'Making waves in the core of the Earth' by Oliver Bardsley (Cambridge)

Duration: 49 mins 5 secs

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Description:	Talk given by Oliver Bardsley (CUED) at Department of Engineering, University of Cambridge, 26 May 2017, as part of the CUED Fluids seminar series. The talk discusses wave motions in the Earth's outer core, focusing on properties of these waves that may encourage dynamo action.


Created:	2017-06-22 17:21
Collection:	Cambridge Engineering Dept Fluids Seminars
Publisher:	University of Cambridge
Copyright:	Oliver Bardsley
Language:	eng (English)
Keywords:	MHD; geodynamo; alpha^2 dynamo; dispersive; anisotropic; ray tracing;


Abstract:	I make the claim that the outer core of the Earth, a rapidly-rotating, electrically-conducting ocean vigorously stirred by convective upwellings, is a breeding ground for a diverse zoo of wave motions. These are highly dispersive (since propagation velocity depends on wavelength), anisotropic (due to the rotation axis and local magnetic field direction), caustical (or “self-focussing”), heterogeneous (due to a spatially-varying field), dissipative (owing to the field’s diffusive nature), and non-linear (necessarily, if they are to alter field topology). I address all but one of these peculiarities, unearthing some interesting phenomena along the way, and perhaps opening a small window onto planetary core dynamics – specifically the mechanisms which may encourage dynamo action.

Abstract:

I make the claim that the outer core of the Earth, a rapidly-rotating, electrically-conducting ocean vigorously stirred by convective upwellings, is a breeding ground for a diverse zoo of wave motions. These are highly dispersive (since propagation velocity depends on wavelength), anisotropic (due to the rotation axis and local magnetic field direction), caustical (or “self-focussing”), heterogeneous (due to a spatially-varying field), dissipative (owing to the field’s diffusive nature), and non-linear (necessarily, if they are to alter field topology). I address all but one of these peculiarities, unearthing some interesting phenomena along the way, and perhaps opening a small window onto planetary core dynamics – specifically the mechanisms which may encourage dynamo action.

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