Comparison between the entropy integral Δs_rot from Eq. (8) denoted by lines and the near-surface entropy perturbation Δs_pert (circles) from 3D rotating MUSIC models. Δs_pert is defined as 1.45 times the standard deviation of the entropy probability density function at r = r₁ = 6.75 × 10¹⁰ cm, which is at a depth equivalent to three percent of the convection zone. The simulations have colatitude extents (centred at the equator) of π/2 rad (black), 3π/4 rad (blue), and 7π/8 rad (red), respectively. In each case, Δs_pert is shown after subtracting the entropy perturbation from a non-rotating model for the sake of clarity.