Establishment of the new gravity reference frame of Kazakhstan (QazGRF)

Abstract The article presents the results of establishing a new national gravimetric reference frame of Kazakhstan (QazGRF) based on absolute gravity measurements. The work was carried out during two field campaigns in 2023 and 2024 for zero-order and first-order stations, respectively, with each campaign lasting no more than three months. As a result, 74 primary absolute stations were created, and around each of them, within a radius of up to 100 km, secondary points were built–ranging from 1 to 20 depending on the order and local conditions. In total, the QazGRF comprises 218 primary and secondary stations. The gravity at the secondary points was determined by relative gravimetry, and the vertical gravity gradient was measured at each absolute station. The work followed the requirements for establishing the International Terrestrial Gravity Reference Frame (ITGRF). Data were processed using both standard software and specially developed packages for the adjustment of local gravimetric networks and for determining the vertical gravity gradient parameters. The mean total standard uncertainty of the gravity values at the primary absolute stations does not exceed 6.5 μGal, with the best results reaching 6.0 µGal, while at the secondary stations it does not exceed 7.7 µGal, with the best results of 7.3 µGal. This implementation represents the first realization of the national gravity reference frame of Kazakhstan using the absolute method.