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| 1 | 深内部地球结构对内核平动振荡本征周期的影响显示文摘地球固态内核的平动振荡是地球的基本简正模之一,又称Slichter模,其本征周期大约为几个小时,与地球内部结构密切相关.为了研究影响内核平动振荡的本征周期与内部结构的依赖关系,本文利用球对称、非自转、弹性和各向同性地球模型(SNREI),通过自由振荡运动方程的数值积分,以地球模型PREM为基础,理论上系统研究了地球内部介质(包括密度、地震波速等)分布异常对Slichter模本征周期的影响.数值结果表明,Slichter模周期随着内外核边界(ICB)密度差的增加以类似于双曲线的特征显著减小,当ICB密度差从597kg·m^-3减小到200kg·m^-3时,周期增大66.44%,当ICB密度差从597kg·m^-3增大到1000kg·m^-3时,周期减小21.48%;Slichter模周期随着核幔边界(CMB)密度差的增大而缓慢增大;相对于PREM,地球模型1066A在ICB和CMB的密度差分别相差45.321%和1.132%,内部地震波速度和密度梯度也存在差异,但是,当密度差减小到1066A模型提供的数值时,得到的Slichter模周期与基于1066A获得的结果(4.599h)非常接近,差异分别只有3.762%和0.037%;表明Slichter模本征周期与地球内部介质的精细结构关系不大,而对ICB的密度差非常敏感.内、外核P波波速分布异常对Slichter模周期的影响基本相当,当内核和外核P波波速均增加5%时,Slichter周期分别减小1.02%和1.69%,P波波速分别减小5%时,Slichter模周期分别增加1.27%和1.847%,内核s波波速分布异常比P波波速分布异常对Slichter模周期的影响小1个量级;与地核相比,地幔中的地震波速异常对Slichter模本征周期的影响小1~2个量级;表明地核中地震波速异常对Slichter模周期的影响很小,目前有关Slichter模周期理论计算的差异主要来自于所采用的地球模型中内核边界的密度差的差异,本文结果可以为Slichter模的研究、探测及其对地球深内部结构的约束提供理论依据. | 江颖 徐建桥 孙和平 | 2014 | 地球物理学报2014，57，4： | 7 |
| 2 | Detection of the Inner Core Translational Triplet Using Superconducting Gravimetric Observations显示文摘Based upon seven superconducting gravimeter(SG) records of 20 000 h length after the2004 Sumatra earthquake, four methods, namely the ensemble empirical mode decomposition(EEMD),the multi-station experiment(MSE) technique, the autoregressive(AR) method and the product spectrum analysis(PSA) method, are chosen jointly together to detect the inner core translational modes(1S1). After the conventional pretreatment, each of the seven simultaneous residual gravity series is divided into five segments with an 80% overlap, and then EEMD is applied to all the 35 residual SG series as a dyadic filter bank to get 35 filtered series. After then, according to different stations and different time windows, five new simultaneous gravity datasets are obtained. After using MSE for each of the five new datasets, the AR method is used to demodulate some known harmonic signals from the new sequences that obtained by using MSE, and three demodulated product spectra are obtained. Then,according to two criterions, two clear spectral peaks at periods of 4.548 9±2.3×10-5and 3.802 3±3.2×10-5h corresponding respectively to the singlets m= 1 and m=+1 are identified from various spectral peaks,and they are close to the predictions of the 1066A model given by Rieutord(2002), but no spectral peak corresponding to the singlet m=0 is found. We conclude that the selected two peaks might be the observed singlets of the Slichter triplet. | 申文斌 丁浩 | 2013 | Journal of Earth Science2013，24，5： | 5 |
