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Estimation of tropospheric wet refractivity using tomography method and artificial neural networks in Iranian case study / Mir Reza Ghaffari Razin in GPS solutions, Vol 24 n° 3 (July 2020)  

Public [article]  inGPS solutions > Vol 24 n° 3 (July 2020) Titre : Estimation of tropospheric wet refractivity using tomography method and artificial neural networks in Iranian case study Type de document : Article/Communication Auteurs : Mir Reza Ghaffari Razin, Auteur ; Behzad Voosoghi, Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] coefficient de corrélation [Termes descripteurs IGN] données GPS [Termes descripteurs IGN] erreur moyenne quadratique [Termes descripteurs IGN] erreur relative [Termes descripteurs IGN] Iran [Termes descripteurs IGN] réfraction atmosphérique [Termes descripteurs IGN] réseau neuronal artificiel [Termes descripteurs IGN] retard troposphérique [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] tomographie par GPS [Termes descripteurs IGN] vapeur d'eau [Termes descripteurs IGN] voxel Résumé : (auteur) Using the observations from local and regional GPS networks, the estimation of slant wet delays (SWDs) is possible for each line of sight between satellite and receiver. The observations of SWD are used to model horizontal and vertical variations of the wet refractivity in the atmosphere above the study area. This work is done using the tomography method. In tomography, the horizontal variations of tropospheric wet refractivity are modeled with the polynomial in degree and rank of 2 with latitude and longitude as variables. Also, altitude variations are modeled in the form of discrete layers with constant heights. The main innovation is to estimate the tropospheric parameters for each line of sight by the artificial neural networks (ANNs). The SWD obtained from GPS observations for the different signals at each station is compared with the SWD generated by the ANNs (SWDGPS–SWDANNs). The square of the difference between these two values is introduced as the cost function in the ANNs. To evaluate, we used observations from October 27 to 31, 2011. The availability of GPS and radiosonde data is the main reason for choosing this timeframe. The correlation coefficient, root mean square error (RMSE), and relative error allow for evaluation of the proposed model. The results were also compared with the results of the voxel-based troposphere tomography method. For a more detailed evaluation, four test stations are selected and ANN zenith wet delays (ZWDANN) are compared with the ZWDGPS. Observations of test stations are not used in the modeling step. The correlation coefficient in the testing step for TomoANN and Tomovoxel is 0.9006 and 0.8863, respectively. The mean RMSE at 5 days for TomoANN and Tomovoxel is calculated as 0.63 and 0.71 mm/km, respectively. Also, the average relative error at the four test stations for TomoANN is 15.37% and for Tomovoxel it is 19.69%. The results demonstrate the better capability of the proposed method in the modeling of the tropospheric wet refractivity in the region of Iran. Numéro de notice : A2020-238 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-00979-y date de publication en ligne : 10/04/2020 En ligne : https://doi.org/10.1007/s10291-020-00979-y Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94986 [article]

The geometric imaging model for high-resolution optical remote sensing satellites considering light aberration and atmospheric refraction errors / Mi Wang in Photogrammetric Engineering & Remote Sensing, PERS, vol 86 n° 6 (June 2020)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 86 n° 6 (June 2020) . - pp 373 -382 Titre : The geometric imaging model for high-resolution optical remote sensing satellites considering light aberration and atmospheric refraction errors Type de document : Article/Communication Auteurs : Mi Wang, Auteur ; Ying Zhu, Auteur ; Yanli Wang, Auteur ; Yufeng Cheng, Auteur Année de publication : 2020 Article en page(s) : pp 373 -382 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes descripteurs IGN] aberration chromatique [Termes descripteurs IGN] aberration géométrique [Termes descripteurs IGN] correction atmosphérique [Termes descripteurs IGN] image optique [Termes descripteurs IGN] réfraction atmosphérique [Termes descripteurs IGN] satellite d'observation de la Terre [Termes descripteurs IGN] télédétection spatiale Résumé : (Auteur) With advances in satellite maneuvering imaging capability, stereoscopic images with large roll and pitch angles can be captured to improve the efficiency of observations. At the same time, the influences of light aberration and atmospheric refraction on image positioning accuracy will be more significant. However, these errors are not accounted for in the traditional imaging and calibration model for optical agile satellites. In this study, the formation mechanisms of the aberration and atmospheric refraction errors in optical remote sensing satellite Earth observation imaging were analyzed quantitatively, and correction models were constructed. From this, the traditional geometric imaging model was refined by introducing a correction model for aberration and atmospheric refraction errors to create a more comprehensive geometric imaging model. The feasibility of an extended rational function model, based on the constructed more comprehensive geometric imaging model, was verified quantitatively. Numéro de notice : A2020-242 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14358/PERS.86.6.373 date de publication en ligne : 01/06/2020 En ligne : https://doi.org/10.14358/PERS.86.6.373 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95204 [article]

