We consider an inviscid and perfectly conducting fluid sphere in rapid rotation and permeated by a background magnetic field. Such a system admits normal modes in the form of torsional oscillations, namely azimuthal motions of cylinders coaxial with the rotation axis.We analyse this system for a particular background magnetic field that provides a new closed form normal mode solution. We derive Wentzel-Kramers-Brillouin-Jeffreys (WKBJ) approximations to the normal modes, and focus particularly on the reflections that take place on the rotation axis and at the equator. We propose a procedure to calculate the reflection coefficients and we discuss the analogy of our findings with well-known seismological results. Our analytical results are tested against numerical calculations and show good agreement.
CITATION STYLE
Maffei, S., & Jackson, A. (2016). Propagation and reflection of diffusionless torsional waves in a sphere. Geophysical Journal International, 204(3), 1477–1489. https://doi.org/10.1093/gji/ggv518
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