Articles | Volume 32, issue 12
https://doi.org/10.5194/angeo-32-1495-2014
https://doi.org/10.5194/angeo-32-1495-2014
Regular paper
 | 
09 Dec 2014
Regular paper |  | 09 Dec 2014

Energy exchange and wave action conservation for magnetohydrodynamic (MHD) waves in a general, slowly varying medium

A. D. M. Walker

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Short summary
The equation for conservation of wave action is explicitly derived for magnetohydrodynamic waves in a plasma that varies slowly in space and time. Together with generalized ray-tracing equations, it is equivalent to a WKBJ solution of the problem and allows the computation of energy exchange between wave and background plasma as well as the variation of the amplitudes of the field components along the ray. The method is illustrated by application to simple examples.