基于超导重力数据的地球固态内核平动振荡的高分辨率时频分析

项目名称： 基于超导重力数据的地球固态内核平动振荡的高分辨率时频分析

项目编号： No.41304067

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 天文学、地球科学

项目作者： 王迪晋

作者单位： 中国地震局地震研究所

项目金额： 25万元

中文摘要： 地球固态内核的平动振荡是地球自由振荡的基本简正模之一。受地球自转的影响，它将分裂成包括赤道面正向、自转轴方向和赤道面逆向振荡三部分，对这三重分裂谱峰的有效检测将为研究地球液态外核和固态内核边界层精细结构及其密度分布特征提供有效约束。本课题将利用全球分布的超导重力台站数据检测固态内核平动振荡的三重分裂。课题在超导重力仪噪声水平分析的基础上，合理选取全球分布的超导重力台站数据，并利用具有时频依赖特性的气压导纳值，更为有效地消除重力观测中的气压噪声，同时基于高分辨率时频分析方法提取地球固态内核平动振荡的特征参数，包括振荡的激发时间，本征频率和品质因子，并计算内核边界处的密度跳跃，为内、外核密度结构提供有效约束。最后结合相关地球物理观测，探寻地球固态内核平动振荡的激发源，并初步讨论其激发机制。

中文关键词： 超导重力仪；地球固态内核平动震荡；气压改正；噪声水平；经验模态分解

英文摘要： The translational oscillation of the Earth's solid inner core (also called the Slichter modes) is one of the elementary normal modes of Earth's free oscillations. Under the influences of earth rotation, it can be divided into 3 components, which are the retrograde equatorial mode, the axial mode and the prograde equatorial mode respectively. Effective detection of the splitting Silchter triplets can provide constraints for detailed structure and density distribution of the Earth's liquid outer core and solid inner core. This proposal will search the Slichter triplets with globally distributed superconducting gravimeters data. Based on the analysis of noise level of superconducting gravimeters, the superconducting gravimeter data will be reasonably selected, and temporal-frequent dependent admittances of atmosphere pressure will be utilized to efficiently remove the noise of gravity observations induced by local atmosphere pressure. Meanwhile, time-frequent analysis with high resolution will be employed to estimate characteristic parameters of the Slichter modes, including excitation time, eigen-frequency and quality factor, and then the density jump at the inner core boundary will be calculated to provide effective constraints for density structure of the Earth's inner and outer core. Finally, combined with othe

英文关键词： superconducting gravimeters；Earth's solid inner core translational oscillation；pressure correction；noise level；empirical mode decomposition