The analysis of the Earth's gravity and magnetic fields is becoming increasingly important in geosciences. Modern satellite missions are continuing to provide data with ever improving accuracy and nearly global, time-dependent coverage. The gravitational field plays an important role in climate research, as a record of and reference for the observation of mass transport. The study of the Earth's magnetic field and its temporal variations is yielding new insights into the behavior of its internal and external sources. Both gravity and magnetic data furthermore constitute primary sources of information also for the global characterization of other planets. Hence, there continues to be a need to develop new methods of analysis, at the global and local scales, and especially on their interface. For over two decades now, methods that combine global with local sensitivity, often in a multiresolution setting, have been developed: these include wavelets, radial basis functions, Slepian functions, splines, spherical cap harmonics, etc. One purpose of this session is to provide a forum for exchange of research projects, whether related to forward or inverse modeling, theoretical, computational, or observational studies.
Besides monitoring the variations of the gravity and magnetic fields, space geodetic techniques deliver time series describing changes of the surface geometry, sea level change variations or fluctuations in the Earth's orientation. However, geodetic observation systems usually measure the integral effect. Thus, analysis methods have to be applied to the geodetic time series for a better understanding of the relations between and within the components of the system Earth. The combination of data from various space geodetic and remote sensing techniques may allow for separating the integral measurements into individual contributions of the Earth system components. Presentations to time frequency analysis, to the detection of features of the temporal or spatial variability of signals existing in geodetic data and in geophysical models, as well as to the investigations on signal separation techniques, e.g. EOF, are highly appreciated. We further solicit papers on different prediction techniques e.g. least-squares, neural networks, Kalman filter or uni- or multivariate autoregressive methods to forecast Earth Orientation Parameters, which are needed for real-time transformation between celestial and terrestrial reference frames.

In recent years we have witnessed a remarkable progress in terms of signals, services and satellite deployment of Global Navigation Satellite Systems (GNSS). The modernisation of fully operational GNSS systems and the development of new constellations, have seen us move towards a new stage of multi-constellation and multi-frequency observations. Meanwhile, the huge technology development provided high-grade GNSS equipment able to collect measurements at much higher rates, up to 100 Hz, hence opening new possibilities. Moreover, the recent progress in low-cost GNSS chipsets is catalyzing an expansion of traditional satellite navigation to novel areas of science and industry.
Therefore, on one side, the new developments in GNSS stimulate a broad range of new applications for solid and fluid Earth investigations, both in post-processing and in real-time; on the other side, this results in new problems and challenges in data processing which boost GNSS research. 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 to discuss new developments in high-precision GNSS algorithms and applications in Geosciences; in this respect, contributions from other branches in Geosciences (geodynamics, seismology, tsunamis, ionosphere, troposphere, etc.) are very welcome.
We encourage, but not limit, submissions related to:
- Processing algorithms in high-precision GNSS,
- Multi-GNSS benefit for Geosciences,
- Multi-GNSS processing and product standards,
- Inter-system and inter-frequency biases,
- GNSS products for high-precision applications (orbits, clocks, UPDs, etc.),
- Precise Point Positioning (PPP, PPP-RTK) and Real Time Kinematic (RTK),
- High-rate GNSS,
- Low-cost receiver and smartphone GNSS observations for precise positioning, navigation and geoscience applications,
- GNSS and other sensors (accelerometers, INS, etc.) integration for high-rate applications,
- Troposphere and ionosphere modelling in GNSS positioning and applications,
- CORS services for Geosciences (GBAS, Network-RTK, etc.),
- Precise Positioning of EOS platforms,
- Precise Positioning for natural hazards prevention,
- Monitoring crustal deformation and the seismic cycle of active faults,
- GNSS and early-warning systems,
- GNSS reflectometry.

This session aims to showcase novel applications of data science and machine learning methods in geodesy.

In recent years, the amount of data from geodetic observation techniques has increased dramatically. Innovative approaches are required to efficiently handle and harness the vast amount of geodetic data available nowadays for scientific purposes. In particular, Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) are facing challenges, but also opportunities, related to the expansive data collection (“big data”). Similarly, numerical weather models and other geophysical models important for geodesy come with ever growing resolutions and dimensions. Strategies and methodologies from the fields of data science and machine learning have shown great potential not only in this context, but also when applied to more limited data sets to solve complex non-linear problems in geodesy.

We invite contributions related to various aspects of applying methods from data science and machine learning (including both shallow and deep learning techniques) to geodetic problems and data sets. 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 data sets, improved predictions of geodetic parameters into the future, combination and extraction of information from multiple inhomogeneous data sets (multi-temporal, multi-sensor, multi-modal fusion), feature selection, super-sampling of geodetic data, and improvements of large-scale simulations. Especially encouraged are contributions that discuss the uncertainty quantification, interpretability and explainability of results from machine learning algorithms, as well as the integration of physical modeling into data-driven frameworks.

