Towards the Establishment of New Gravity Control in Poland

Abstract

The existing Polish gravity control (POGK) was established in the last few years of twentieth century (Sas-Uhrynowski et al. (A new national gravity control network—POGK97 (in Polish). Proceedings of the Institute of Geodesy and Cartography, 1999); Sas-Uhrynowski et al. (A new gravimetric control network for Poland. Reports on Geodesy, 2000)) according to the international standards (Boedecker (BGI Bull d’Inf 63:51–56, 1988)). It is based on 12 absolute gravity stations surveyed with four different types of absolute gravimeters. Relative measurements performed by various groups on nearly 350 points with the use of LaCoste & Romberg (LCR) gravimeters were linked to those 12 stations.

The development of absolute gravity survey technologies, in particular instruments for precise field absolute gravity measurements, provides an opportunity to establish a new type of gravity control consisting of stations surveyed with absolute gravimeters. The projects of the densification of the gravity control with absolute gravity measurements using the A10 gravimeter were performed in France (Duquenne et al. (Gravity measurements on the French geodetic network. Symposium of the IAG subcommission for Europe (EUREF), Vienna, 2005)) and in Germany (Falk et al. 2009). The establishment and maintenance of this kind of gravity control is much easier than the one performed with the use of relative gravity measurement technique. It also better fulfills the recent requirements of geodesy and geodynamics in terms of accuracy and efficiency of its re-survey. The two absolute gravimeters: the FG5-230 of the Warsaw University of Technology and the A10-020 of the Institute of Geodesy and Cartography, Warsaw, along with a set of LCR gravimeters are available to be used for the establishment of new gravity control in Poland planned for the years 2012–2014.

New gravity control will consist of 28 fundamental points (surveyed with the FG5 gravimeter), and 169 base points (surveyed with the A10 gravimeter). Base points include chosen existing POGK points, POLREF and EUVN stations, as well as eccentric stations of the Active Geodetic Network (ASG-EUPOS). The fundamental stations are located in thebasements of buildings, 14 of them coincide with those of the existing gravity control, while base stations are well monumented field stations. Methodology and measurement schemes for both gravimeters, as well as the technology for vertical gravity gradient determinations in the new gravity control were developed and tested. Also the way to assure proper gravity reference level with relation to ICAG (International Comparison of Absolute Gravimeters) and ECAG (European Comparison of Absolute Gravimeters) campaigns as well as local absolute gravimeter comparisons are described. As the new gravity control will be based on absolute gravity determinations, metrology plays an especially important part of the whole project. Integral part of the project are proposals of re-computation of old gravity data and their transformation to a new system (as second order network) as well as a definition of gravity system as “zero-tide” system.