IC SG5

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)