Precision Evaluation of Continuous Observation Gravimeters Based on CEEMD Method

High-precision gravity observation is key to studying Earth’s gravity field, which reflects matter distribution and movement of matter within the Earth’s interior, on its surface, and in outer space. Compared to traditional mobile observations, continuous gravity array observations can effectively improve both accuracy and temporal resolution. The China Earthquake Administration has deployed a total of 115 continuous gravimeters, including superconducting gravimeters (SG), atom gravimeters (AG), and spring gravimeters, preliminarily establishing a continuous gravity observation network. However, the accuracy differences among different types of instruments constrain the comprehensive application of the data. To address this, it is imperative to conduct research on the accuracy evaluation of various gravimeters. This study innovatively introduces the Complementary Ensemble Empirical Mode Decomposition (CEEMD) algorithm to decompose and reconstruct the measured data from continuous gravimeters, extracting the solid Earth tide signal. Subsequently, an external conformity accuracy evaluation is performed by comparing it with theoretical tidal models, thereby achieving instrument accuracy assessment. To verify the feasibility and superiority of the CEEMD algorithm, this paper first designs a combined simulation signal experiment, in which the performance of Bessel filtering, Kalman filtering, Variational Mode Decomposition (VMD), Empirical Mode Decomposition (EMD), and CEEMD in extracting tidal frequency band signals is comparatively analyzed. Finally, these methods are applied to process observational data from three gravimeters (SG, AG, and DZW relative gravimeter (DZW)) at the Yilan station, extracting the solid Earth tide signal and comparing its external conformity accuracy with theoretical models. The results show that these algorithms can effectively extract the solid Earth tide signal, with the evaluated accuracy of the three instruments consistently ranked as follows: SG > AG > DZW. However,The CEEMD method demonstrated optimal performance in the accuracy evaluation of the three gravimeters, with the following external conformity accuracies achieved: SG: 1.83 μGal, AG: 2.59 μGal, DZW: 3.83 μGal.