Figure 4.

Median altitude profiles of nightside ${\text{O}}_2^{+}$, NO⁺, O⁺, and ${\text{CO}}_2^{+}$ during times of low and high ionizing electron flux. The solid lines show median profiles for high ionizing electron flux (<10⁶ eV/cm²/s/sr) and the dashed lines show median profiles for low ionizing electron flux (<10⁶ eV/cm²/s/sr). The most significant effects of electron impact ionization are seen below 200 km, where distinct peaks in the ${\text{O}}_2^{+}$, O⁺, and ${\text{CO}}_2^{+}$ profiles are present when the electron flux is high, but absent when the electron flux is low.