Two-dimensional power spectrum P(k, ν) of the horizontal velocity at a height z₀ = 0.7H for the simulation with Pr = 0.01 (gray shades). To reduce random noise, the data were binned to the spectral resolutions Δk = 50/R and Δν = 0.2 μHz. The grayscale is saturated to highlight the peaks near ±ν₀. For reference, the red curves correspond to the dispersion relation observed on the Sun (Langfellner et al. 2018), together with the full widths at half maximum of the power peaks (red shades).