Geoscience Reference
In-Depth Information
5.1.2 On the Height of the Daytime F2 Layer
For an overhead ionization source with a highly absorbing neutral gas (E and
F1 regions), the production function has the form of a layer with a peak at some
z
=
z
0
:
q
O
+
=
q
0
exp
1
e
−
z
z
−
−
(5.5)
where
z
H
, with
H
being the vertical scale height (Rishbeth and
Garriott, 1969; Schunk and Nagy, 2000). Equation (5.5) is the Chapman func-
tion. In a steady state, the curves labeled E and F1 in Fig. 5.2 are of this form.
The predicted electron density in a quasi-steady state would have the form
=
(
z
−
z
0
)/
exp
1
e
−
z
n
z
=
q
0
α
z
−
−
(5.6)
α
where
is the recombination for molecular ions in a molecular neutral gas,
which is dependent on height only through a temperature dependence. For a
combination of E and F1 production functions and without atomic ions, the
ionosphere would have a single layer with a peak near 120 km.
The situation is quite different in the F2 or main F region. Neglecting transport,
during the day the continuity equation for the main F region for O
+
production
200
180
160
F1
140
120
E
1
F
UV(E )
E
X(E )
100
0
2000 4000
q
(cm
23
s
21
)
6000
Figure 5.2
Electron production profiles
q
(
h
)
for the E and F1 regions for vertically inci-
dent radiation at sunspot number
R
=
60. The curves refer to the following wavelength
bands: X(E), 8-140
Å
; UV(E) 796-1027
Å
;E
; F, 140-796
Å
;E
F,
total 8-1027
Å
, where 1
Å
= 0.1 nm. [After Allen (1965). Reproduced with permission
of Springer Netherlands.]
=
UV
(
E
)
+
X
(
E
)
+
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