The use of the A10-022 absolute gravimeter to construct the relative gravimeter calibration baselines in China

Abstract

The A10-022 absolute gravimeter is utilised to measure the gravitational acceleration (g) for the first time at the 24 sites of the six relative gravimeter calibration baselines (the required absolute standard uncertainty for 10 µGal, 1 µGal = 1 × 10−8 m s−2) in China. The A10-022 was firstly used in long-term indoor observations and compared with a FG5 absolute gravimeter. The analysis of the data indicates that the standard deviation of the measurements was 4.7 µGal, the maximum peak-to-peak gravitational acceleration was 16.9 µGal at the laboratory and the offset compared to the FG5-232 absolute gravimeter was less than 4 µGal. The expanded uncertainties of A10-022 are approximately 22.0 µGal combining the uncertainty of the KCRV (Key Comparison Reference Value), the stability of the reference absolute gravimeter (FG5-232 in this case) and the bias measured during the comparison. Since 2011, the experiment has been implemented at the Lushan (LS) relative gravimeter calibration baseline to detect the feasibility and technical requirements of the A10 in field absolute gravity measurements. The gravitational acceleration was measured using the A10-022 at five new calibration baselines in 2012. Finally, all of the data from the A10-022 were adjusted to the height (25 cm) of the CG-5 relative gravimeter to compare with the results of gravity differences from the CG-5 at the six baselines. The results indicate that the average bias and the standard deviation of the differences between the A10 and the relative gravity differences measured by CG-5 were 5.1 µGal and 2.8 µGal, respectively. The expanded uncertainty of the A10-022 measurements covers the average biases between the A10-022 and CG-5 for each calibration baseline.