基于重力卫星数据探测核幔边界动态过程信号

Dynamic Process Signal of Core-Mantle Boundary Based on GRACE Satellite Observation Data

摘要:

使用GRACE（Gravity Recovery and Climate Experiment）重力场数据，联合多源数据模型剔除地表过程的重力信号，以分离得到核幔边界处包含液态外核流体运动特征的重力信号，同时根据CHAOS-7地磁场模型重建核幔边界与地球表面的地核地磁场变化，以此为基础使用主成分分析（PCA）与独立主成分分析（ICA）方法对重力信号与磁场信号进行统计分解，得到2种信号的时变模态与空间模态，对比分析2种信号分解结果的相关性，研究表明，重力信号第3模式的时变模态与磁场信号第2模式的时变模态相关性较好，同时，其空间模态反映了太平洋低纬度地区较为明显的东西向“偶极子”形式的变化特征，与地磁场二阶导数在太平洋地区的空间变化特征相对应，在2014年以后重力信号的时变模态与磁场信号二阶导数的时变模态均表现出相同的线性快速变化特征，与现有的研究成果相符合。

Abstract:

Based on the Gravity Recovery and Climate Experiment （GRACE） data， this paper attempts to eliminate the gravity signals of surface processed and separate the gravity signals containing the movement characteristics of liquid outer core fluid at the core-mantle boundary from the raw data. According to the CHAOS-7 geomagnetic field model， the core geomagnetic field changes on the core-mantle boundary and the surface of the earth are reconstructed. It decomposes the gravity and magnetic signals using principal component analysis （PCA） and independent principal component analysis （ICA）， and then compares and analyzes the correlation between the two signal decomposition results. The time-varying characteristics of the third mode of the gravity field signal have good correlation with the time-varying signals of the second mode of the magnetic field signal. Meanwhile， their spatial modes reflect the obvious change characteristics of an east-west aligned “dipole” form in the low latitude area of the Pacific Ocean， corresponding to the spatial change characteristics of the second mode of the geomagnetic field in the Pacific region. After 2014， the time-varying modes of both gravity signals and the second-order conductivity of magnetic field signals exhibit the same linear and rapid change characteristics， which is also consistent with existing research results.