Journal of Geodesy最新文献

{"title":"IAG Newsletter","authors":"Gyula Tóth","doi":"10.1007/s00190-025-02016-7","DOIUrl":"https://doi.org/10.1007/s00190-025-02016-7","url":null,"abstract":"","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"22 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145448352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analytical solution of tesseroid gravitational effect with linear approximation I: under spherical polar coordinates","authors":"Linshan Zhong, Jiancheng Li, Xiancai Zou","doi":"10.1007/s00190-025-02014-9","DOIUrl":"https://doi.org/10.1007/s00190-025-02014-9","url":null,"abstract":"","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"9 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145448351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advancing multi-GNSS orbit combination in the variance component estimation framework","authors":"Radosław Zajdel, Gustavo Mansur, Pierre Sakic, Paul Rebischung, Andreas Brack, Benjamin Männel, Jan Douša","doi":"10.1007/s00190-025-02005-w","DOIUrl":"https://doi.org/10.1007/s00190-025-02005-w","url":null,"abstract":"The International GNSS Service (IGS) requires advanced multi-GNSS orbit combination strategies to replace current GPS/GLONASS-focused operations with consistent products covering GPS, GLONASS, Galileo, and BDS. We developed an enhanced orbit combination methodology using a modified Förstner Variance Component Estimation (VCE) scheme that optimizes weighting strategies through data clustering approaches, including individual satellite weighting, satellite-type grouping, and machine-learning-generated clusters. Our novel approach incorporates a priori knowledge from Satellite Laser Ranging (SLR) orbit validations and sequential weight information from previous combinations to refine Analysis Center (AC) weights. Sequential weight estimation significantly reduces day boundary orbit misclosures and stabilizes temporal AC weight variability. The combined solutions demonstrate exceptional inter-consistency with RMS values below 3–5 mm for GPS and Galileo, while GLONASS and BDS show higher variability (10–15 mm), highlighting the importance of satellite grouping strategies. Intermediate grouping approaches based on IGS metadata or hierarchical clustering provide optimal balance between constellation-level oversimplification and satellite-specific day-to-day variability. SLR-based knowledge incorporation offers targeted improvements, particularly for challenging high and low β angle conditions, demonstrating the effectiveness of external validation in multi-GNSS orbit combination.","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"19 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145404170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Grazing-angle ionospheric delays observed during the GNSS-R PRETTY mission","authors":"Mario Moreno, Maximilian Semmling, Florian Zus, Georges Stienne, Andreas Dielacher, Mainul Hoque, Jens Wickert, Hossein Nahavandchi","doi":"10.1007/s00190-025-02010-z","DOIUrl":"https://doi.org/10.1007/s00190-025-02010-z","url":null,"abstract":"Spaceborne GNSS reflectometry (GNSS-R) has emerged as a valuable technique for surface and atmospheric remote sensing, particularly under grazing-angle geometries where atmospheric effects are amplified. Single-frequency missions such as ESA passive REflecTomeTry and dosimetrY (PRETTY) rely on model-based corrections to account for ionospheric and tropospheric delays. In this study, we exploit PRETTY’s capabilities to perform observations down to 1 degree (at the specular point) to investigate ionospheric effects at very low angles. We analyze six GNSS-R events recorded over the North Polar region in July 2024, focusing on the estimation of the relative ionospheric delay using code delay observations. Comparisons with model-based ionospheric delays from NEDM2020, NeQuick, and IRI show close agreement, with NEDM2020 consistently exhibiting the lowest residual differences, ranging from 1.28 to 4.39 m across all events. This supports the ability of GNSS-R code delay observables to capture the first-order ionospheric delay with reasonable fidelity. Uncertainty analysis reveals that the observed delay fitting process dominates the overall error budget, with additional contributions from tropospheric correction and surface height uncertainty. Furthermore, inversion of the fitted delays using the Chapman layer model yields plausible F-layer parameters, with peak heights ranging from 307 to 367 km and a mean delay RMSE of approximately 1.2 m (~ 4 TECU). Comparisons with ionosonde and EISCAT measurements show differences within ± 15 km. These results demonstrate the potential of single-frequency GNSS-R missions for retrieving ionospheric structure, particularly in remote regions where conventional techniques are limited or unavailable.","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"101 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145382431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of the Exail absolute quantum gravimeters AQG-A02 and AQG-B10 by comparison to a precise gravity reference","authors":"Julian Glässel, Hartmut Wziontek, Ezequiel Antokoletz, Erik Brachmann, Reinhard Falk, Jan Müller","doi":"10.1007/s00190-025-01995-x","DOIUrl":"https://doi.org/10.1007/s00190-025-01995-x","url":null,"abstract":"<p>We present an evaluation of the novel absolute quantum gravimeters AQG-A02 and AQG-B10 by the French manufacturer Exail with an emphasis on the user's application and outlook for integration into the