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Extraction of the EPP Component from the Surface EMG
Published on: December 16, 2009
The origin of geomagnetic jerks
Jeremy Bloxham1, Stephen Zatman, Mathieu Dumberry
1Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, USA. Jeremy_Bloxham@harvard.edu
Nature
|November 8, 2002
Summary
Geomagnetic jerks are abrupt changes in Earth's magnetic field secular acceleration. Our study explains these events using a combination of steady and time-varying fluid flow within the Earth's core, consistent with torsional oscillations.
Area of Science:
- Geophysics
- Earth Science
- Geomagnetism
Background:
- Geomagnetic jerks are abrupt changes in the Earth's magnetic field's secular acceleration.
- These events, occurring periodically, indicate a reorganization of the magnetic field's secular variation.
- The internal origin and core surface fluid flow dynamics of geomagnetic jerks are known, but their physical cause remains unclear.
Purpose of the Study:
- To elucidate the physical origin of geomagnetic jerks.
- To explain the abrupt changes in Earth's magnetic field secular acceleration.
- To connect geomagnetic jerks to fluid dynamics within the Earth's core.
Main Methods:
- Analysis of geomagnetic secular variation data.
- Modeling of fluid flow at the Earth's core surface.
- Spherical harmonic analysis to determine the internal origin of the phenomenon.
Main Results:
- Geomagnetic jerks can be explained by a combination of steady and time-varying toroidal zonal flow at the core surface.
- This flow is axisymmetric and equatorially symmetric.
- The proposed flow model is consistent with torsional oscillations in the Earth's core.
Conclusions:
- The physical origin of geomagnetic jerks is linked to torsional oscillations within the Earth's core.
- The findings support theoretical expectations and observations from core flow and dynamo models.
- This research provides a new dynamical explanation for geomagnetic jerks.
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