Combination Procedure

  1. Before accumulating the individual normal equation matrices the matrices are transformed to the mean epoch of all contributions by using the respective earth orientation parameter rates.
  2. Furthermore the individual normal equation matrices have to be transformed to a common set of apriori values for station coordinates and earth orientation parameters.
  3. Weighting factors determined by variance component estimation are applied to the normal equation systems.
  4. The datum-free normal equation matrices are accumulated.
  5. Earth orientataion parameters are estimated by fixing all station components to their ITRF2008 values.
  6. To perform a quality check comparisons are carried out
    • internal comparisons of the individual solutions with respect to the combined solution,
    • external comparisons with the earth orientation parameters of the IGS Final Combined Solution (igs00p03.erp) as well as with the IERS C04 (eopc04.62-now) earth orientation parameter series.

Notice: To get comparable results, the calculations of bias, WRMS and RMS were carried out only for those sessions that were analysed by every analysis center.