Difference between pages "IC SG4" and "IC SG5"

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<big>'''JSG 0.4: Coordinate systems in numerical weather models'''</big>
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<big>'''Satellite gravity theory'''</big>
  
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Chair:''T. Hobiger (Japan)''<br>
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Chair: ''T. Mayer-Gürr (Germany)''<br>
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Affiliation:''all Commissions''
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Affiliation: ''Comm. 2''
  
 
__TOC__
 
__TOC__
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===Introduction===
 
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Numerical weather models (NWMs) contain valuable information that is relevant for a variety of geodetic models. Currently no clear description exists regarding how to deal with the NWM coordinate systems when carrying out the calculations in a geodetic reference frame. The problem can be split into two questions: First, how to relate the horizontal NWM coordinates, which are in most cases geocentric coordinates, derived initially from either Cartesian or spectral representations, properly into an ellipsoidal/geodetic frame? Second, how to transform the NWM height system into elliptical heights as used within geodesy? Although some work has been already done to answer these questions, still no procedures, guidelines or standards have been defined in order to consistently transform the meteorological information into a geodetic reference frame.
 
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The study group will categorize the NWM coordinate systems, create mathematical models for transformation and summarize these findings in a peer-reviewed paper that will act as guidelines for those who intend to utilize NWM information. In addition, it will be necessary to define such transformations in both ways, in order to enable the assimilation of geodetic measurements into meteorological models as well. Moreover, the study group will deal with the issue of surface data contained in NWM and how this information can be consistently used.
 
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===Objectives===
 
===Objectives===
  
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* Understand the horizontal coordinate systems of the different NWMs, ranging from global to small-scale regional models
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* Gravity field estimation
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* Understand the vertical coordinate systems of the different NWMs, ranging from global to small-scale regional models
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** Perturbation techniques versus in-situ measurements and new aproaches like short-arc integration, energy balance and so on.
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* Formulate a clear mathematical description on how to transform between NWMs and a geodetic frame (in both directions)
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** Computational problems related to the huge quantities of data. Algorithms to divide the computational tasks to run on massive parallel systems.
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* Summarize these findings in a peer-reviewed paper that will act as a standard for future use of NWM-produced fields.
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* Noise and error treatment
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** Estimating the variance-covariance matrices of the observations, filtering techniques.
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** Integrated analysis of different sensors featuring individual noise characteristics (like Accelerometer and K-band sensor in case of GRACE), calibration of instruments (internal and external).
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** A-posteriori variance-covariance matrices, error propagation, validation.
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** Space-time resolution, de-aliasing. Which signals can be estimated and which must be modeled?
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* Gravity field modeling
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** Choice of basis functions in time and space (with respect to applications in hydrology, oceanography).
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** Global and regional modeling, modeling in terms of gravity sources (mass variations).
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** Reference systems and datum problems (origin, orientation, static and temporal datum systems for gravity field changes).
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* Aspects of data combination
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** Combination of the satellite gravity missions (CHAMP, GRACE and GOCE) with terrestrial and aerial gravity information.
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** Combination at the data level versus combination of results.
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** A-priori information from non-gravity data such as changes in the geometry of the Earth and its rotation.
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** Unified approaches: Joint analysis of gravity field observations, Earth rotation, and geometry changes.
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* Future satellite missions
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** Theory of new observation types and intruments.
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** Formation flights. Investigation into stability of satellite formations and their sensitivity to aliasing errors.
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** Follow-on gravity field missions.
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** Orbit determination: theory, perturbation techniques, stability problems.
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** Challenges caused by the inceasing accuracy of the observations: integration techniques, numerical problems due to limited digits in computation.
  
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===Program of Activities===
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===Program of activities===
  
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* Launch a webpage for dissemination of information, presentation, communication, outreach purposes.
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* Email:<br /> Internal email discussions
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* Provide a bibliography.
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* Meeting:<br /> Organization of working group meeting at larger meetings.
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* Conduct working meetings in association with international conferences.  
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* Website:<br /> Launch of a website for communications, informations and links to data sources
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* Present research results in appropriate sessions.
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* Simulation data:<br /> Assemble of a simulated data set with orbits, background models and artificial noise. This data set serves to test new algorithms and make different aproaches comparable.
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* Organize workshops dedicated mainly to problem identification and to motivation of relevant scientific research.
 
