A method primarily used to determine emission features of the auroral spectrum can be used to test the effects of electron precipitation on the ionosphere at F-layer heights, namely ionization rate estimation. Using a model of the angular distribution for the primary electron stream, one can compute ionization rate height profiles from a given energy spectrum. This ionization rate can serve as an indicator for modification of the ionospheric conditions by the electron precipitation for heights from 100 to 500 km, i.e. most importantly at F-layer heights above 180 km.
The actual formula used for this thesis is based on original work by Rees
[Ree63]. An empirical function for the energy absorption of an electron
beam in matter was derived by Lazarev [Laz65] and related to
the energy distribution of an electron beam as it travels through air layers
of different mass. A formula was obtained for computing the ionization rate
at various levels in the upper atmosphere during injection of electron beams
of various energies. The Lazarev model has advantages over that of Rees, since it
requires knowledge only of density, depth, energy and flux and is simpler to
calculate. The ionization rate 
at some depth x
(corresponding to the penetrated mass) is given by the following expressions:
where 
is the intensity of the electron beam,
is the energy of the electrons in the beam, 
is the average energy necessary to achieve
a single ionization (34 eV for air), 
is the density of the medium.
Since x and are height dependent, an atmospheric model can be used to
give estimates of their values over a broad range of heights. Thus
In the actual calculations, density and depth profiles derived from the
MSIS86 model were used.
To estimate the total ionization rate due to a particular energy spectrum at
a given height h, one has to simply integrate over all energy channels
available:
More recently, the occurrence of F-layer patches due to soft-electron
precipitation has been confirmed by Watermann et al.
[WdN92, WLd 
94]. These comparisons of
incoherent scatter radar and DMSP satellite measurements show patches
produced by the direct entry of magnetosheath electrons into the
magnetosphere followed by precipitation into the upper F-layer.
Nakajima et al. [NFRO93] observed suprathermal
electron bursts at low energies that are very
localized (approximately 20-30 km along the satellite path
at satellite altitudes of 
) .