Remarkable advances over recent years give an evidence that geodesy today develops under a broad spectrum of interactions, including theory, science, engineering, technology, observation, and practice-oriented services. Geodetic science accumulates significant results in studies towards classical geodetic problems and also problems that only emerged or gained new interest, in many cases as a consequence of synergistic activities in geodesy and tremendous advances in the instrumentations and computational facilities. In-depth studies progressed in parallel with investigations that mean a broadening of the traditional core of geodesy. The scope of the session is conceived with a certain degree of freedom, though the session is primarily intended to provide a forum for all investigations and results of theoretical and methodological nature.

Within this concept we seek contributions concerning problems of reference frames, gravity field studies, dynamics and rotation of the Earth, positioning, but also presentations, which surpass frontiers of these topics. We invite presentations illustrating the use of mathematical and numerical methods in solving geodetic problems, showing advances in mathematical modeling, estimating parameters, simulating relations and systems, using high-performance computations, and discussing also methods that enable to exploit data essentially associated with new and existing satellite missions. Presentations showing mathematical and physical research directly motivated by geodetic need, practice and ties to other disciplines are welcome. In parallel to theory oriented results also examples illustrating the use of new methods on real data in various branches of geodetic science and practice are very much solicited in this session.

Precise orbit determination is of central importance for many applications of geodesy and earth science. The challenge is to determine satellite orbits in an absolute sense at the centimeter or even sub-centimeter level, and at the millimeter or even sub-millimeter level in a relative sense. Four constellations of GNSS satellites are available and numerous position-critical missions (e.g. altimetry, gravity, SAR and SLR missions) are currently in orbit. Altogether, outstanding data are available offering new opportunities to push orbit determination to the limit and to explore new applications.

This session aims to make accessible the technical challenges of orbit determination and modelling to the wider community and to quantify the nature of the impact of dynamics errors on the various applications. Contributions are solicited from, but not limited to, the following areas: (1) precise orbit determination and validation; (2) satellite surface force modelling; (3) advances in modelling atmospheric density and in atmospheric gravity; (4) advances in modelling earth radiation fluxes and their interaction with space vehicles; (5) analysis of changes in geodetic parameters/earth models resulting from improved force modelling/orbit determination methods; (6) improvements in observable modelling for all tracking systems, e.g. SLR, DORIS, GNSS and their impact on orbit determination; (7) advances in combining the different tracking systems for orbit determination; (8) the impact of improved clock modelling methods/space clocks on precise orbit determination; (9) advances in modelling satellite attitude.

The International Terrestrial Reference System (ITRS) and its realizations are nowadays widely used for all applications in geosciences. A new realization, the ITRF2020 is being released, based on the combination of DORIS, GNSS, SLR and VLBI station coordinate time series provided by the IAG/IERS technique services.

The goal of this session is to provide a forum to discuss the following topics:
- Contribution of IAG/IERS technique services;
- Evaluation of state of the art GNSS, VLBI, DORIS and SLR position time series (similar to ITRF2020 input data) and associated datum parameters by comparing them with:
* new coordinate series based on enhanced data modeling strategies or combination at the observation level;
* non-tidal loading displacement models.
- Combination strategy and results using ITRF2020 input data;
- Evaluation of the combined terrestrial reference frames derived with ITRF2020 input data;
- Discrepancies between local ties and space geodesy results. Advanced local tie data acquisition and analysis. Study of station coordinate bias at co-location site;
- Impact of terrestrial reference frame station coordinate modeling (pseudo-periodic signals and post-seismic deformations) on Earth science applications and operational geodetic activities.

Contributions are sought from the individual technique services, space geodetic data analysts, the ITRS combination centres and ITRF users. Methodological and theoretical studies on the use of the ITRS realizations on a global or regional scale are also welcome.

The Global Geodetic Observing System (GGOS) provides measurements of the time varying gravity, rotation, and shape of the Earth using space and terrestrial geodetic techniques. These measurements must be accurate to better than a part per billion in order to advance our understanding of the underlying processes responsible for temporal changes in the Earth's
rotation, gravity, and shape. Demanding applications of geodesy include mass transport in the global water cycle, sea level
and climate change, and crustal deformation associated with geohazards. All these measurements require a common reference with the same precision, like the Terrestrial Reference Frame and the Unified Height System. GGOS is designed to unite the individual observations and model into one consistent frame with the highest precision available to be realized as
Global Geodetic Reference Frame (GGRF). This session welcomes contributions on general GGOS topics, particularly those related to scientific and social aspects of GGOS applications.

