Iterative Method for Accounting the Lunar–Solar Tide and Changes in Atmospheric Pressure

Abstract

Obtaining the most accurate and reliable gravimetric data has always been and remains the main task of gravimetry. The purpose of the authors’ long-term research and this work in particular is to determine interference in gravimetric data caused by various external influences and to find ways to take them into account or eliminate them. The proposed method of iteratively taking pressure and tidal correction into account made it possible to increase the accuracy of single gravimetric readings to ±2 µGal. The main instruments for many years of research were relative automated gravimeters of the CG Autograv series from Scintrex; the main results obtained in this work are shown based on their example. In CG-5 and CG-6 gravimeters, the instrumental accuracy is 1.0 and 0.1 µGal, respectively. However, it cannot be said that a single reading will give the gravity increment with the specified accuracy. Relative gravimeters, in addition to the desired value, also record the device response to inertial influence, changes in meteorological factors, and its own hardware errors, which cannot be eliminated without additional information. Under the conditions of the Zapolskoye geophysical observatory in the Vladimir region, continuous gravimetric, seismic, and meteorological measurements were carried out for 8.5 months. The obtained data made it possible to analyze the possibility of partially taking the influence of the atmospheric pressure and determining the correct delta factors for 20 groups of waves with periods of 48 days or less into account. The minimum duration of the gravimetric series to obtain delta factors of waves with periods from 0.02 to 3.38 cycles per day was also estimated at 6 months.