routine gravity measurements of the German Federal Agency for Cartography and Geodesy (BKG). Since the delivery of these instruments to BKG, test measurements have been performed at the well-established gravity reference stations in Wettzell and Bad Homburg. Our measurements confirm a sensitivity of 500 nm s⁻² Hz^−1/2 at a quiet site, as specified, equivalent to a precision of 10 nm/s² after 1-h integration time, and a combined uncertainty on the order of 100 nm/s², based on a comparison to the local gravity reference function. We conclude that, as of yet, both AQGs do not reach the accuracy of FG5-type gravimeters, but provide advantages for continuous measurements and operation. Despite occasional technical issues with system reliability and pending research on improving the systematic errors, we expect the AQGs will find a central role in BKG's routine gravity measurements in the near future.</p>","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"141 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145003474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deriving a global troposphere model for space geodetic simulations based on an ML ensemble featuring uncertainty quantification","authors":"Matthias Schartner","doi":"10.1007/s00190-025-01996-w","DOIUrl":"https://doi.org/10.1007/s00190-025-01996-w","url":null,"abstract":"<p>This work presents a global, three-dimensional (latitude–longitude–time) model of the refractive index structure constant (<span><span style=\"\"></span><span style=\"font-size: 100%; display: inline-block;\" tabindex=\"0\"><svg focusable=\"false\" height=\"2.309ex\" role=\"img\" style=\"vertical-align: -0.505ex;\" viewbox=\"0 -777 1240.1 994.3\" width=\"2.88ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"><use x=\"0\" xlink:href=\"#MJMATHI-43\" y=\"0\"></use><use transform=\"scale(0.707)\" x=\"1011\" xlink:href=\"#MJMATHI-6E\" y=\"-213\"></use></g></svg></span><script type=\"math/tex\">C_n</script></span>), enabling the spatiotemporally correlated simulation of tropospheric delays for space geodetic observations at radio frequencies. The model is based on an ensemble of 100 XGBoost models trained on 21 years of observations from 18,500 GNSS stations, using meteorological variables from ERA5 as features. It effectively captures high-frequency spatial and temporal variations, achieving a mean absolute error of <span><span style=\"\"></span><span style=\"font-size: 100%; display: inline-block;\" tabindex=\"0\"><svg focusable=\"false\" height=\"2.409ex\" role=\"img\" style=\"vertical-align: -0.205ex;\" viewbox=\"0 -949.2 4492.4 1037.3\" width=\"10.434ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"><use xlink:href=\"#MJMAIN-30\"></use><use x=\"500\" xlink:href=\"#MJMAIN-2E\" y=\"0\"></use><use x=\"779\" xlink:href=\"#MJMAIN-35\" y=\"0\"></use><use x=\"1279\" xlink:href=\"#MJMAIN-32\" y=\"0\"></use><g transform=\"translate(1946,0)\"><use x=\"0\" xlink:href=\"#MJMAIN-6D\" y=\"0\"></use><g transform=\"translate(833,362)\"><use transform=\"scale(0.707)\" x=\"0\" xlink:href=\"#MJMAIN-2212\" y=\"0\"></use><use transform=\"scale(0.707)\" x=\"778\" xlink:href=\"#MJMAIN-31\" y=\"0\"></use><use transform=\"scale(0.707)\" x=\"1279\" xlink:href=\"#MJMAIN-2F\" y=\"0\"></use><use transform=\"scale(0.707)\" x=\"1779\" xlink:href=\"#MJMAIN-33\" y=\"0\"></use></g></g></g></svg></span><script type=\"math/tex\">0.52,hbox {m}^{-1/3}</script></span>. To simplify the use of the model, monthly average <span><span style=\"\"></span><span style=\"font-size: 100%; display: inline-block;\" tabindex=\"0\"><svg focusable=\"false\" height=\"2.309ex\" role=\"img\" style=\"vertical-align: -0.505ex;\" viewbox=\"0 -777 1240.1 994.3\" width=\"2.88ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"><use x=\"0\" xlink:href=\"#MJMATHI-43\" y=\"0\"></use><use transform=\"scale(0.707)\" x=\"1011\" xlink:href=\"#MJMATHI-6E\" y=\"-213\"></use></g></svg></span><script type=\"math/tex\">C_n</script></span> values are computed on a regular <span><span style=\"\"></span><span style=\"font-size: 100%; display: inline-block;\" tabindex=\"0\"><svg focusable=\"false\" height=\"1.909ex\" role=\"img\" style=\"vertical-align: -0.205ex;\" viewbox=\"0 -733.9 3781.9 822.1\" width=\"8.784ex\" ","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"32 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145003475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A unified model of feed rotation in radio telescopes and GNSS antennas","authors":"Joe Skeens, Johnathan York, Leonid Petrov, Kyle Herrity, Richard Ji-Cathriner, Srinivas Bettadpur","doi":"10.1007/s00190-025-01993-z","DOIUrl":"https://doi.org/10.1007/s00190-025-01993-z","url":null,"abstract":"<p>We describe a model that accounts for the phase rotation that occurs when a receiver or transmitter changes orientation while observing or emitting circularly polarized electromagnetic waves. This model extends work detailing Global Navigation Satellite Systems (GNSS) carrier phase wind-up to allow us to describe the interaction of changing satellite orientation with phase rotation in observing radio telescopes. This development is motivated by, and a critical requirement of, unifying GNSS and Very Long Baseline Interferometry (VLBI) measurements at the observation level. The model can be used for either stationary choke ring antennas or steerable radio telescopes observing either natural radio sources or satellites. Simulations and experimental data are used to validate the model and to illustrate its importance. In addition, we rigorously lay out the feed rotation correction for radio telescopes with beam waveguide and full Nasmyth focuses and validate the correction by observing the effect with dual polarization observations. Using this feed rotation model for beam waveguide telescopes, we produce the first phase delay solution for the VLBI baseline WARK30M–WARK12M. We provide a practical guide to using the feed rotation model in Appendix D.