This session invites innovative Earth system and climate studies based on geodetic measuring techniques. Modern geodetic observing systems document a wide range of changes in the Earth’s solid and fluid layers at very diverging spatial and temporal scales related to processes as, e.g., glacial isostatic adjustment, the terrestrial water cycle, ocean dynamics and ice-mass balance. Different time spans of observations need to be cross-compared and combined to resolve a wide spectrum of climate-related signals. Geodetic observables are also often compared with geophysical models, which helps to explain observations, evaluate simulations, and finally merge measurements and numerical models via data assimilation.
We appreciate contributions utilizing geodetic data from diverse geodetic satellites including altimetry, gravimetry (CHAMP, GRACE, GOCE and GRACE-FO), 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) instruments. We welcome studies that 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. Any new approaches helping to separate and interpret the variety of geophysical signals are equally appreciated. Contributions working towards any of the goals of the Inter-Commission Committee on "Geodesy for Climate Research" (ICCC) of the International Association of Geodesy (IAG) are also welcomed in this session.
With author consent, highlights from this session will be tweeted with a dedicated hashtag during the conference in order to increase the impact of the session.

Satellite altimetry provides the possibility to observe key parts of the hydrosphere, namely the ocean, ice, and continental surface water from space. Since the launch of Topex/Poseidon in 1992, the applications of altimetry have expanded from the open oceans to coastal zones, inland water, land, and sea ice. Today, seven missions are in orbit, providing dense and near-global observations of surface elevation and several other parameters. Satellite altimetry has become an integral part of the global observation of the Earth‘s system and changes therein.

In recent years, new satellite altimetry missions have been launched carrying new instruments; the CryoSat-2/Sentinel-3 missions equipped with a Delay/Doppler altimeter, the Saral AltiKa mission carrying the first Ka-band altimeter, and 2018 launched six beam photon-counting laser altimeter onboard NASAs ICESat-2. Further, new orbits with high inclination and long-repeat time are used for CryoSat-2 and ICESat-2.


Fully exploiting this unprecedented availability of observables will enable new applications and results but also require novel and adapted methods of data analysis.
Across the different applications for satellite altimetry, the data analysis and underlying methods are similar and a knowledge exchange between the disciplines has been proofed to be fruitful.
In this multidisciplinary altimetry session, we therefore invite contributions which discuss new methodology and applications for satellite altimetry in the fields of geodesy, hydrology, cryosphere, oceanography, and climatology.
Topics of such studies could for example be (but not limited to); creation of robust and consistent time series across sensors, validation experiments, combination of radar and laser altimetry for e.g. remote sensing of snow, classification of waveforms, application of data in a geodetic orbit, retracking, or combination with other remote sensing data sets.

Glacial Isostatic Adjustment (GIA) describes the dynamic response of the solid Earth to ice sheet glaciation/deglaciation, which affects the spatial and temporal sea level changes, and induces surface deformation, gravitational field variation and stress changes in the subsurface. The process is influenced by the ice sheet characteristics (e.g., extent, volume, grounding line) and solid Earth structure. With more observational data (e.g., relative sea-level data, GPS data, tide gauges, terrestrial and satellite gravimetry, glacially induced faults) are available/standardized, we can better investigate the interactions between the ice sheets, solid Earth and sea levels, and reveal the ice sheet and sea-level evolution histories and rheological properties of the Earth.

This session invites contributions discussing observations, analysis, and modelling of ice sheet dynamics, solid Earth response, and the resulting global, regional and local sea-level changes and land deformation, including paleo ice sheet and paleo sea-level investigations, geodetic measurements of crustal motion and gravitational change, GIA modelling with complex Earth models (e.g., 3D viscosity, non-linear rheologies) and coupled ice-sheet/Earth modelling, investigations on glacially triggered faulting as well as the Earth’s elastic response to present-day ice mass changes. We also welcome abstracts that address the future ice sheets/shelves evolution and sea-level projection as well as GIA effects on oil migration and nuclear waste repositories. Contributions related to both polar regions and previously glaciated regions are welcomed. This session is co-sponsored by the SCAR sub-committee INSTANT-EIS, Earth - Ice - Sea level, in view of instabilities and thresholds in Antarctica https://www.scar.org/science/instant/home/.

The study of the deformation processes in the interior and boundaries of oceanic and continental plates relies strongly on geodetic surveys. The recent development of dense GNSS networks and Interferometric Synthetic Aperture Radar (InSAR) satellite missions with higher spatio-temporal resolution data, and seafloor geodesy experiments (pressure monitoring, acoustic ranging, GNSS-Acoustic positioning...) has significantly enhanced the level of observations and analysis of numerous active deformation areas, and the understanding of geodynamics of lithospheric plates. Interplate and intraplate tectonic domains may also expose striking examples of crustal deformation including large or moderate earthquakes. Such great wealth of new data allows us to tackle fundamental questions to understand strain-partitioning in present-day active zones, the kinematics of crustal tectonic blocks and its relationship with seismogenic fault sources, and between lithospheric processes and surface deformation. Such new knowledge will be greatly benefited from comparisons with theoretical and experimental models, or joint inversion efforts including sea-land- or space-based geophysical and geochemical surveys.
In this session, we seek contributions using geodetic, geophysical, geologic and seismotectonic data analysis in continental and oceanic active deformation zones, including intraplate volcanic provinces. In particular, studies with multidisciplinary approaches using geodesy, seismology, tectonics and geophysics that bring new constraints on the strain distribution, plate kinematics and lithospheric deformation. Our aim is to discuss new geodetic results and show how they contribute to our understanding of the geodynamics of the lithosphere.

