Variations of the Reference Evapotranspiration and Aridity Index Over Northeast China: Changing Properties and Possible Causes

Figure 7

Morlet wavelet transformation of annual ET₀ from1965 to 2017 over Northeast China. (a) The ET₀ time series applied for the wavelet analysis. (b) The local wavelet power spectrum of (a). The thick black contour designates the 5% significance level against red noise and the cone of influence (COI) where edge effects might distort the picture is shown under a thin black curve. (c) Fourier power spectrum of annual ET₀ (solid). The dashed line is the 95% confidence spectrum. (d) Scale-averaged wavelet power over the 2–8 yr band for annual ET₀ (solid). The dashed line is 95% confidence level (The method cite from [35, 49].

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