Remarkable advances in recent years demonstrate that geodesy today is driven by a broad spectrum of interactions, including theory, science, engineering, technology, observations, and practice-oriented services. Geodetic science accumulates significant results in studies towards classical geodetic problems and problems that have only recently emerged or gained new interest - in many cases due to synergistic activities in geodesy and tremendous advances in instrumentation and computational tools. In-depth studies have progressed in parallel with investigations that led to a broadening of the traditional core of geodesy. Within this concept, we seek contributions concerning problems of reference frames, gravity fields, geodynamics, or positioning, but also studies surpassing the frontiers of these topics. We invite presentations discussing analytical and numerical methods in solving boundary-value or inverse problems, geoid determination, advances in spatial/temporal modelling, estimation theory, or the use of high-performance facilities. Demonstrations of mathematical and physical research directly motivated by geodetic practice and ties to other disciplines are welcome. In parallel with theory-oriented results, examinations of novel data-processing methods in various branches of geodetic science and practice are also acceptable. The scope of the session is conceived with a degree of freedom, even though it intends to provide a forum for all theoretical and methodological investigations and results.

This session showcases novel applications of artificial intelligence and machine learning in geodesy.

In recent years, the exponential growth of geodetic data from various observation techniques has created challenges and opportunities. Innovative approaches are required to efficiently handle and harness the vast amount of geodetic data available for scientific purposes, for example, when dealing with “big data” from Global Navigation Satellite Systems (GNSS) and Interferometric Synthetic Aperture Radar (InSAR). Likewise, numerical weather models and other environmental models important for geodesy come with ever-growing resolutions and dimensions. Artificial intelligence and machine learning have shown great potential not only in this context but also when applied to more limited datasets to solve complex non-linear problems in geodesy.

We invite contributions related to applying methods from artificial intelligence and machine learning (including shallow, deep, and generative learning architectures, as well as geospatial foundation models) to geodetic problems and datasets. We welcome investigations related to (but not limited to): more efficient and automated processing of geodetic data, pattern and anomaly detection in geodetic time series, images, or higher-dimensional datasets, implicit neural representations for continuous spatial field modeling, improved predictions of geodetic parameters, such as Earth orientation, atmospheric, or hydrological parameters into the future, combination and extraction of information from multiple inhomogeneous datasets (multi-temporal, multi-sensor, multi-modal fusion), feature selection and sensitivity, downscaling geodetic data, and improvements of large-scale simulations. We strongly encourage contributions that address crucial aspects of uncertainty quantification and integration of physical relationships into data-driven frameworks (physics-informed machine learning). Moreover, reproducibility, interpretability, and explainability of machine learning outcomes are fundamental to ensuring the scientific rigor of novel AI-based solutions.

By combining the power of artificial intelligence with geodetic science, we aim to open new horizons in our understanding of Earth's dynamic geophysical processes. Join us in this session to explore how the fusion of physics and machine learning promises advantages in generalization, consistency, and extrapolation, ultimately advancing the frontiers of geodesy.

Global Terrestrial Reference Frames (TRF) are fundamental for monitoring the Earth's rotation in space, and to many Earth science applications that need absolute positioning and precise orbit determination of near-Earth satellites. Accurate and stable TRFs are especially needed for the quantification of global change phenomena such as sea level rise, current ice melting, tectonic, and seismic deformations. This session generally welcomes contributions on the computation, the evaluation and the use of TRFs.

The computation of TRFs relies on space geodetic observations acquired by ground networks of stations. Nowadays, measurement biases and imperfect background models in space geodetic data analysis are the main factors limiting the accuracy of TRFs. This session therefore welcomes contributions that develop strategies to overcome systematics in space geodetic observing systems such as range biases in SLR observations, gravitational deformation of VLBI antennas, GNSS antenna phase patterns, etc. The understanding of the discrepancies between the terrestrial scale observed by the different space geodetic techniques, and the improvement of geocentre motion determination are of particular interest.

Another key ingredient to the construction of TRFs are geometric ties between instruments of the different space geodetic techniques, be they co-located on ground (“local ties”) or onboard satellite missions (“space ties”). Contributions are therefore strongly encouraged on the determination of new local ties at co-location sites, on new methods for local tie determination, as well as on the handling and impact of space ties in TRF determination, with the perspective of exploiting ESA’s dedicated GENESIS mission. Papers that explore new TRF construction strategies, e.g., combination of the different techniques at the observation level, or any type of development that could improve future TRF solutions, are also highly welcome.

Besides reviewing improvements in TRF determination, another objective of this session is to bring together contributions from individual technique services, space geodetic data analysts, ITRS combination centers and TRF users to discuss the TRF solutions produced by different groups, with a special focus on their comparison and evaluation. Papers on the exploitation of different TRF solutions for various geodetic and geophysical applications are therefore also solicited.

