Fine-scale correction methods for large-scale gravity survey data

Performing various corrections to the measured gravity values relative to a datum plane serves as a necessary step in obtaining the values of Bouguer gravity anomalies. Currently, the various corrections of large-scale gravity survey data primarily follow the requirements and methods of regional gravity surveys. The obtained Bouguer gravity anomalies often contain false anomalies, failing to accurately interpret the relevant properties and details of targets. Moreover, there exists neither systematic research on the variable-density terrain correction for large-scale gravity survey data nor publicly available variable-density correction calculation software. Therefore, this study proposed a set of fine-scale correction methods for large-scale gravity survey data. Specifically, the traditional datum plane for various corrections was elevated. Based on the rating of density property data, the variable-density generalized terrain correction method was employed to integrally calculate the values of traditional terrain and intermediate layer corrections. The Li-Gotze96 equation was applied to integrally calculate the values of traditional latitude and height corrections, as well as the height correction value based on the custom datum plane. A new equation for calculating the value of Bouguer gravity anomalies was derived. Moreover, the universal gravity survey correction calculation software was developed accordingly. The verification based on simulated and measured data shows that these methods can significantly reduce false anomalies within the Bouguer gravity anomalies and their association with terrains, thereby highlighting the anomaly characteristics of the targets and revealing richer anomaly details.