Over the past years significant progress has been made in the advancement of geodetic observation systems that resulted in largely improved accuracies of parameters related to the Earth's rotational motion and its variability. In this session we seek contributions in the following areas:
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 that address questions raised in the final report of 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 Earth Rotation Parameters (EOP) series and their analyses, including combinations of different observing techniques.
We also invite discussions 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 also of 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 due to angular momentum exchange. Observations of the geophysical fluids (e.g., atmosphere, oceans) have achieved a new maturity in recent years. Independent observations 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, variability, and excitations of the rotation parameters of other planets or planetary bodies.

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 the newly established Inter-Commission Committee on "Geodesy for Climate Research" (ICCC) of the International Association of Geodesy (IAG) would be particularly interesting for 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 and operating in new orbits; the CryoSat-2/Sentinel-3 missions equipped with a Delay/Doppler altimeter, the Saral AltiKa mission carrying the first Ka band altimeter, and the recently launched photon counting laser altimeter on-board NASAs 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 will 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 e. g. for remote sensing of snow, classification of waveforms, application of data in a geodetic orbit, retracking, or combination with other remote sensing data sets.

Low-lying coastal areas can be an early casualty to accelerating rates of sea-level rise, especially if land subsidence enhances such rates. More and more studies indicate that land subsidence due to natural and anthropogenic causes, including excessive groundwater extraction from coastal 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, have caused damages to wetland ecosystems and increased flooding risk. While sea-level rise is a global issue and requires a global collaborative response, natural and anthropogenic coastal subsidence develops mainly at the local to regional scale, and its causes and severity vary substantially from place to place. Therefore, specific communities living on coastal areas can try to offset or reduced land subsidence.

The combination of geological and historical measurements and data from ongoing monitoring techniques is required to understand all drivers of coastal land motion and their contributions to past, present, and future subsidence. Research on coastal subsidence encompasses multidisciplinary expertise, requiring measuring and modeling techniques from geology, geodesy, natural hazards, oceanography, hydrogeology, and geomechanics. In this session, we want to bring together the expertise of all the involved disciplines. We invite contributions on all aspects of coastal subsidence research including recent advances on i) measurement through ground-based and remote sensing techniques, ii) numerical models, iii) their applicability to distinguish between the different drivers contributing to land subsidence, and iv) quantification of coastal hazards associated to relative sea-level rise. In particular, efforts towards characterizing human intervention on coastal land motion are welcome.

The growth and decay of the Polar Ice Sheet reshapes the solid Earth via isostasy and erosion. In turn, the shape of the bed exerts a fundamental control on ice dynamics as well as the position of the grounding line—the location where ice starts to float. A complicating issue is the fact that the Earth displays large spatial variations in rheological properties. These properties affect the timescale and strength of feedbacks between ice-sheet change and solid Earth deformation, and hence must be accounted for when considering the future evolution of the ice sheet. This session invites contributions discussing observations, analyses, and modelling of the coupling of the Solid Earth and glacial isostatic adjustment (GIA) and/or addressing the Earth properties from seismological, gravity, magnetic and heat-flow studies. Contributions related to both polar regions are welcomed.

Invited Speaker: Javier Fullea, Dublin Institute for Advanced Studies, Ireland

The WEGENER initiative was started in 1981 with the aim of creating an interdisciplinary forum supporting geodynamic studies by means of space and terrestrial geodetic techniques. Therefore, WEGENER promotes the establishment of a consistent framework leading from data acquisition, to data analysis, modeling and interpretation of the results. These activities provide key information to a broad range of phenomena that have critical implications for society, particularly in the field of natural hazards and climate change using techniques such as GNSS, InSAR, LiDAR, space/air/terrestrial gravimetry and ground-based geodetic observations.
In this session, we seek contributions that improve our understanding of geodynamical processes and crustal deformations at the local-to-global scale by means of geodetic techniques and innovative modeling approaches. Contributions showing the benefit of integrating geodetic and complementary geophysical, hydrological, geological, oceanographical and climatological information are also welcome. Relevant submissions may focus on the earthquake cycle, volcanic processes, sea-level changes, fluid redistributions and near surface motions such as landslides and subsidence. We also encourage contributions discussing the realization and outcomes of Supersites in the frame of the GEO initiative, as well as reports of the establishment of new geodetic networks in tectonically active areas.
Among other activities, the WEGENER will contribute to the joint IAG-IASPEI sub-commission on Seismo-Geodesy.