Accurate modeling and prediction of Earth rotation is important for geodesy, astronomy and navigation, and relates to the variability of the circulation of the fluid components of the planet. Over the past years geodetic observation systems have made significant advances in monitoring Earth rotational motion and its variability, which must be accompanied by an enhancement of theories and models.

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 Global Geodetic Observing System and respond to IAG Res. 5. We invite presentations within the scope of the IAU/IAG JWG Improving Theories and Models of the Earth’s Rotation.

We welcome contributions that highlight new determinations, analyses, and predictions 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, as tackled in the IAG/IAU/IERS JWG Consistent Realization of TRF, CRF and EOP. We are particularly interested in results from the current 2nd EOP Prediction Comparison Campaign.

We invite contributions of both the dynamical basis for 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 variable motions and mass redistribution of the fluid portions of the planet. Observations and analyses of the geophysical fluids (e.g., atmosphere and oceans) have been continually improving over time, and independent observations include the results of gravity missions like GRACE.

We welcome contributions about the relationship between EOP variability and current or potential variability in fluids due to climate variation or global change signals. Forecasts of these quantities are important especially for the operational determination of Earth orientation and the effort to improve predictions is an important topic. We also welcome input on the modeling, variability, and excitations of the rotation of other planetary bodies.

Tides underlie many processes in the ocean, atmosphere and solid Earth, and influence ocean biogeochemistry and ecosystems. They drive ocean mixing, contribute to coastal erosion and sediment transport, and may provide a renewable energy source. Tides influence coastal infrastructure and safe port operations. The severity of storm surge events and coastal flooding is modulated by tides. The relationship between tides and sea ice is also important, not only for sea ice dynamics, but also for transport and mixing processes in the Arctic and Antarctic regions. Interannual variability in the tides may arise from variations in ice extent, changes in ocean stratification or regional climate processes.

Precise knowledge of tides is also necessary for earth observation where the tides are not the main target of study. They play a significant role in determining high-resolution temporal gravity fields from satellite gravimetry as well as sea-level rise estimations from satellite altimetry. Therefore, understanding the evolution of tides from both models and in-situ observations is necessary to understand the implications of tides in current and future climate estimations.

Observations and models of coastal and internal tides continue to develop, as well as their relationships to wind-driven processes and mixing processes. We welcome submissions on observations and models of surface or internal tides in the context of long-term changes in tides, tidal variability, tidal dynamics and the impacts of tides. Submissions are encouraged both from regional and global-scale studies on all aspects of tides.

To address societal concerns over rising sea level and extreme events, understanding the contributions behind these changes is key to predict potential impacts of sea level change on coastal communities and global economy, and is recognized as one of the Grand Challenges of our time by the World Climate Research Programme (WCRP). To continue this discussion, we welcome contributions from the international sea level community that improve our knowledge of the past and present changes in global and regional sea level, extreme events, and flooding, and produce improved predictions of their future changes.

We welcome studies on various drivers of sea level change and linkages between variability in sea level, heat and freshwater content, ocean dynamics, land subsidence from natural versus anthropogenic influences, and mass exchange between the land and the ocean associated with ice sheet and glacier mass loss and changes in the terrestrial water storage. Studies focusing on future sea level changes are also encouraged, as well as those discussing potential short-, medium-, and long-term impacts on coastal and deltaic environments, as well as the global oceans.

The session deals with the documentation and modelling of the tectonic, deformation and geodetic features of any type of volcanic area, on Earth and in the Solar System. The focus is on advancing our understanding on any type of deformation of active and non-active volcanoes, on the associated behaviours, and the implications for hazards. We welcome contributions based on results from fieldwork, remote-sensing studies, geodetic and geophysical measurements, analytical, analogue and numerical simulations, and laboratory studies of volcanic rocks.

Studies may be focused at the regional scale, investigating the tectonic setting responsible for and controlling volcanic activity, both along divergent and convergent plate boundaries, as well in intraplate settings. At a more local scale, all types of surface deformation in volcanic areas are of interest, such as elastic inflation and deflation, or anelastic processes, including caldera and flank collapses. Deeper, sub-volcanic deformation studies, concerning the emplacement of intrusions, as sills, dikes and laccoliths, are most welcome.

We also particularly welcome geophysical data aimed at understanding magmatic processes during volcano unrest. These include geodetic studies obtained mainly through GPS and InSAR, as well as at their modelling to imagine sources.



The session includes, but is not restricted to, the following topics:

volcanism and regional tectonics;
formation of magma chambers, laccoliths, and other intrusions;
dyke and sill propagation, emplacement, and arrest;
earthquakes and eruptions;
caldera collapse, resurgence, and unrest;
flank collapse;
volcano deformation monitoring;
volcano deformation and hazard mitigation;
volcano unrest;
mechanical properties of rocks in volcanic areas.

