G01 Reference Systems and Frames

Convener(s): Christopher Kotsakis (Greece)

Co-Convener(s): Geoff Blewitt (USA) Johannes Boehm (Austria) Xavier Collilieux (France) Susanne Glaser (Germany)

Description
Reference systems and frames are of primary importance for scientific research, satellite navigation, and geospatial applications. A precisely defined and accurate reference frame improves our understanding of the Earth’s system and its time variations, including Earth’s variable rotation and gravity field, sea level changes and their global environmental impact, tectonic plate motion, glacial isostatic adjustment, geocenter motion, deformation due to the earthquake cycle, terrestrial water storage, ice-sheet melting, ocean and atmospheric loading, and volcanism. An accurate reference frame is also needed to position GNSS, SLR and DORIS satellites, and any Earth observation satellite or aircraft with geodetic sensors such as those used for ocean and ice-sheet altimetry, InSAR, gravimetry, and LiDAR. Furthermore, self-consistency is required to connect the terrestrial frame, celestial frame, and Earth rotation to realize the inherent stability in orientation and scale provided by VLBI quasar observations. Co-location, whether it be on the ground or in space as planned with VLBI transmitters on satellites, is essential to tie the various space geodetic techniques together into one consistent global reference system to be used for Earth monitoring. For this symposium, we solicit presentations dealing with theoretical aspects of reference systems and the practical realization of the celestial, global and regional terrestrial reference frames, as well as their various applications like those mentioned above, and beyond. The contributing role of space geodetic techniques in the realization of the origin and scale of global frames through new and improved modeling of their systematic errors and novel exploitations of LEO satellites is also a topic of great interest for this symposium. We also solicit presentations on new and emerging technologies applicable to the future of reference frames such as inter-satellite links, as well as relativistic and quantum geodetic sensors.

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G02 Static Gravity Field and Height Systems

Convener(s): Laura Sanchez (Germany)

Co-Convener(s): Hussein Abd-Elmotaal (Egypt) Roland Pail (Germany) Elmas Sinem Ince (Germany)

Description
Global and regional static gravity field models of high accuracy and spatial resolution encapsulate important information for a wide range of applications. They are essential for the unification of existing height systems and the establishment of an International Height Reference System (IHRS), inertial navigation, the derivation of the mean dynamic ocean topography and geostrophic ocean currents (in combination with satellite altimetry), and also for constraining geophysical models of lithospheric structures. Input to these models are satellite-based data, especially from dedicated space missions such as CHAMP, GRACE, GOCE, other low Earth orbiters, and next-generation missions in the future, satellite altimetry, and ground, air- and shipborne data. An essential element of such model developments is the availability of global digital topographic models. The error assessment of global and regional gravity solutions is of equal importance to the signal information. Modern developments of sensor technology both, for ground- and satellite-based systems, and new measurement concepts, such as quantum gravimeters and optical clocks, will complement and support gravity campaigns and networks using absolute, superconducting and other relative gravimeters. This session solicits contributions on all aspects of global and regional high resolution gravity model developments and assessment. We also seek contributions on effective parsimonious representations of gravity model functionals, geophysical and oceanographic applications, as well as mission concepts, instrumentation and processing strategies for future gravity field missions. A further main topic of this symposium is the determination of modern height systems, especially the precise geoid modelling, the establishment of the International Height Reference Frame (IHRF), and theory and methods for the vertical datum unification.

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G03 Time-variable Gravity Field

Convener(s): Adrian Jaeggi (Switzerland)

Co-Convener(s): Srinivas Bettadpur (USA) Frank Flechtner (Germany) Shuanggen Jin (China)

Description
The time-variable Earth’s gravity field is related to the mass transport and the physical processes within Earth’s system (including the atmosphere, oceans, hydrology and cryosphere), such as melting of ice sheets and glaciers, ocean circulation and sea level variations, hydrological cycle, post-glacial rebound and earthquake-induced gravity change. Satellite gravimetry missions, particularly the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-on, have provided new insights at unprecedented accuracy and resolution, which has been widely used to investigate mass flux within the ocean-land water cycle and Earth’s system coupling as well as responses to climate change together with complimentary data from other space missions, such as Jason-1/2, ICESat, Cryosat-2, GNSS, and InSAR. This interdisciplinary session solicits contributions on (1) time-varying gravity field estimation and improvement from satellite gravimetry missions and combination synergies, (2) extraction and interpretation of mass transport in the Earth system and responses to climate change, and (3) ideas and for innovations for in future time-varying gravity field measurement missions.