This session is open to science on the tides of the ocean, atmosphere and solid earth; on spatial scales from global to coastal, estuarine and river; and on all timescales. Tides can cause flooding, particularly in combination with storm surge, and tidal currents and water levels can be both a help and a hindrance to shipping and energy generation. There is a critical role for tides in ocean mixing and the cryosphere, and accurate tide models are required for the processing of remote sensing and satellite geodesy data.
We welcome presentations on progress in modelling of past, present, and future tides, assessment of the accuracy of tide models, novel methods for tide predictions, advances in instrumentation and data processing, new findings from the analysis of historical tide gauge data, and understanding of secular changes in tides due to sea-level change and other environmental forcing factors. We also invite submissions on tides of lakes and of other planets.
Déborah Idier of BGRM, the French Geological Survey, will give the invited presentation for this session, on the mechanisms of changes to tides on the European Shelf under sea-level rise.

The largest single source of uncertainty in projections of future global sea level is associated with the mass balance of the Antarctic Ice Sheet (AIS). In the short-term, it cannot be stated with certainty whether the mass balance of the AIS is positive or negative; in the long-term, the possibility exists that melting of the coastal shelves around Antarctica will lead to an irreversible commitment to ongoing sea level rise. Observational and paleoclimate studies can help to reduce this uncertainty, constraining the parameterizations of physical processes within ice sheet models and allowing for improved projections of future global sea level rise. This session welcomes presentations covering all aspects of observation, paleoclimate reconstruction and modeling of the AIS. Presentations that focus on the mass balance of the AIS and its contribution towards changes in global sea level are particularly encouraged.

Public information:
We will allocate five minutes of text-based discussion time to each abstract, as follows:

10:45-10:50 Introduction
10:50-10:55 Eelco Rohling
10:55-11:00 Jim Jordan
11:00-11:05 Javier Blasco
11:05-11:10 Emily Hill
11:10-11:15 Felicity McCormack
11:15-11:20 Gordon Bromley
11:20-11:25 Christian Turney
11:25-11:30 Tyler Pelle
11:30-11:35 Liyun Dai
11:35-11:40 Jun-Young Park
11:40-11:45 Christian Ohneiser
11:45-11:50 Catherine Beltran
11:50-11:55 Johannes Sutter
11:55-12:00 Nicolas Ghilain
12:00-12:05 Torsten Albrecht
12:05-12:10 Nicolas Jourdain
12:10-12:15 Christoph Kittel
12:15-12:20 Caroline van Calcar
12:20-12:25 James O'Neill
12:25-12:30 Thore Kausch

Seismic activity and crustal deformation are indicative of underlying plate tectonic and/or volcanic processes. Their connectedness is often non-linear and non-sequential. Seismic activity can result in crustal deformation in a tectonically or volcanically active region, while deformation arising from these forces can harness seismic potency. In isolation, seismic and geodetic (GNSS, InSAR) analysis potentially run the risk of delivering partial inferences, especially in compound geodynamic settings. Evidently, independently obtained results from seismic and geodetic observations are heavily reliant on the data type, methodology, model assumptions, and error estimations. In recent times, there have been several measures to jointly employ seismic and geodetic data to understand complex processes in aforementioned settings. Such studies have made significant contributions to modern and reliable data analysis practices. Therefore, this session aims to explore ongoing research that works towards arriving at comprehensive results from both ends of the spectrum; seismicity, a form of fast deformation, and its relationship with the slower geodetically measured deformation.

The current session invites presentation of research that simultaneously incorporates seismic and geodetic (GNSS, InSAR) techniques to investigate any given tectonic and/or volcanic setting. The study may include analyses of selected earthquakes and related deformation, comparison studies between seismic and geodetic data analysis, volcanic deformation and associated seismicity, and seismic cycle monitoring based on both seismology and geodesy. We also encourage studies using models (analytical or numerical) linking geodetic and seismic research, such as stress-strain models in volcanic and tectonic areas.

Invited Abstract:
Using Seismic and Geodetic Observations in a Simultaneous Kinematic Model of the 2019 Ridgecrest, California Earthquakes
Dara Goldberg1, Diego Melgar1, Valerie Sahakian1, Amanda Thomas1, Xiaohua Xu2, Brendan Crowell3, and Jianghui Geng4
1Department of Earth Sciences, University of Oregon, Eugene, Oregon, United States of America
2Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
3Department of Earth and Space Sciences, University of Washington, Seattle, Washington, United States of America
4Wuhan University, Wuhan, China