Long term observations are of vital importance in the Earth Sciences, yet often difficult to pursue and fund. The distinction of a fluctuation from a long-term change in Earth processes is a key question to better understand processes within the Earth and in the Earth system. Likewise, it is a prerequisite for the assessment of the Earth's climate change as well as risk assessment. In order to distinguish fluctuations from a steady change, knowledge on the time variability of the signal itself and long term observations are required. Exemplarily, due to the decadal variability of sea level, reliable sea level trends can only be obtained after about sixty years of continuous observations. Reliable strain rates of deformation require a minimum of a decade of continuous data, due to ambient and anthropogenic factors leading to fluctuations. This session invites contributions demonstrating the importance of long term geophysical, geodynamic, oceanographic, geodetic, and climate observatories. Advances in sensors, instrumentation, monitoring techniques, analyses, and interpretations of data, or the comparison of approaches are welcome, with the aim to stimulate a multidisciplinary discussion among those dedicated to the accumulation, preservation and dissemination of data over decadal time scales or beyond. Studies utilizing novel approaches such as AI for analysis of long time series are very welcome. Likewise, studies that show the mutual transfer of knowledge of terrestrial and satellite observations are a topic of interest. With this session, we also would like to provide an opportunity to gather and exchange experiences for representatives from observatories both in Europe and worldwide.

The increase of climate-related hazards has been driven by climate change, increasing human activities and infrastructure development, particularly in vulnerable areas. More efforts should be directed towards effective disaster risk management to reduce damages and losses, focusing on hazard, vulnerability, and risk mapping. Remote Sensing (RS) and Geographic Information Systems (GIS) are powerful tools in mapping change and rate of change concerning natural hazards, particularly in data-scarce environments, thanks to the great advantage of sensing extended areas at low cost and with regular revisit capability. Furthermore, satellite RS offers the opportunity to gain fresh insights into biophysical environments through satellite systems' spatial, temporal, spectral, and radiometric resolutions. The advantages of RS are further supported by the analytical and geospatial data integration capabilities of GIS.
On the other hand, proximal RS offers a unique opportunity to observe processes characterized by fast dynamics and complex geometries and provides data at ultra-high temporal and spatial resolution. The number of proximal RS solutions currently adopted to study and monitor natural hazards has progressively increased in the last decades. Nowadays, UAV, terrestrial radar interferometry, and digital photogrammetry are among the most diffuse proximal systems adopted to identify precursor elements for detailed hazard assessment and support decision-makers during emergencies. In particular, the use of these systems helps create high-resolution 3D models of the study area and monitor natural hazards. The adoption of multi-scale and multi-sensor approaches can be beneficial for studying the same phenomenon from different points of view and can support a detailed description of the studied process and the most critical parameters that can be adopted for its characterization. The availability of many technical solutions represents an additional value, but the lack of defined methodologies can limit these systems' standardized use, particularly during emergencies. This session aims to explore the use of satellite and proximal RS techniques and GIS analysis in different scenarios related to natural hazards and impact analysis and mitigation, including the preliminary characterization of potential dangerous processes, the evaluation of the elements at risk, the management of the emergency phase and the support of recovery and post-emergency reconstruction.

Low-lying coastal areas can be an early casualty to sea-level rise, especially where enhanced by land subsidence. An ever increasing number of studies indicates that land subsidence due to natural and anthropogenic causes has induced damage to wetland ecosystems in many countries worldwide, and has increased flooding hazard and risk. Coastal subsidence causes include excessive groundwater extraction from aquifers, peat oxidation due to surface water drainage through land reclamation, urbanization and agricultural use, as well as sediment starvation due to construction of dams and artificial levees. Contrary to the global processes behind sea-level rise, natural and anthropogenic coastal subsidence is primarily a local phenomenon, and its causes and severity may vary substantially from place to place.
The combination of geological and historical measurements with remote sensing data is required to understand all drivers of coastal vertical land motion and the contributions to past, present, and future subsidence.
Understanding coastal subsidence requires multidisciplinary expertise, models, and remote and in-situ observations from geology, geodesy, natural hazards, oceanography, hydrogeology, and geomechanics. In this session, we aim to bring together all the involved disciplines. We invite contributions on all aspects of coastal subsidence research and applications, including recent advances on: i) measurement through ground-based, aerial and satellite remote sensing techniques, ii) numerical models and future projections, iii) their applicability to distinguish between the different drivers contributing to land subsidence, and iv) quantification of coastal hazards associated with relative sea-level rise. In particular, efforts towards characterizing human intervention on coastal vertical land motion are welcomed.