In recent years, we have observed steady progress in signals, services, and satellite deployment of Global Navigation Satellite Systems (GNSS). Consequently, modernizing and developing GNSS constellations have moved us towards an era of multi-constellation and multi-frequency GNSS signal availability. Also, the deployment of LEO constellations brings opportunities for LEO-augmented PNT services and applications, which, however, require revisiting existing processing algorithms and developing novel ones when fusing LEO and GNSS. Meanwhile, technological development has provided high-grade GNSS user receivers capable of collecting high-rate, low-noise, and multipath-impact measurements. Also, recent extraordinary progress in low-cost GNSS chipsets, smartphones, and sensor fusion must be acknowledged. Such advancements boost GNSS research and catalyze an expansion of satellite navigation to novel areas of science and industry. On one side, the developments stimulate a broad range of new GNSS applications. On the other hand, they pose new challenges for data processing. Hence, algorithmic advancements are needed to address the opportunities and challenges in enhancing the accuracy, availability, interoperability, and integrity of high-precision GNSS applications.
This session is a forum for discussing advances in high-precision GNSS algorithms and their applications in geosciences, including geodesy, geodynamics, seismology, tsunamis, the ionosphere, and the troposphere.
We encourage but do not limit submissions related to:
- GNSS processing algorithms,
- Multi-GNSS benefits for Geosciences,
- Multi-constellation GNSS processing and product standards,
- High-rate GNSS,
- Low-cost receiver and smartphone GNSS observations for precise positioning, navigation, and geoscience applications,
- LEO observations modeling and processing algorithms,
- Precise Point Positioning (PPP, PPP-RTK) and Real Time Kinematic (RTK),
- GNSS and other sensors (accelerometers, INS, etc.) fusion,
- GNSS products for high-precision applications (orbits, clocks, uncalibrated phase delays, inter-system and inter-frequency biases, etc.),
- Troposphere and ionosphere modeling and sounding with GNSS,
- CORS services for Geosciences (GBAS, Network-RTK, etc.),
- Precise Positioning of EOS platforms,
- GNSS for natural hazards prevention,
- Monitoring crustal deformation and the seismic cycle of active faults,
- GNSS and early-warning systems,
- GNSS reflectometry.

The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) collaborates with IAG components and other entities to provide precise, consistent and long-term observations of the Earth's shape, rotation and gravity field, and to maintain global reference frames. In line with the essential variables that are already operational in the climate and ocean domains, GGOS has introduced the Essential Geodetic Variables (EGVs) framework. This framework identifies and characterizes the geodetic observations and products that are fundamental to monitoring and understanding changes in the Earth system. It also supports a wide range of scientific and societal applications on Earth and in space.
Advancing the implementation of the EGVs requires their systematic identification and classification, together with assessments of their availability, quality and performance against user. It also requires sustainable observing infrastructure, reliable data and product supply chains, adequate human resources, and effective access to geodetic data and products in accordance with FAIR principles.
This session welcomes contributions across the full EGV value chain, ranging from the definition and nature of EGV and their user requirements to observing techniques and infrastructure, data processing and product generation, assessments of availability, quality and performance, sustainable supply chains and human resources, and FAIR access to essential geodetic data and products.

The increasing availability of affordable hardware for global navigation satellite systems (GNSS) and open-source software for GNSS data processing is shaping geoscience research in novel ways. By using these technologies, researchers can now perform highly accurate positioning and data analysis at a fraction of the cost of geodetic quality hardware and software. Given that positioning, reflectometry, radio occultation, space weather monitoring, and atmospheric sounding with GNSS have become operational techniques, and new experiments are being conducted with low-cost GNSS hardware and open source GNSS processing software, it augurs well for the geosciences at large to exploit these developments for furthering our understanding of the Earth system. In this session we solicit abstracts on use, development and novel geoscience applications of low-cost GNSS hardware and open source GNSS software. In addition, we welcome other contributions highlighting the opportunities and challenges in using low-cost GNSS hardware and open source GNSS software.

GNSS stations represent one of the major observation infrastructures for geoscientific research. Depending on where one needs measurements, the station design needs to weigh up several factors including signal to noise, power consumption, data telemetry, and expense of installation. Recent years have seen the increase in deployments of lower cost hardware, in particular multi-frequency receiver modules and cheaper antennas which have lowered the financial stakes for more risky, experimental installations. Some teams have deployed large numbers of such lower-cost stations while others have successfully continued working with higher tier geodetic-grade hardware. In this session, we welcome contributions from researchers involved with GNSS station deployment, design, and maintenance. In particular, topics of interest for this session include the evaluation of data quality, innovative case study uses of these data, and we welcome insights from the community on collaborative ways forward for sustainable GNSS station densification.

