Top panel: normalized Fourier amplitudes for the wavenumbers , where k₁ = 2π/L_x, as functions of time from a depth of 0.6 Mm in Run C1v. The inset shows the same in linear scale. The dotted lines in the inset indicate growth linearly proportional to time. Bottom panel: Fourier amplitudes of (solid lines) and 2 (dashed lines) for runs A3h (black lines) and corresponding runs without backreaction from the magnetic field to the flow (red lines).