(a) Top-of-atmosphere Galactic cosmic ray spectrum at 1 au at 200 Myr. Spectra for a slow (dotted black line), medium (dashed red line), and fast (dot-dashed blue line) solar rotation rate. The LIS is shown by the solid grey line. The enhanced LIS shown by the dot-dashed grey line is discussed in Section 4. The spectrum for the fast rotation rate has been multiplied by 10² to allow all of the spectra to be shown within a reasonable range on the same axes. (b) Top-of-atmosphere solar cosmic ray spectrum at 1 au at 200 Myr for a slow, medium, and fast solar rotation rate. The linestyles represent the same scenarios as in the Galactic cosmic ray spectra. The green line represents the fit of the observed spectrum Reeves et al. (1992) of the solar energetic particle event measured at Earth in October 1989.