JWG C.6: Numerical Simulations for Recovering Climate-Related Mass Transport Signals

Chair: Mehdi Khaki (Australia)
(Affiliation: Commission 2, GGOS)


Gravity field missions are a unique geodetic measuring system to directly observe mass transport processes in the Earth system. Past and current gravity missions such as CHAMP, GRACE, GOCE and GRACE-Follow On have improved our understanding of many mass change processes, such as the global water cycle, ice mass melting of ice sheets and glaciers, changes in ocean mass being closely related to the mass-related component of sea level rise, which are subtle indicators of climate change, on global to regional scale. Next Generation Gravity Missions (NGGMs) expected to be launched in the midterm future have set high anticipations for an enhanced monitoring of mass transport in the Earth system with significantly improved spatial and temporal resolution and accuracy. Science and user needs have been collected and consolidated mainly for the application fields hydrology, cryosphere, ocean and solid Earth, and a corresponding resolution on the need of NGGMs was expressed by IUGG resolution no. 2 adopted in 2015. However, mass transport observations are also very valuable for long-term climate applications. According to GCOS, in genera time series of minimum 30 years are needed to decouple natural and anthropogenic forcing mechanisms. Up to now, this hypothesis has never been checked and evaluated for gravity field observations.


The main objective of this working group is to set-up and run long-term numerical simulation studies to evaluate the usefulness of gravity field missions for climate-related applications. As a first step, mass transport time series containing long-term changes of climate relevant signals have to be generated in close interaction with climate modelers. They shall then be used for the numerical simulations on the recoverability by means of different NGGM concepts, e.g. GRACEtype in-line single-pair missions, Bender double-pair mission being composed of a polar and an inclined satellite pair, or high-precision high-low tracking missions following the MOBILE concept. In this respect, special emphasis shall be given to the separability of natural and anthropogenic forcing mechanisms in dependence of the length of the measurement time series, the quantification of robustness of derived trends and systematic changes, and the evaluation of their impact to climate modeling.

Program of Activities

The following activities shall be performed:

  • Generation of mass transport time series for a time-span of at least 30 years containing climate-relevant signals
  • Numerical closed-loop simulations for various mission concepts that are currently in discussion as potential candidates for an NGGM
  • Evaluation of recoverability of climate-related signals from these mass transport time series
  • Detectability of climate change pathways in the future mass transport time series
  • Investigation of separability of natural and anthropogenic forcing processes
  • Evaluation of impact for climate model applications towards societal applications
  • Evaluation of the detectability of thresholds for early warning


  • Alejandro Blazquez (France)
  • Qiang Chen (Luxembourg)
  • Lijing Cheng (China)
  • Henryk Dobslaw (Germany)
  • Andreas Groh (Germany)
  • Martin Horwath (Germany)
  • Vincent Humphrey (USA)
  • Erik Ivins (USA)
  • Laura Jensen (Germany)
  • Laurent Longuevergne (France)
  • Ingo Sasgen (Germany)
  • Bert Wouters (Netherlands)

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