Modernization and current status of the Polish gravity control
Creators: name: Dykowski, Przemyslaw
name: Krynski, Jan
name: Olszak, Tomasz
Publisher: name: Zenodo
Year: 2023
Subjects: absolute gravimeter, gravity control

description: Gravity control in Poland had been modernized in the years 2011 - 2015. The goal for the modernization was to renew/remeasure the POGK99 gravity network established in mid 1990s and propose the most efficient way to proceed with the use of the state of the art gravity instruments and methods. The realization of the project consisted of three major steps: 1) the preparation of a detail technical project, 2) gravity surveys, 3) processing of gravity measurements. The review of the POKG99 gravity network showed a 30% of its gravity stations being destroyed or unusable. Thus, the old gravity network could not be remeasured in its original state. The new gravity control was designed to consist of absolute gravity stations only: fundamental stations measured with the FG5 gravimeter, and base stations measured with the A10 gravimeter. To ensure a reliable link to the old gravity control, stations selected for the new gravity control included all possible old gravity network (90) stations that fulfilled the requirements for absolute gravity stations. The technical project also included the requirements for quality control based on gravimeter calibrations and link to the international gravity reference level. Majority of gravity measurements were carried out separately on the fundamental and base stations in 2012 and 2013. Gravity at fundamental stations (28) were measured with the FG5-230 gravimeter (owned by the Warsaw University of Technology), while at base stations (168) - with the A10-020 gravimeter (owned by the Institute of Geodesy and Cartography - IGiK). On each fundamental and base station vertical gravity gradients were determined. Both the A10 and FG5 gravimeters participated in the 2013 ICAG meeting allowing the modernized Polish Gravity Control to be linked to the international gravity reference level. Gravimetric calibration baselines: two meridional ones running from southern border to the Baltic See cost, and two vertical ones, one in the Tatra mountains and one in the Sudety mountains, are integral part of the modernized Polish Gravity Control. Laser, clock and barometer of both A10 and FG5 gravimeters were calibrated at the Central Office of Measures in Poland to assure quality control. Both instruments participated in local AG inter-comparisons as well as performed regular absolute gravity measurements at their designated Observatories in Jozefoslaw (FG5-230) and Borowa Gora (A10-020). In the final stage, processing of the measurements included uncertainty evaluation as well as the developing of the map of differences between POG14 and POGK99 gravity systems. Complementary measurements were done in 2014 and 2015. Additionally, within the EPOS-PL project, IGiK performed regular gravity measurements with the A10-020 on 5 POG stations in the Upper Silesian region as well as regular measurements on the field station at the Borowa Góra Observatory, giving indication on the stability of POG gravity values over time. Time interval for remeasurement of the POG gravity control will be discussed.