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.

The analysis of potential fields, especially of the Earth's gravity and magnetic fields, is becoming increasingly important for the geosciences community. The modern satellite missions are continuing to provide data with ever improving accuracy and nearly global, time-dependent coverage. The gravitational field, respectively the geoid, 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. With this vast quantity of data and the richness of research topics that can be addressed with it, there continues to be a need to develop new methods of analysis, at the global and local scales, and especially on their interface, where high- and low resolution data are to be jointly represented and interpreted, and where global/local contributions to noise/signal need to be differentiated. Global fields have traditionally been modeled in the spherical harmonics basis; local observations typically in a Cartesian space-based or Fourier framework. For over two decades now, methods that combine global with local sensitivity, often in a multiresolution setting, have been developed as alternatives: these include wavelets, radial basis functions, Slepian functions, splines, spherical cap harmonics, etc. With these, a growing range of problems can be addressed, but many further developments, including particular aspects of their algorithmic implementation, or the explicit search for sparsity in the modeling domain are awaiting further study. On the one hand side the purpose of this session is to provide a forum for exchange on the current state-of-the-art on these research topics, whether related to forward or inverse modeling, theoretical, computational, or observational studies. Especially studies on regional gravity field modeling from the combination of different input data sets as well as comparisons between different solutions are welcome.

On the other hand, besides monitoring the variations of the Earth's 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 of all effects. 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 the past two decades high-precision GPS has been applied to support numerous applications in Geosciences. Currently, there are two fully operational Global Navigation Satellite Systems (GNSS), and two more are in the implementation stage. The new Galileo and BDS systems already provide usable signals, and both, GPS and GLONASS, are currently undergoing a significant modernization, which adds more capacity, more signals, better accuracy and interoperability, etc. Meanwhile, the huge technology development provided GNSS equipment (in some cases even at low-cost) able to collect measurements at much higher rates, up to 100 Hz, hence opening new possibilities. 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 related to activities of IAG SC4.4 'Multi-constellation GNSS' and IAG-ICCT JSG 0.10 'High-rate GNSS'. It 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:
- Modeling and strategies in high-precision GNSS,
- Multi-GNSS benefit for Geosciences,
- Multi-GNSS processing and product standards,
- Inter-system and inter-frequency biases and calibrations,
- New or improved GNSS products for high-precision applications (orbits, clocks, UPDs, etc.),
- Precise Point Positioning (PPP, PPP-RTK),
- High-rate GNSS,
- GNSS and other sensors (accelerometers, INS, ecc.) integration for high-rate applications,
- Ambiguity resolution and validation,
- 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,
- High-precision applications for Geosciences,
- and more.

The IAG's Global Geodetic Observing System (GGOS) provides the means for integrating ground- and space-based geodetic and gravimetric observations. Modernizing the existing geodetic and gravimetric infrastructure homogenizing the processing of data are essential for consistent observations of Earth's time-variable shape, rotation, and gravity. This session is a forum for discussing ongoing and planned improvements to the geodetic and gravimetric observing systems and for using the observations from those systems to improve our understanding of the dynamic Earth. We particularly welcome contributions on the observation and determination of essential geodetic variables, including essential variables for global climate and ocean studies. We also welcome general contributions on GGOS including the progress and plans for building next generation geodetic and gravimetric stations.

The goal of this session is to provide a forum to discuss reference systems theory, realization and applications in geosciences and society, with a special emphasis on the scientific applications of the International Terrestrial Reference Frame (ITRF), and namely the ITRF2014. Participants can discuss concerns not only related to the contributing technique services, but also all ITRF uses, ranging from local, regional to global applications. Contributions are sought from the individual technique services and various ITRF users, covering the complete range of topics, such as data analysis, parameter estimation and correction models. Of special interest is the assessment of the impact of non-linear station motions, e.g. periodic signals and post-seismic deformations. Contributions by the technique services focusing on identifying and mitigating technique systematic errors in preparation for the ITRF2020 are most welcome.

Since 1989, the IAG regional reference frame sub-commission 1.3a EUREF has merged efforts of National Mapping and Cadastral Agencies (NMCA), Universities and Research Institutes to define, realize and maintain the European Terrestrial Reference System 1989 (ETRS89) and the European Vertical Reference System (EVRS) for scientific and practical purposes in Europe. Technical development, new applications and increased accuracy of observations are setting new demands for the realizations of the reference systems.

The EUREF community, mainly consisting of National Mapping Agencies and research institutes, is providing a large variety of data and data products. The product catalogue covers file-based and real-time GNSS data, position and velocity estimates from multi-year solutions, position time series, zenith path delay estimates, and real-time GNSS corrections (see http://www.euref.eu/euref_pr.html for details). Many products are based on improved results coming from repeated GNSS re-processing.

