Panel a: normalised parametrised chromospheric profiles reported in Fig. 2; Auchère (2005; blue solid line) and Kowalska-Leszczynska et al. (2018; green dashed line at minimum and red dot-dashed line at maximum), overlapped with a normalised Gaussian coronal profile (black dotted line) computed by setting the coronal H I temperature at 1.5 × 10⁶ K, considering θ = 0°. Panel b: Doppler factor relative to the profiles shown in panel a. Triangles, squares, and asterisks: see Fig. 3.