The main effort in the Action is concentrated in four different working groups.

 
  WG1- Geodetic observation-level modelling and systematic biases

  WG2- Velocity determination/reference frame realization

  WG3- Noise characteristics of station coordinate time series/velocities

  WG4- GIA model optimisation and ice mass balance computations

WGs1-3 focus on improved geodetic measurement of 3d surface velocity, and WG4 seeks to produce new, more accurate models of GIA in part using new geodetic data developed by WGs1-3. The individual WG pages contain WG membership information, including contact details for the WG Chairs.