Dense Regional Velocity Field Realization Based on the Integration of the National Active Gnss Networks

The European contribution to the IAG Working Group on Dense Velocity Fields should rely on the integration of the dense national permanent GNSS networks. In Europe the situation is more complex than in other regions because numerous countries operate independent networks. Fortunately the EUREF Permanent Network (EPN) and its products can be used as backbone infrastructureand the separate national GNSS data processing practically rely on the strategy defined for the EPN analysis. In order to avoid any inconsistencies the combination will be done on the weekly SINEX level. The national weekly SINEX submissions are combined with the actual weekly EPN SINEX solution, than a multiyear cumulative solution is created, which already includes all input. Before the creation of the integrated cumulative solution several quality and homogeneity tests (strategies, models, naming, data availability, site stability, weighting) are being performed. The integration is done with the CATREF software using the Minimum Constraint approach. The preparatory work is already in progress, the data from several countries is already investigated and promising test results have been created. The ongoing EPN densification action is one of the leading activity of EUREF for the next few years. The derived position and velocity product will be an essential material for geokinematic studies and also for the better definition and realization of ETRS89 reference frame. In order to cover the greatest part of the continent all European countries are invited to submit their weekly GNSS SINEX solutions. In this paper a status report is presented, where the issues to be solved are emphasized, but also the latest velocity field solution is shown.