Many applications, in particular those covering global or worldwide aspects will most likely use global reference systems like the International Terrestrial Reference Frame (ITRF). In this session we would like to figure out the potential of specific continental reference frame realizations. We are looking for contributions using EUREF data and/or products, in particular (but not limited to)
- Usage of ETRS89 and EVRS
- Potential of the EPN Densification
- Investigations on position time series and on velocities
- Crustal deformation and modelling for deformation
- National realizations of the ETRS89 or EVRS
- Future on regional reference frame realisation

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. New constellations of GNSS satellites are currently being completed and numerous position-critical missions (e.g. altimetry, gravity, SAR and SLR missions) are currently in orbit. All together 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 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 geodetic products that describe the system Earth are of high quality. However, there are limiting factors that need to be detected, analyzed, quantified, and possible improvements need to be investigated. In this context, the usage of selected observations only, degrading station equipment quality, limitations in the observing concepts, limitations in the analysis and combination methods evoke the question whether and how the derived Earth system products can be improved. Most of these questions can be answered only by carrying out simulation studies.

This session provides a platform for presentations of various simulation studies that seek to improve the observation and the determination of Earth system parameters. We welcome papers that describe simulations investigating the impact of extending the ground networks and space segment to better determine geodetic and geodynamic parameters (e.g., station coordinates and velocities, Earth rotation parameters, satellite orbits, geocenter, scale, gravity field, sea level). The Terrestrial Reference Frame (TRF) being the foundation of all Earth observations, we also seek papers that simulate space geodetic observations such as Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) with a view of better understanding systematic sources of error. In addition, we welcome papers that describe simulations that either follow contemporary approaches (e.g., combination by applying local ties) or focus on alternative concepts such as co-location in space, clock ties, time transfer by laser link, and atmospheric ties to improve the TRF. For this session we also seek to stimulate presentations of novel observation concepts such as VLBI satellite tracking, inclusion of Low Earth Orbit (LEO) satellites, use of ultra-precise clocks (chronometric geodesy), and inter-satellite links to be used for determining the Earth system parameters including gravity field, geocenter and Earth orientation. Simulation studies focused on developing new satellites or measurement concepts are also welcome to contribute to this session. Furthermore, the session is also open for contributions based on the analysis of real data in order to support and confirm the simulation results.

Many of the aspects mentioned are brought together within the Global Geodetic Observing System (GGOS) standing committee PLATO (Performance Simulations and Architectural Trade-Offs). Therefore, contributions related to the activities carried out within the PLATO group are also highly appreciated.

The availability of high spatial resolution Synthetic Aperture Radar (SAR) data, the advances in SAR processing techniques (e.g. interferometric, polarimetric, and tomographic processing), and the fusion of SAR with optical imagery as well as geophysical modelling allow ever increasing use of Imaging Geodesy using SAR/InSAR as a geodetic method of choice for earth system monitoring and investigating geohazard, geodynamic and engineering processes. In particular, the exploitation of data from new generation SAR missions such as Sentinel-1 that provide near real-time measurements of deformation and changes in land cover/use has improved significantly our capabilities to understand natural and anthropogenic hazards and then helped us mitigate their impacts. The development of high-resolution X-band SAR sensors aboard missions such as Italian COSMO-SkyMed (CSK) and German TerraSAR-X (TSX) has also opened new opportunities over the last decade for very high-resolution radar imaging from space with centimetre geometric accuracy for detailed analysis of a variety of processes in the areas of the biosphere, geosphere, cryosphere and hydrosphere. All scientists exploiting radar data from spaceborne, airborne and/or ground-based SAR sensors are cordially invited to contribute to this session. The main objective of the session is to present and discuss the progress, state-of-the-art and future perspectives in scientific exploitation of SAR data, mitigating atmospheric effects and error sources, cloud computing, machine learning and big data analysis, and interpretation methods of results obtained from SAR data for various types of disasters and engineering applications such as earthquakes, volcanoes, landslides and erosion, infrastructure instability and anthropogenic activities in urban areas. Contributions addressing scientific applications of SAR/InSAR data in biosphere, cryosphere, and hydrosphere are also welcome.

There is great interest in the Earth’s rotational motion and variability and much work on challenging problems in this field. We are looking forward to receiving your abstracts as well as learning about and discussing the ideas and findings relevant to one of the following areas:
First, we are interested in the progress of theories of Earth rotation. We seek contributions on theoretical developments that are consistent internally and with the highly accurate observations at the mm-level, to meet the requirements of the IAG's Global Geodetic Observing System (GGOS). In particular, we invite presentations from the IAU/IAG joint working group, 'Theory of Earth Rotation and Validation'.
With respect to geodetic and astrometric observational techniques, we seek contributions that highlight new determinations of EOP series and their analyses, including combinations of different observing techniques.
We also invite discussions of the dynamical basis for links between Earth rotation, geophysical fluids, and other geodetic quantities, such as the Earth gravity field or surface deformation, and investigations leading to more detailed 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 the changing motions and mass redistribution of the fluid portions of the planet. Observations of the geophysical fluids, such as the atmosphere, oceans, and other hydrological reservoirs, have achieved a new maturity in recent years. Independent observations of the relevant mass fields include the results of recent gravity missions like GRACE. We also welcome contributions about the relationship between EOP variability and current or potential variability in fluids due to climate variation or global change signals.
Besides contemporary determination of the EOP and the related geophysical excitations, forecasts of these quantities are important especially for the operational determination of Earth orientation, e.g., for spacecraft navigation; the effort to improve predictions currently is a topic of strong interest. In this sense, the session is also open to contributions dealing with the operative use of Earth orientation in different applications.
In addition, we will welcome input on the modeling, characteristics and variability of the rotation parameters of other planets or planetary bodies.

