The goal of the project is to deliver a quasi-inertial reference frame realised by quasar positions and a terrestrial reference frame which are consistent with each other, based on a common set of Parameters and in particular on homogeneous geophysical fluid models. Although first realizations already exist, their quality and accuracy is limited by various factors, such äs deficits regarding the geophysical background models, neglect of non-linear Station motions and inadequate combination processes that do not allow for a consistent and reliable estimation of the geodetic reference frames. The combinations of the VLBI, SLR and GNSS time series and the reference frame computations will be performed by applying two different approaches, (a) on the level of the observation equations (at BKG), and (b) on the level of constraint-free normal equations (at DGFI). At BKG, the combination at the level of observation equations with one Software package for the three space techniques will allow a selection of geophysical (fluid) models consistently and an improved combination strategy. At DGFI, advanced methods will be developed for the combination of long-term observation time series to compute two different types of reference frames: (1) improved long-term reference frame realizations taking non-linear Station motions into account, and (2) epoch reference frame realizations (e.g., weekly) that are essential for near real time applications and for monitoring global change.
Time series of the station height of the Siberian GNSS station Irkutsk
