GRIM5-C1: Combination solution of the global gravity field to degree and order 120

The new satellite Earth gravity field model GRIM5-SI was recently prepared in a joint GFZ and GRGS effort. Based on this satellite solution and terres trial and altimetric gravity anomalies from NIMA, a combined model GRIM5-C1 , with full variance-covariance matrix up to degree and order 120, was comp uted. Surface gravity and altimetric gravity data are corrected for several systematic effects, such as ellipsoidal corrections and aliasing. A weight ing scheme for gravity anomalies, according to their given standard deviati ons was developed. From each data set full normal equations were set up and finally combined with the GRIM5-S1 normals. To take into account good info rmation from the satellite-only model a procedure was developed to identify such coefficients and appropriately weighed them in the final normal equat ion system. Internal error propagation and comparisons to external data set s show, that the GRIM5-C1 model represents the best state of long wavelengt h gravity field models.