Following the launch of the first artificial satellite in 1957, geodesists refined knowledge of Earth’s flattening and used orbital drag observations from Sputnik to estimate upper atmosphere density. Since then, Precise Orbit Determination (POD)—where the satellite itself acts as a sensor through its orbital perturbations—has progressed to absolute orbit solutions at the centimeter (or sub centimeter) level to demanding long term stability on the order of 0.1 mm yr⁻¹ over decadal timescales, a prerequisite for quantitative climate change studies.

Today four Global Navigation Satellite System (GNSS) constellations are operational, and numerous Earth Observation missions rely on POD (e.g., satellite altimetry, gravimetry, InSAR, and Satellite Laser Ranging to passive spheres). Together they provide an unprecedented data set that can push orbit determination to its limits and enable new geophysical applications across the atmosphere (density and water vapor content), the ocean (sea level rise), land (large scale fluid mass redistribution and present day deformation), and the deep Earth (rheology at decadal scales).

This session aims to make the emerging challenges of orbit determination and modeling accessible to a broader community and to quantify how dynamics errors affect the many applications that depend on POD as their primary source of observations. Contributions are solicited (but not limited) to the following areas:

1. Precise orbit determination and absolute validation approaches.
2. Advances in modeling solar/terrestrial/thermal radiation pressure, atmospheric density and their interaction with space vehicles.
3. Updates on large-scale time-variable changes in the Earth’s gravity field (e.g., motion of the Earth’s center of mass relative to the crust).
4. Observational constraints on essential variables defining the status of climate change.
5. Improvements in observable modeling for all tracking systems (SLR, DORIS, GNSS) and assess their impact on POD.
6. Integration of refined clock modeling methods/space clocks into POD.
7. Studies for the co location of geodetic techniques in space (e.g., GENESIS) to strengthen the stability of future terrestrial reference frames.

This session addresses the challenge of consistently combining terrestrial and marine datasets referenced to different vertical reference surfaces, a fundamental requirement for, among other applications, effective coastal-zone management and robust coastal-hazard assessment. This includes the integration of terrain elevations, bathymetric data, and/or sea-level data, including model-derived water levels, as well as the realization and unification of the vertical reference surfaces to which these datasets are referenced.
We welcome contributions proposing strategies for land–sea vertical reference integration across scales, from global to local, as well as studies applying and evaluating such strategies. Contributions are also invited on the realization of height and depth reference surfaces, including (marine) geoid and chart datum models, height-system unification, and the transfer of vertical datums across the land–sea interface.

This session invites innovative Earth system and climate studies employing geodetic observations and methods. Modern geodetic observing systems have been instrumental in studying a wide range of changes in the Earth’s solid and fluid layers at various spatiotemporal scales. These changes are related to surface processes such as glacial isostatic adjustment, the terrestrial water cycle, ocean dynamics, and ice-mass balance, which are primarily due to changes in the climate. To understand the Earth system response to natural climate variability and anthropogenic climate change, different time spans of observations need to be cross-compared and combined with several other datasets and model outputs. Geodetic observables are also often compared with geophysical models, which helps in explaining observations, evaluating simulations, and finally merging measurements and numerical models via data assimilation.

We look forward to contributions that:
1. Utilize geodetic data from diverse geodetic satellites, including altimetry, gravimetry (CHAMP, GRACE, GOCE, and GRACE-FO, SWOT), navigation satellite systems (GNSS and DORIS) or remote sensing techniques that are based on both passive (i.e., optical and hyperspectral) and active (i.e., SAR, Sentinel, NISAR) instruments.
2. Cover a wide variety of applications of geodetic measurements and their combination to observe and model Earth system signals in hydrological, ocean, atmospheric, climate, and cryospheric sciences.
3. Show a new approach or method for separating and interpreting the variety of geophysical signals in our Earth system and combining various observations to improve spatio-temporal resolution of Earth observation products.
4. Work on simulations of future satellite missions (such as MAGIC and NGMM) that may advance climate sciences.
5. Work towards any of the goals of the Inter-Commission Committee on "Geodesy for Climate Research" (ICCC) of the International Association of Geodesy (IAG).

We are committed to promoting gender balance and ECS in our session. With the author consent, highlights from this session will be shared on social media with a dedicated hashtag during the conference in order to increase the impact of the session.

The redistribution of geophysical fluids across the Earth’s surface and near surface driven by water cycle dynamics and its extremes can cause measurable load-induced deformation. In the last decades, increasingly accurate and available space geodetic measurement techniques (among others GNSS, InSAR, satellite gravimetry and altimetry) have enriched our understanding of this response. Accurate observations of crustal deformation together with geophysical models can be applied to quantify the hydrological loads, and through that, they provide new insight into the related hydrological processes. With changing climate also cryospheric mass changes get increasingly important to consider, but usually hydrological models do not explicitly address them. There is still a lack of a unified global mass transport model.

