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

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.

Key words:geodesy;GRACE (Gravity Recovery and Climate Experiment) mission;time variable gravity;core-mantle boundary;mass transfer