Relative frequency distributions of horizontal flow speeds computed with time cadences Δt = 10–480 s (bottom to top) and Gaussian sampling windows with an FWHM = 400–1800 km (left to right). The three vertical lines mark the position of median v_med (solid), mean (long-dashed), and 10th percentile v₁₀ (dash-dotted) values of speed. The frequency distributions were normalized such that the modal values correspond to unity, i.e., major tickmarks are separated by 0.2 on the ordinate. The speed distributions cover the range 0.0–4.0 km s^-1, i.e., major tickmarks are separated by 1.0 km s^-1 on the abscissae.