Fig. 5

Incident electron energy spectra (left) and their ion production rate in the atmosphere (right) over Syowa Station obtained from the PHITS simulation. The red lines represent broadband electrons associated with discrete auroras in model A, the blue lines represent the diffuse pulsating auroras in model B, and the black lines represent the energetic electrons in model C. Peak HEP and XEP omnidirectional flux values are depicted by diamonds. The contributions of X-rays are shown by dotted lines