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decay more slowly. It seems clear that energy is being transferred out of larger
scales and into small scales analogously to neutral turbulence. Hysell and Kelley
(1997) discussed this process in terms of a three-wave interaction, one of which
is the damped small scale structure. They also created a structure balance model
of the form
d
k
d
k
D
eff
k
2
δ
δ
2
)
)
2
γ(
k
)
n
(
k
=
n
(
k
to see if classical diffusion represented by a constant value of
D
eff
can explain the
observations. To carry out these integrals they created an anisotropic irregularity
model
|
δ
2
/
k
0
n
|
+
k
2
k
0
1
k
1
k
0
<
k
<
k
2
(4.32)
k
x
/
1
/
+
where
k
2
k
z
with
a
x
in the zonal direction and
a
z
vertical. This model is
meant to represent the spectra from the outer scale,
k
x
+
=
λ
o
=
(
2
π/
k
0
)
=
60 km, to
some inner scale
. Projected in the
a
x
direction the spectrum has two
power law regimes with
k
−
1
behavior changing to
k
−
3
form at the wave number
k
1
. Projected in the vertical, this model has a spectral slope that ranges from
λ
2
=
(
2
π/
k
2
)
−
1
s
−
1
and use observed values for
k
1
and
k
2
, the integrals can be carried out and solved
for
D
eff
:
10
−
4
to
−
2. If we take the observed value of
γ(
k
)
to be constant at
−
(
2
×
)
ln
2
k
1
/
k
0
D
eff
=−
γ
(4.33)
k
1
k
2
Livingston et al. (1981) have shown that
λ
1
≈
1000m. Using
k
2
=
2
π/
80
from Fig. 4.2b yields
2m
2
D
eff
=
/
s
(4.34)
=
which is higher than the classical electron diffusion coefficient for
T
e
1000K
500 s
−
1
but less than the typical ion diffusion coefficient.
and
ν
ei
=
4.5 Convective Equatorial Ionospheric Storm Summary
Great strides have occurred concerning convective ionospheric storms. Reason-
able hypotheses exist for the entire range of observed structures spanning at least
six orders of magnitude in spatial scale (0.1-105m). In order of descending scale,
these are the possible contributing processes:
1. Gravity wave seeding and electrodynamic uplift (
λ>
200 km)
2. Shear effects (200 km
>λ>
20 km)
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