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Impact of GPS processing on the estimation of snow water equivalent using refracted GPS signals / Ladina Steiner in IEEE Transactions on geoscience and remote sensing, vol 58 n° 1 (January 2020)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 58 n° 1 (January 2020) . - pp 123 - 135 Titre : Impact of GPS processing on the estimation of snow water equivalent using refracted GPS signals Type de document : Article/Communication Auteurs : Ladina Steiner, Auteur ; Michael Meindl, Auteur ; Christoph Marty, Auteur ; Alain Geiger, Auteur Année de publication : 2020 Article en page(s) : pp 123 - 135 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] Alpes [Termes descripteurs IGN] altitude [Termes descripteurs IGN] antenne GPS [Termes descripteurs IGN] eau de fonte [Termes descripteurs IGN] étalonnage des données [Termes descripteurs IGN] manteau neigeux [Termes descripteurs IGN] modèle hydrographique [Termes descripteurs IGN] neige [Termes descripteurs IGN] phase GPS [Termes descripteurs IGN] pondération [Termes descripteurs IGN] réfraction [Termes descripteurs IGN] signal GPS [Termes descripteurs IGN] Suisse Résumé : (auteur) Global navigation satellite system (GNSS) antennas buried underneath a snowpack have a high potential for in situ snow water equivalent (SWE) estimation. Automated and continuous SWE quantification independent of weather conditions could enhance snow hydrological monitoring and modeling. Accurate and reliable in situ data are needed for the calibration and validation of remote sensing data and snowpack modeling. A relative bias of less than 5% is achieved using sub-snow global positioning system (GPS) antennas (GPS refractometry) during a three full seasons time period in the Swiss Alps. A systematic overview regarding the temporal reliability of the sub-snow GPS derived results is, however, missing for this emerging technique. Moreover, GPS processing impacts the results significantly. Different GPS processing parameters are therefore selected and their influence on the SWE estimation is investigated. The impact of elevation-dependent weighting, the elevation cutoff angles, and the time intervals for SWE estimation are systematically assessed. The best results are achieved using all observations with an elevation-dependent weighting scheme. Moreover, the SWE estimation performance is equally accurate for hourly SWE estimation as for lower temporal resolutions up to daily estimates. The impact of snow on the coordinate solution is furthermore evaluated. While the east and north components are not systematically influenced by the overlying snowpack, the vertical component exhibits a significant variation and strongly depends on the SWE. The biased vertical component therefore provides an additional possibility to estimate SWE. Numéro de notice : A2020-074 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2019.2934016 date de publication en ligne : 06/09/2019 En ligne : https://doi.org/10.1109/TGRS.2019.2934016 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94605 [article]

High-resolution models of tropospheric delays and refractivity based on GNSS and numerical weather prediction data for alpine regions in Switzerland / Karina Wilgan in Journal of geodesy, vol 93 n°6 (June 2019)  

Public [article]  inJournal of geodesy > vol 93 n°6 (June 2019) . - pp 819 - 835 Titre : High-resolution models of tropospheric delays and refractivity based on GNSS and numerical weather prediction data for alpine regions in Switzerland Type de document : Article/Communication Auteurs : Karina Wilgan, Auteur ; Alain Geiger, Auteur Année de publication : 2019 Article en page(s) : pp 819 - 835 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] Alpes [Termes descripteurs IGN] collocation par moindres carrés [Termes descripteurs IGN] correction troposphérique [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] données météorologiques [Termes descripteurs IGN] interféromètrie par radar à antenne synthétique [Termes descripteurs IGN] modèle mathématique [Termes descripteurs IGN] précision de l'estimation [Termes descripteurs IGN] prévision météorologique [Termes descripteurs IGN] réfraction [Termes descripteurs IGN] retard troposphérique [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] Suisse Résumé : (auteur) The tropospheric delay of a microwave signal affects all space geodetic techniques. One possibility of modeling the delay is by introducing tropospheric models from external data sources. In this study, we present high-resolution models of tropospheric total refractivity and zenith total delay (ZTD) for the alpine area in Switzerland. The troposphere models are based on different combinations of data sources, including numerical weather prediction (NWP) model COSMO-1 with high spatial resolution of 1.1 km × 1.1 km, GNSS data from permanent geodetic stations and GPS L1-only data from low-cost permanent stations. The tropospheric parameters are interpolated to the arbitrary locations by the least-squares collocation method using the in-house developed software package COMEDIE (Collocation of Meteorological Data for Interpretation and Estimation of Tropospheric Pathdelays). The first goal of this study is to validate the obtained models with the reference radiosonde and GNSS data to show the improvement w.r.t. the previous studies that used lower resolution input data. In case of total refractivity, the profiles reconstructed from COSMO-1 model show the best agreement with the reference radiosonde measurements, with an average bias of 1.1 ppm (0.6% of the total refractivity value along a vertical profile) and standard deviation of 2.6 ppm (1.6%) averaged from the whole profile. The radiosondes are assimilated into COSMO-1 model; thus, a high correlation is expected, and this comparison is not independent. In case of ZTD, the GNSS-based model shows the highest agreement with the reference GNSS data, with an average bias of 0.2 mm (0.01%) and standard deviation of 4.3 mm (0.2%). For COSMO-based model, the agreement is also very high, especially compared to our previous studies with lower resolution NWPs. The average bias is equal to − 2.5 mm (0.1%) with standard deviation of 9.2 mm (0.5%). The second goal of this study is to test the feasibility of calculating high-resolution troposphere models over a limited area from coarser data sets. We calculate the ZTD models with spatial resolution of 20 m for a test area in Matter Valley. We include the information from the low-cost GPS stations (X-Sense), to also assess the performance and future usability of such stations. We validate the models based on three data sources w.r.t. the reference GNSS data. For the station located inside the area of the study, the models have an agreement of few mm with the reference data. For stations located further away from the study area, the agreement for X-Sense is smaller, but the standard deviations of residuals are still below 15 mm. We consider also another factor of evaluating the high-resolution models, i.e., spatial variability of the data. For designing a GNSS network, also for the tropospheric estimates, the height variability of the network may be as important as the horizontal distribution. The GNSS-based models are built from the coarsest network; thus, their variability is the lowest. The variability of X-Sense-based stations is the highest; thus, such data may be suitable for building troposphere models for very high-resolution applications. Numéro de notice : A2019-350 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1203-6 date de publication en ligne : 01/10/2018 En ligne : https://doi.org/10.1007/s00190-018-1203-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93394 [article]