A wide range of processes in the earth system directly affect geodetic observations. This session invites a wide array of contributions which showcase the use of geodesy for Earth science and climate applications, providing crucial insights into the state and change of the earth system and/or understanding its processes.

Data driven quantification of water mass fluxes through boundaries of Earth’s different regions and spheres provides important insights to other geoscience communities and informs model validation and improvement. Changes in regional sea level and ocean circulation are observed by altimetry and gravimetry. Natural and anthropogenic alterations of the terrestrial water cycle lead to changes in river runoff, precipitation, evapotranspiration, and water storage which may cause surface deformation sensed by GNSS stations and InSAR measurements as well as mass/gravity changes observed by satellite/ground gravimetry. Mass changes in the ice sheets and glaciers are detectable by both geometrical and gravimetric techniques. And other novel applications of geodetic techniques are emerging in many fields.

In addition, individual sensor recordings are often affected by high-frequency variability caused by, e.g., tides in the solid Earth, oceans, and atmosphere and their corresponding crustal deformations affecting station positions; non-tidal temperature and moisture variability in the troposphere modifying microwave signal dispersion; rapid changes in the terrestrially stored water caused by hydrometeorologic extreme events; as well as swift variations in relative sea-level that are driven by mass and energy exchange of the global oceans with other components of the Earth system, which all might lead to temporal aliasing in observational records. 

This session invites a wide array of contributions which showcase the use of geodesy for Earth science and climate applications. This session aims to cover innovative ways to use GRACE, GRACE-FO and other low Earth orbiters, GNSS techniques, InSAR, radar altimetry, and their combination with in-situ observations. We welcome approaches which tackle the problem of separating signals of different geophysical origin, by taking advantage of model output and/or advanced processing and estimation techniques. Since the use of geodetic techniques is not always straightforward, we encourage authors to think of creative ways to make their findings, data and software more readily accessible to other communities in hydrology, ocean, cryospheric, atmospheric and climate sciences. With author consent, highlights from the oral and poster session will be tweeted with a dedicated hashtag during the conference in order to increase the impact of the session.

The processes of the Earth deformation can be revealed by means of diverse methods of investigations. The seasonal distribution of surface loading, the earthquake cycle, volcanic processes (eruptions, dike intrusions, induced seismic activity), near surface motions (landslides, induced and natural superficial subsidence/collapse).
Recently, major earthquakes in Sumatra (2004, Mw 9.2), Maule (2010, Mw 8.8), Haiti (2010, Mw 7.1) and Tohoku (2011, Mw 9.0) have exposed the impact of such events and the need for better understanding of Earth deformation processes. These events illustrate the geodynamic complexities that include subduction zones and giant earthquakes, continental faults and depth versus surface deformation, the seismic cycle and seismotectonics of active zones, magmatism processes and crustal deformation. The observation techniques, methods and data analysis need the Earth observation systems and reference frames that include remote sensing and surface and satellite gravity observations
This session is conducted in the frame of the WEGENER consortium*) and we seek submissions that emphasize multidisciplinary studies of Earth deformation using geodetic techniques (GPS, InSAR, LiDAR, space/air/terrestrial gravity, ground-based geodetic observations), complementary tectonic and geophysical observations, and modeling approaches focusing on the European-Mediterranean and Northern African regions. We also welcome contributions discussing the realization and outcomes of Supersites in the frame of the GEO initiative, as well as fundamental studies of natural and induced physical phenomena, strategies to develop early warning and rapid response systems.
*) The World Earthquake GEodesy Network for Environmental Hazard Research (Sub-commission 3.5 of IAG commission 3, namely Tectonics and Earthquake Geodesy)

Geodesy is becoming increasingly important for observing the hydrological cycle and its effects on solid Earth shape. Signals in geodetic data have revealed water's influence on other geophysical processes including earthquakes, volcanos, land subsidence, mountain uplift, and other aspects of long- and short-term vertical land motion. GPS and InSAR measurements, for example, respectively provide high temporal and spatial resolution to study natural hydrologically-related deformation and monitor anthropogenic groundwater extraction and recharge, and GRACE is helping to track changes in the global terrestrial water storage. Signals of loading from changes in surface and groundwater storage are seen from basin to continental scale. Additionally, novel use of GPS reflectometry is operational for monitoring soil moisture and snow depth at continuous GPS stations in the western USA and Canada. We encourage contributions describing new observations and models of hydrological signals in geodetic time series and/or imaging. These include but are not limited to studies exploring deformation induced by loading, aquifer extraction/recharge, poroelastic deformation and stress changes, techniques for removing hydrological signals from geodetic datasets, monitoring water resources, or teleconnections between hydrologic and other geophysical phenomena.

