Variation of EUHFORIA cells volumes and radio source volume (black line) as a function of their distance from the Sun. The radio source volume points are estimated assuming spherical shape sources, with the distance between the wave vectors being sphere diameter. The blue, yellow, and red lines represent EUHFORIA cell volumes at low, intermediate, and high resolutions, respectively. The EUHFORIA cell volumes are notably smaller compared to the radio source volumes and therefore, can effectively model the regions occupied by the radio sources.