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Variations of precipitable water vapor using GNSS CORS in Thailand / Chokchai Trakolkul in Survey review, vol 53 n°376 (January 2021)
Titre : Variations of precipitable water vapor using GNSS CORS in Thailand Type de document : Article/Communication Auteurs : Chokchai Trakolkul, Auteur ; Chalermchon Satirapod, Auteur Année de publication : 2021 Article en page(s) : pp 90 - 96 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes descripteurs IGN] amplitude
[Termes descripteurs IGN] analyse comparative
[Termes descripteurs IGN] données WVR
[Termes descripteurs IGN] précipitation
[Termes descripteurs IGN] série temporelle
[Termes descripteurs IGN] station de référence
[Termes descripteurs IGN] station GNSS
[Termes descripteurs IGN] Thaïlande
[Termes descripteurs IGN] vapeur d'eau
[Termes descripteurs IGN] variation saisonnièreRésumé : (auteur) This research aims to analyze variation in a time series of Precipitable Water Vapor (PWV time series) using data at 11 widely-distributed Continuously Operating Reference Stations (CORS) in Thailand. In this paper, the PWV time series is estimated based on data from 2007 to 2015, used to monitor trends and seasonal variations. Significant annual variations of PWV are found at all GNSS stations, with amplitude from 6 to 19 kg/m2. The variations between the annual amplitudes of PWV in the South and near the ocean coasts are generally smaller than in the inland regions. The phase shift of annual PWV variation is about −0.43 (around July, rainy season). The comparison of PWV and 24-hour cumulative rainfall data showed that the rainy season (running from around mid-May to the end of October) exhibits the slightest swing, and the highest average amount of PWV. These results are consistent with the 24-hour cumulative rainfall data. Numéro de notice : A2021-070 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2020.1713611 date de publication en ligne : 20/01/2020 En ligne : https://doi.org/10.1080/00396265.2020.1713611 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96791
in Survey review > vol 53 n°376 (January 2021) . - pp 90 - 96[article]
Titre : An assessment of wide-lane ambiguity resolution methods for multi-frequency multi-GNSS precise point positioning Type de document : Article/Communication Auteurs : Viet Duong, Auteur ; Ken Harima, Auteur ; Suelynn Choy, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 442 - 453 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] combinaison linéaire
[Termes descripteurs IGN] délai d'obtention de la première position
[Termes descripteurs IGN] fréquence multiple
[Termes descripteurs IGN] mesurage de phase
[Termes descripteurs IGN] mesurage par GNSS
[Termes descripteurs IGN] phase
[Termes descripteurs IGN] positionnement par GNSS
[Termes descripteurs IGN] positionnement ponctuel précis
[Termes descripteurs IGN] résolution d'ambiguïté
[Termes descripteurs IGN] station GNSS
[Termes descripteurs IGN] taux d'échantillonnageRésumé : (auteur) We assess the time-to-first-fix (TTFF) and the ambiguity fixing rate of two PPP wide-lane ambiguity resolution (WL-AR) methods, namely the geometry-based and ionospheric-free (GB-IF) method, and the geometry-free and ionospheric-free (GF-IF) method. First, an optimal GF-IF WL linear combination is selected based on the ratio between the code and carrier phase measurement noise (RT). Then, the relation between ambiguity variance and satellite geometry in the GB-IF WL-AR is investigated. Both simulated and real data from 31 GNSS stations over 37 consecutive days in 2017 were used. Numerical results show that the GF-IF WL-AR method has shorter TTFF and higher ambiguity fixing rate compared to the GB-IF method when RT≤150. However, when RT≥150, the GB-IF method outperforms the GF-IF method. Depending on RT values used, 2–10 min would be required to resolve the WL ambiguities when using GNSS measurements with one second sampling rate. Numéro de notice : A2020-518 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2019.1634339 date de publication en ligne : 02/07/2019 En ligne : https://doi.org/10.1080/00396265.2019.1634339 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95678
in Survey review > vol 52 n° 374 (August 2020) . - pp 442 - 453[article]
Titre : Improving GNSS-acoustic positioning by optimizing the ship’s track lines and observation combinations Type de document : Article/Communication Auteurs : Guanxu Chen, Auteur ; Yang Liu, Auteur ; Yanxiong Liu, Auteur ; et al., Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes descripteurs IGN] contrainte géométrique
[Termes descripteurs IGN] fond marin
[Termes descripteurs IGN] GNSS-Acoustique
[Termes descripteurs IGN] navire
[Termes descripteurs IGN] positionnement par GNSS
[Termes descripteurs IGN] précision du positionnement
[Termes descripteurs IGN] profondeur
[Termes descripteurs IGN] station GNSS