Arpent : un prototype de haute exactitude pour les mesures de grande distance / Maylis Teyssendier de la Serve in XYZ, n° 154 (mars - mai 2018)

Public [article]  inXYZ > n° 154 (mars - mai 2018) . - pp 31 - 36 Titre : Arpent : un prototype de haute exactitude pour les mesures de grande distance Type de document : Article/Communication Auteurs : Maylis Teyssendier de la Serve , Auteur ; Jean-Pierre Wallerand, Auteur ; Joffray Guillory, Auteur ; Daniel Truong, Auteur ; Christophe Alexandre, Auteur ; José Cali, Auteur ; Stéphane Durand, Auteur Année de publication : 2018 Article en page(s) : pp 31 - 36 Note générale : Bibliographie Le premier design du FPGA constituant le phasemètre de l’instrument a été réalisé dans le cadre du projet ANR-07-BLAN-0309-01 de l’Agence nationale de la recherche. Langues : Français (fre) Descripteur : [Vedettes matières IGN] Métrologie [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] courbe sinusoidale [Termes descripteurs IGN] diode laser [Termes descripteurs IGN] distance kilométrique [Termes descripteurs IGN] distancemètre [Termes descripteurs IGN] écart type [Termes descripteurs IGN] onde porteuse [Termes descripteurs IGN] prototype [Termes descripteurs IGN] radiofréquence [Termes descripteurs IGN] réfraction atmosphérique [Termes descripteurs IGN] télémètre laser Résumé : (Auteur) L'équipe de métrologie dimensionnelle du Laboratoire commun de métrologie LNE-Cnam (LCM) travaille sur le développement de distance-mètres absolus, basés sur la mesure du déphasage accumulé par une onde radiofréquence durant sa propagation dans l'air à l'aide d'une porteuse optique. Cet article présente un télémètre à 1550 nm développé au LCM et détaille sa caractérisation au Laboratoire national de métrologie et d'essais (LNE) et à l'Ecole Supérieure des Géomètres et Topographes (ESGT). Numéro de notice : A2018-085 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueNat DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89456 [article]

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Utilisation de la photogrammétrie numérique pour la modélisation de fonds mobiles de modèles physiques / Maxime Cartier Xatard in XYZ, n° 154 (mars - mai 2018)

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Etude d'un nouveau procédé pour la mesure et la correction de la réfraction par corrélation d'images / Michel Kasser in XYZ, n° 153 (décembre 2017 - février 2018)

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Mobile precise trigonometric levelling system based on land vehicle: an alternative method for precise levelling / J. Zou in Survey review, vol 49 n° 355 (October 2017)  

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Pushing the sensitivity limits of RTS-based continuous deformation monitoring of an alpine valley / Mariusz Frukacz in Applied geomatics, vol 9 n° 2 (June 2017)  

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Analysis of Galileo and GPS integration for GNSS tomography / Pedro Benevides in IEEE Transactions on geoscience and remote sensing, vol 55 n° 4 (April 2017)  

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Monitoring and prediction of precipitable water vapor using GPS data in Turkey / Kutubuddin Ansari in Journal of applied geodesy, vol 10 n° 4 (December 2016)  

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Correction of atmospheric refraction geolocation error for high resolution optical satellite pushbroom images / Ming Yan in Photogrammetric Engineering & Remote Sensing, PERS, vol 82 n° 6 (June 2016)  

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External error modelling with combined model in terrestrial laser scanning / J. Wang in Survey review, vol 48 n° 346 (January 2016)  

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Propagation des ondes électromagnétiques dans l’atmosphère terrestre / Jonathan Chenal (2016) 

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A fast and accurate algorithm for high-frequency trans-ionospheric path length determination / Dudy D Wijaya in Journal of geodesy, vol 89 n° 12 (december 2015)  

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