The research team combined satellite gravity measurements from the GRACE mission with core magnetic field information from the CHAOS-7 geomagnetic field model. By separating the core mass transfer contributions from GRACE global gravity data using various global hydrological models, they analyzed how changes in the gravity field relate to temporal variations in Earths magnetic field. The comparison focused on the main principal components of both fields, revealing that the variation trends in the second time derivative of the core magnetic field closely match those observed in the gravity field.
Using GRACE observations, the researchers detected pronounced gravity field variations with periods of roughly 4.6 to 8.6 years. These gravity variations show a strong association with the core magnetic field, indicating that part of the gravity signal reflects processes occurring within Earths liquid core rather than solely surface mass redistribution. In parallel, the team identified periodic signals with substantial power on interannual to decadal timescales in the first six components of the CHAOS-7 radial secular acceleration, consistent with earlier findings on core dynamics.
Previous studies have suggested that dynamic processes in the core could account for a measurable fraction of observed gravity field changes, possibly up to about 10 percent. The new correlations between gravity and magnetic field components strengthen the case that core mass transfer contributes to the global gravity field and that these deep-Earth processes can be probed using geodetic observations. This connection underscores the importance of joint analyses of gravity and magnetic data for understanding large-scale mass redistribution inside the planet.
A major challenge is that gravity observations are dominated by signals from surface processes, such as hydrology, ice mass changes, and ocean dynamics. To isolate the contribution from the core, the authors used a wide range of global models to remove these surface effects from the GRACE data. Despite these efforts, uncertainties and imperfections in the surface models remain a key limitation, making it difficult to unambiguously extract the relatively small signature of core dynamics.
The study highlights that more accurate modeling and removal of surface mass variations will be essential for clearly detecting the gravity imprint of core processes. As surface models improve, geodesy may be able to confirm and quantify the fraction of gravity field variability arising from the deep interior. Such progress would enable more reliable monitoring of core mass transfer and its role in Earths long-term mass and angular momentum balance.
Identifying clear signatures of core processes in gravity and other geodetic observations is crucial for advancing the study of core dynamics and their links to global geophysical fields. By demonstrating strong correlations between gravity field variations and core magnetic field behavior, this work provides a new perspective and an important foundation for future investigations. Further exploration of how core dynamics drive global mass redistribution and surface deformation will contribute to a more comprehensive picture of Earths large-scale mass dynamics and internal evolution.
Research Report:Detecting the signal cycle of the deep Earths dynamic processes based on GRACE satellite and CHAOS-7 model data
Related Links
School of Geodesy and Geomatics at Wuhan University
The Physics of Time and Space
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