Difference between revisions of "IC SG8"

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<big>'''Towards cm-accurate geoid - Theories, computational methods and validation'''</big>
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<big>'''JSG 0.8: Earth System Interaction from Space Geodesy'''</big>
  
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Chair: ''Y.M. Wang (USA)''<br>
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Chair: ''S. Jin (China)''<br>
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Affiliation:''Comm. 2''
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Affiliation:''Comm. 2, 3 and 4''
  
 
__TOC__
 
__TOC__
 
===Introduction===
 
===Introduction===
  
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In today's satellite age, the ellipsoidal height can be determined up to 2 cm-accuracy geometrically by the global positioning system (GPS). If geoid models reach the same accuracy, national or global vertical systems can be established in a quick and economical way with cm-accuracy everywhere.
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The gravity field and geodetic mass loading reflect mass redistribution and transport in the Earth’s fluid envelope, and in particular interactions between atmosphere, hydrosphere, cryosphere, land surface and the solid Earth due to climate change and tectonics activities, e.g., dynamic and kinematic processes and co-/post-seismic deformation. However, the traditional ground techniques are very difficult to obtain high temporal-spatial resolution information and processes, particularly in Tibet.
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With the launch of the Gravity Recovery and Climate Experiment (GRACE) mission since 2002, it was very successful to monitor the Earth’s time-variable gravity field by determining very accurately the relative position of a pair of Low Earth Orbit (LEO) satellites. Therefore, the new generation of the gravity field derived from terrestrial and space gravimetry, provides a unique oppor-tunity to investigate gravity-solid earth coupling, physics and dynamics of the Earth’s interior, and mass flux interaction within the Earth system, together with GPS/InSAR.
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Geoid modeling has been based on Stokes and Molodensky's theories. In both theories, including the theories of gravity and topographic reductions which are fundamentally important for precise geoid computation, approximations and assumptions are made. The evaluation and verification of the effects of assumptions and approximations in the theories are urgently called for. Due to the massive effort on data collection that has improved our knowledge of the Earth's physical surface and its interior, fixed-boundary value problems become practical and useful. Theoretical and numerical studies along this line are not only important in practice, but also may be a fundamental change in physical geodesy.
 
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The working group aims at bringing together scientists concerned with all aspects of the diverse areas of geodetically relevant theory and its applications. Its goal is to provide a framework consisting of theories and computational methods to ensure that cm-accurate geoid is achievable.
 
  
 
===Objectives===
 
===Objectives===
  
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Theoretical research related to precise geoid computations; studies of geodetic boundary values problems (free and fixed boundary value problems); development and refinement of gravity/topographic reduction theories; exploration and implementation of numerical methods of partial differential equations for Earth's gravity field determination (e.g., domain decomposition, spectral combination and others).
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* To quantify mass transport within the Earth’s fluid envelope and their interaction in the Earth system.
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* To monitor tectonic motions using gravimetry/GPS, including India-Tibet collision, post-glacial uplift and the deformation associated with active tectonic events, such as earthquakes and volcanoes.
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In more details, this includes:
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* To develop inversion algorithm and theories in a Spherical Earth on gravity field related deformation and gravity-solid Earth coupling, e.g. crust thickness, iso-static Moho undulations, mass loadings and geodynamics.
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* To develop methods to extract a geodynamic signals related to Solid-Earth mantle and/or core and to under-stand the physical properties of the Earth interior and its dynamics from the joint use of gravity data and other geophysical measurements.
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* Studies of the effect of topographic density variations on the Earth's gravity field, especially the geoid.
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* To analyze and model geodynamic processes from iso-static modelling of gravity and topography data as well as density structure of the Earth’s deep interior.
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* Rigorous yet efficient calculation of the topographic effects, refinement of the topographic and gravity reductions.
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* To address mantle viscosity from analyzing post-seismic deformations of large earthquakes and post-glacial rebound (PGR) and to explain the physical relationships between deformation, seismicity, mantle dynamics, litho-spheric rheology, isostatic response, etc.
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* Studies on harmonic downward continuations.
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* To achieve these objectives, the IC SG interacts and collaborates with the ICCT and all IAG Commissions.
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* Non-linear effects of the geodetic boundary value problems on the geoid determinations.
 
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* Optimal combination of global gravity models with local gravity data.
 
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* Exploration of numerical methods in solving the geodetic boundary value problems (domain decomposition, finite elements, and others)
 
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* Studies on data requirements, data quality, distribution and sample rate, for a cm- accurate geoid.
 
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* Studies on the time variations of the geoid caused by geodynamics.
 
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* Studies on the interdisciplinary approach for marine geoid determination, e.g., research on realization of a global geoid consistent with the global mean sea surface observed by satellites.
 
