Scientific Program

IAG Symposia

IAG01 Reference Frames

G01 Reference frames

Convener: (University of Nevada, USA)
Co-convener: Johannes Böhm (Vienna Technical University, Austria)


Reference systems and frames are of primary importance for Earth science based research, satellite navigation as well as for practical applications in geo-information. A precisely defined reference frame is needed for an improved understanding of the Earth's rotation and its gravity field, sea level change with time, tectonic plate motion and deformation, glacial isostatic adjustment, geocenter motion, deformation due to Earthquakes, local subsidence and other crustal displacements. We invite presentations dealing with theoretical aspects and the practical realization of reference frames, as well as their application for research tasks like those mentioned above. Further emphases of the session are on global terrestrial and regional reference frames, celestial reference frames, and the co-location of space geodetic techniques on ground and in space.

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IAG02 Gravity field

G02 Static gravity field

Convener: (Technical University Munich, Germany)
Co-convener: Leonid Vitushkin (D.I. Mendeleyev Institute for Metrology, Russia), Hussein Abd-Elmotaal (Minia University, Egypt), Michael Sideris (University of Calgary, Canada)


Global and regional static gravity field models of high accuracy and spatial resolution encapsulate important information for a wide range of applications. Input to these models are on the one hand data satellite-based data, especially from dedicated space missions such as GRACE, GOCE and next-generation missions in the future, satellite altimetry and ground, air- and shipborne data. The development of such gravity models requires effective combination of these data applying advanced methods on global down to local scale. Modern developments of sensor technology both, for ground-and satellite-based systems, and new measurement concepts, such as quantum gravimeters and optical clocks, will in the near future complement and support gravity campaigns and networks using absolute, superconducting and other relative gravimeters.

Static gravity field models are essential for the unification of the existing height systems around the world 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.

This session solicits contributions that focus on all aspects of

  • (1) global high-resolution static gravity model developments and assessment, from methodological issues to modeling results, evaluation of uncertainties, and applications
  • (2) solution of various formulations of geodetic boundary-value problems resulting in precise local and regional high-resolution gravity/geoid models
  • (3) gravity campaigns and networks using absolute, superconducting and other relative gravimeters, as well as future technologies
  • (4) unification of existing height systems and the establishment of an IHRS
  • (5) developments in theory, processing methods, downward continuation of satellite and airborne data, treatment of altimetry and shipborne data, terrain modeling
  • (6) geophysical and oceanographic applications of static gravity field models
  • (7) mission concepts, instrumentation and processing strategies for future gravity field missions

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G03 Time variable gravity field

Convener: (Astronomical Observatory, China)
Co-convener: Srinivas Bettadpur (University of Texas, USA), Jürgen Kusche (University of Bonn, Germany)


The time variable Earth's gravity field is related to the mass transport and the physic processes within Earth's system (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. Nowadays, satellite gravimetry missions, particularly the Gravity Recovery and Climate Experiment (GRACE), showed great success to estimate the time-varying gravity field with 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 Jason-1/2, ICESat, Cryosat-2, GNSS, and InSAR. Furthermore, various initiatives are ongoing to prepare for future gravity mission and most promising is the US/German GRACE Follow-on (GRACE-FO) mission in August 2017.

This interdisciplinary session solicits contributions on (1) time-varying gravity field estimation and improvement from satellite gravimetry missions and combination synergies, (2) mass transport in the Earth system and responses to climate change, and (3) status and simulated results of future time-varying gravity field missions.

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IAG03 Earth rotation and Geodynamics

G04 Earth rotation and geodynamics

Convener: (Kyoto University, Japan)
Co-convener: Chengli Huang (Shanghai Astronomical Observatory, China), Janusz Bogusz (Military University of Technology, Poland), Matt King (University of Tasmania, Australia), Jianli Chen (University of Texas, Center for Space Research, USA)


The Earth is moving and deforming in response to forces acting on the Earth from outside or inside of our planet. Geodynamics, studies of motion and deformation of the Earth, includes the entire range of phenomena associated with Earth rotation and Earth orientation such as polar motion, Universal Time or length of day, precession and nutation, the observation and understanding of which are critical to the transformation between terrestrial and celestial reference frames. It also includes tidal processes such as solid Earth and ocean loading tides, and crust and mantle deformation associated with tectonic motions and isostatic adjustment etc.

During the last couple of decades, research of geodynamics significantly advanced owing to rapid development of measurement and computation technologies, understanding of the Earth's dynamics and kinematics were deepened. Many geoscientists have come to use the fruit of geodynamics in a more restricted sense to address processes such as plate tectonics and postglacial rebound. Because the Earth as a mechanical system responds to both internal and external forces, and because these responses are sometimes coupled, this session covers studies on the entire range of physical processes associated with the motion and the deformation of the solid Earth. We saw the significant progress of observation in Earth rotation exploiting newly developed observation/measurement technologies, besides traditional VLBI/SLR/LLR/GPS/DORIS, including Super-conductive laser gyroscope measurement, GRACE date on hydrological contribution to earth rotation, Galileo/BeiDou, etc. VGOS will be put into work next year. Studies on developments of new theories or computational techniques, new observation/measurement techniques using emerging technologies are also welcome.

