SC 2.6: Gravity Inversion and Mass Transport in the Earth System

Chair: Wei Feng (China)
Vice-Chair: Roelof Rietbroek (Germany)

Terms of Reference

Spatial and temporal variations of gravity are related to the dynamics of the Earth’s interior, land surface, oceans, cryosphere, and atmosphere. The geoid maps equilibrium dynamic processes in the ocean and in the Earth’s mantle and crust, and large-scale coherent changes in gravity result from mass transports in atmosphere, hydrosphere, cryosphere, and the ocean, and across these. The gravity field, derived from terrestrial and space gravimetry (SLR, CHAMP, GRACE, GOCE, GRACE-FO, NGGM, …) with unprecedented accuracy and resolution, provides a unique opportunity to investigate gravity- solid earth coupling, the structure of the globe from the inner core to the crust, and mass transports such as those associated within the global water cycle. Gravimetry also contributes to a better understanding of the interactions in the Earth system, and to its response to climate change and the anthropogenic fingerprint.

Objectives

• To further the understanding of the physics and dynamics of the Earth’s interior, land surface, cryosphere, oceans and atmosphere using gravity and other geodetic and geophysical measurement techniques.
• To promote the study of solid Earth mass (re-)distribution from gravity and gravity gradient tensor variations, e.g. crust thickness, isostatic Moho undulation, mass loadings, basin formation, thermal effects on density, deformations, as well as interactions with the Earth’s interior.
• To advance the investigation of mass transports in the Earth system, and, in particular, to contribute to the understanding of the global water cycle, of the storage of water in cryosphere and hydrosphere, of the fluxes across these sub-systems and the atmosphere, and of sea level.
• To contribute to the operationalization of mass transport monitoring, e.g. for water resource monitoring.
• To aid in reconciling multiple geodetic observations at various spatio-temporal scales for mass transport monitoring and interpretation.
• To stimulate new techniques and potential applications of gravimetry and mass transport monitoring, e.g. quantum gravimeter, optical clock, new satellite gravimetry concept,
• To communicate with gravity-related communities in oceanography, hydrology, cryosphere, solid Earth, geodesy, etc.

Program of Activities 

The sub-commission will establish Work Groups (WGs) on relevant topics. The Steering Committee will work closely with members and other IAG commissions and sub-commissions to obtain mutual goals. Also it will promote and jointly sponsor special sessions at IAG Symposia and other workshop/conferences.

Working Groups of Sub-Commission 2.6

WG 2.6.1: Geodetic observations and physical interpretations in the Tibetan Plateau

Chair: Wenbin Shen (China)
Vice-Chair: Cheinway Hwang (China-Taipei)

Terms of Reference

Mass transport and (re-)distribution of the Tibetan Plateau is a research hotspot in the field of geoscience, relevant to global climate, glaciers, lakes, permafrost and deep geodynamics. The mountain building processes and their dynamic mechanisms of the Tibetan Plateau are still unclear and remain a key topic of research in geosciences. As multiple-type of data continue rapidly to grow on the Tibetan Plateau, advanced techniques in signal processing are needed to effectively extract targeted signals. Cross-correlations between different data types are important keys to discover the connections between the data, and to understand the causes and the consequences of the phenomena of interest. This working group will concentrate on but not limit to the studies of hydrological change, crustal deformation, regional gravity field and its variation, mass migration and Moho variation, geodynamic and cryospheric processes and climate change of the Tibetan Plateau, based on various observations from space-borne and terrestrial sensors, such as GNSS, GRACE, GRACE-FO, satellite altimetry, InSAR, and ground gravity. Relevant investigations and studies will significantly promote the understanding and revealing of the uplift processes and dynamic mechanisms of mass transport in the Tibetan Plateau.

Objectives

• Hydrological change over river basins, lake level variation, permafrost, vertical deformation, mountain glacier change, atmospheric circulation of the Tibetan Plateau, and their interpretations from altimeter, GNSS, GRACE, GRACE-FO, and gravimeters;
• Geopotential and orthometric height determinations and unification of world height datum systems;
• Long-term monitoring of surface processes from satellite altimeters such as ICESat, TOPEX, Jason-1, -2, and -3, ERS-1, -2, ENVISAT, and Sentinel series;
• Results of satellite and terrestrial-based gravimetric observations;
• Results of GNSS observations, GNSS meteorology, and ionosphere;
• Geophysical interpretations and consequences of gravity, GNSS, satellite altimetry, and seismic observations;
• SAR and LiDAR detections of surface deformation, especially over the Tibetan Plateau; 
• Crust structure and density refinement especially in the Tibetan region using multi-datasets;

Members 

• Chair: Wenbin Shen (China)
• Vice-Chair: Cheinway Hwang (China-Taipei)
• Benjamin Fong Chao (China-Taipei)
• Tonie van Dam (Luxembourg)
• Xiaoli Deng (Australia)
• Hao Ding (China)
• Xiaoli Ding (Hong Kong, China)
• Jeffrey T. Freymueller (USA)
• Yuanjin Pan (China)
• Jim Ray (USA)
• Xiaodong Song (USA)
• CK Shum (USA)
• Heping Sun (China)
• Wenke Sun (China)
• Robert Tenzer (Hong Kong, China)
• Leonid Zotov (Russia)