Structure of supra-arcade EUV emission in terms of spatial frequency. The power spectrum of any vertical slice in the time-distance diagram (panel c of Figs. 2–5) is fitted with a power-law function. The temporal variation of the power-law index γ_s is shown in the left panels. The orange bars indicate the 1σ uncertainty estimates in the fittings. The power spectrum of the time-distance diagram collapsed along the time axis is shown in the right panels.