Geophysical research: article

L. Zheleznyak
Schmidt Institute of Physics of the Earth, Russian Academy of Sciences
Journal: Geophysical research
Tome: 21
Number: 4
Year: 2020
Pages: 70-81
UDK: 550.831.015:550.831.23
DOI: 10.21455/gr2020.4-5
Full text
Keywords: Earth’s gravitational field, marine gravimetry, relative gravimeter, processing of marine gravimetric surveys
Аnnotation: The operating experience of the Chekan-AM marine gravimetric complex showed that the actual measurement error in difficult weather conditions of the survey can exceed the calculated one. This is due both to the excess of the permissible inertial accelerations and to the fact that when processing the primary data, the effect of the influence of vector of inertial accelerations is not fully taken into account. Theoretical substantiation and experimental study of the source of error was carried out. The fundamentally known corrections made to the measurements are refined due to the fact that when the device is installed the plane of rotation of the proof mass is extended in azimuth relative to the center plane of the vessel. This setting is not optimal. Experimental studies were carried out using areal survey materials. In this case, the inertial accelerations recorded by the gravimeter and accelerometers during the survey are used as test signals, instead of usually set by the corresponding stands. The survey was performed using a system of parallel working profiles and secant control lines, which allows obtaining a number of residuals at the intersection points. The study of the dependence of the magnitude of the residuals on the disturbing accelerations made it possible to obtain its analytical expression and experimental confirmation. To improve the accuracy, corrections should be introduced into the measurement results in accordance with this expression. The result of the study is confirmation that the cause of the additional measurement error is the azimuthal turn of the elastic system of the gravimetric sensor. To eliminate it, it is necessary to include in the measurement processing program the calculation of the correction according to the readings of each of the quartz systems and accelerometers along both roll axes. In this case, the measurement accuracy is significantly increased and the range of permissible weather conditions increases.