Metallicity distribution function for stars in BW. Only sources with R_GC< 3.5 kpc are included. Top panel: MDF of the GES BW data (iDR1). Middle panel: MDF of the APOGEE data. In each case, the GMM decomposition is depicted by dashed (individual components) and solid (global profile) lines, with mean and width values in parentheses. Lower panel: MDF of the closest field to BW from ARGOS data (Ness et al. 2013). The GMM decomposition is depicted as in the other panels. For comparison, the GMM decomposition of the b = −5° strip, as taken from Ness et al. (2013), is depicted by the three Gaussian profiles, with the corresponding mean and width values quoted in parentheses.