Search for the Splitting of the Slichter Mode Based on the Global Superconducting Gravimeter Observations

Observations of the Slichter mode can help us constrain the inner structure of the Earth, while the detection of it is still open. In this study, we chose 11 Superconducting Gravimeter (SG) records from nine SG stations, and based on the optimal sequence estimation (OSE) method to search for the Slichter mode triplet. We used the synthetic records to further confirm the validity of OSE, and then use OSE to process the chosen SG records, which were preprocessed using conventional procedures. For residuals that may still contain high-order tide signals in the new sequences obtained after using OSE, we subtracted them from the sequences to improve the identification of the target Slichter mode signals. Our experimental results show that there are no possible signals corresponding to the claimed Slichter modes by Smylie (1992), whereas one possible signal set is suggested by this study. The periods of one set were: 4.310±5.7×10^-3(m=-1), 3.914±6.4×10^-3(m=0), and 3.642±5.1×10^-3(m=+1) hours. We consider that this signal set might be the splitting signals of the Slichter mode. However, further confirmations are needed.