Tides form a unique process in the Earth system because of their predictability, and because of their impact on many Earth system processes. This session is open to any aspect of tidal research, including the accuracy of present-day coastal, regional and global tide models, tidal dissipation, and the role of tides in geophysics, internal tides and their role in mixing the ocean and the impact on the global ocean circulation, secular and long-term changes in tides, insights on tidal variability from global geodetic observing techniques, and new techniques for measuring tides and analysing the data. We also welcome new findings on Earth and atmospheric tides, the role of tides in Earth’s ability to host and evolve life, tides in lakes, and planetary tides. The session is also intended to mark the 100th anniversary of the founding of the Liverpool Tidal Institute (LTI). The LTI for many years was the world centre for knowledge of the tides, with Joseph Proudman taking the lead in dynamical theories, and Arthur Doodson in the analysis of tidal information from around the world, and on tidal prediction. We therefore also welcome presentations on the history of tidal research.

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 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.

The US/German GRACE Follow-on (GRACE-FO) mission, successfully launched on 22 May 2018, prolongs the observations of the Gravity Recovery and Climate Experiment (GRACE). Satellite gravimetry missions such as GRACE, GRACE-FO and the Gravity field and steady-state Ocean Circulation Explorer (GOCE) have showed their fundamental impact for climate research studies and other geophysical or geodetic applications. The gravity field solutions can be complemented by data from other non-dedicated satellite missions like SWARM.
The great success of these missions clearly shows that global gravity variations can be at best monitored from space. Therefore, various initiatives are ongoing to prepare for future gravity missions: simulation studies have been performed, user and mission requirements have been defined and potential measurement equipment and orbit scenarios have been investigated.

This session solicits contributions about
(1) results from satellite gravimetry missions as well as from non-dedicated missions in terms of
- data analyses
- combination synergies
- Earth science applications
(2) status and study results for future gravity field missions.

In this Session, we will discuss new sensor measurement and mission concepts that apply advanced techniques for the study of the gravitational field of the Earth on ground and in space. Novel developments in quantum physics can excellently be used for geodetic applications, where new technologies and concepts lead to enhanced capabilities for satellite geodesy and terrestrial gravity sensing. Terrestrial gravity anomalies will be determined by observing free-falling atoms (quantum gravimetry) instead of using falling corner cubes. Additionally, changes in the gravity field can also be derived from GNSS displacement which play an increasingly important role due to their cheap and easy deployment and large number of available stations. This will open the door for a vast bundle of applications such as fast local gravimetric surveys and exploration, and the observation of Earth system processes with high spatial and temporal resolution.
Furthermore, highly precise optical clocks connected by dedicated fiber links have reached an accuracy level to measure differences of the gravity potential over long distances (relativistic geodesy), that is interesting for geodesy now. In future, relativistic geodesy might be applied for defining and realizing height systems in a new way, locally as well as globally. Moreover, accurate clocks help to improve the accuracy of the International Atomic Time standard TAI. They are important for all space geodetic techniques as well as for the realization of reference systems and their connections. One example of increasing importance is positioning and navigation with GNSS for terrestrial and space applications.
Finally, laser-interferometric ranging between test masses in space with nanometer accuracy does also belong to those novel developments. GRACE-FO will demonstrate it, and in the future even more refined concepts (tracking a swarm of satellites, space gradiometry) will be realized.
We invite presentations to illustrate the principles and state of the art of those novel techniques and the application of the new methods for terrestrial and satellite geodesy (where local and global mass variations and surface deformations will be observed with unforeseen accuracy and resolution, variations that reflect changes in the Earth system), navigation and fundamental physics. We also welcome papers for further applications and invite contributions covering the theoretical description of the new methods, introducing novel theoretical concepts as well as new modelling schemes.

The session is dedicated to aspects of high accuracy terrestrial gravity observations. Monitoring of long-term processes in geosciences with gravity meters yields many applications, e.g. in tectonics and land uplift, glacial isostatic adjustment and reveals trends in continental hydrology. Studies in these fields are subject of the session.
The International Gravity Reference System and Frame aims to provide A stable reference for absolute gravity measurements and is planned to rely on reference stations and distributed international and regional comparisons. In combination with continuous monitoring of gravity changes, a comparison function for the validation of absolute meters can be established, ensuring their traceability. Contributions to these aspects are invited. The infrastructure needed to make the frame accessible for the user on the level of national infrastructure, like updates of first order gravity networks, are within the scope of the session.
Advances in the instrumentation for absolute gravimetry are important. Contributions regarding the assessment of the uncertainty budget and systematic instrumental effects as well as the development and deployment of new technologies like quantum sensors are welcome.
The session addresses also the interpretation of high resolution temporal gravity changes, e.g. from superconducting and absolute gravimeters, including the analysis of Earth tides or the impact of water storage changes as well as geophysical applications like geothermal fields, volcano monitoring, the study of loading effects or the comparison with satellite gravity models.

