Theoretical study: Influence of different energy sources on the cusp neutral density enhancement

Imposing a Poynting flux of 75 mW/m² in the cusp within the model increases the neutral density by 34%. The direct heating from 100 eV, 2 mW/m² soft electron precipitation produces only a 5% neutral density enhancement at 400 km.

However, the associated enhanced ionization in the F-region from the electron precipitation leads to a neutral density enhancement of 24% through increased Joule heating. Thus, the net effect of the soft electron is close to 29%, and the combined influence of Poynting flux and soft particle precipitation causes a more than 50% increase in neutral density at 400 km, which is consistent with CHAMP observations in extreme cases.