Relative frequency distributions for the horizontal plasma velocities corresponding to different optical depths of log τ = −1, 0, and +1, which are depicted as long-dashed, dashed, and dash-dotted curves, respectively. The three vertical lines mark the position of median v_med (solid), mean (long-dashed), and 10th percentile v₁₀ (dash-dotted) values of speed at an optical depth of log τ = 0. A frequency distribution (solid) for LCT flow velocities was stretched by a factor of about three so that the root-mean-square deviation from the profile with log τ = 0 was minimal. The LCT input parameters were image scale 80 km pixel^-1, time cadence Δt = 60 s, and a Gaussian sampling window with an FWHM = 1200 km.