Electrodynamic Properties of Space - Hydromagnetic Waves in the Magnetosphere and the Ionosphere - page 30

e-O

e-m

400

e-N 2

e-i

Summer
12.00 LT

i-m

e-O 2

200

e-m
e-N 2

e-O

1E-1 1E+0 1E+1 1E+2 1E+3 1E+4 1E+5 1E+6

e-O

400 e-m

e-i

i-m

Summer
00 LT

e-N 2

e-O 2

200

e-m

e-i

e-N 2

e-O

1E-1 1E+0 1E+1 1E+2 1E+3 1E+4 1E+5 1E+6

Colission frequency[s-1]

Fig. 2.3. Collision frequencies of electron-ion (dots), electron-neutral (solid lines),
ion-neutral (dashed) versus height. Top frame: summer, noon; bottom frame: sum-
mer, midnight

Electron collision frequencies with different ionospheric species and to-
tal electron collision frequency height dependencies are shown in Fig. 2.3.
Two ionospheric models corresponding to the summer nightside and summer
dayside models were used in Fig. 2.3. Electron-neutral collisions ν en has a
dominant role up to 170 km during the day and 200 km at night. At higher
altitudes, the ionospheric plasma is strongly ionized. The main contribution
to the total ν e comes from the electron-ion collisions ν ei .