(a) Time–distance plot of normalized v_θ. The velocity is negative upon forward propagation and positive on backward propagation of the Alfvén wave. The signal is amplified at the shock location upon each reflection, with a portion of the signal being transmitted. A standing slow shock forms at the gas-dynamic shock location and can be seen as a faint, white line after t = 2 at z = 0.5. Panel (b) shows the trapped portion of the Alfvén wave at z = 0.3. The transmitted portion is shown in panel (c) for z = 0.99.

(An animation of this figure is available.)

The video/animation of this figure is available in the online journal.