Recent developments in quantum physics has enabled novel applications and measurement concepts in geodesy and Earth‘s gravitational field observation. In this Session, we discuss new types of sensors and gravity mission concepts that require the application of the advanced techniques. We will address the measurement of the terrestrial gravity anomalies by means of observing free-falling atoms (quantum gravimetry) which is gradually replacing the falling corner cubes. Atom interferometry allows nearly continuous measurements and offers the access to gradients. It is also supposed for future gradiometric measurements in space.
According to Einstein’s theory of general relativity, frequency comparisons of highly precise optical clocks connected by optical links give a direct access to differences of the gravity potential (relativistic geodesy) which allows gravity field recovery and height determination on long baselines. In future, precise optical clocks can be applied for defining and realizing an international height system in a new way, and moreover, help to improve the accuracy of the International Atomic Time scale TAI. Optical clocks are important for all space geodetic techniques as well as for the realization of reference systems.
Additionally, laser interferometry between test masses in space with nanometer accuracy – which has been realized as a demonstrator in the GRACE-FO mission – also belongs to these novel concepts, and in the future even more refined concepts (tracking swarms of satellites, space gradiometry) will be realized.
Finally, changes in the gravity field can be derived from GNSS displacement values which play an increasingly important role due to the relatively cheap and easy deployment of GNSS receivers and the large number of stations.
All these above-mentioned techniques will open a door to a vast bundle of applications such as fast local gravimetric surveys, the gravimetric observation of the Earth-Moon system with high spatial-temporal resolution. Terrestrial mass variations can be monitored at various scales providing unique information on the climate change processes.
We invite presentations illustrating the principles and state of the art of those novel techniques and the application of the new methods for terrestrial and satellite geodesy, navigation and fundamental physics. We also welcome papers covering theoretical foundations and description of the new methods as well as revised modeling schemes.

For about two decades now, satellite missions dedicated to the determination of the Earth's gravity field have enabled a wide variety of studies related to climate research as well as other geophysical or geodetic applications. Continuing the successful, more than 15 years long data record of the Gravity Recovery and Climate Experiment (GRACE, 2002-2017) mission, its Follow-on mission GRACE-FO, launched in May 2018, is currently in orbit providing fundamental observations to monitor global gravity variations from space. Regarding the computation of high-resolution static gravity field models of the Earth and oceanic applications, the Gravity field and steady-state Ocean Circulation Explorer (GOCE, 2009-2013) mission plays an indispensable role. Complementary to these dedicated missions, observations from other non-dedicated missions such as Swarm as well as satellite laser ranging (SLR) have shown to be of significant importance, either to bridge gaps in the GRACE/GRACE-FO time series or to improve gravity field models and scientific results derived thereof. The important role of satellite gravimetry in monitoring the Earth from space has led to various ongoing initiatives preparing for future gravity missions, 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.

Gravity and magnetic field data contribute to a wide range of geo-scientific research, from imaging the structure of the earth and geodynamic processes near surface investigations. The first part of this session is dedicated to contributions related to spatial and temporal variations of the Earth gravity and magnetic field at all scales. Contributions to modern potential field research are welcome, including instrumental issues, data processing techniques, machine learning, interpretation methods, innovative applications of the results and data collected by modern satellite missions, potential theory, as well as case histories.
The second part of this session will focus on the practical solution of various formulations of geodetic boundary-value problems to yield precise local and regional high-resolution (quasi)geoid models. Contributions describing recent developments in theory, processing methods, downward continuation of satellite and airborne data, treatment of altimetry and shipborne data, terrain modeling, software development and the combination of gravity data with other signals of the gravity field for a precise local and regional gravity field determination are welcome. Topics such as the comparison of methods and results, the interpretation of residuals as well as geoid applications to satellite altimetry, oceanography, vertical datums and local and regional geospatial height registration are of a special interest.

Terrain gravimetry is a powerful geophysical tool that, through sensing changes in subsurface mass, can supply unique information on the dynamics of underground fluids, like water, magma, hydrocarbons, etc. This is critically important for energy industry (not just petroleum and natural gas, but also geothermal), resource management (particularly, with regard to water), and natural hazards (especially volcanoes).
Despite its potential, terrain gravimetry is currently underexploited, owing to the high cost of available instrumentation and the difficulty in using it under harsh environmental conditions and to the major challenge posed by retrieving useful information from gravity changes in noisy environments.
Major technology developments have recently occurred in instrumentation and methodology and are being demonstrated, opening up new perspectives to increase the capability of terrain gravimetry. On one hand, new types of sensors are being developed and ruggedized, expanding the measurement capabilities. On the other hand, methodologies and workflows are developed to exploit more efficiently hybrid networks of sensors. As an example, a recently funded H2020 project, called NEWTON-g, targets the development and field application of a “gravity imager” exploiting MEMS (relative) and quantum (absolute) gravimeters. These advancements will give new impulse to terrain gravimetry, thus helping its transition from a niche field into a cornerstone resource for geophysical monitoring and research. However, for this transition to succeed, technology developments must be complemented by constructive feedback from the gravimetry community
This session aims at bringing together instrument and tool developers and end-users of terrain gravimetry in a variety of fields, including, but not limited to, hydrology, volcanology and petroleum geology. We aim at discussing the state of the art of terrain gravimetry and the added value it provides with respect to other geophysical techniques, as well as the exciting opportunities offered by the new technologies under development.

