1-only or iono-free combinations in differential positioning of receivers 100 to 10 km apart, finding that L1-only data provide more accurate results. Therefore, comparisons between local coordinates and ZWD obtained from relative and absolute positioning were performed to provide the statistics of the differences; the agreement between the results for short baselines is always better than 1 cm standard deviation. In order to assess the differences in the results that can be obtained from the two strategies when applied to the same observation set, a further comparison was carried out in terms of baseline components and ZWD increments. It results that, even for dense networks, the differential approach produces accurate results without losing information compared to the absolute one. Numéro de notice : A2019-159 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s12518-018-0234-2 Date de publication en ligne : 19/07/2018 En ligne : https://doi.org/10.1007/s12518-018-0234-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92520 [article]

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)  

Public [article]  inAtmospheric measurement techniques > vol 11 n° 1 (January 2018) . - pp 81 - 94 Titre : Precipitable water vapour content from ESR/SKYNET sun–sky radiometers : validation against GNSS/GPS and AERONET over three different sites in Europe Type de document : Article/Communication Auteurs : Monica Campanelli, Auteur ; Alessandra Mascitelli, Auteur ; Paolo Sano, Auteur ; Henri Diémoz, Auteur ; Victor Estellés, Auteur ; Stefano Federico, Auteur ; Anna Maria Iannarelli, Auteur ; Francesca Fratarcangeli, Auteur ; Augusto Mazzoni, Auteur ; Eugenio Realini, Auteur ; Mattia Crespi, Auteur ; Olivier Bock , Auteur ; Jose A. Martínez-Lozano, Auteur ; Stefano Dietrich, Auteur Année de publication : 2018 Projets : 1-Pas de projet / Article en page(s) : pp 81 - 94 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] Aoste (val d') [Termes IGN] constante [Termes IGN] coordonnées GPS [Termes IGN] données météorologiques [Termes IGN] données spatiotemporelles [Termes IGN] étalonnage d'instrument [Termes IGN] photomètre [Termes IGN] précipitation [Termes IGN] retard troposphérique zénithal [Termes IGN] Rome [Termes IGN] teneur en vapeur d'eau [Termes IGN] Valence (Espagne) [Termes IGN] water vapour radiometer Résumé : (Auteur) The estimation of the precipitable water vapour content (W) with high temporal and spatial resolution is of great interest to both meteorological and climatological studies. Several methodologies based on remote sensing techniques have been recently developed in order to obtain accurate and frequent measurements of this atmospheric parameter. Among them, the relative low cost and easy deployment of sun–sky radiometers, or sun photometers, operating in several international networks, allowed the development of automatic estimations of W from these instruments with high temporal resolution. However, the great problem of this methodology is the estimation of the sun-photometric calibration parameters. The objective of this paper is to validate a new methodology based on the hypothesis that the calibration parameters characterizing the atmospheric transmittance at 940 nm are dependent on vertical profiles of temperature, air pressure and moisture typical of each measurement site. To obtain the calibration parameters some simultaneously seasonal measurements of W, from independent sources, taken over a large range of solar zenith angle and covering a wide range of W, are needed. In this work yearly GNSS/GPS datasets were used for obtaining a table of photometric calibration constants and the methodology was applied and validated in three European ESR-SKYNET network sites, characterized by different atmospheric and climatic conditions: Rome, Valencia and Aosta. Results were validated against the GNSS/GPS and AErosol RObotic NET-work (AERONET) W estimations. In both the validations the agreement was very high, with a percentage RMSD of about 6, 13 and 8 % in the case of GPS intercomparison at Rome, Aosta and Valencia, respectively, and of 8 % in the case of AERONET comparison in Valencia. Analysing the results by W classes, the present methodology was found to clearly improve W estimation at low W content when compared against AERONET in terms of % bias, bringing the agreement with the GPS (considered the reference one) from a % bias of 5.76 to 0.52. Numéro de notice : A2018-053 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/amt-11-81-2018 Date de publication en ligne : 09/01/2018 En ligne : http://dx.doi.org/10.5194/amt-11-81-2018 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89371 [article]