Using WGM2012 to Compute Gravity Anomaly Corrections of Leveling Observations in China

Gravity Anomaly Correction (GAC) is a very important term in leveling data processing. In most cases, it is troublesome for field surveyors to measure gravity when leveling. In this paper, based on the complete Bouguer Gravity Anomaly(BGA) map of WGM2012, the feasibility of replacing in-situ gravity surveying in China is investigated. For leveling application, that is to evaluate the accuracy of WGM2012 in China. Because WGM2012 is organized with a standard rectangle grid, two interpolation methods, bilinear interpolating and Inverse Distance Weighted (IDW) interpolating, are proposed. Four sample areas in China, i.e., Hanzhong, Chengdu, Linzhi and Shantou, are selected to evaluate the systems bias and precision of WGM2012. Numerical results show the average system bias of WGM2012 BGA in west China is about -100.1mGal (1mGal=10-5m/s2) and the standard deviation is about 30.7mGal. Tests in Shantou indicate the system bias in plain areas is about -130.4mGal and standard deviation is about 6.8mGal. All these experiments means the accuracy of WGM2012 is limited in high mountain areas of western China, but in plain areas, such as Shantou,WGM2012 BGA map is quite good for most leveling applications after calibrating the system bias.