I Basic discussion about the ionosphere

[HCD]

The region of the ionosphere with highest electron density is where molecules and atoms are being ionized by photons radiated directly from the Sun. Is the rest of the ionosphere staying ionized mainly due to interactions with the free electrons and recombination photons that spread out from this region? Or is it something else?

Also, how accurately can we model the behavior of the ionosphere by treating it as a plasma but not considering its interaction with the magnetic field generated by the Earth and the Sun?

 

[jasonRF]

The region of the ionosphere with highest electron density is where molecules and atoms are being ionized by photons radiated directly from the Sun. Is the rest of the ionosphere staying ionized mainly due to interactions with the free electrons and recombination photons that spread out from this region? Or is it something else?

The UV from the sun ionizes atoms along the entire path. Of course there is recombination all the time, and on the night side the electron density depletes to some degree. Some portions of the ionosphere can last a long time, even at night, due to the specific chemistries involved at the given altitudes ("sporadic E layers").

Not that there is also ionization from precipitating high energy electrons and protons. The lower layer of the ionosphere (D layer) has very complicated chemistry that comes into play when trying to understand the electron density. I cannot give details - what little I used to know I forgot many years ago (my research was on magnetospheric physics).

Have you tried googling this?

Also, how accurately can we model the behavior of the ionosphere by treating it as a plasma but not considering its interaction with the magnetic field generated by the Earth and the Sun?

The behavior of the ionosphere is very strongly effected by the magnetic field; if you ignore it you cannot understand much about ionospheric dynamics.

It is also strongly effected by collisions with neutrals (~ 1% of ionosphere is ionized) and hence neutral winds and waves. It is also effected by the dynamics of the magnetosphere, which in turn interacts with the sun's "atmosphere" (solar wind, interplanetary magnetic field). It is very complicated, and the behavior at different latitudes is very different, mostly due to the Earth's magnetic field geometry.

jason