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Figure 3: Diagram showing the continuous wavelet time-frequency spectrum for the Svalbard MAAT series 1912–2010 [4]. Time (AD) and frequency (yr−1) of cyclic variations embedded in the temperature data are shown along the horizontal axes. Frequencies higher than 0.25 yr−1 are not shown, corresponding to showing only periods longer than 4 yr. The vertical axis (and colour scale) shows the magnitude of the Continuous Wavelet Spectrum at a given time and frequency. The magnitude is calculated as sqrt(Re*Re + Im*Im), where Re is the real component of a given segment’s FFT at a given frequency and Im is the imaginary component. Usually the magnitude is 3-4 times the corresponding amplitude. The dotted line indicates the extent of the cone of influence, where the magnitude of oscillations may be diminished artificially due to zero padding, especially towards the ends of the time scale, see, for example, the 26 and 7.8 yr period.