Wind model adopted in this work. Panel a: schematic view of the geometry of the model. Streamlines are assumed to be straight lines launched from the disk (see Fig. 1a). The wind velocity V_j is constant and equal to 100 km s⁻¹. The wind launching region extends from R_in = 0.05 au out to R_out = 0.3 au. We focus on the chemical evolution of a representative streamline launched from 0.15 au in the disk and reduce the problem to 1D (see Sect. 4.1). Panel b: prescribed density n_H and unshielded FUV flux G₀ profile along the representative streamline launched from 0.15 au for wind solution ⓐ (see Table 3). For other models, n_H and G₀ are simply rescaled according to the Eqs. (19) and (17), respectively. Panel c: prescribed n_H ∕G₀ and n_H ∕W ratio along the same streamline. We note that due to the collimation of the flow (z₀ ≫ R₀), these ratios increase with distance by a factor of . In the absence of dust, the opacity of the gas in the visible is negligible so that the n_H ∕W ratio is expected to be the true local ratio between the density and visible field.