Scholarly record
ACCURACY ASSESSMENT OF NATIONAL GRAVITY DATA FOR GEODETIC INFRASTRUCTURE MODERNIZATION: A CASE STUDY IN BULGARIA
Abstract
The maintenance of a modern vertical reference system in Bulgaria, aligned with the European Vertical Reference System (EVRS) standards, is directly dependent on the precise knowledge of the Earth's gravity field. The research presented in this paper is motivated by the 5th cycle of the 1st order National Leveling Network (NLN) re-measurement, initiated in 2021, which involves complex observations across 55 leveling lines. The primary objective of this study is to evaluate the extent to which existing gravity resources – the digitized 1:200,000 Bouguer anomaly map and the National Geofund database – meet the strict accuracy requirements for calculating geopotential numbers and normal heights. The focus of the study is the first fully measured polygon in Southeast Bulgaria within the current 5th NLN cycle. Three 1st order leveling lines with a total length of 435 km and approximately 390 benchmarks were analyzed. The study includes a comparative analysis between the terrestrial gravity observations for each benchmark, conducted in conjunction with the leveling measurements, and the values derived from available national data, taking into account terrain corrections. Based on the formulas for determining geopotential numbers and normal heights, it is possible to assess the required accuracy of the gravimetric data and to quantitatively evaluate the impact of potential errors in the gravimetric data on the accuracy of the determined height components. The obtained results provide a basis for conclusions regarding the applicability of these data for processing precise leveling, as well as for other research purposes such as quasi-geoid modeling. The analysis of the data along the measured leveling lines suggests that the available sources (and specifically the gravity map) have the potential to satisfy the requirements for precise vertical determinations, although their reliability should be thoroughly verified. This study justifies the necessity of continuing systematic gravity measurements in parallel with the NLN re-measurement as the only reliable method for the objective assessment and verification of the entire available national resource.
Publication details
ReferencesPending
Structured references will appear here after the reference import pass. The count is preserved now so the scholarly record is not incomplete.