Integrated modelling of gravity, magnetic, seismological and petrological data contributes to a wide range of geo-scientific research, from imaging the structure of the Solid earth and geodynamic processes (e.g. GIA and the coupling between Solid Earth and Cryosphere) to near surface investigations. The session especially welcomes contributions related to spatial and temporal variations of the Earth gravity and magnetic field at all scales and their application in an integrated context.

Many recent advances in aeronomy, space sciences, geomagnetism, and gravity arose from combining specific knowledge of these areas in interdisciplinary research. Current outstanding questions are, for example: What features of ionospheric currents do we discover when we understand the shape, strengths, and variation of the geomagnetic background field? What is the role of upward propagating atmospheric waves in energy and momentum transport into the ionosphere? Which ionospheric processes need to be better quantified to achieve complete knowledge of global core or crustal field variations? How does knowledge of the geometry of ionospheric and magnetospheric sources help in determining Earth’s conductivity in the geomagnetic field? How strongly do we need to consider Earth’s conductivity in quantifying ionospheric currents? How can we quantify and correct for ionospheric perturbations to achieve the best gravity field solutions? Finally, what can we learn about space sciences by studying ionospheric effects on geodetic measurements?

The session invites contributions on any of the subjects and in particular on results that benefit from interdisciplinary works in the areas of space science, geomagnetism, and gravity. Submissions are welcomed that contain analyses of global satellite or ground-based observations or modelling studies, including a combination of them.

The term space weather indicates physical processes and phenomena in space caused by the radiation of energy mainly from the Sun. Solar storms can cause disturbances in positioning, navigation and communication; coronal mass ejections (CME) can affect serious disturbances and in extreme cases damages or even destructions of modern infrastructure. Since the ionosphere and thermosphere are very dynamic and strongly coupled over various spatial and time scales, space weather also influences the orbits of Low-Earth orbiting (LEO) satellite, since thermospheric drag is the largest part of the non-gravitational distortion accelerations within the equation of motion. As a consequence of these interrelations and impacts the Focus Area on “Geodetic Space Weather Research” was implemented under the umbrella of GGOS within the International Association of Geodesy (IAG).

This session will address the recent progress, current understanding, and future challenges of thermospheric and ionospheric research including the coupling processes. Special emphasize is laid on the modelling and forecasting of space weather time series, e.g. EUV-, X-ray radiation and CMEs, and their impact on ionospheric key parameters such as VTEC and electron density. We encourage further contributions to the dynamo electric field, the variations of neutral and ion compositions on the bottomside and topside of the ionosphere, atmospheric gravity waves and TIDs. Furthermore, we appreciate contributions on the equatorial ionospheric electrodynamics and disturbances, including plasma drift, equatorial spread F, plasma bubbles, and resultant scintillations. Another topic is global and regional high-resolution and high-precision modelling of VTEC and electron density maps.

The session is aiming on presentations from observational, theoretical, and modeling studies that improve our understanding and enable a better forecasting capability of ionospheric and thermospheric dynamics.

Geodesy contributes to Atmospheric Science by providing some of the Essential Climate Variables of the Global Climate Observing System (GCOS) such as: sea level from radar altimetry, mass changes ofice and terrestrial water from satellite gravimetric missions, atmospheric water vapor from ground-based and space-based GNSS, as well as from VLBI and DORIS, atmospheric temperature from GNSS RO. Sensing of the neutral atmosphere with space geodetic techniques is an established field of research and applications, thanks to the availability of regional and global ground-based networks as well as satellite-based missions. Water vapor, the most abundant greenhouse gas of the atmosphere, is under-sampled in the current meteorological and climate observing systems, therefore obtaining and exploiting more high-quality humidity observations is essential to weather forecasting and climate monitoring. The production, exploitation and evaluation of operational GNSS-Meteorology for weather forecasting is well established in Europe due to two decades of outstanding cooperation between the geodetic community and European national meteorological services. Advancements in Numerical Weather Prediction Models (NWP) to improve forecasting of extreme precipitation, require GNSS troposphere products with a higher resolution in space and shorter delivery times than are currently in use. Homogeneously reprocessed GNSS observations on a regional and global scale have high potential for monitoring water vapor climatic trends and variability. With shortening orbit repeat periods SAR measurements are a new potential source of information to improve NWP models. At the same time, high-resolution NWP data have recently been used for deriving a new generation of mapping functions. In real-time GNSS processing these data can be employed to initialize Precise Point Positioning (PPP) processing algorithms, shortening convergence times and improving positioning. Furthermore, GNSS-reflectometry is establishing itself as an alternative method for retrieving soil moisture and has the potential to be used to retrieve near-surface water vapor.

