Rossby number vs. the mean latitude of active regions. Each black point represents the best match between the observation and the simulated LaDAR in a Ro bin (the green dashed line in Figure 3). The blue point is obtained by the upper envelope of the sini–flaring activity relationship in Figure C3. The Sun is marked with a red ⊙ symbol. The uncertainty of the mean latitude is ±7°, which is the same as the Sun. The uncertainty of Ro represents the range of each Ro bin used to fit the sini–flaring activity relationship.