This session aims to attract research that further advances our ability to accurately quantify hydrological mass loads across different temporal and spatial scales, and involving different hydrological compartments (e.g., groundwater, surface water, snow, ice). We invite studies focusing on innovative measurement and modeling approaches and reconciling observations from different geodetic measurement techniques used to study hydrological loading as well as the disentangling of cryospheric and hydrologic signals. Research that assesses the strengths and limitations of each approach and that proposes strategies for a seamless and accurate integration, particularly of cryospheric processes, is highly encouraged. Additionally, we seek studies that conduct intercomparisons of different hydrological model data (land surface, hydrological models) and geodetic measurement techniques to understand their relative strengths, weaknesses, and accuracies.

The growth and decay of large ice sheets on the Earth's surface during the past, present and future leads to glacial isostatic adjustment (GIA) triggered by the redistribution of surface ice and ocean masses, and the flow of mantle rocks. It changes solid Earth's geometric shape, sea levels, the Earth's gravity field, rotational motion, lithospheric bending, and the state of stress inside the Earth. This process is primarily driven by ice-sheet dynamics and Earth's structure, while it crucially feedbacks other Earth systems like the cryosphere and hydrosphere. GIA controls relative sea-level change through vertical land motion and gravitational–rotational effects, making it fundamental for ocean sciences, hydrological sciences, and climate investigations. Furthermore, differential uplift and tilting due to GIA reshapes landscapes and drainage networks, while emergent land and basin connections drive ecosystem succession and carbon burial. Moreover, GIA-related stress redistribution influences a region’s seismicity and its seismic hazard, which must be considered in nuclear waste storage safety assessments. Similarly, such stress changes can alter volcanic activity even thousands of kilometres away from the glaciated area. GIA effects are present in a wealth of standardized observational data, such as GNSS measurements, tide gauges, relative sea levels, and terrestrial and satellite gravimetry. These data help refine GIA models, which enhance our understanding of ice-sheet history, sea-level changes, Earth's rheology and near-surface processes. The GIA theory can also be applied to study other planets and moons.

We welcome contributions studying GIA's effects across various scales, including geodetic measurements, complex GIA modelling, the Earth's response to current ice-mass changes, and overview on emerging GIA data collections. We also invite abstracts on Earth structure and rheology, ice history and on GIA's impact on nuclear waste sites, volcanism, groundwater, permafrost, and carbon resources. We especially appreciate new model developments, model intercomparisons and model benchmarks in local, high spatial and temporal resolution for GIA assessments, results of fully coupled ice dynamics-GIA models, studies of broader environmental relevance, and improved GIA corrections for other geoscientific fields.

Global Navigation Satellite System Reflectometry (GNSS-R) has come of age. Two decades after the first spaceborne demonstrations, and almost a decade into the CYGNSS mission, GNSS-R has moved to a established source of Earth observation, with a growing constellation of missions delivering frequent and all-weather observations of ocean winds and sea state, soil moisture, freeze/thaw, inundation and wetlands, snow and sea ice, and vegetation. The recent launch of HydroGNSS, ESA's first Scout mission and the first GNSS-R mission dedicated to the terrestrial water cycle, marks the start of a new phase in which GNSS-R can address Earth system science questions at the scale, quality, and continuity required for operational monitoring and modeling.
Until now, GNSS-R contributions at EGU have been distributed across sessions. This session, the first at EGU dedicated to GNSS-R, brings this community together in one place and shifts the emphasis from the technique to its use. Its focus is on how GNSS-R observations, alone and in combination with other satellite and ground-based data, advance understanding of the hydrosphere, cryosphere, atmosphere, biosphere, and ocean, and how they are integrated into Earth system models to constrain water, energy, and carbon exchanges and to improve weather, hydrological, and climate prediction.
We welcome, but do not limit, contributions on:
• First results, validation, and early science from HydroGNSS
• Monitoring of soil moisture, floods and wetlands, snow, sea ice, freeze-thaw, permafrost, and vegetation with GNSS-R
• Ocean surface winds, sea state, and extreme events such as tropical cyclones observed with GNSS-R
• Assimilation of GNSS-R products into land surface, hydrological, ocean, weather, and climate models
• AI-based data fusion, gap filling, and emulation of forward models, as well as integration of GNSS-R into AI-based weather and Earth system models
• Use of GNSS-R for model evaluation, parameter calibration, and process understanding
• Synergy of GNSS-R with passive microwave, SAR, altimetry, optical, and in-situ observations
• Long-term records, product intercomparison, and machine learning approaches bridging observations and models
• Airborne GNSS-R supporting Earth system applications
• Perspectives on future GNSS-R missions and the role of GNSS-R in the multi-mission Earth observing system