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* Produce at least one peer-reviewed paper that presents a clear and consistent description of how to transform information from and to NWMs, and the relevance of different NWM structures, and, if possible, a second paper that deals with the uncertainty of the NWM related coordinate information will be considered.
 
  
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===Members===
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===Membership===
  
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'' '''Thomas Hobiger (Japan), chair'''<br /> Johannes Boehm (Austria)<br /> Tonie van Dam (Luxembourg) <br />Pascal Gegout (France) <br /> Rüdiger Haas (Sweden) <br /> Ryuichi Ichikawa (Japan) <br /> Arthur Niell (USA) <br /> Felipe Nievinski (USA) <br /> David Salstein (USA) <br /> Marcelo Santos (Canada) <br />Michael Schindelegger (Austria) <br /> Henrik Vedel (Denmark) <br /> Jens Wickert (Germany) <br /> Florian Zus (Germany) <br />''
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'' '''Torsten Mayer-Guerr (Germany)'''<br /> Oliver Baur (Germany)<br /> Wolfgang Bosch (Germany)<br /> Pavel Ditmar (Netherlands)<br /> Thomas Gruber (Germany)<br /> Shin-Chan Han (USA)<br /> Michael Kern (Netherlands)<br /> Juergen Kusche (Germany)<br /> Michael Schmidt (Germany)<br /> Roland Schmidt (Germany)<br /> Roland Pail (Austria)<br /> Insa Wolf (Germany)<br />''

Revision as of 13:52, 22 April 2008

Satellite gravity theory

Chair: T. Mayer-Gürr (Germany)
Affiliation: Comm. 2

Objectives

  • Gravity field estimation
    • Perturbation techniques versus in-situ measurements and new aproaches like short-arc integration, energy balance and so on.
    • Computational problems related to the huge quantities of data. Algorithms to divide the computational tasks to run on massive parallel systems.
  • Noise and error treatment
    • Estimating the variance-covariance matrices of the observations, filtering techniques.
    • Integrated analysis of different sensors featuring individual noise characteristics (like Accelerometer and K-band sensor in case of GRACE), calibration of instruments (internal and external).
    • A-posteriori variance-covariance matrices, error propagation, validation.
    • Space-time resolution, de-aliasing. Which signals can be estimated and which must be modeled?
  • Gravity field modeling
    • Choice of basis functions in time and space (with respect to applications in hydrology, oceanography).
    • Global and regional modeling, modeling in terms of gravity sources (mass variations).
    • Reference systems and datum problems (origin, orientation, static and temporal datum systems for gravity field changes).
  • Aspects of data combination
    • Combination of the satellite gravity missions (CHAMP, GRACE and GOCE) with terrestrial and aerial gravity information.
    • Combination at the data level versus combination of results.
    • A-priori information from non-gravity data such as changes in the geometry of the Earth and its rotation.
    • Unified approaches: Joint analysis of gravity field observations, Earth rotation, and geometry changes.
  • Future satellite missions
    • Theory of new observation types and intruments.
    • Formation flights. Investigation into stability of satellite formations and their sensitivity to aliasing errors.
    • Follow-on gravity field missions.
    • Orbit determination: theory, perturbation techniques, stability problems.
    • Challenges caused by the inceasing accuracy of the observations: integration techniques, numerical problems due to limited digits in computation.

Program of activities

  • Email:
    Internal email discussions
  • Meeting:
    Organization of working group meeting at larger meetings.
  • Website:
    Launch of a website for communications, informations and links to data sources
  • Simulation data:
    Assemble of a simulated data set with orbits, background models and artificial noise. This data set serves to test new algorithms and make different aproaches comparable.

Membership

Torsten Mayer-Guerr (Germany)
Oliver Baur (Germany)
Wolfgang Bosch (Germany)
Pavel Ditmar (Netherlands)
Thomas Gruber (Germany)
Shin-Chan Han (USA)
Michael Kern (Netherlands)
Juergen Kusche (Germany)
Michael Schmidt (Germany)
Roland Schmidt (Germany)
Roland Pail (Austria)
Insa Wolf (Germany)

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