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IAG04 Positioning and Applications

G05 Multi-signal positioning: Theory and applications

Convener: (University of New Brunswick, Canada)
Co-convener: Allison Kealy (University of Melbourne, Australia)


Signals of various types have been used for positioning in different applications at different levels of accuracy. They can be used separately but have been increasingly integrated. This symposium deals with theoretical developments and applications of multi-signal positioning. We invite the submissions of papers dealing with, but not excluded to, manned or unmanned, multi-sensor systems navigation and guidance, transportation, personal mobility, industrial and indoor positioning applications environmental monitoring, used of low-cost sensors including GNSS systems and smartphone navigation 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. The integration of different types of signals brings all sorts of challenges and opportunities and this symposium is open to any discussion about them.

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G06 Geodetic remote sensing

Convener: (Technische Universität München, Germany)
Co-convener: Jens Wickert (GFZ Potsdam, Germany), Felipe Nievinski (Federal University of Rio Grande do Sul, Brazil), Lung-Chih Tsai (National Central University, Taiwan), Yoshinori Shoji (Meteorological Research Institute, Japan)


In the context of this session the expression “Geodetic Remote Sensing” comprises atmosphere (including e.g. troposphere and ionosphere) monitoring, space weather studies as well as GNSS reflectometry. In general the Earth's atmosphere can be structured into various vertical layers depending on physical parameters such as temperature, water vapor or charge state. From the geodetic point of view the atmosphere is nowadays not only seen as a disturbing quantity which has to be corrected but also as a target quantity, since almost all geodetic measurement techniques provide valuable information about the atmospheric state. A prominent example for these developments is the operational use of ground- and space-based GNSS measurements to improve global and regional weather forecasts since 2006.

One of the major tasks in ionosphere research activities concerns the determination of physically relevant parameters from space geodetic observations to monitor ionosphere phenomena, such as the equatorial anomaly, and to perform space weather studies. Space weather and especially its impacts and risks are gaining more and more importance in politics and sciences, since our modern society is highly depending on space-borne techniques, e.g., for communication, navigation and positioning. Near real-time or even real-time approaches are currently under development, e.g. to monitor and analyse the state of the ionosphere, to predict ionosphere target parameters, or to optimize ultra-fast tropospheric products using data from GNSS permanent networks. Coupling processes between different atmospheric layers and inter-relations with climate change and natural hazards are further up-to-date topics. The backbone of all these studies and investigations is the integration of different geodetic observation techniques, consistent models and appropriate approaches following the goals of the Global Geodetic Observing System (GGOS).

Another important geodetic remote sensing technique is GNSS reflectometry (GNSS-R). After interacting with the neutral and ionized atmospheric layers, GNSS signals can be reflected off water, ice, and soil surface and exploited to derive geophysical properties of these surfaces as altimetric height, surface roughness, soil moisture, snow height, humidity or vegetation index. Such products are not only relevant for the geodetic community but also for an interdisciplinary geophysical user community with regard to important topics such as global sea-level monitoring, hydrological loading or drought/flooding observations.

In this session, contributions on atmosphere modeling including post-processing and (near) real-time approaches as well as studies on the combination of ground- and space-based geodetic observation techniques (including terrestrial GNSS, satellite altimetry, radio occultations, VLBI, DORIS) are welcome. Hereby we appreciate studies on the neutral and ionized atmosphere, including space weather related investigations, atmospheric coupling processes and climate change studies. We also welcome studies on GNSS reflectometry and related geophysical applications. Presentations on the estimation and forecast of atmospheric parameters (including atmospheric data assimilation) and on the usage of numerical weather models to improve GNSS positioning are other examples which would be appreciated.

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IAG05 IAG Joint

G07 Global Geodetic Observing System (GGOS) and Earth monitoring services

Convener: (BKG, Germany)
Co-convener: Richard S. Gross (JPL, California Institute of Technology, USA), Detlef Angermann (DGFI-TUM, Germany), Toshi Otsubo (Hitotsubashi University, Japan)


The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) has been designed to advance our understanding of the dynamic Earth by quantifying our planet's changes in space and time. It provides the observations needed to map, monitor and understand changes in the geodetic parameters describing the Earth system and the underlying processes. A global geodetic frame of reference of high quality and consistency is provided as the fundamental backbone for monitoring and consistently interpreting key processes. Moreover, GGOS complements other Earth monitoring systems and services as a unique contribution of the global scientific geodetic community. Present challenges are the monitoring of geo-hazards, sea level variations, global height changes or atmospheric parameters.

The focus of this symposium lies on the progress of the consistent scientific integration of Earth geometry, rotation and gravity observations as well as related numerical and geophysical models. Presentations are welcome which address (1) the observation architecture, (2) the standardization, management, processing and interpretation of the GGOS observation data, (3) the implementation of new observations technologies such as atom-interferometry, highly precise clocks, ring laser gyroscopes, (4) the integrated analysis and interpretation of geodetic parameters, time series and fields.

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