Accurate modeling and prediction of Earth rotation is important for numerous applications in geodesy, astronomy, navigation, and geophysics. In recent years, geodetic observation systems have made significant progress in monitoring the temporal variability of the Earth's rotation, which is largely related to dynamic processes in the planet's fluid components. The increase in observation accuracy must go along with the improvement of theories and models. Estimates of variability over a wide range of time scales have been noted as well.
We welcome contributions that highlight new determinations and analyses of Earth Orientation Parameters (EOP), including combinations of different geodetic and astrometric observational techniques for deriving UT1/length-of-day variations and polar motion. We welcome discussions of EOP solutions in conjunction with a consistent determination of terrestrial and celestial frames. We are interested in the latest achievements in EOP forecasting, especially reports exploring the potential of innovative techniques, such as machine learning, in improving forecast accuracy.
 We invite contributions on the dynamical links between Earth rotation, geophysical fluids, and other geodetic quantities, such as the Earth gravity field or surface deformation, and of explanations for the physical excitations of Earth rotation. Besides tidal influences from outside the Earth, the principal causes for variable EOP appear to be related to angular momentum exchange from motions and mass redistribution of the fluid portions of the planet, including the atmosphere, oceans, hydrological reservoirs, and the fluid core.
We welcome contributions about the relationship between EOP variability and the variability in fluids due to climate effects or global change. Forecasts of these impacts are important especially for the operational determination of EOP, and the effort to improve predictions is an important topic, and projections of EOP variability into the future.
We are interested in the progress in the theory of Earth rotation. We seek contributions that are consistent internally with the accurate observations at the mm-level, to meet the requirements of the Global Geodetic Observing System and respond to IAG 2019 Res. 5 and IAU 2021 Res. B2, as well as those derived from the research of current IAU/IAG/IERS working groups on these topics. We also welcome contributions on the variability and excitation of the rotation of other planetary bodies.

The rapid growth of SAR constellations, continental-scale ground-motion services, cloud computing, and artificial intelligence is transforming radar remote sensing from specialist analysis toward scalable and operational monitoring. Beyond interferometric phase and displacement time series, SAR amplitude observations can support rapid change detection and contextual interpretation of surface processes.

A key challenge is no longer only how to generate interferograms or deformation maps, but how to convert large volumes of radar observations into reliable, interpretable, predictive, and actionable information. Important barriers include automated quality control, large-scale processing, complex spatio-temporal interpretation, model transferability, uncertainty quantification, forecasting, and integration with operational decisions.

This session focuses on the transition from scalable SAR and InSAR processing to predictive and actionable ground-motion intelligence. We welcome contributions on AI and machine learning for SAR amplitude and InSAR processing; scalable, cloud-native, high-performance, and near-real-time workflows; automated detection, classification, attribution, and change-point analysis of radar image stacks and deformation time series; physics-informed, explainable, and uncertainty-aware learning; deformation forecasting, anomaly detection, early warning, and alert generation; and integration with GNSS, optical, geological, meteorological, infrastructure, and in-situ data.

Applications may include subsidence, landslides, infrastructure, mining, groundwater or hydrocarbon extraction, volcanic and seismic deformation, and other natural or human-induced ground-motion processes. We also encourage studies on validation, benchmarking, reproducibility, transferability, failure modes, and operational implementation.

Particular emphasis is placed on contributions that critically assess when AI adds measurable value, quantify uncertainty and limitations, and demonstrate how SAR- and InSAR-derived information can support transparent, timely, and defensible decisions for hazard assessment, infrastructure management, early warning, and risk-informed decision-making.

25 years ago, with the launch of the Gravity Recovery and Climate Experiment (GRACE, 2002-2017) mission, a new era of satellite gravimetry began, enabling a wide variety of studies related to climate research as well as other geophysical or geodetic applications. Currently, the GRACE Follow-on (GRACE-FO, launched in 2018) mission continues this successful US-German partnership, providing this invaluable data record to monitor global gravity variations from space. Yet another US-German mission, GRACE Continuity (GRACE-C, planned launch end of 2028), is already in its implementation phase and will ensure that the GRACE data record becomes even longer. At the same time, ESA's Next Generation Gravity Mission (NGGM) is approved and planned for a launch in 2033. With its low altitude (~400 km) and controlled inclined (70 degrees) orbit, NGGM offers higher spatial and temporal resolution compared to the presently available near-polar orbit missions, in particular when combined with GRACE-C. This planned concept consisting of two satellite pairs is referred as MAss Change and Geosciences International Constellation (MAGIC).

