Fig. 4
From: Recovery of the 6-year signal in length of day and its long-term decreasing trend
Comparison of the |W g f(a, b)| spectrum from a original LOD series and b the AAM effect (motion term + mass term) has been removed, on 1.6–6.7-year scales. The black lines refer to “ridgeline”, and the location of “ridgeline” shows the instantaneous periodic of the target signals. We can recover the target 6-year signal through extracting the wavelet transform coefficient real part values that the “ridgeline” corresponds to, from the NMWT spectrum, without inverse transformation, directly and quantitatively