Journal of Geodesy最新文献

{"title":"ITRF2020 updates: motivations, usage and uncertainty evaluation","authors":"Zuheir Altamimi,Paul Rebischung,Xavier Collilieux,Laurent Métivier,Julien Barnéoud,Kristel Chanard,Maylis de La Serve","doi":"10.1007/s00190-026-02125-x","DOIUrl":"https://doi.org/10.1007/s00190-026-02125-x","url":null,"abstract":"Abstract The ITRF2020 marked considerable innovations compared with previous versions of the International Terrestrial Reference Frame (ITRF), by modeling nonlinear station motions (seasonal signals and post-seismic deformation for sites subject to major earthquakes). It was also demonstrated that the accuracy and long-term stability of the frame origin, based on the Earth’s center of mass as sensed by Satellite Laser Ranging (SLR), are, since ITRF2005, at the level of or better than 5 mm at epoch 2015.0 and 0.5 mm/yr. Moreover, for the first time in the ITRF history, the scale agreement between the SLR and Very Long Baseline Interferometry (VLBI) input solutions was at the level of 1 mm at the equator at epoch 2015.0, with no drift. Motivated by these results, and for a number of reasons exposed in this paper, the International Terrestrial Reference System (ITRS) Center decided to regularly (yearly) update ITRF2020. The first two ITRF2020 updates, named ITRF2020-u2023 and ITRF2020-u2024, were released in 2024 and 2025, respectively. They are aligned to ITRF2020, thus preserving the same frame parameters (origin, scale, and orientation), while providing improved and up-to-date station trajectory models. The results of the first two ITRF2020 updates are discussed, with a special focus on the evaluation of the uncertainties of the alignment over the frame physical parameters (origin and scale), as well as on Earth Orientation Parameters. We show in particular that the addition of 4 years of extended data from the four space geodetic techniques impacts the transfer of origin and scale between techniques at the level of only 1 mm, demonstrating a high-level of consistency between the frame parameters of ITRF2020 and its updates.","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"36 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149091363","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 bias-weighted model for GLONASS ambiguity resolution: from short to medium baselines","authors":"S. Yang,A. Khodabandeh,S. Zaminpardaz,P. J. G. Teunissen","doi":"10.1007/s00190-026-02112-2","DOIUrl":"https://doi.org/10.1007/s00190-026-02112-2","url":null,"abstract":"Abstract Integer ambiguity resolution (IAR) is crucial for fully exploiting the ultra-precise carrier phase measurements in global navigation satellite system positioning. To achieve IAR, phase biases that violate the integer property of ambiguities are typically either estimated together with other model parameters or eliminated through differencing techniques. Observing that these biases can be bounded, exploring the impact of constraining their extreme bounds on IAR performance is a logical next step yet one that has received limited attention in existing research. This study proposes a bias-weighted model that constrains the random variations in GLONASS between-receiver single-difference phase biases to enhance IAR. Real-world short-baseline ( $$sim $$ ∼ 1–5 km in length) positioning results demonstrate that the bias-weighted model enables instantaneous, centimeter-level dual-frequency GLONASS-only ambiguity-resolved positioning. For longer baselines (from 10 to 100 km), instantaneous, centimeter-level ambiguity-resolved positioning can also be achieved by combining dual-frequency GLONASS and GPS observations based on the proposed bias-weighted model, showing improvements over its counterpart in which the phase biases are treated completely unknown, i.e., the bias-unknown model. A formal analysis for both standalone GLONASS and combined GLONASS+GPS constellations at 1-km and 100-km baselines across various global locations, further highlights the improvements brought by the bias-weighted model in enhancing IAR performance worldwide. The bias-weighted model shows strong potential for improving GLONASS-included IAR and positioning performance, especially in weaker models where ionospheric parameters must be estimated–such as those typical of medium-to-long baselines.","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"8 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149049772","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":"Multi-facility GNSS antenna calibration","authors":"Tobias Kersten,Johannes Kröger,Steffen Schön,Andria Bilich,Igor Sutyagin,Martin Schmitz,Ansgar Dreier,Heiner Kuhlmann,Stefano Caizzone,Benedikt Soja,Andreas Brown,Gregor Möller,Guorong Hu,Zhigang Hu,Arturo Villiger","doi":"10.1007/s00190-026-02111-3","DOIUrl":"https://doi.org/10.1007/s00190-026-02111-3","url":null,"abstract":"Abstract Accurate antenna calibrations are a cornerstone of high-quality global navigation satellite systems (GNSS) positioning, time and frequency transfer, precise