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G04 Earth Rotation and Geodynamics

Convener(s): Janusz Bogusz (Poland)

Co-Convener(s): Chengli Huang (China) Severine Rosat (France) Michael Schindelegger (Germany)

Description
This session discusses recent progress of the studies of Earth rotation and geodynamics using geodetic techniques. Relevant geophysical phenomena include those associated with changes in Earth’s shape, gravity field and rotation. These include the wide spectra of observational/analytical/theoretical studies of Earth rotation and orientation such as polar motion, Universal Time or length of day, precession and nutation, critical parameters for transformation between terrestrial and celestial reference frames at the mm level required by GGOS. Measurements of Earth’s static and time-varying gravity field from space-based and ground-based sensors, including comparison of results to models. We encourage researchers to contribute early results from the GRACE Follow-on mission. In terms of solid Earth deformation, relevant research includes those related to tidal processes (solid Earth and ocean loading tides), Earth’s free oscillations, crust and mantle deformation due to tectonic motions and isostatic adjustment etc. as well. Studies with traditional techniques and historical data are also encouraged to be contributed.

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G05 Multi-signal positioning, Remote Sensing and Applications

Convener(s): Kealy Allison (Australia)

Co-Convener(s): Zaminpardaz Safoora (Australia) Wielgosz Pawel (Poland) Beata Milanowska (Poland)

Description
Positioning applications are, today, as diverse as they are vast. They can be done using just a single signal from a single system but more often they are done merging multiple signals from distinct systems, including, at times, signals of opportunity. Among the applications are the ones that perform remote sensing of the environment from where signals propagate, either below, near or above the Earth’s surface, including its atmospheric layers, either land-based, airborne or from space. This symposium focuses on theoretical and practical advancements as well as innovative applications and architectures for multi-signal positioning, remote sensing and applications. We invite the submission of papers that address, navigation, timing and guidance systems for autonomous vehicles, intelligent transport systems, personal mobility, and other safety and liability critical applications. Indoor positioning systems and sensors and solutions for positioning in GNSS difficult environments.  Alternative positioning technologies and techniques including collaborative positioning and innovative integration architectures.  Positioning using low-cost sensors including GNSS and smartphone sensors, geospatial mapping and engineering, ranging from construction work, geotechnical and structural health monitoring, mining, to natural phenomena such as landslides and ground subsidence. Geodetic applications and high-precision GNSS technologies and applications and the use of multi-signals stemming from modernized signals and issues and opportunities coming from multi-constellation signals. In delivering multi-sensor systems numerous challenges emerge. This symposium welcomes any topic that addresses these challenges.

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G06 Monitoring and Understanding the Dynamic Earth with Geodetic Observations

Convener(s): Basara Miyahara (Japan)

Co-Convener(s): Detlef Angermann (Germany) Allison Craddock (USA) Hansjörg Kutterer (Germany)

Description
Geodetic observations of the Earth’s shape, rotation, and gravity show that these Earth properties change on a wide range of timescales reflecting the wide range of processes affecting them, from external tidal forces to surficial processes involving the atmosphere, oceans, and hydrosphere to internal processes acting both at the core-mantle boundary as well as within the solid Earth itself. Measurements of the Earth's shape, rotation, and gravity can therefore be used to gain greater understanding of mass transport within the entire Earth system, from tracking water in its various phases as it cycles through the atmosphere, oceans, and land, to crustal deformation associated with tectonic motions and glacial isostatic adjustment, to torsional, rotational, and inertial oscillations of the core. Geodetic observations provide the basis on which future advances in the geosciences can be built. By considering the Earth system as a whole (including the geosphere, hydrosphere, cryosphere, atmosphere and biosphere), monitoring Earth system components and their interactions by geodetic techniques and studying them from the geodetic point of view, the geodetic community provides the global geosciences community with a powerful tool consisting mainly of high-quality services, standards and references, and theoretical and observational innovations. Earth observations are needed not only for scientific research but also for societal applications such as disaster prevention and mitigation, managing resources like energy, water, and food, mitigating the effects of climate change, and protecting the biosphere, the environment, and human health. Geodetic observations provide the metrological foundation for Earth observations and provide the means to determine mass transport in the Earth system. Geodetic observations are therefore a cornerstone of the Earth observing systems needed for scientific research and societal applications. This Symposium will highlight the importance of geodetic observations to monitoring and understanding the dynamic Earth system for the benefit of both science and so

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