[Termes descripteurs IGN] trajectoireRésumé : (auteur) The position of a seafloor geodetic station can be determined by combining Global Navigation Satellite System (GNSS) and acoustic technologies, called GNSS-acoustic positioning. The precision of GNSS-acoustic positioning, a technique that employs the distance intersection, is determined by the positioning geometry formed by the ship’s track lines with respect to the seafloor station and the errors in the measurements. In the context of a shallow sea trial, we studied three key techniques in GNSS-acoustic positioning: the optimal geometric configuration, differencing techniques for acoustic observations and depth constraints offered by pressure gauges. The results showed that the optimal geometric configuration is a circular track with a radius of 2‾√ times the depth plus an overhead cross-track with a length of the circle diameter. Differenced observations can improve the horizontal positioning precision but will worsen the vertical positioning precision due to the change in the geometric configuration and the elimination of vertical information if the number of observations is limited. The proposed difference strategy, that is, applying a symmetric location difference operator to the circular track and an undifference operator to the cross-track, can effectively improve the horizontal precision and avoid vertical defects. By using relative depth observations from two pressure gauges as constraints, the vertical defects of GNSS-acoustic positioning can be improved, achieving a better vertical positioning precision. Applying the proposed methods to high-quality GNSS and acoustic observations, the positioning precision of a shallow seafloor geodetic station can be better than 2 cm. Numéro de notice : A2020-377 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern date de publication en ligne : 27/06/2020 En ligne : https://doi.org/10.1007/s00190-020-01389-1 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95369
in Journal of geodesy > vol 94 n° 6 (June 2020)[article]
Titre : Comparative analysis of different atmospheric surface pressure models and their impacts on daily ITRF2014 GNSS residual time series Type de document : Article/Communication Auteurs : Zhao Li, Auteur ; Chen Wu, Auteur ; Tonie M. van Dam, Auteur ; Paul Rebischung Année de publication : 2020 Projets : 3-projet - voir note / Article en page(s) : n° 42 Note générale : bibliographie
This research is supported by the National Key Research and Development Program of China (Project 2016YFB0502101), the European Commission/Research Grants Council (RGC) Collaboration Scheme sponsored by the Research Grants Council of Hong Kong Special Administrative Region, China (Project No. E-PolyU 501/16), and the National Science Foundation for Distinguished Young Scholars of China (Grant No. 41525014).Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes descripteurs IGN] analyse comparative
[Termes descripteurs IGN] coefficient de corrélation
[Termes descripteurs IGN] données GNSS
[Termes descripteurs IGN] International Terrestrial Reference Frame
[Termes descripteurs IGN] MERRA
[Termes descripteurs IGN] modèle atmosphérique
[Termes descripteurs IGN] pression atmosphérique
[Termes descripteurs IGN] radar JPL
[Termes descripteurs IGN] résidu
[Termes descripteurs IGN] série temporelle
[Termes descripteurs IGN] station GNSSRésumé : (auteur) To remove atmospheric pressure loading (ATML) effect from GNSS coordinate time series, surface pressure (SP) models are required to predict the displacements. In this paper, we modeled the 3D ATML surface displacements using the latest MERRA-2 SP grids, together with four other products (NCEP-R-1, NCEP-R-2, ERA-Interim and MERRA) for 596 globally distributed GNSS stations, and compared them with ITRF2014 residual time series. The five sets of ATML displacements are highly consistent with each other, particularly for those stations far away from coasts, of which the lowest correlations in the Up component for all the four models w.r.t MERRA-2 become larger than 0.91. ERA-Interim-derived ATML displacement performs best in reducing scatter of the GNSS height for 90.3% of the stations (89.3% for NCEP-R-1, 89.1% for NCEP-R-2, 86.4% for MERRA and 85.1% for MERRA-2). We think that this may be possibly due to the 4D variational data assimilation method applied. Considering inland stations only, more than 96% exhibit WRMS reduction in the Up direction for all five models, with an average improvement of 3–4% compared with the original ITRF2014 residual time series before ATML correction. Most stations (> 67%) also exhibit horizontal WRMS reductions based on the five models, but of small magnitudes, with most improvements (> 76%) less than 5%. In particular, most stations in South America, South Africa, Oceania and the Southern Oceans show larger WRMS reductions with MERRA-2, while all other four SP datasets lead to larger WRMS reduction for the Up component than MERRA-2 in Europe. Through comparison of the daily pressure variation from the five SP models, we conclude that the bigger model