HD 1–0 integrated fluxes and 870 μm continuum flux densities for the models described in Table 4. Colours indicate various gas-to-dust ratios, where the shaded region shows the flux variations from different vertical structures. For each Δ_gd, the coloured line shows models with (ψ,h_c) = (0.3, 0.1). The crosses denote observations for TW Hya (black; Bergin et al. 2013; Andrews et al. 2012), DM Tau (purple; McClure et al. 2016; Andrews et al. 2013) and GM Aur (green; McClure et al. 2016; Andrews et al. 2013). Both the model fluxes and the observations were scaled to a distance of 140 pc.