The term space weather indicates physical processes and phenomena in space caused by the radiation of energy mainly from the Sun. Solar and geomagnetic storms can cause disturbances in positioning, navigation and communication; coronal mass ejections (CME) can affect serious disturbances and in extreme cases damages or even destruction of modern infrastructure. The ionosphere and the thermosphere are parts of a physically coupled systems ranging from the Earth surface to the Sun including the magnetosphere and the lower atmosphere. Therefore, conducting detailed investigations on governing processes in the solar-terrestrial environment have key importance to understand the spatial and temporal variations of ionospheric and thermospheric key parameters such as the total electron content (TEC) and the plasma density of the ionosphere, as well as the thermospheric neutral density, which are influencing the orbits of Low-Earth orbiting (LEO) satellites. To address all these interrelations and impacts, the Global Geodetic Observing System (GGOS) Focus Area on Geodetic Space Weather Research was implemented into the structure of the International Association of Geodesy (IAG).

This session will address recent progress, current understanding, and future challenges of thermospheric and ionospheric research including the coupling processes. Special emphasise is laid on the modelling and forecasting of space weather time series, e.g. EUV-, X-ray radiation and CMEs, and their impact on VTEC and electron density. We encourage further contributions to the dynamo electric field, the variations of neutral and ion compositions on the bottom and top side of the ionosphere, atmospheric gravity waves and TIDs. Furthermore, we appreciate contributions on the wind dynamo, electrodynamics and disturbances, including plasma drift, equatorial spread F, plasma bubbles, and resultant scintillation.

Another main topic is global and regional high-resolution and high-precision modelling of VTEC and the electron density based on empirical, analytical or physical data assimilation approaches, which are designed for post-processing or (near) real-time purposes.

Geodesy contributes to atmospheric science by providing some of the essential climate variables of the Global Climate Observing System. Water Vapor (WV) is currently under-sampled in meteorological and climate observing systems. Obtaining more high-quality humidity observations is essential to weather forecasting and climate monitoring. The production, exploitation and evaluation of operational GNSS-Met for weather forecasting is well established in Europe due to 20+ years of cooperation between the geodetic community and the national meteorological services. Improving the skill of numerical weather prediction (NWP) models to forecast extreme precipitation requires GNSS products with a 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. With shortening orbit repeat periods, SAR measurements are a new source of information to improve NWP models. Using NWP data within real-time (RT) GNSS data analysis can initialize PPP algorithms, thus shortening convergence times and improving positioning. GNSS signals can be used for L-band remote sensing when Earth-surface reflected signals are considered. GNSS-R contributes to environmental monitoring with estimates of soil moisture, snow depth, ocean wind speed, sea ice concentration and has the potential to be used to retrieve near-surface WV.
We welcome, but not limit, contributions on:
•Estimates of the neutral atmosphere using ground- and space-based geodetic data and the use thereof in weather forecasting and climate monitoring
•Retrieval and comparison of tropospheric parameters from multi-GNSS, VLBI, DORIS and multi-sensor observations
•Now-casting, forecasting, and climate research using RT and reprocessed tropospheric products, employing numerical weather prediction and machine learning
•Assimilation of GNSS tropospheric products in NWP and in climate reanalysis
•Production of SAR tropospheric parameters and assimilation thereof in NWP
•Homogenization of long-term GNSS and VLBI tropospheric products
•Delay properties of GNSS signals for propagation experiments
•Exploitation of NWP data in GNSS data processing
•Techniques for soil moisture retrieval from GNSS data and for ground-atmosphere boundary interactions
•Detection and characterization of sea level, snow depth and sea ice changes, using GNSS-R
•Studying the atmospheric water cycle employing satellite gravimetry.

What is the “Potsdam Gravity Potato”? What is a reference frame and why is it necessary to know in which reference frame GNSS velocities are provided? Geodetic data, like GNSS data or gravity data, are used in many geoscientific disciplines, such as hydrology, glaciology, geodynamics, oceanography and seismology. This course aims to give an introduction into geodetic datasets and presents what is necessary to consider when using such data. This 105-minute short course is part of the quartet of introductory 101 courses on Geodynamics 101, Geology 101 and Seismology 101.

The short course Geodesy 101 will introduce basic geodetic concepts within the areas of GNSS and gravity data analysis. In particular, we will talk about:
- GNSS data analysis
- Reference frames
- Gravity data analysis
We will also show short examples of data handling and processing using open-source software tools. Participants are not required to bring a laptop or have any previous knowledge of geodetic data analysis.

Our aim is to give you more background information on what geodetic data can tell us and what not. You won’t be a Geodesist by the end of the short course, but we hope that you are able to have gained more knowledge about the limitations as well as advantages of geodetic data. The course is run by early career scientists from the Geodesy division, and is aimed for all attendees (ECS and non-ECS) from all divisions who are using geodetic data frequently or are just interested to know what geodesists work on on a daily basis. We hope to have a lively discussion during the short course and we are also looking forward to feedback by non-geodesists on what they need to know when they use geodetic data.