Apart from the above-mentioned GRACE-like missions, observations of other satellite missions can be used to compute high-resolution static gravity field models (GOCE mission) and to bridge gaps in the GRACE/-FO time series or to enhance gravity field models and scientific results derived thereof (e.g., Swarm, satellite laser ranging).

The important role of satellite gravimetry in monitoring the Earth from space has led to various ongoing initiatives preparing for future gravity missions (beyond NGGM/MAGIC), including simulation studies, the definition of user and mission requirements and the investigation of potential measurement equipment and orbit scenarios.

This session solicits contributions about:
(1) Results from satellite gravimetry missions as well as from non-dedicated satellite missions in terms of
- data analyses to retrieve time-variable and static global gravity field models,
- combination synergies, and
- Earth science applications.
(2) The status and study results for future gravity field missions.

This session invites contributions on the observation, processing, modelling, integration, and application of the Earth’s gravity field at regional to global scales. Topics include the acquisition, evaluation, processing, and combination of terrestrial, airborne, shipborne, and satellite gravity observations; forward and inverse gravity modelling, including approaches incorporating laterally varying density structures; the development, evaluation, combination, and application of regional and global gravity field models; and gravity field modeling for physical height determination and vertical datum definition. Contributions integrating gravity with complementary geodetic, geophysical, seismic and oceanographic observations for the investigation and interpretation of crustal and lithospheric structure, retrieval of Mean Dynamic Topography, studies related to monitoring sea level as well as the contribution of recent, novel, altimetry missions like SWOT to the determination of the Earth’s marine gravity field are particularly welcome. We further invite contributions on emerging methods and technologies for gravity data processing, filtering, modelling, combination, and interpretation, including artificial intelligence and machine learning, as well as approaches that integrate heterogeneous and multi-sensor observations for geophysical and oceanographic applications.

Advances of recent decades made high accuracy gravimetry widely available as a reliable tool to not only realize the terrestrial gravity reference with absolute gravimeters, but also to monitor gravity changes with high precision continuously over years by deploying superconducting gravimeters or with new survey concepts using quantum gravimeters. Mass change processes such as loading effects of atmosphere and ocean, volcanic activities, land uplift and glacial isostatic adjustment or water storage changes at different temporal scales can now be detected.

Technological leaps made quantum and MEMs based gravity sensors available, enabling new measurement scenarios including mobile measurements and observations of gravity gradients. Ultra stable optical clocks allow to directly determine gravity potential differences based on Einstein's theory of general relativity. Thereby, different functionals of the Earth gravity field are now accessible by measurements, opening new fields of applications with great future potential.

The session is dedicated to all aspects of high accuracy terrestrial gravity field determinations and its applications, reaching from monitoring of sub-daily variations to long-term processes in the different fields of geosciences. Contributions that document the stability and traceability of applied gravimeters and the progress of the International Terrestrial Gravity Reference Frame of IAG are as welcome as reports about the state of the art of novel techniques, improvement of established measurement solutions and advances in instrumental developments. We also strongly invite studies on field applications, e.g. volcanoloy, geothermal energy, hydrology as well as tidal, atmospheric and non-tidal loading effects.

This session is organized jointly with the IAG (International Association of Geodesy) Subcommission 2.1, IAG project "Novel Sensors and Quantum Technology for Geodesy (QuGe)" and the Horizon Europe projects EQUIP-G (Grant ID 101215427) and ERIgMEA (Project Nr: 25IEM07).

In the some parts of the world, the request of precise regional geoid determination has been still ongoing. Thus, scholars need to share their own experiences about geoid modelling in their study areas. This session will collect all scholars which are interested in precise geoid determination in countries.

Gravity and magnetic data are fundamental tools to investigate lithospheric structures over a wide range of spatial scales. The expansion of innovative acquisition systems (airborne, helicopter and UAV) and satellite surveys has considerably increased the volume, resolution and diversity of potential field datasets. These developments raise important challenges related to data acquisition, processing, harmonization, levelling and integration of heterogeneous datasets into coherent regional grids. The integration of gravity and magnetic data with complementary geological and geophysical information (e.g. petrology, geochemistry, structural geology, seismic, electromagnetic) provide powerful constraints on the architecture and tectonic evolution of the lithosphere in various tectonic settings. We invite contributions combining gravity and/or magnetic data with complementary geological and geophysical constraints through joint inversion, forward and inverse modelling, machine learning or other innovative approaches. Contributions spanning scales from local to lithospheric, addressing methodological developments, data processing, uncertainty assessment, and applications across a broad range of tectonic settings are particularly welcome.

