Results of the EMD analysis. Left panel: example of IMFs ϕ_j(t) for sample 1 (black lines). The bottom plot (red line) represents the residual r_n(t). For better readability, only odd IMFs have been plotted. Central panel: average timescale ⟨τ_j⟩ of each IMF of sample 1 as a function of the mode j. Error bars represent the 95% confidence bounds. The dashed line is a least square fit obtained from the relation ⟨τ_j⟩=αγ^j. Right panel: IMF variance Var(ϕ_j) as a function of the average period ⟨τ_j⟩ for sample 1, with the associated 95% confidence bounds. The dashed line represents the relation Var(ϕ_j)∼⟨τ_j⟩^2ℋ, being ℋ the Hurst number (see the list for all intervals in Table A.1).