Upper panel: summed up logarithmic powers of the periodograms of the individual segments from Fig. 4. The solid blue curve shows a fourth order polynomial fit. Lower panel: exponential power of the upper panel with the polynomial fit subtracted. Peaks above the arbitrarily chosen significance limit of 0.5 h₁ (dashed red line) are considered as significant, and used as a measure of DR in the following. In this picture the harmonics (P₁/ 2 and P₁/ 3) are also more pronounced.