Dependence of the magnetic-field contribution ℱ_B to the angular-momentum flux on the radial proton bulk speed U_r. We show the measurements of ℱ_B as points and overplot the linear fit to Eq. (5) as a black line. All measurement points have horizontal and vertical error bars, which are small due to the time-averaging. The fit parameters are given in Table 2. The magenta squares represent the measurements of ℱ_B during the time of the compression region (CR) on 2020-09-06.