Observed and modelled radial and vertical force field profiles as functions of Galactocentric distances. Top: rotation curve of the Galaxy. The observed rotation curve is represented by the points with error bars, which indicate masers data from high-mass star-forming regions (Reid et al. 2019; Rastorguev et al. 2017), and H I and CO tangent-point data (Burton & Gordon 1978; Clemens 1985; Fich et al. 1989). The red curve shows the analytical rotation curve expressed by Eq. (10). The contributions of the modelled disc (continuous curve), bulge (short-dashed line), and dark halo (long-dashed line) to the axisymmetric Galactic potential are also shown. Bottom: vertical force, K_z, at z = 1.1 kpc as a function of the Galactic radius. The black dots with error bars are from observation measurements by Bovy & Rix (2013), while the solid grey curve shows the K_z force radial profile at z = 1.1 kpc resulting from our Galactic model.