</p>","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"40 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145003476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigations on the contribution of precise levelling for regional realisation of IHRS: a case study over Sweden","authors":"A. Alfredsson, J. Ågren","doi":"10.1007/s00190-025-01992-0","DOIUrl":"https://doi.org/10.1007/s00190-025-01992-0","url":null,"abstract":"<p>The International Association of Geodesy defined the International Height Reference System (IHRS) in 2015. IHRS will be realised through the International Height Reference Frame (IHRF) primarily by geopotential numbers. On the global scale, a sparse core reference network is utilised to realise the IHRS, but denser realisations (or densifications) are needed to ensure local access and height datum unification. ITRF ellipsoidal heights and a gravimetric (quasi-) geoid model form the basis for a model-based IHRS realisation, which can be enhanced by levelling to improve local accessibility to the global frame and relative uncertainty. This study investigates incorporating levelling observations in the IHRS realisation process and explores potential improvements. A case study over Sweden using an initial model-based IHRS realisation and precise levelling observations from the Baltic Levelling Ring (BLR) project was performed. The levelling network was adjusted relative to the model-based IHRF geopotential numbers using three approaches regarding the a priori variance–covariance matrix for weighting of the observations: constrained adjustment, weighted adjustment with realistic a priori uncertainties, and weighted adjustment with Variance Component Estimation (VCE) to iteratively tune the variance–covariance matrix. It is shown that the model-based IHRS realisation improves significantly. Both the estimated standard uncertainty of the adjusted IHRF geopotential numbers and the relative standard uncertainty between nodal benchmarks are reduced by approximately 40 per cent in the Swedish case. To fully exploit precise levelling observations in the IHRS realisation process, a weighted adjustment, preferably using VCE to optimally combine the initial model-based geopotential numbers and the levelling observations is recommended.</p>","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"124 3 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145003482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IAG newsletter","authors":"Gyula Tóth","doi":"10.1007/s00190-025-01994-y","DOIUrl":"https://doi.org/10.1007/s00190-025-01994-y","url":null,"abstract":"","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"72 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145003477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single-station-augmented PPP-B2b considering the satellite-specific clock bias via short-message communication","authors":"Haijun Yuan, Zhetao Zhang, Xiufeng He, Hao Wang","doi":"10.1007/s00190-025-01965-3","DOIUrl":"https://doi.org/10.1007/s00190-025-01965-3","url":null,"abstract":"<p>BeiDou Global Navigation Satellite System (BDS-3) PPP-B2b service greatly promotes the real-time precise point positioning applications. However, previous research works have revealed that a nonnegligible satellite-specific clock bias (SCB) exists in the PPP-B2b clock offset, causing the degradation of PPP-B2b positioning performance. In this paper, a single-station-augmented PPP-B2b considering the SCB via BDS-3 short-message communication (SMC) is proposed. Specifically, an easy-to-implement real-time extraction method of single-differenced (SD) SCB is proposed using a single reference station. Then, based on the extracted SCB augmentation information, a new full-rank estimable SCB-weighted model is proposed to enhance the PPP-B2b positioning. In addition, to effectively transmit the SCB augmentation information without regard to Internet, a delicate design of encoding and broadcast strategy is developed via the BDS-3 SMC function. The results show that the extracted SD SCB series of each satellite is highly stable over a certain period of observation arc. The precision of extracted SD SCB series of each satellite varies from 0.11 to 0.28 ns with a mean value of 0.18 ns. In addition, compared with the traditional PPP-B2b model, the proposed SCB-weighted model improves the positioning performance in the static and kinematic applications. Specifically, for the static application, the positioning accuracy of SCB-weighted model exhibits 35.3%, 66.7%, and 48.2% improvements in east, north, and up directions, respectively; the convergence time exhibits a 39.7% improvement. For the kinematic vehicle application, the SCB-weighted model exhibits a faster re-convergence speed. The positioning accuracy is improved from 0.421 to 0.208 m with a 50.6% improvement. In conclusion, the proposed single-station-augmented PPP-B2b using the SCB-weighted model is highly appreciated for enhancing the PPP-B2b positioning performance.</p>","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"55 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144137091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}