We welcome, but not limit, contributions on the subjects below:

· Estimates of the state of the neutral atmosphere using ground-based and space-based geodetic data, use of those estimates in weather forecasting and climate monitoring.
· Multi-GNSS and multi-instruments approaches to retrieve and inter-compare tropospheric parameters.
· Real-Time and reprocessed tropospheric products for now-casting, forecasting and climate monitoring.
· Assimilation of GNSS tropospheric products in NWP and in climate reanalysis models.
· Production of SAR-based tropospheric parameters and use of them in NWP.
· Methods for homogenization of long-term GNSS tropospheric products.
· Studies of the delay properties of the GNSS signals for Earth-space propagation experiments.
· Usage of NWP data in GNSS data processing.
· Techniques on retrieval of soil moisture from GNSS observations and of ground-atmosphere boundary interactions.
· Usage of satellite gravity observations, as obtained from GRACE and its successor GRACE-FO, for studying the atmospheric water cycle.

Recent advances in rotational seismology have led to new applications in various geophysical disciplines such as earthquake physics, broadband seismology, seismic exploration, strong ground motion, and earthquake engineering. The progress is mainly driven by the development of new, sensitive rotational sensors that, when combined with classical seismometers and strain sensors, enable the complete observation of seismic ground motion.

The instrumental development overlap with considerable improvements in optical and atom interferometry for inertial rotation and gravity sensing which has led to a variety of improved sensor concepts over the last two decades. Thus, advanced instrumentation enables applications in seismology, geodesy, and fundamental physics.

We invite all contributions on theoretical advances to the seismic wavefield gradient, on novel measurement techniques, and on all aspects of applications in seismic, seismology, geodesy, and fundamental physics.

In this session we search for contributions of general interest within the geodesy community which are not covered by the other sessions.

Topographic data are fundamental to landscape characterization across the geosciences, for monitoring change and supporting process modelling. Over the last decade, the dominance of laser-based instruments for high resolution data collection has been challenged by advances in digital photogrammetry and computer vision, particularly in ‘structure from motion’ (SfM) algorithms, which offer a new paradigm to geoscientists.

High resolution topographic (HiRT) data are now obtained over spatial scales from millimetres to kilometres, and over durations of single events to lasting time series (e.g. from sub-second to decadal-duration time-lapse), allowing evaluation of dependencies between event magnitudes and frequencies. Such 4D-reconstruction capabilities enable new insight in diverse fields such as soil erosion, micro-topography reconstruction, volcanology, glaciology, landslide monitoring, and coastal and fluvial geomorphology. Furthermore, broad data integration from multiple sensors offers increasingly exciting opportunities.

This session will evaluate the advances in techniques to model topography and to study patterns of topographic change at multiple temporal and spatial scales. We invite contributions covering all aspects of HiRT reconstruction in the geosciences, and particularly those which transfer traditional expertise or demonstrate a significant advance enabled by novel datasets. We encourage contributions describing workflows that optimize data acquisition and post-processing to guarantee acceptable accuracies and to automate data application (e.g. geomorphic feature detection and tracking), and field-based experimental studies using novel multi-instrument and multi-scale methodologies. A major goal is to provide a cross-disciplinary exchange of experiences with modern technologies and data processing tools, to highlight their potentials, limitations and challenges in different environments.

Solicited speaker: Kuo-Jen Chang (National Taipei University of Technology) - UAS LiDAR data processing, quality assessment and geosciences prospects

The use of Remotely Piloted Aircraft Systems (RPAS) for geosciences applications has strongly increased in last years. Nowadays the massive diffusion of mini- and micro-RPAS is becoming a valuable alternative to the traditional monitoring and surveying applications, opening new interesting viewpoints. The advantages of the use of RPAS are particularly important in areas characterized by hazardous natural processes, where the acquisition of high resolution remotely sensed data could be a powerful instrument to quickly assess the damages and plan effective rescues without any risk for operators.
In general, the primary goal of these systems is the collection of different data (e.g., images, LiDAR point clouds, gas or radioactivity concentrations, etc.) and the delivery of various products (e.g., 3D models, hazard maps, high-resolution orthoimages, etc.).
The possible use of RPAS has promising perspectives not only for natural hazards, but also in the different field of geosciences, to support a high-resolution geological or geomorphological mapping, or to study the evolution of active processes. The high repeatability of RPAS flight and their limited costs allows the multi-temporal analysis of a studied area. However, methodologies, best practices, advantages and limitations of this kind of applications are yet unclear and/or poorly shared by the scientific community.
This session aims at exploring the open research issues and possible applications of RPAS in geosciences, collecting experiences, case studies, and results, as well as define methodologies and best practices for their practical use. The session will concern the contributions aiming at: i) describing the development of new methods for the acquisition and processing of RPAS dataset, ii) introducing the use of new sensors developed or adapted to RPAS, iii) reporting new data processing methods related to image or point cloud segmentation and classification and iv) presenting original case studies that can be considered an excellent example for the scientific community.