Geodesy contributes to atmospheric science by providing some of the essential climate variables of the Global Climate Observing System. Water vapor is currently under-sampled in meteorological and climate observing systems. Thus, obtaining more high-quality humidity observations is essential for weather forecasting and climate monitoring. The production, exploitation, and evaluation of operational GNSS Meteorology for weather forecasting is well established in Europe thanks to a long-lasting cooperation between the geodetic community and the meteorological services. Improving the skill of numerical weather prediction (NWP) models, e.g., to forecast extreme precipitation, requires GNSS products with higher spatio-temporal resolution and shorter turnaround. Homogeneously reprocessed GNSS data (e.g., IGS repro3) have high potential for monitoring water vapor climatic trends and variability. Advances in SLR atmospheric delay modelling are using NWP data and 3D ray-tracing to improve tropospheric corrections. With shorter orbit repeat periods, SAR measurements are a source of information to improve NWP models. Additionally, emerging LEO-PNT missions offer capabilities for atmospheric and environmental monitoring due to their dense geometry, rapid revisit times and new signals that will be defined. Their integration with GNSS and other geodetic techniques could open new possibilities for real-time correction models. Reflected signals of GNSS and future LEO-PNT provide additional opportunities for remote sensing of the Earth system. GNSS-R contributes to environmental monitoring with estimates of soil moisture, snow depth, ocean wind speed, sea ice concentration and can be used to retrieve near-surface water vapor. We welcome, but do not limit, contributions on:
-Estimates of the neutral atmosphere using ground- and space-based geodetic data
-Retrieval and comparison of tropospheric parameters from multi-GNSS, VLBI, DORIS and multi-sensor observations
-Nowcasting, forecasting, and climate research using RT and repro tropospheric products, employing NWP and machine learning
-Assimilation of GNSS tropospheric products in NWP and in climate reanalysis
-Production of SAR tropospheric parameters and assimilation in NWP
-Homogenization of long-term GNSS, VLBI tropospheric products
-Detection and characterization of sea level, snow depth, and sea ice changes, using GNSS-R
-Monitoring of soil moisture and ground-atmosphere boundary interactions using GNSS data

In this session we search for contributions of general interest for the geodesy community which fall outside the scope of the other sessions. Contributions can cover theoretical aspects to practical or experimental nature.

This session focuses on studies that use space or sea-floor geodetic data in order to investigate and infer tectonic plate motions, deformation zones between and within plates, and the current status of earthquake cycles in different settings.

We are looking for studies that investigate how tectonic plates move through time, how such movements are accommodated in deformation zones, and how elastic strain builds up and is then released along faults and at plate boundaries. These studies should combine space or sea-floor geodesy with observations like seismicity, geological slip-rates and rakes, or sea-level and gravity changes.
Key questions concentrate on earthquake likelihood, fault slip-rates, uplift rates, non-elastic strain, and sea-level changes: How to best reference relative InSAR rate maps to plate motions? How to distinguish between horizontal/vertical InSAR signals in order to inform geodynamical inferences? How can we infer the likelihood of future earthquakes from elastic strain buildup? How persistent are fault asperities over multiple earthquake cycles? Are paleoseismic fault slip rates identical to those constrained by geodesy? What portion of plate motion results in earthquakes, and where does the rest go? How do mountains grow in the geologically-short term? How well can we constrain the stresses that drive the observed deformation? How much do the nearly-constant velocities of plates vary during the earthquake cycle, and does this influence the definition of Earth's reference frame?

The investigation of the surfaces and internal structures of planetary bodies provides key insights into their formation and evolution. The surfaces of planets and moons can be studied using cameras, multispectral data, geochemical measurements, and laboratory experiments. Geophysical datasets—especially seismic, gravity and (electro)magnetic observations—are key to inferring the internal structure and dynamics of terrestrial and giant planets, their moons, as well as asteroids and planetesimals.
The combination of surface observations and laboratory experiments with geophysical modeling is crucial to reconstruct the internal structure of planetary bodies and to explore the geodynamic processes that have shaped planetary surfaces and interiors. For instance, multispectral imaging and experimental analyses link remote sensing data to mineralogical and physical properties, offering insights into the composition of outer and internal shells. Gravity and magnetic data together with altimetry measurements provide constraints on the differentiation, density structure, and mechanical properties (i.e., rheology, elastic properties) of planetary interiors. Terrestrial analogs (e.g., terrestrial lava tubes, impact craters, volcanic products, tectonic structures, glaciers, subglacial lakes, etc.) are also investigated through a multidisciplinary approach that combines surface observations with modeling of magnetic and gravity data to understand the geological, volcanic, and tectonic processes across terrestrial planets and icy satellites. These complementary approaches, together with geological mapping and interpretation, provide an integrated framework for how planetary bodies formed, differentiated, and evolved.
This session focuses on the instruments, measurement techniques, modeling approaches, geological interpretation, terrestrial analogues and laboratory studies that provide important constraints on the evolution of planetary surfaces and interiors. We invite contributions addressing current methods and innovative strategies to overcome existing scientific/technical/methodological challenges. Results from past, ongoing, and forthcoming missions, integrative multi-dataset analyses, and forward-looking exploration concepts are also encouraged. The session aims to provide an overview of the latest observations, methods, and experiments that allow exploring the processes shaping planetary bodies and outline pathways for major discoveries in the coming decades.

