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tokens: β is examined. 3.1. Analysis of 100 minute Intervals Some examples of the spectra calculated with Blackman–Tukey and Morlet wavelet methods are shown in Figure 1 . The position of the peak in the signature toward higher frequencies is consistent with both methods. The Morlet method yields a smoother time-averaged spectrum than does the Blackman–Tukey method. Figure 1 (a) is a case where the two methods closely follow one another through the signature. About 30% of all cases have signature peaks within 20% of each other. More cases show a greater difference in magnitudes of the peak value such as those in Figures 1 (b) and (c). The rare case is shown in Figure 1 (d). Only about 4% of cases have a relative difference in peaks that are more than 80%. In no case did the sign of the signatures disagree. Figure 1. Sample magnetic helicity spectra σ m calculated with the Blackman–Tukey (black line) and Morlet wavelet (magenta, gray line) methods. Wind spacecraft data are employed in this figure and all subsequent figures. Intervals evaluated come from 2004 December 1 to 2005 December 31. In this figure, panel (a) shows an interval starting on 2005 January 10 17:47 UTC, (b) 2005 January 3 22:21, (c) 2004 December 29 17:25, and (d) 2005 January 16 18:25. The positions of the peaks in the signatures ν MW and ν BT are close for each interval. The corresponding scatter plot in Figure 2 shows that the data points cluster tightly along the line of equal values. In 3 of 289 intervals, the signature was absent from the Morlet wavelet spectrum (e.g., Figure 1 (d)), so the peak position could not be obtained. Markovskii et al. ( 2016 ) had established for the peak positions determined by the Blackman–Tukey method that the position in wavenumber based on the solar wind speed convecting the structure correlates with an inverse scale based on β 1/2 . Since the Blackman–Tukey method agrees with the Morlet wavelet method with respect to signature position, the correlation with this inverse scale is obtained with either method. Figure 2. Scatter plot of the magnetic helicity signature position calculated with the Blackman–Tukey ( ν BT ) and Morlet wavelet ( ν MW ) methods. The values of the signatures were not equal to each other in each interval. Figure 3 displays the scatter plot of the signature magnitude . The average absolute difference between σ BT and σ MW is 0.07, which can be regarded as an uncertainty in the measured peak value. Nevertheless, statistically, the results of the two methods are not much different. Figure 3. Scatter plot of the magnetic helicity signature magnitude calculated with the Blackman–Tukey ( σ BT ) and Morlet wavelet ( σ MW ) methods. Figure 4 plots the distribution functions of for each method. The distributions show comparable maxima and spreads. A student’s T-test (Trumpler Weaver 1953 ) calculation found that the means of each distribution are very likely the same (probability equals 0.82). The Blackman–Tukey distribution extends