V − b correlation. Panels a–c: RTN components of b = B/(μ₀ρ)^1/2 (in black) and of proton velocity (in red). To better show the correlation, −b is plotted. The averaged value of V_R, computed over a 1 h sliding window, is removed in (a). Panel d: cross-correlation of R (black), T (red) and N (blue), calculated on ten-minute sliding windows; panel e: scatter plots of b_T and V_T, the color (from blue to red) indicates the time; panel f: power spectra of b (black) and V (red) fluctuations.