This special session will synthesize rapid scientific insights from recent large and/or disruptive earthquake sequences, highlighting what we have learned, what remains uncertain, and which methods prove most informative. We aim to feature concise, data-driven and integrative modeling spotlights on earthquake physics, rupture dynamics, ground motions, geological field analysis, geodesy, tsunami observations, early analyses, and community data/model sharing. Emphasis is on timely results emerging up to March 2026, with flexibility to include very recent events of scientific and societal relevance. The format is a moderated panel with invited talks and time for Q&A, designed to surface cross-disciplinary takeaways and priorities for follow-up studies. No abstracts are required.

The Antarctic continent contains approximately 10% of Earth's least understood continental crust, much of it hidden beneath the Antarctic Ice Sheet. Yet this concealed lithosphere exerts a fundamental influence on geothermal heat flow, subglacial hydrology, sediment and nutrient fluxes, ice-sheet behaviour, ocean productivity, and climate feedbacks. Understanding Antarctica therefore requires a truly interdisciplinary perspective that links solid Earth processes with the cryosphere, hydrosphere, biosphere and atmosphere. This session provides a forum for the newly approved SCAR Scientific Research Programme Antarctic Geosphere Evolution (AGE), which aims to advance understanding of Antarctica's four-dimensional lithospheric evolution and its interactions with Earth-system processes. We welcome contributions spanning geological, geophysical, geochemical, biological and modelling approaches, particularly studies that bridge traditional disciplinary boundaries. Topics may include, but are not limited to:
• Antarctic lithospheric architecture and tectonic evolution
• Geodynamics, mantle structure and geothermal heat flow
• Lithosphere-cryosphere coupling and ice-sheet dynamics
• Subglacial hydrology and groundwater systems
• Sediment, dust and nutrient fluxes from Antarctica to the Southern Ocean
• Provenance studies and reconstruction of the hidden Antarctic continent
• Interactions between geological processes, marine productivity and biogeochemical cycles
• Integration of geological, geophysical and geochemical datasets
• Integration of Antarctica’s components in full-plate reconstructions and computational tectonics.
The session particularly encourages studies that develop new connections between disciplines and improve understanding of how Antarctica's lithosphere influences the wider Earth system across spatial and temporal scales.

Sitting under a tree, you feel the spark of an idea, and suddenly everything falls into place. The following days and tests confirm: you have made a magnificent discovery — so the classical story of scientific genius goes…

But science as a human activity is error-prone, and might be more adequately described as "trial and error". Handling mistakes and setbacks is therefore a key skill of scientists. Yet, we publish only those parts of our research that did work. That is also because a study may have better chances to be accepted for scientific publication if it confirms an accepted theory or reaches a positive result (publication bias). Conversely, the cases that fail in their test of a new method or idea often end up in a drawer (which is why publication bias is also sometimes called the "file drawer effect"). This is potentially a waste of time and resources within our community, as other scientists may set about testing the same idea or model setup without being aware of previous failed attempts.

Thus, we want to turn the story around, and ask you to share 1) those ideas that seemed magnificent but turned out not to be, and 2) the errors, bugs, and mistakes in your work that made the scientific road bumpy. In the spirit of open science and in an interdisciplinary setting, we want to bring the BUGS out of the drawers and into the spotlight. What ideas were torn down or did not work, and what concepts survived in the ashes or were robust despite errors?

We explicitly solicit Blunders, Unexpected Glitches, and Surprises (BUGS) from modeling and field or lab experiments and from all disciplines of the Geosciences.

In a friendly atmosphere, we will learn from each other’s mistakes, understand the impact of errors and abandoned paths on our work, give each other ideas for shared problems, and generate new insights for our science or scientific practice.

Here are some ideas for contributions that we would love to see:
- Ideas that sounded good at first, but turned out to not work.
- Results that presented themselves as great in the first place but turned out to be caused by a bug or measurement error.
- Errors and slip-ups that resulted in insights.
- Failed experiments and negative results.
- Obstacles and dead ends you found and would like to warn others about.

For inspiration, see the collection of BUGS - ranging from clay bricks to atmospheric temperature extremes - at https://meetingorganizer.copernicus.org/EGU25/session/52496