Vertical mass distribution of H, deuterium inH isotopologues, CO, HCO⁺, and DCO⁺ as a function of the radius. The color-filled stripes show the vertical location of the 25, 50, and 75 mass percentiles (bottom border, median line, and top border, respectively). Half of the total molecular gas mass is located within the corresponding stripe. The dotted contour lines show the gas isodensities from 1 × 10⁻¹⁸ to 1 × 10⁻¹⁴ g cm⁻³ with a logarithmic step of 10^0.5, which is thesame as in the top panel of Fig. 1. Left panel: reference model (R), middle panel: gas-poor gap model (A), and right panel: gas-rich gap model (B). The location of the gap is shown as a hatched background. When molecules are co-spatial, their mass distributions overlap (e.g., as in the case of deuterated isotopologues of H in the model (A)).