Fig. 4.
From: Cosmic ray and solar energetic particle flux in paleomagnetospheres
(a) Magnetospheric field lines of the magnetic field of a zonal dipole, (b) particle impact regions on the Earth (proton energy 4 GeV, g 01 = 30000 nT), (c) cutoff latitudes and (d) impact area. Particles reach the Earth (100 km above the surface) in regions ϑcutoff ≤ ϑ ≤ 90°, where ϑcutoff is the cutoff latitude. The impact area indicates how many percent of the Earth’s surface are penetrated by energetic particles.