We have developed an open source software package in python for ground-based GNSS reflections – gnssrefl (https://github.com/kristinemlarson/gnssrefl). This new software supports geoscientists wishing to measure in situ snow accumulation, permafrost melt, firn density, tides, and lake/river levels. We have developed videos (hosted on youtube) to help new users understand both the basic concepts of GNSS reflections and how to install and run the gnssrefl code. More than a dozen use cases are available online; Jupyter Notebooks have been developed as well. We envision the EGU tutorial session to be hands-on and interactive, with a focus on demonstrating the gnssrefl software and online tools (https://gnss-reflections.org), examining and discussing environmental results derived from GNSS data taken from public archives, and analyzing new datasets suggested by the students.

How do seismologists detect earthquakes? How do we locate them? Is seismology only about earthquakes? Seismology has been integrated into a wide variety of geo-disciplines to complement many fields such as tectonics, geology, geodynamics, volcanology, hydrology, glaciology and planetology. This 90-minute course is part of the Solid Earth 101 short course series together with ‘Geodynamics 101’ and ‘Geology 101’ to better illustrate the link between these fields.

In ‘Seismology 101’, we will introduce the basic concepts and methods in seismology. In previous years, this course was given as “Seismology for non-seismologists”, and it is still aimed at those not familiar with seismology -- particularly early-career scientists. An overview will be given on various methods and processing techniques applicable to investigate surface processes, near-surface geological structures, and the Earth’s interior. The course will highlight the role that advanced seismological techniques can play in the co-interpretation of results from other fields. The topics will include:

- the basics of seismology, including the detection and location of earthquakes
- understanding and interpreting those enigmatic “beachballs”
- an introduction to free seismo-live.org tutorials and other useful tools
- how seismic methods are used to learn about the Earth, such as imaging the Earth’s interior (on all scales), deciphering tectonics, monitoring volcanoes, landslides and glaciers, etc...

We likely won’t turn you in the next Charles Richter in 90 minutes but would like to make you aware of how seismology can help you with your research. The intention is to discuss each topic in a non-technical manner, emphasizing their strengths and potential shortcomings. This course will help non-seismologists better understand seismic results and facilitate more enriched discussion between different scientific disciplines. The short course is organised by early-career scientist seismologists and geoscientists who will present examples from their own research experience and high-impact reference studies for illustration. Questions from the audience on the topics covered will be highly encouraged.

The main goal of this short course is to provide an introduction into the basic concepts of numerical modelling of solid Earth processes in the Earth’s crust and mantle in a non-technical manner. We discuss the building blocks of a numerical code and how to set up a model to study geodynamic problems. Emphasis is put on best practices and their implementations including code verification, model validation, internal consistency checks, and software and data management. 

The short course introduces the following topics:
(1) The physical model, including the conservation and constitutive equations
(2) The numerical model, including numerical methods, discretisation, and kinematical descriptions
(3) Code verification, including benchmarking
(4) Model design, including modelling philosophies
(5) Model validation and subsequent analysis
(6) Communication of modelling results and effective software, data, and resource management

Armed with the knowledge of a typical numerical modelling workflow, participants will be better able to critically assess geodynamic numerical modelling papers and know how to start with numerical modelling.

This short course is run by early career geodynamicists. It is aimed at everyone who is interested in, but not necessarily experienced with, geodynamic numerical models; in particular early career scientists (BSc, MSc, PhD students and postdocs) and people who are new to the field of geodynamic modelling.

This 105-minute short course aims to introduce non-geologists to structural and petrological geological principles, which are used by geologists to understand system earth.

The data available to geologists is often minimal, incomplete and representative for only part of the geological history. Besides learning field techniques to acquire and measure data, geologists need to develop a logical way of thinking to close gaps in the data to understand the system. There is a difference in the reality observed from field observation and the final geological model that tells the story.

In this course we briefly introduce the following subjects:
1) Grounding rocks: Introduction to the principles of geology.
2) Collecting rocks: The how, what, and pitfalls of field data acquisition.
3) Failing rocks: From structural field data to (paleo-)stress analysis.
4) Dating rocks: Absolute and relative dating of rocks using petrology and geochronology methods.
5) Shaping rocks: The morphology of landscapes as tectonic constraints
6) Crossing rocks over: How geology benefits from seismology, geodynamic and geodesy research, and vice-versa.
7) Q&A!

Our aim is not to make you the next specialist in geology, but we would rather try and make you aware of the challenges a geologist faces when they go out into the field. Additionally, the quality of data and the methods used nowadays are addressed to give other earth scientists a feel for the capabilities and limits of geological research. This course is given by Early Career Scientist geologists and geoscientists and forms a quartet with the short courses on ‘Geodynamics 101 (A&B)’, ‘Seismology 101’, and ‘Geodesy 101’. For this reason, we will also explain what kind of information we expect from the fields of seismology, geodynamics and geodesy, and we hope to receive some feedback in what kind of information you could use from our side.