| 3 | Characteristics of tidal gravity changes in Lhasa,Tibet,China显示文摘Tidal gravity changes arise from the response of the solid Earth to the tidal forces of the Sun,Moon and planets close to the Earth,and are a comprehensive reflection of the structure and distribution of physical properties of the Earth's interior.As a result,observations of tidal gravity changes are the basis of studies on other global and/or regional dynamic processes.The characteristics of tidal gravity changes in the region of the Tibetan Plateau were investigated through continuous gravity measurements recorded with a superconducting gravimeter (SG) installed in Lhasa over a year.Through contrast measurements with a spring gravimeter LaCoste-Romberg ET20 at the same site,the gravity observations in Lhasa were scaled to the international tidal gravity reference in Wuhan.Meanwhile,the scale factor of the SG was determined accurately as-777.358 ± 0.136 nm s-2V-1,which is about 2.2% less than the value provided by the manufacturer.The results indicate that the precision of the tidal gravity observations made with the SG in Lhasa was very high.The standard deviation was 0.459 nm s-2,and the uncertainties of for the four main tidal waves (i.e.O 1,K 1,M 2 and S 2) were better than 0.006%.In addition,the observations of the diurnal gravity tides had an obvious pattern of nearly diurnal resonance.As a result,it is affirmed that the Lhasa station can provide a local tidal gravity reference for gravity measurements on the Tibetan Plateau and its surrounding regions.The loading effects of oceanic tides on tidal gravity observations in Lhasa are so weak that the resulting perturbations in the gravimetric factors are less than 0.6%.However,the loading effects of the local atmosphere on either the tidal or nontidal gravity observations are significant,although no seasonal variations were found.After removal of the atmospheric effects,the standard deviation of the SG observations in Lhasa decreased obviously from 2.009 to 0.459 nm s-2.Having removed the loading effects of oceanic tides and local atmosphere,it was found that the tidal gravity observations made with the SG in Lhasa significantly differed by about 1% from those expected theoretically,which may be related to active tectonic movement and the extremely thick crust in the region of the Tibetan Plateau.A more-certain conclusion requires longer accumulation of SG data and further associated theoretical studies. | XU JianQiao CHEN XiaoDong ZHOU JiangCun SUN HePing | 2012 | Chinese Science Bulletin2012，57，20： | 5 |
| 4 | Detection of Inner Core Translational Oscillations Using Superconducting Gravimeters显示文摘An attempt has been made to search for the translational oscillations of the Earth's solid inner core in the gravity measurements recorded with the superconducting gravimeters(SG) from the worldwide network of the Global Geodynamics Project(GGP). All the SG data were prepared and analyzed by the same method to remove accurately the signatures related to gravity tides, local barometric pressure, the Earth's rotation, the long-term trend and so on. We obtained the estimations of the power spectral densities of each residual series and the estimations of the product spectral densities