Open AccessCore–mantle relative motion and coupling
Author(s) -
Vanyo J. P.
Publication year - 2004
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2004.02296.x
Subject(s) - mantle (geology) , geology , geophysics , geodesy , earth's magnetic field , core–mantle boundary , geodynamics , inner core , dissipation , polar motion , physics , earth's rotation , magnetic field , seismology , tectonics , quantum mechanics , thermodynamics
SUMMARY Core motion induced by lunisolar precession of the mantle is analysed and compared with experiments and Earth observations. First‐order motion has the core axis lagging the mantle axis in precession by a small angle. This misalignment of the axes results in core–mantle relative velocities and displacements over the core–mantle interface as second‐order flow. A third‐order flow seen in experiments consists of nested fluid cylinders concentric with the core axis. First‐order motion can be compared with westward drift and energy dissipation. Second‐order motion can be compared with Earth observations using geomagnetic data, although its complexity may require numerical studies for detailed analysis. A specific lag angle and corresponding surface motions are suggested for comparison with Earth data leading to an apparent need for magnetic coupling between the core and the mantle.