175296.fig.006a
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175296.fig.006b
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Figure 6: Diagrams showing the continuous wavelet time-frequency spectrum for the Svalbard winter (DJF) and summer (JJA) temperature series 1912–2010. The time (AD) and frequency (yr−1) of cyclic variations embedded in the temperature data 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. Identical colour scales have been used for both diagrams to emphasise the winter-summer difference as to signal magnitude. The winter data shows the edge effect of zero padding, see, for example, the 5.2 and 9.2 yr oscillations.