orbits, and troposphere estimates. The international GNSS service (IGS) antenna committee maintains antenna phase center corrections in the ANTEX file relying on five calibration facilities. Since new calibration facilities have been set up and user demands have grown along with hardware and software updates of GNSS, we organized an international inter-comparison across nine facilities, using both anechoic chambers and field robots. Six antennas with different designs were calibrated by each facility and compared with the Geo++ robot solution (GPP4), a proxy for the IGS ANTEX. Where available, we also considered the IGS type means. We examined differences between the antenna patterns and subsequent differences in station coordinates. To this end, we used a standardized forward simulation as well as multi-GNSS PPP solutions using the GNSS toolbox developed at Leibniz University Hannover, Institut für Erdmessung (IfE). Our study yields several important results. We found that multi-GNSS antenna calibrations exhibit frequency- and elevation-dependent variations, with deviations of up to 3 mm to 4 mm at low elevations. We show that organizations like Topcon (TPS), national geodetic survey (NGS), and Wuhan GNSS Research Center (WHU) yield calibration results that are in very good agreement with those of IGS accepted facilities such as GPP, IfE, and to some extent geoscience Australia (GA). These differences result in position deviations of a few millimeters, with the Up component being the dominant contributor.","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"36 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149049773","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 sub-daily polar motion from BeiDou: assessment and analysis with emphasis on the impact of constellation configurations","authors":"Xingxing Li,Xia Yao,Yongqiang Yuan,Hongjie Zheng,Kang Zhou","doi":"10.1007/s00190-026-02113-1","DOIUrl":"https://doi.org/10.1007/s00190-026-02113-1","url":null,"abstract":"","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"399 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149049774","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":"Machine learning algorithms for transplanting accelerometer observations in future satellite gravimetry missions","authors":"Mohsen Romeshkani,Jürgen Müller,Sahar Ebadi,Alexey Kupriyanov,Annike Knabe,Nina Fletling,Manuel Schilling","doi":"10.1007/s00190-026-02108-y","DOIUrl":"https://doi.org/10.1007/s00190-026-02108-y","url":null,"abstract":"Abstract Accurate and continuous monitoring of Earth’s gravity field is essential for tracking mass redistribution processes linked to climate variability, hydrological cycles, and geodynamic phenomena. While the GRACE and GRACE Follow-On (GRACE-FO) missions have set the benchmark for satellite gravimetry using low–low satellite-to-satellite tracking (LL-SST), the precision of gravity field recovery still strongly depends on the quality of accelerometer (ACC) performance. Traditional electrostatic accelerometers (EA) face limitations that can hinder mission outcomes, prompting exploration of advanced sensor technologies and data recovery techniques. This study presents a systematic evaluation of accelerometer data transplantation (i.e., the reconstruction and transfer of non-gravitational acceleration measurements between satellites) using novel accelerometer configurations, including Cold Atom Interferometry (CAI) accelerometers and hybrid EA-CAI setups, and applying both analytical and machine learning-based methods. Using comprehensive closed-loop LL-SST simulations, we compare four scenarios ranging from the conventional EA-only setup to ideal dual hybrid configurations, with a particular focus on the performance of transplant-based approaches using different neural network approaches. Our results show that the dual hybrid configuration provides the most accurate gravity field retrieval. However, the transplant-based hybrid setup, particularly when supported by machine learning (ML), emerges as a robust and cost-effective alternative, achieving comparable performance while significantly reducing the need for high-precision accelerometers across the constellation, thereby lowering mission costs and system complexity. These findings highlight the promise of combining quantum sensor technology and data-driven transplantation for future satellite gravimetry missions, paving the way for improved global monitoring of Earth’s dynamic gravity field.","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"9 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149022040","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":"Explainable machine learning empowers Tianmu-1 spaceborne GNSS-R soil moisture inversion: mechanism analysis and accuracy improvement from orbital-point assessment to multi-system weighted grid construction","authors":"Naiquan Zheng,Ying Xu,Mingzhen Xin,Fanlin Yang","doi":"10.1007/s00190-026-02109-x","DOIUrl":"https://doi.org/10.1007/s00190-026-02109-x","url":null,"abstract":"","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"8 