利用全球分布超导重力台站探测Slichter模分裂信号

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

  • 摘要: 观测地球内核平动振荡Slichter模有助于约束地球内部结构,但其探测仍是国际性难题。基于全球分布的9个超导重力(Superconductiug Gravimeter, SG)台站的11个观测序列,利用最优序列估计(optimal sequence estimation, OSE)方法进行了探测实验。首先利用模拟的11个SG台站记录验证了OSE方法的有效性,然后将OSE方法用于剔除潮汐及气压等影响后的实测重力残差数据,但所得结果中仍残留有高阶潮波信号。针对此,利用解调过程进一步剔除了这些信号,以消除对目标信号识别的影响。最终结果表明,没有发现Smylie于1992年发表论文中所声称的观测结果,但找到了另外一组满足分裂规律的可能信号,其周期分别为4.310±5.7×10-3 h(m=-1)、3.914±6.4×10-3 h(m=0)和3.642±5.1×10-3 h(m=+1)。该组信号很可能是Slichter模三重分裂信号,但仍需进一步验证。

     

    Abstract: 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.

     

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