Wavelet results for the locations at a distance of 2.6 Mm (left panels) and 20.2 Mm (right panels) from the limb brightening height for a plume region marked in Fig. 1 in AIA 171 Å channels. In each set, the top panels show the trend subtracted (100-point running average) intensity variation with time. The bottom-left panels show the colour-inverted wavelet power spectrum with 99% confidence-level contours, while the bottom-right panels show the global wavelet power spectrum (wavelet power spectrum averaged over time) with 99% global confidence level drawn. The periods P1 and P2 at the locations of the first two maxima in the global wavelet spectrum are shown above the global wavelet spectrum.