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148933501","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":"Effects of glacial loading in Svalbard on the VLBI scale realisation","authors":"Halfdan Pascal Kierulf, Lisa Maria Kern, Clinton Phillips Conrad, Ann-Silje Kirkvik, Hana Krásná, Geir Moholdt, Thomas Vikhamar Schuler","doi":"10.1007/s00190-026-02121-1","DOIUrl":"https://doi.org/10.1007/s00190-026-02121-1","url":null,"abstract":"In the realisation of the International Terrestrial Reference System in 2000, and in the realisations since 2008, the scale of the International Terrestrial Reference Frame (ITRF) has been defined based on Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) solutions, whereas ITRF2005 relied solely on VLBI. In the latest ITRF realisation, i.e. ITRF2020 with its first and second updates, VLBI sessions after September 2013 are excluded from the ITRF scale definition due to a detected drift in the VLBI solution with respect to the average scale trend computed from September 1997 until September 2013. Ny-Ålesund station in Svalbard, the northernmost fundamental geodetic station hosting all major techniques, plays a key role in ITRS realisation due to its location. Crustal motion measurements at Ny-Ålesund reveal nonlinear vertical motion, largely explained by elastic deformation caused by thinning glaciers. In the ITRF2020 updates (u2023 and u2024), a discontinuity in August 2016 was introduced for the VLBI station to account for the increasing uplift, reducing the detected scale drift relative to ITRF2020 by approximately 50%. In this study, we analyse the nonlinear vertical motion at Ny-Ålesund, compare it with predicted elastic loading signals arising from glacier thinning, and assess its impact on the VLBI scale estimates. Over the past 25 years, the land uplift rate increased from about 6 mm/year to 14 mm/year, indicating that the vertical displacement through time is not well described by a constant-rate model. The record also shows substantial interannual variability, of which the glacier loading model explains only about 50%. Including a nonlinear station motion model—based on Global Navigation Satellite System (GNSS) observations or loading predictions—for the VLBI station in Ny-Ålesund reduces the relative scale drift by 30–60%. Finally, we discuss alternative approaches to mitigate the negative effects of nonlinearity, such as modelling the elastic glacier signal or better integrating VLBI station motion with GNSS-derived displacement.","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"31 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149086490","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":"Implementation and validation of orbital dynamics for accelerometers displaced from the center of mass","authors":"Juanxia Pan, Xiancai Zou, Minxing Zhao, Luping Zhong, Bingshi Liu","doi":"10.1007/s00190-026-02119-9","DOIUrl":"https://doi.org/10.1007/s00190-026-02119-9","url":null,"abstract":"Spaceborne accelerometers provide precise measurements of the non-conservative forces acting on the satellite, which makes a significant contribution in refining the satellite dynamical models. Currently, to accurately determine the non-gravitational acceleration at the satellite’s center of mass (CoM), onboard electrostatic accelerometers require precise control systems to align the proof mass with the satellite’s CoM, or rely on additional corrections using pre-flight designed accelerometer CoM offsets to separate accelerations induced by angular motion. These requirements pose one of the challenges for the widespread application of accelerometers. This paper proposes an orbital dynamics method for accelerometers displaced from the satellite CoM, designed to simultaneously estimate the CoM offsets with the accelerometer scale factors, biases, and orbital parameters. This methodology is implemented and validated using a specific case study, the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite. The accelerometer scale factors, biases, and CoM offsets are determined using a high-precision a priori global gravity field model and the precise kinematic orbit products from GOCE. The results indicate that using the a priori nominal CoM offset values, the proposed method demonstrates good consistency with accelerometer calibration parameters derived from the common-mode acceleration at the satellite’s CoM. When CoM offsets are treated as unknown parameters, the <italic>y-</italic> and <italic>z</italic>-components achieve millimeter-level accuracy. Using the uncalibrated nominal accelerometer data in the estimation, the maximum deviation of the gradiometer baseline lengths from design values is approximately 2.8 mm during the early phase, with relative errors not exceeding 1%. The <italic>x</italic>-component of the GOCE satellite is found to be difficult to estimate accurately, which is initially speculated to result from the influence of the drag-free and attitude