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A consistent regional vertical ionospheric model and application in PPP-RTK under sparse networks / Sijie Lyu in Navigation : journal of the Institute of navigation, vol 70 n° 3 (Fall 2023)  

Public [article]  inNavigation : journal of the Institute of navigation > vol 70 n° 3 (Fall 2023) . - n° 568 Titre : A consistent regional vertical ionospheric model and application in PPP-RTK under sparse networks Type de document : Article/Communication Auteurs : Sijie Lyu, Auteur ; Yan Xiang, Auteur ; Tiantian Tang, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 568 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] carte ionosphérique mondiale [Termes IGN] correction ionosphérique [Termes IGN] modèle ionosphérique [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté [Termes IGN] retard ionosphèrique [Termes IGN] teneur totale en électrons [Termes IGN] teneur verticale totale en électrons Numéro de notice : A2023-201 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.568 Date de publication en ligne : 23/09/2022 En ligne : https://doi.org/10.33012/navi.568 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103096 [article]

Ambiguity resolution method using BDS/INS model / F. Wu in Survey review, vol 55 n° 390 (May 2023)  

Public [article]  inSurvey review > vol 55 n° 390 (May 2023) . - pp 274 - 284 Titre : Ambiguity resolution method using BDS/INS model Type de document : Article/Communication Auteurs : F. Wu, Auteur ; J. Zhao, Auteur ; J. Xue, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : pp 274 - 284 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] BDS-INS [Termes IGN] correction atmosphérique [Termes IGN] ligne de base [Termes IGN] modèle atmosphérique [Termes IGN] navigation inertielle [Termes IGN] positionnement par BeiDou [Termes IGN] résolution d'ambiguïté Résumé : (auteur) Due to the highly dynamic changes of the environment, the frequent loss of signal will seriously reduce the accuracy of realtime dynamic positioning. Meanwhile, the ambiguity resolution for medium/long baseline is more affected by atmospheric delay. To solve this problem, an Inertial Navigation System (INS) assisted Beidou Navigation System (BDS) medium/long baseline partial ambiguity resolution (PAR) method is designed. Firstly, constructing the BDS/INS tight integrated system that uses INS provided initial information to ambiguity resolution when the signal outages. Secondly, the atmospheric delay constraint is introduced to improve the precision of float ambiguity. Finally, the PAR based on the elevation angle information is applied to enhance fixed speed and accuracy. The vehicle experiments show that the proposed algorithm can quickly fix the ambiguity of medium/long baseline when the satellite signal outages for a short time, and improve the positioning accuracy of medium/long baseline in the dynamic environment. Numéro de notice : A2023-192 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2022.2089822 Date de publication en ligne : 28/06/2022 En ligne : https://doi.org/10.1080/00396265.2022.2089822 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103067 [article]

Evaluating TROPOMI and MODIS performance to capture the dynamic of air pollution in São Paulo state: A case study during the COVID-19 outbreak / A.P. Rudke in Remote sensing of environment, vol 289 (May 2003)  