differences in the SP-induced surface displacements and their impacts on the ITRF2014 residuals for coastal/island stations are mainly due to the IB correction based on the different land–sea masks. A unique high spatial resolution land–sea mask should be applied in the future, so that model differences would come from only SP grids. Further research is also required to compare the ATML effect in ice-covered and high mountainous regions, for example the Qinghai–Tibet Plateau in China, the Andes in South America, etc., where larger pressure differences between models tend to occur. Numéro de notice : A2020-159 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01370-y date de publication en ligne : 20/03/2020 En ligne : https://doi.org/10.1007/s00190-020-01370-y Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94813
in Journal of geodesy > vol 94 n°4 (April 2020) . - n° 42[article]
Titre : Estimation and representation of regional atmospheric corrections for augmenting real-time single-frequency PPP Type de document : Article/Communication Auteurs : Peiyuan Zhou, Auteur ; Jin Wang, Auteur ; Zhixi Nie, Auteur ; Yang Gao, Auteur Année de publication : 2020 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes descripteurs IGN] correction atmosphérique
[Termes descripteurs IGN] correction ionosphérique
[Termes descripteurs IGN] correction troposphérique
[Termes descripteurs IGN] décalage d'horloge
[Termes descripteurs IGN] positionnement ponctuel précis
[Termes descripteurs IGN] Quasi-Zenith Satellite System
[Termes descripteurs IGN] récepteur monofréquence
[Termes descripteurs IGN] retard ionosphèrique
[Termes descripteurs IGN] retard troposphérique
[Termes descripteurs IGN] satellite GPS
[Termes descripteurs IGN] station GNSS
[Termes descripteurs IGN] temps réel
[Termes descripteurs IGN] teneur totale en électronsRésumé : (Auteur) Real-time single-frequency precise point positioning (PPP) can be significantly augmented by applying high-quality atmospheric corrections. In previous work, the satellite-and-station-specific slant total electron content (STEC) ionospheric corrections, derived from a regional reference network, are commonly used to augment single-frequency PPP for improving positioning accuracy and faster convergence. However, since the users are required to interpolate STEC ionospheric corrections from nearby reference stations, either duplex communication links should be established or all corrections of the reference network must be retrieved, which makes it inefficient to provide augmentation services to many users. Moreover, the regional tropospheric corrections are generally neglected in augmenting real-time single-frequency PPP. In this study, we present a method to estimate and represent tropospheric and ionospheric corrections from a regional reference network, which can be efficiently disseminated to users through a simplex communication link. First, the uncombined dual-frequency PPP, with external ionospheric constraints derived from international GNSS service predicted global ionospheric map, is used for estimating atmospheric delays with observations from a regional GNSS reference network. Then, the atmospheric delays are properly represented to facilitate real-time transmission by applying a polynomial model for the representation of zenith wet tropospheric corrections, and satellite-specific STEC maps for representing the slant ionospheric corrections. The above results in only simple communication links required to retrieve the regional atmospheric corrections for real-time single-frequency PPP augmentation. Observations from a regional network of 30 GNSS reference stations with inter-station distances of about 70 km during a 1-week-long period, including both quiet and active geomagnetic conditions, are used for generating the regional atmospheric corrections. The results indicate that the average root-mean-square errors of the obtained regional tropospheric and ionospheric corrections are better than 0.01 and 0.05 m when compared with those derived from dual-frequency uncombined PPP, respectively. The positioning accuracy of the single-frequency PPP augmented with regional atmospheric corrections is at 0.141 m horizontally and 0.206 m vertically under a 95% confidence level, a significant improvement compared to single-frequency PPP without atmospheric augmentation. The convergence time is also significantly reduced with 70.4% of the positioning sessions achieving instantaneous 3D convergence. Numéro de notice : A2020-023 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-019-0920-5 date de publication en ligne : 13/11/2019 En ligne : https://doi.org/10.1007/s10291-019-0920-5 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94466
in GPS solutions > vol 24 n° 1 (January 2020)[article]PermalinkPermalinkPermalinkPermalinkPermalinkCartographie des déformations sur le site de colocalisation de Grasse par méthode INSAR / Isabelle Delprat (2019)
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