in the subtidal band(0.162–0.285 cph) were obtained by using a multi-station stacking technique after further eliminating atmospheric effects. The inner core translation triplet was detected in the subtidal band. We find 6 groups of signal with high signal-to-noise ratio that are consistent with the characteristics of the triplet, and 4 groups of the results that are close to the previous studies and the differences are less than 0.92%. It implies that the groups of signatures all have the possibility to be related to the inner core translational oscillations. | 江颖 徐建桥 孙和平 | 2013 | Journal of Earth Science2013，24，5： | 2 |
| 5 | The observation of the Earth tide is irrelevant to the speed of gravity显示文摘Recently, the observations on the earth tide at Shiquanhe and Wushi were used to show that gravity propagates at the speed of light. Based on the brief review of general relativity and the Newtonian gravitational theory, we re-analyze the experiments and cannot reach the same conclusion from the observations. | HUANG ChaoGuang | 2013 | Chinese Science Bulletin2013，58，26： | 1 |
| 6 | 中国大陆PET/gPhone重力仪背景噪声水平分析显示文摘重力仪背景噪声水平分析有助于台站选址、仪器调整、检测微弱的地球动力学信号、判断仪器近期是否有检测地震简正模的能力.因此,噪声分析对于仪器数据质量评估工作具有重要意义.为评价国家重力台网PET/gPhone重力仪背景噪声水平,本文选用其中52台重力仪在2014~2017年连续4年的观测记录,对比分析了现有的地震噪声等级(seismic noise magnitude,SNM)计算方法,提出了一种改进的数据选取策略(DaySNM法),我们计算了所有重力仪在地震频段(200~600 s)的背景噪声水平,通过拟合52条功率谱密度曲线的下包络线,给出了中国大陆新低噪声水平模型(CNNLNM).结果表明:DaySNM法计算得到的SNM值更低;中国大陆SNM的变化范围为2.013(于田站)~4.654(银川站);沿海地区SNM普遍比内陆大,表明海浪脉动可能是沿海台站噪声较大的主要原因;华北地区、青藏高原东部和北部SNM较大,可能与这些地区地质构造活动频繁有关. | 苟家宁 张晓彤 江颖 周浩 魏工哲 刘子维 | 2022 | 地球与行星物理论评2022，53，3： | 1 |
| 7 | 基于旋转微椭地球模型的内核平动振荡三重谱线理论模拟与实验探测显示文摘本文基于旋转微椭地球模型,采用简正模理论计算了地球内核平动振荡三重谱线的本征周期,理论上系统研究了地球内部介质(包括密度、地震波速等)分布异常对三重谱线本征周期的影响,计算了不同的内外核密度差和地核中的不同的P/S波速对应的内核平动振荡理论三重谱线周期;利用全球分布的9个超导台站,迭积每个台站长达54个月的高精度超导重力仪数据,在亚潮汐频段(0.162~0.285cph)检测内核平动振荡三重谱线.结果发现,三重谱线本征周期对内外核边界的密度跳跃非常敏感,随着密度差的增加,以类似于双曲线的特征减小;无论是采用地球质量不变的方法还是采用浮力频率为常数的方法,计算得到的三重谱线本征周期结果相差较小,且随着内外核密度差的增大,差距逐渐减小;内、外核P波波速分布异常对三重谱线周期的影响基本相当,内核S波波速分布异常比P波波速分布异常对三重谱线周期的影响小1个量级;探测到一组信噪比较高且满足谱峰分裂特征的三重谱线的信号(0.19281,0.21456和0.24151cph),有极大的可能是来自于内核平动振荡.基于探测结果可以推断实际的地球模型其内外核密度差应该介于PREM模型和1066A地球模型之间,更接近于1066A模型. | 江颖 徐建桥 孙和平 刘子维 李辉 | 2016 | 地球物理学报2016，59，8： | 1 |
| 8 | 利用全球分布超导重力台站探测Slichter模分裂信号显示文摘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。 | 卢衍军 申文斌 潘元进 丁浩 | 2016 | 武汉大学学报(信息科学版)2016，41，8： | 1 |
| 9 | 地球内核平动振荡模研究进展显示文摘地球内核平动振荡模,即Slichter模,是地球自由振荡的基本简正模之一,其三重分裂周期是确定地球内外核密度差异的重要物理量,对于约束地球深内部密度结构具有重要研究价值。然而,Slichter模的激发机制、衰减机制以及实际探测结果至今悬而未决,具有极大争议,其本征周期的确定也成为当前基础地球物理学的一个国际性难题。首先,总结了地球内核平动振荡模的基本理论,包括其动力学方程和主要求解理论与数值方法,并概述了在不同地球模型下利用不同求解理论计算的Slichter模理论周期。其次,讨论了Slichter模的激发机制和衰减机制的主要假设与猜想,其中液核一阶压力流可能激发Slichter模至可观测水平。最后,回顾了过去30年国内外利用超导重力数据开展Slichter模三重分裂信号探测的主要研究进展,探讨了关于Slichter模探测的未来可能研究方向,即从激发机制探究、超导重力数据精细预处理和极微弱信号叠积增强3个不同角度研究突破,有望实现Slichter模三重分裂信号的可靠探测。 | 栾威 申文斌 | 2021 | 地球科学进展2021，36，5： | 0 |
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