Estimation of gravity variations at absolute stations in the Czech Republic from measurements compatible with ITGRS

Absolute gravity measurements with the FG5-215 and FG5X-251 gravimeters have been repeatedly conducted in the Czech Republic since 2001. At the same period, the gravimeters regularly took part at 12 international comparisons of absolute gravimeters and the gravity reference function at the reference station Pecný has been continuously maintained through the combination of absolute measurements with the measurements of the superconducting gravimeter OSG-050. The absolute gravity measurements in the Czech gravity network have been significantly extended since 2020 aiming to determine gravity variations at the stations, focusing on seasonal variations. These measurements have already been realized under the scope of CIPM MRA with declared uncertainty of 2.2 µGal. This uncertainty has been reached thanks to extensive investigation of systematic effects, enhanced measurement techniques and data re-processing. On the example of relevant data sets and investigations, we are presenting our approach to reach gravity results fully compatible with ITGRS, which could be characterized by exceptional accuracy with possibility to validate the measurement consistency and also to estimate the gravity variations mainly due to hydrological effects.