Upper left: normalised flux for the RSG HD 95687 (grey), as observed with VLT/AMBER for the K − 2.1 µm bands. Our initial best-fit model with β = −1.10 and γ = 0.45 is shown in red, corresponding to the parameters of the density profile by Harper et al. (2001). The final best-fit model with β = −1.60 and γ = 0.05 is shown in green. Upper right: same as the upper left panel, but for the K − 2.3 µm band. Lower left: same as the upper left panel, but for the |V|² and a baseline of B = 60.8 m. Lower right: same as the lower right panel, but for the K − 2.3 µm band and a baseline of B = 63.2 m. The best-fit model for β and γ can reproduce the water features in λ = 2.29–2.5 µm with a better accuracy than our initial best fit.