Public [article]  inRemote sensing of environment > vol 289 (May 2003) . - n° 113514 Titre : Evaluating TROPOMI and MODIS performance to capture the dynamic of air pollution in São Paulo state: A case study during the COVID-19 outbreak Type de document : Article/Communication Auteurs : A.P. Rudke, Auteur ; J.A. Martins, Auteur ; R. Hallak, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 113514 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] correction atmosphérique [Termes IGN] dioxyde d'azote [Termes IGN] épidémie [Termes IGN] image Sentinel-5P-TROPOMI [Termes IGN] image Terra-MODIS [Termes IGN] pollution atmosphérique [Termes IGN] qualité de l'air [Termes IGN] Sao Paulo Résumé : (auteur) Atmospheric pollutant data retrieved through satellite sensors are continually used to assess changes in air quality in the lower atmosphere. During the COVID-19 pandemic, several studies started to use satellite measurements to evaluate changes in air quality in many different regions worldwide. However, although satellite data is continuously validated, it is known that its accuracy may vary between monitored areas, requiring regionalized quality assessments. Thus, this study aimed to evaluate whether satellites could measure changes in the air quality of the state of São Paulo, Brazil, during the COVID-19 outbreak; and to verify the relationship between satellite-based data [Tropospheric NO2 column density and Aerosol Optical Depth (AOD)] and ground-based concentrations [NO2 and particulate material (PM; coarse: PM10 and fine: PM2.5)]. For this purpose, tropospheric NO2 obtained from the TROPOMI sensor and AOD retrieved from MODIS sensor data by using the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm were compared with concentrations obtained from 50 automatic ground monitoring stations. The results showed low correlations between PM and AOD. For PM10, most stations showed correlations lower than 0.2, which were not significant. The results for PM2.5 were similar, but some stations showed good correlations for specific periods (before or during the COVID-19 outbreak). Satellite-based Tropospheric NO2 proved to be a good predictor for NO2 concentrations at ground level. Considering all stations with NO2 measurements, correlations >0.6 were observed, reaching 0.8 for specific stations and periods. In general, it was observed that regions with a more industrialized profile had the best correlations, in contrast with rural areas. In addition, it was observed about 57% reductions in tropospheric NO2 throughout the state of São Paulo during the COVID-19 outbreak. Variations in air pollutants were linked to the region economic vocation, since there were reductions in industrialized areas (at least 50% of the industrialized areas showed >20% decrease in NO2) and increases in areas with farming and livestock characteristics (about 70% of those areas showed increase in NO2). Our results demonstrate that Tropospheric NO2 column densities can serve as good predictors of NO2 concentrations at ground level. For MAIAC-AOD, a weak relationship was observed, requiring the evaluation of other possible predictors to describe the relationship with PM. Thus, it is concluded that regionalized assessment of satellite data accuracy is essential for assertive estimates on a regional/local level. Good quality information retrieved at specific polluted areas does not assure a worldwide use of remote sensor data. Numéro de notice : A2023-170 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1016/j.rse.2023.113514 Date de publication en ligne : 21/02/2023 En ligne : https://doi.org/10.1016/j.rse.2023.113514 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102930 [article]

Establishing a high-precision real-time ZTD model of China with GPS and ERA5 historical data and its application in PPP / Pengfei Xia in GPS solutions, vol 27 n° 1 (January 2023)  

Public [article]  inGPS solutions > vol 27 n° 1 (January 2023) . - n° 2 Titre : Establishing a high-precision real-time ZTD model of China with GPS and ERA5 historical data and its application in PPP Type de document : Article/Communication Auteurs : Pengfei Xia, Auteur ; Mengxiang Tong, Auteur ; Shirong Ye, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 2 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Chine [Termes IGN] correction troposphérique [Termes IGN] données météorologiques [Termes IGN] grille [Termes IGN] positionnement ponctuel précis [Termes IGN] retard troposphérique zénithal [Termes IGN] série de Fourier [Termes IGN] série temporelle [Termes IGN] station GNSS [Termes IGN] temps de convergence [Termes IGN] temps réel [Termes IGN] variation diurne Résumé : (auteur) A high-precision real-time troposphere model is constructed by combining ground-based GNSS observation data and the latest European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5). First, the zenith tropospheric delay (ZTD) is extracted in real time with high accuracy by combining the data of more than 500 GNSS stations in the Crustal Movement Observation Network of China (CMONOC) and national reference station network (NRSN); second, a grid model of the elevation normalization model (ENM) in China using ERA5 data is constructed, which takes into account the annual, semiannual and daily cycles. The ZTD estimated by GNSS stations at different heights based on precise point positioning (PPP) is normalized to a uniform height based on ENM; in addition, the optimal smoothing factors of the Gauss distance weighting function in different seasons are determined based on ERA5, which contributes to improved accuracy of ZTD interpolated from GNSS-derived ZTD to ZTD at grid points; finally, a real-time 1° × 1°ZTD grid model of China is created; the broadcast interval is extended to 6 min from few seconds. The new ZTD model has been evaluated using the data of 15 GNSS stations in China in 2020. The test results show that the new ZTD model deviates from the reference value with a mean value better than − 0.09 cm and RMSE, better than 1.44 cm compared with the ZTD estimated by post-processing GNSS, while the mean value of the deviation is -0.13 cm, and the RMSE is approximately 3.11 cm compared with radiosonde-derived ZTD. The new ZTD grid model can be used to enhance GNSS/PPP. Two weeks of GNSS observations, one week in winter and another in summer, were randomly collected for PPP processing. The statistical results show the convergence time in the vertical directions is shortened by 37.4% and 38.6% at the 95% and 68% confidence levels after ZTD constraints are applied to the float PPP solution, respectively. Numéro de notice : A2023-004 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-022-01338-9 Date de publication en ligne : 07/10/2022 En ligne : https://doi.org/10.1007/s10291-022-01338-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101874 [article]

Multipath mitigation for improving GPS narrow-lane uncalibrated phase delay estimation and speeding up PPP ambiguity resolution / Kai Zheng in Measurement, vol 206 (January 2023)  

