Orientation of the Galactic spiral arms in the present model. Norma, Scutum, Saggitarius, and Perseus arms are colored by green, blue, red, and purple, respectively. The black line shows the solar orbit, and the Galactic center region is marked in black. The four  × -markings indicate the positions at 90°, 108°, 126°, and 144°, where the CR spectra have been calculated (see Sect. 3).