Impact of the observed chemical inhomogeneities on azimuthal variations. Upper panel: Map of the mean metallicity in the Galactic plane for Sample A, with overlaid rings of constant Galactocentric radius at R = 6, 7, 8, 9, 10, and 11 kpc. Lower panels: Median metallicity for Sample A and C (filled and open dots, respectively) as a function of Galactic azimuth ϕ for different rings in R (as specified in each panel), after the median metallicity of the stars for each ring was subtracted.