Public [article]  inMeasurement > vol 206 (January 2023) . - n° 112243 Titre : Multipath mitigation for improving GPS narrow-lane uncalibrated phase delay estimation and speeding up PPP ambiguity resolution Type de document : Article/Communication Auteurs : Kai Zheng, Auteur ; Lingmin Tan, Auteur ; Kezhong Liu, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 112243 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] analyse en composantes principales [Termes IGN] atténuation [Termes IGN] correction du trajet multiple [Termes IGN] mesurage de pseudo-distance [Termes IGN] phase GPS [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté [Termes IGN] temps de convergence [Termes IGN] trajet multiple Résumé : (auteur) Precise point positioning (PPP) has been recognized as a powerful tool for various geophysical applications. However, the long convergence time required to resolve a reliable ambiguity impedes its further application in time-critical scenarios. Although PPP ambiguity resolution (AR) can shorten the convergence time, its performance is subject to the quality of float ambiguity estimates and the uncalibrated phase delay (UPD), which can be contaminated by multipath errors. Furthermore, the observation residuals derived from PPP are very likely to be affected by the common-mode error (CME), thereby deteriorating the multipath modeling accuracy. The principal component analysis (PCA) is employed to mitigate the CME effect, and the multipath is modeled using a multipath hemispherical map (MHM). Consequently, the narrow-lane (NL) UPDs with multipath correction have better temporal stability and residual distributions than those without correction. Compared with sidereal filtering (SF), the MHM0.5 has comparable residual variance reduction percentages, indicating its capability of capturing high-frequency multipath. For static PPP AR, the averaged time to first fix (TTFF) can be reduced by 24.2% to about 26 min and the convergence time can be achieved within 16.2 min after multipath correction. The pseudorange multipath correction significantly contributes to shortening the TTFF and convergence time. Reducing the resolution of MHM increases the risk of extending the TTFF. For kinematic PPP AR with MHM0.5, the convergence time exhibits a remarkable improvement when compared with that of the uncorrected case (21.7 min versus 40.2 min), and 20% of the stations achieve convergence within 10 min. Meanwhile, a few stations only take one minute to achieve convergence. The contribution of the multipath correction to the fixing rate is comparatively small. After applying MHM0.5, the kinematic positioning accuracies are improved by 35.7%, 12.6%, and 24.4% to 1.26, 1.39, and 2.73 cm for the east, north, and up components, respectively. Numéro de notice : A2023-027 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.measurement.2022.112243 Date de publication en ligne : 24/11/2022 En ligne : https://doi.org/10.1016/j.measurement.2022.112243 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102267 [article]

Bathymetry and benthic habitat mapping in shallow waters from Sentinel-2A imagery: A case study in Xisha islands, China / Wei Huang in IEEE Transactions on geoscience and remote sensing, vol 60 n° 12 (December 2022)  

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Multi-frequency simulation of ionospheric scintillation using a phase-screen model / Fernando D. Nunes in Navigation : journal of the Institute of navigation, vol 69 n° 4 (Fall 2022)  

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Navigation and Ionosphere Characterization Using High-Frequency Signals: A Performance Analysis / Yoav Baumgarten in Navigation : journal of the Institute of navigation, vol 69 n° 4 (Fall 2022)  

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Toward BDS/Galileo/GPS/QZSS triple-frequency PPP instantaneous integer ambiguity resolutions without atmosphere corrections / Jun Tao in GPS solutions, vol 26 n° 4 (October 2022)  

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Global forecasting of ionospheric vertical total electron contents via ConvLSTM with spectrum analysis / Jinpei Chen in GPS solutions, vol 26 n° 3 (July 2022)  

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Synergistic use of the SRAL/MWR and SLSTR sensors on board Sentinel-3 for the wet tropospheric correction retrieval / Pedro Aguiar in Remote sensing, vol 14 n° 13 (July-1 2022)  

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Regional ionospheric corrections for high accuracy GNSS positioning / Tam Dao in Remote sensing, vol 14 n° 10 (May-2 2022)  

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Characteristics of the BDS-3 multipath effect and mitigation methods using precise point positioning / Ran Lu in GPS solutions, vol 26 n° 2 (April 2022)  

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Improving the (re-)convergence of multi-GNSS real-time precise point positioning through regional between-satellite single-differenced ionospheric augmentation / Ahao Wang in GPS solutions, vol 26 n° 2 (April 2022)  

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On enhanced PPP with single difference between-satellite ionospheric constraints / Yan Xiang in Navigation : journal of the Institute of navigation, vol 69 n° 1 (Spring 2022)  

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