Profiles of differential rotation used in this study. (a) Observed 2D profile in a meridional plane, taken from Larson & Schou (2018). (b) Simplified differential rotation profile, given by Eq. (5), used to model the observed differential rotation. The dotted black lines indicate the base of the CZ at r = 0.71 R_⊙. The Carrington rotation rate, Ω₀/2π = 456 nHz, is marked on the colour bar. (c) Cuts of observed (solid) and simplified (dashed) differential rotation profiles at fixed latitudes: 0° (red), 30° (blue), 45° (brown), and 75° (dark green). The green-shaded area denotes the CZ, the grey-shaded region the OS, and the orange-shaded region the RZ.