control system in the along-track direction. For satellites with millimeter- or centimeter-level requirements for CoM offsets accuracy, the proposed method has the potential to alleviate stringent requirements for accelerometer installation and satellite control, providing a possible choice for future spaceborne accelerometer applications.","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"20 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149086491","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":"First demonstration of long-time absolute atomic gravity measurement trials in open\u0000sea areas","authors":"Tiangao Zhu, Fangjun Qin, Jiujiang Yan, Hao Chen, Kailong Li, An Li, Hao Che, Chunfu Huang, Zhichao Ding, Leiyuan Qian, Hongyang He, Ning Mao, Xi Chen, Biao Tang","doi":"10.1007/s00190-026-02117-x","DOIUrl":"https://doi.org/10.1007/s00190-026-02117-x","url":null,"abstract":"High-precision gravimetric measurement constitutes a foundational capability for geodesy, geophysical exploration, resource prospecting, and navigation systems. Current marine gravimetric systems employing relative gravimeters encounter inherent limitations due to progressive zero-point drift and obligatory recalibration requirements, constraining sustained oceanic operational capacity. Atomic interferometric gravimeters offer a paradigm-shifting solution, though previous validation efforts remained restricted to static/moored configurations or brief coastal deployments without verified long-term dynamic performance. This study details absolute gravity measurements obtained through transoceanic campaigns across Pacific, Atlantic, and Indian Ocean using atomic interferometry. Repeat-line experiments under challenging sea conditions (Sea State 3–4) yielded internal consistency better than 0.33 mGal (1 mGal = 10⁻⁵ m/s²), quantified by the root mean square of gravity differences along repeated survey lines. Comparative analyses demonstrate operational superiority over conventional relative gravimeters, maintaining drift-free performance during seven-month transoceanic campaigns with closed-loop verification. To the best of our knowledge, this experiment demonstrates one of the best reported levels of repeat-line agreement for shipborne atomic absolute gravity measurements under dynamic open-sea conditions, together with the longest sustained operational duration and the farthest voyage range reported in the open literature. This breakthrough transitions from validation to deployment, enabling advanced underwater navigation and facilitating deep-sea exploration, marine dynamics research, and the development of marine absolute gravity reference networks and improved global marine gravity field models.","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"393 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149003647","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":"Machine-learned mapping functions for the asymmetric troposphere","authors":"Zhenyi Zhang, Benedikt Soja","doi":"10.1007/s00190-026-02101-5","DOIUrl":"https://doi.org/10.1007/s00190-026-02101-5","url":null,"abstract":"Accurate empirical tropospheric mapping functions (MFs) are essential for high-precision geodetic applications such as GNSS and VLBI. However, traditional MFs assume azimuthal symmetry or explicitly model gradients on regular grids, limiting their ability to represent real atmospheric conditions. To address the limitation, this study designs a novel physics-constrained machine learning-based framework implemented with a multilayer perceptron and develops global empirical asymmetric MFs on five years of ERA5-based ray-tracing data. Compared to the widely used GPT3 model, our models reduce global RMSE by up to 12.0% for hydrostatic and 2.8% for wet components. Relative to GPT3 with gradient corrections, they remain globally competitive, with locally improved performance, especially at low elevations, high altitudes, and over many continental regions. The improvements are particularly evident at low elevation angles, high-altitude sites, and over continental regions. To our knowledge, this work marks the first global machine learning-based empirical MF models that directly capture atmospheric asymmetry, offering a flexible and physically consistent alternative to traditional models in space geodesy. Research Highlights <jats:list list-type=\"order\"> <jats:list-item> The first global machine-learning-based empirical mapping functions for the asymmetric troposphere are developed. </jats:list-item> <jats:list-item> A physics-constrained machine-learning framework enables robust and physically consistent mapping function modeling. </jats:list-item> <jats:list-item> The models outperform symmetric GPT3, remain competitive with GPT3 with gradients, and support flexible updating and extension. </jats:list-item> </jats:list>","PeriodicalId":54822,"journal":{"name":"Journal of Geodesy","volume":"166 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148883910","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}