The Fourier transform remains one of the most popular spectral methods in time‐series analysis, so much so that the word “spectrum” is virtually equivalent to “Fourier spectrum” (Huang et al., 2001). This method assumes that a time series extends from positive to negative infinity (stationarity) and consists of a linear superposition of sinusoids (linearity). However, geophysical signals are never stationary and are not necessarily linear. This results in a trade‐off between time and frequency resolution for nonstationary signals and the creation of spurious harmonics for nonlinear signals. We present an open‐source implementation of the Hilbert–Huang transform (HHT),...

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