Since 2003 the "International Centre for Global Earth Models" (ICGEM) is established as an IAG service under the roof of the International Gravity Field Service (IGFS). The major task of ICGEM is to make all global gravity field models of the Earth, which are provided as sets of spherical harmonic coefficients, available to the public. This covers the most recent models back to historical data. The spherical harmonic coefficients are available in a standardised self-explanatory format.
The models can not only be downloaded from the ICGEM website but also be used within an interactive visualisation tool and in a dedicated gravity function calculation service. The visualisation service shows the models (or the difference of two models) in terms of quasigeoid heights or gravity anomalies as illuminated projection on a freely rotatable sphere. Additionally, an animation over time of the monthly solutions from GRACE is included. Finally, the calculation service provides the possibility to compute different functionals of the gravity field, such as gravity anomalies, geoid undulations or equivalent water heights on grids of the users’ choice.
In particular, thanks to the availability of the monthly model series from GRACE, the static models from the GOCE mission, and the combined models of high spatial resolution, the importance of gravity field functionals for nearly all geosciences is rising permanently. In addition to its use for educational purposes, ICGEM helps researchers from different geoscientific fields to overcome obstacles in using these models and to get acquainted with the mathematical representation of gravity field in terms of spherical harmonic series. In this way ICGEM enables and stimulates the research based on these products.

Example of the on-line visualisation service: geoid hights of the model EIGEN-6C2 as illuminated projection on a sphere
Example of the on-line visualisation service: gravity anomalies of the model EIGEN-6C2 as illuminated projection on a sphere
Example from the animation of the monthly models: geoid differences of the model for November 2010 to the mean model EIGEN-6S. Visible are the effect of mass loss (blue) due to deglaciation during the last years in Greenland and Alaska as well as the snapshot of the annual hydrological mass variations in the Amazon Basin and the effect of increasing mass (red) due to postglacial uplift in North America


Mr. Dr. Franz Barthelmes
Global Geomonitoring and Gravity Field

Building A 17, room 00.16
14473 Potsdam
tel. +49 331 288-1143