a) The time series for the normalised intensity in 171 Å located at 10 arcsec in cross-cut No. 2 shown in Fig. 4. The time is measured in seconds from 09:00 UT on 20 January 2011. b) The wavelet plot for the time series with regions of significant power (>99%) contoured with the white line. The coloured regions show power above 95%. c) The Fourier and global powers spectra for the analysed time series.