Panel a: normalised AR profiles with and without reversal relevant to AR 2363 (magenta dash-dot-dot-dot line) and AR 2340 (blue solid line; see Fontenla et al. 1988), respectively, 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 as a function of v_w calculated considering each chromospheric profile. Triangles, squares, and asterisks: see Fig. 3. Panels c and d: same as in panels a and b, but concerning the AR 2340 profile (blue solid line; Fontenla et al. 1988) and the normalised flare profile (green dash-dotted line; Lemaire et al. 1984), respectively.