Wed, 10 Apr, 12:45-14:00 / Room E1

This year marks the 250th anniversary of the birth of Alexander von Humboldt (1769-1859), the intrepid explorer of the Andes and other regions in the world, and the most famous scientist of his time. Alexander von Humboldt is perhaps best known for his radical new vision of nature as a complex and interconnected global force, thereby becoming the founder of the field of biogeography and laying the ground for modern Earth-System Science approaches. It seems fitting to pay tribute to Alexander von Humboldt’s legacy by reviewing the state of the art in studies of the coupled lithosphere – atmosphere – hydrosphere – biosphere system with a focus on the Andean mountain belt. The Andes have become one of the main natural laboratories in the world to explore these questions and many recent studies have addressed its tectonic and geodynamic evolution, but also the two-way couplings between surface uplift, climatic evolution and biodiversity in the Andes and its foreland. This Union Session will bring together world-leading specialists on these questions with the aim to shed light on both suspected and unexpected couplings in the system.

Over the whole Earth history, the climate has encountered tipping points, shifting from one regulated system to the other. This tilting motion affects both climate and the carbon cycle and has played a major role in the evolution of the Earth climate, at all timescales. Earth History has been ponctuated by large climate changes and carbon cycle reorganizations, from large climate variations occurring in deep times (snowball events, terrestrialisation, Mesozoic and early Cenozoic warm episodes, quaternary glacial cycles…) to past and on-going abrupt events. Many potential triggers of those climate and carbon cycle shifts have been proposed and tested through modeling studies, and against field data, such as those directly or indirectly linked with tectonics (plate motion, orogenesis, opening/closing of seaways, weathering…) and orbital forcing. Given that the Earth climate is currently experiencing an unprecedented transition under anthropogenic pressure, understanding the mechanisms behind the scene is crucial.

Our aim is to point out the most recent results concerning how a complex system as the climate of the Earth has undergone many tipping points and what is the specificity of the future climate changes. Therefore, within this session, we would like to encourage talks discussing advances in our record and modeling of the forces triggering and amplifying the changes of Earth climate and carbon cycle across spatial and temporal scales.

In today’s changing world we need to tap the potential of every talented mind to develop solutions for a sustainable future. The existence of under-representation of different groups (cultural, national and gender) remains a reality across the fields of science, technology, engineering, and mathematics (STEM fields) around the world, including the geosciences. This Union Symposium will focus on remaining obstacles that contribute to these imbalances, with the goal of identifying best practices and innovative ideas to overcome obstacles.

EGU is welcoming six high-level speakers from the funding agencies and research centres on both sides of the Atlantic related to geosciences to present efforts and discuss initiatives to tackle both implicit and explicit biases. Speakers are:

Jill Karsten, AGU Diversity and Inclusion Task Force (confirmed)
Erika Marín-Spiotta, University of Wisconsin - Madison (confirmed)
Daniel Conley, Lund University (confirmed)
Giulio di Toro, University of Padua (confirmed)
Liviu Matenco, Utrecht University (confirmed)
Barbara Romanowicz, European Research Council (confirmed)

Atmospheric composition matters to climate, weather forecasting, human health, terrestrial and aquatic ecosystems, agricultural productivity, aeronautical operations, renewable energy production, and more. Hence research in atmospheric composition is becoming increasingly cross-cutting and linked to many disciplines including climate, biogeosciences, hydrology, natural hazards, computer and data sciences, socio-economic studies and many others. There is a growing need for atmospheric composition information and an improved understanding of the processes that drive changes in the composition and resulting impacts. While atmospheric composition research is advancing rapidly, there is a need to pay more attention to the translation of this research to support societal needs. Although translational research is a major focus of the health sciences and meteorology, it is in a relatively early stage in atmospheric composition. In this Union Symposium, we plan to highlight the need for, and to illustrate exciting advances in the translation of atmospheric composition research to support services. We will build upon work within the World Meteorological Organization and other communities related to the closer linkages of weather, atmospheric composition, and climate research and related services. We will also articulate the needs for advances in observing systems, models and a better understanding of fundamental processes. This session will also serve as a celebration of the 30 year anniversary of the WMO Global Atmosphere Watch programme and an opportunity for the broader community to envision partnerships needed to facilitate the effective translation of atmospheric composition research.

In October 2018, the IPCC published its special report on impacts of global warming of 1.5 deg C. Another recent, highly publicised study suggests that the planet could pass an irreversible threshold into a so called “Hothouse Earth” state for a temperature increase of as low as 2 degrees C above pre-industrial temperatures, while other studies and commentaries have emphasised the urgency on climate action, arguing that 2020 must be a turning point for global fossil fuel emissions, to increase the chance of maintaining a safe operating space for the humans on the planet. In 2018, the IPCC celebrated its 30th anniversary. The importance of taking action on human-induced climate change has been emphasised with governments around the world since the 1990s yet CO2 concentrations continue to rise and international initiatives have, to date, had limited and insufficient impact to avert some of the most serious consequences of climate change.
How close are we to one or more critical thresholds (cliff edge)? Is there time to avert passing one or more of these thresholds? What can the geoscience community do to reduce the risks? How important is bottom up versus top down action to ensuring the least worst outcome? These are some of the questions we will debate with world experts in their field and authors of the thought papers on these topics.

