a) The GOES X-ray flux during the period 06 April 2003 20:00−15 April 2003 10:00, showing events that occurred in AR 10330 and elsewhere. b) The original time series obtained from NoRH images. The Mt. Wilson classification for AR 10330 is also shown. c) The dominant periods in the range P = 50−120 min, obtained with all three of the methods for computing the power spectrum. The error bars on the global wavelet spectrum were obtained using the full width at half maximum (FWHM) of the corresponding spectral peak. d) The power for each Fourier component in the range P = 50−150 min for each day. In panels c) and d), the points for each day have been plotted at the midpoint of each signal.