Aerogravimetric measurements over Baikal

The article presents the results of the first high-precision route aerogravimetric survey, carried out in 2023 along the “cross” profile of Lake Baikal at a flight altitude of 5300 meters. The airborne gravimetric complex used in the measurements, based on the laboratory's AN-26BRL aircraft, is described. Directly above the lake water area, the largest negative value of the measured gravity field anomaly was -180.8 mGal, the horizontal gradient of the field measurement along the profile was up to 9 mGal/km in the area of the western and up to 5 mGal/km in the area of the eastern shores of Lake Baikal. The internal convergence of anomaly values on the route profile for a complex of three instruments was 0.74 mGal. For the Baikal Rift Basin, the resolution and reliability of the most current modern global models of the Earth's gravity field UGM-SGG-2, EGM2008, XGM2019 and Sandwell and Smith v32, based on satellite data, were assessed. It is shown that the standard deviations of the field along the entire profile between the values calculated from satellite models with the number of expansion coefficients of 2190 or more from airborne gravimetric observations are 9.5 - 17.9 mGal, and the maximum deviations at individual points of the route are 40-80 mGal. Using airborne gravity profile data, a comparison was made with marine gravity survey data at a scale of 1:500,000. Due to the high detail of the data along the airborne gravity profile, it was determined that the actual value of the main negative anomaly on the airborne profile is higher than that accepted for the analysis and integrated interpretation of geophysical data in the area of Lake Baikal.