The geosciences are currently used by policymakers in a wide variety of areas to help guide the decision-making process and ensure that the best possible outcome is achieved. While the importance of scientific advice and the use of evidence in the policymaking process is generally acknowledged by both policymakers and scientists, how scientific advice is integrated and who is responsible is still unclear.

EU Policymakers frequently highlight institutionalised processes for integrating scientific advice into policy such as European Commission's Group of Chief Scientific Advisors (SAM) and the EU Commission’s Register of Expert Groups. But how efficient and accessible are these mechanisms really?

Some emphasise the need for scientists to have their own policy networks in place so that they can share their research outcomes with policymakers who can then use it directly or pass it on to those responsible for relevant legislation. But from funding applications to teaching and even outreach activities – scientists are often already overloaded with additional tasks on top of their own research. Can they really be held responsible for keeping up with the latest policy news and maintaining a constantly changing network of policymakers as well?

This debate will feature a mixed panel of policymakers and geoscientists who have previously given scientific advice. Some key questions that the panel will debate include:
• How can the accessibility of current EU science-advisory mechanisms be improved?
• Are scientists doing enough to share their research?
• And who is responsible for ensuring that quality scientific evidence is used in policymaking?

Speakers will be encouraged to explain any science advisory mechanism that they highlight (e.g. SAM) to ensure that the debate is understood by all those in attendance.

While the panel and subsequent debate will have an EU focus, it is likely that many of the issues discussed will be applicable to countries around the world.

The ever more challenging work environments and increasing pressures on Early Career Scientists e.g. publish or perish, securing grant proposals, developing transferable skills and many more – and all while having a lack of job security. This puts a big strain on Early Career Scientists and this can lead to neglected mental well-being which in turn increases the risk of developing anxiety, depression or other mental health issues. The graduate survey from 2017 (https://www.nature.com/nature/journal/v550/n7677/full/nj7677-549a.html) shows that 12% of respondents had sought help or advice for anxiety or depression during their PhD.

In this debate we want to discuss: Is there a problem? How ECS can take control of their mental wellbeing and prioritise this in the current research environment? And what support would ECS like to see from organisations like EGU or their employers?

"What counts may not be countable and what is countable may not count". Assessments of scientists and their institutions tend to focus on easy-to-measure metrics related to research outputs such as publications, citations, and grants. However, society is increasingly dependent on Earth science research and data for immediate decisions and long-term planning. There is a growing need for scientists to communicate, engage, and work directly with the public and policy makers, and practice open scholarship, especially regarding data and software. Improving the reward and recognition structure to encourage broader participation of scientists in these activities must involve societies, institutions, and funders. EGU, AGU, and JPGU have all taken steps to improve this recognition, from developing new awards to starting journals around the topic of engaging the public to implementing FAIR data practices in the Earth, environmental, and space sciences, but far more is needed for a broad cultural change. How can we fairly value and credit harder-to-measure, these less tangible contributions, compared to the favoured metrics? And how can we shift the emphasis away from the "audit culture" towards measuring performance and excellence? This session will present a distinguished panel of stakeholders discussing how to implement and institutionalize these changes.

Wed, 10 Apr, 12:45-14:00 / Room E1

Plastic pollution is recognized as one of the most serious and urgent problems facing our planet. Rates of manufacture, use and ultimately disposal of plastics continue to soar, posing an enormous threat to the planet’s oceans and rivers and the flora and fauna they support. There is an urgent need for global action, backed by sound scientific understanding, to tackle this problem.

This Union Symposium will address the problems posed to our planet by plastic pollution, and examine options for dealing with the threat.

The Games Night is a space to gather, socialise, and play some games. The catch is that all the games are based on Geoscience! Bring along your own games or try one of the others in the session and meet the people who created them. This will also be your chance to try games featured in the Games for Geoscience session.

Join us to help put some of the world's most vulnerable places on the map. A mapathon is a mapping marathon, where we get together to contribute to OpenStreetMap - the world's free map.
No experience is necessary - just bring your laptop and we will provide the training. Learn more about crowdsourcing, open data and humanitarian response - we will also provide some tips for how to host a mapathon at your home institution.

Plastic Oceans UK have been experts on plastic pollution for nearly a decade - solving the plastic crisis through their science, sustainability and education programmes. This all began with the award-winning documentary A Plastic Ocean, now available for streaming on Netflix.

Through changing attitudes, behaviours and practices on the use and value of plastics, we can stop plastic pollution reaching the ocean within a generation.

Come along to the screening of A Plastic Ocean to understand the impacts of plastic pollution around the world, what action we can take to stop plastics entering our natural world and pose your questions to the film's producer, Jo Ruxton, at the end of film.

http://plasticoceans.uk/