  
 
===Program of activities===
 
===Program of activities===
  
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* Organization of meetings and conferences.
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* Organization of SG workshop and of conference sessions,
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* Organizing WG meetings or sessions, in coincidence with a larger event, if the presence of working group members appears sufficiently large.
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* Participation in related scientific conference and sympo-sia,
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* Email discussion and electronic exchange.
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* Supporting contributions to the ICCT activities.
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* Launching a web page for dissemination of information, expressing aims, objectives, and discussions.
 
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* Monitoring and reporting activities of working group members and interested external individuals.
 
  
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===Membership===
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===Members===
  
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'' '''Y.M. Wang, (USA, chair)'''<br /> W. Featherstone, Australia<br /> N. Kühtreiber, Austria<br /> H. Moritz, Austria<br /> M.G. Sideris, Canada<br /> M. Véronneau, Canada<br /> J. Huang, Canada<br /> M. Santos, Canada<br /> J.C. Li, China<br /> D.B. Cao, China<br /> W.B. Shen, China<br /> F. Mao, China<br /> Z. Martinec, Czech Republic<br /> R. Forsberg, Denmark<br /> O. Anderson, Denmark<br /> H. Abd-Elmotaal, Egypt<br /> H. Denker, Germany<br /> B. Heck, Germany<br /> W. Freeden, Germany<br /> J. H. Kwon, Korea<br /> L. Sjöberg, Sweden<br /> D. Roman, USA<br /> J. Saleh, USA<br /> D. Smith USA<br />''
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'' '''Shuanggen Jin (China), chair'''<br />  
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David J. Crossley (USA)<br />
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Carla Braitenberg (Italy)<br />
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Isabelle Panet (France)<br />
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Jacques Hinderer (France)<br />
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Séverine Rosat (France)<br />
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Tonie M. van Dam (Luxembour)<br />
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Urs Marti (Switzerland)<br />
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Patrick Wu (Canada)<br />
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Isabella Velicogna (USA)<br />
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Nico Sneeuw (Germany)<br />''

Revision as of 12:34, 29 June 2012

JSG 0.8: Earth System Interaction from Space Geodesy

Chair: S. Jin (China)
Affiliation:Comm. 2, 3 and 4

Introduction

The gravity field and geodetic mass loading reflect mass redistribution and transport in the Earth’s fluid envelope, and in particular interactions between atmosphere, hydrosphere, cryosphere, land surface and the solid Earth due to climate change and tectonics activities, e.g., dynamic and kinematic processes and co-/post-seismic deformation. However, the traditional ground techniques are very difficult to obtain high temporal-spatial resolution information and processes, particularly in Tibet. With the launch of the Gravity Recovery and Climate Experiment (GRACE) mission since 2002, it was very successful to monitor the Earth’s time-variable gravity field by determining very accurately the relative position of a pair of Low Earth Orbit (LEO) satellites. Therefore, the new generation of the gravity field derived from terrestrial and space gravimetry, provides a unique oppor-tunity to investigate gravity-solid earth coupling, physics and dynamics of the Earth’s interior, and mass flux interaction within the Earth system, together with GPS/InSAR.

Objectives

  • To quantify mass transport within the Earth’s fluid envelope and their interaction in the Earth system.
  • To monitor tectonic motions using gravimetry/GPS, including India-Tibet collision, post-glacial uplift and the deformation associated with active tectonic events, such as earthquakes and volcanoes.
  • To develop inversion algorithm and theories in a Spherical Earth on gravity field related deformation and gravity-solid Earth coupling, e.g. crust thickness, iso-static Moho undulations, mass loadings and geodynamics.
  • To develop methods to extract a geodynamic signals related to Solid-Earth mantle and/or core and to under-stand the physical properties of the Earth interior and its dynamics from the joint use of gravity data and other geophysical measurements.
  • To analyze and model geodynamic processes from iso-static modelling of gravity and topography data as well as density structure of the Earth’s deep interior.
  • To address mantle viscosity from analyzing post-seismic deformations of large earthquakes and post-glacial rebound (PGR) and to explain the physical relationships between deformation, seismicity, mantle dynamics, litho-spheric rheology, isostatic response, etc.
  • To achieve these objectives, the IC SG interacts and collaborates with the ICCT and all IAG Commissions.

Program of activities

  • Organization of SG workshop and of conference sessions,
  • Participation in related scientific conference and sympo-sia,
  • Supporting contributions to the ICCT activities.

Members

Shuanggen Jin (China), chair
 David J. Crossley (USA)
Carla Braitenberg (Italy)
Isabelle Panet (France)
Jacques Hinderer (France)
Séverine Rosat (France)
Tonie M. van Dam (Luxembour)
Urs Marti (Switzerland)
Patrick Wu (Canada)
Isabella Velicogna (USA)
Nico Sneeuw (Germany)

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