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Earth's Subdecadal Angular Momentum Balance from Deformation and Rotation Data
Andrew Watkins1, Yuning Fu2, Richard Gross3
1Department of Geology, School of Earth, Environment and Society, Bowling Green State University, Bowling Green, OH, 43403, USA.
Scientific Reports
|September 15, 2018
Summary
A ~6-year signal in Earth's rotation (Length-of-Day variations) may stem from core-mantle coupling. GPS data reveal a similar deformation signal, supporting this link but requiring further investigation.
Area of Science:
- Geophysics
- Earth Sciences
- Solid Earth Physics
Background:
- Length-of-Day (LOD) variations reflect changes in Earth's angular momentum.
- A ~6-year LOD signal is hypothesized to result from core-mantle coupling.
- Core flow could induce mantle deformation, creating a detectable surface signal.
Purpose of the Study:
- To investigate the link between core-mantle coupling and Earth's surface deformation.
- To analyze a ~6-year radial deformation signal observed in GPS data.
- To model outer core flow and angular momentum changes responsible for observed signals.
Main Methods:
- Analysis of Length-of-Day (LOD) data.
- Stacking and analysis of Global Positioning System (GPS) data for radial deformation.
- Inversion of deformation data to infer outer core flow and angular momentum.
Main Results:
- A ~6-year radial deformation signal was detected in stacked GPS data.
- Inversion results showed agreement with LOD signals in some instances.
- Computed gravitational field changes due to deformation were below current data error thresholds.
Conclusions:
- The findings provide support for subdecadal core-mantle coupling.
- The observed deformation signal is consistent with core-induced mantle deformation.
- Results are not fully robust and require consideration of methodological limitations.