Power spectral densities of the outward, P^out (top panel), and inward, Pⁱⁿ (bottom panel) corresponding to Elsässer fluctuations, z^out and zⁱⁿ, for switchback (blue dashed curves) and nonswitchback (black solid curves) intervals. The spectra are plotted as a function of frequency in the spacecraft frame. The dotted and solid reference lines indicate power-law scalings proportional to f^−3/2 and f^−1.6, respectively. The power spectra corresponding to the nonswitchback intervals are multiplied by a factor of 0.1 for better visibility.