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.