Dust surface density of the big-grain population (top panels) and midplane temperature (bottom panels). (a) Model with α = 2 × 10⁻³, Σ_g = 4.1 g cm⁻², ϵ = 0.01 at the ring. (b), (c) Models with α = 7 × 10⁻⁴ and with different radial resolutions. In these models small grains’ surface density is 100 × higher than that in model (a). The small grains’ densities are marked by gray solid curves and gas surface densities are marked by gray dashed curves.