Chemical turbulent transport for run C5 at 𝒩 = 10 and Pr = 10⁻³ (left panels) and for the unstratified run C0 (right panels). (a,b) Radial distribution of the horizontally averaged mean chemical concentration at the times t − t₀ indicated in the legend. The first three times cover the diffusive phase of the transport. (c,d) Variance σ² of the mean chemical concentration as a function of t − t₀. The dashed line is defined by the time average of dσ²/dt evaluated over the diffusive phase of the transport (orange shaded background). The vertical dotted line marks the time t − t₀ = τ_M/τ_Ω after which the meridional flow is expected to dominate the transport. Here τ_M is the meridional flow timescale estimated as explained in the main text. The upper horizontal axis displays time scaled in units of the eddy turnover time τ_eddy.