ULF-Sounding of Magnetosphere and Earth - Hydromagnetic Waves in the Magnetosphere and the Ionosphere - page 338

at the minimum of ρ S ( x ). If δ i lesser than the thickness of the atmosphere h
then the atmospheric field decreases so rapidly that there is no contribution
of the ground resistivity into ρ S .
In the reflected FMS-wave the horiz ont al wavenumber on these scales ex-
ceeds the Alfven wavenumber k A = k 0 √ ε m = ω/c A . For a reflected FMS-wave
the impedance Z is

k 0
k 2 Z = .

− k A

At the minimum of ρ S ( x ) the value of k k A . Then impedance

k 0
k ,

Z ≈

and

8 π
Tc 2 δ i .
It is evident that it is possible to define the scale size of the half-width of the
FLR-region δ i by measuring ρ S ( x ).
The asymmetry of ρ ap ( x )-curves is connected only to the wave-phase ve-
locity in the FLR-shell. At large distances from the axis, the curves ρ S ( x )
flatten out at an asymptotic value. By measuring ρ S ( x )( ω )itispossibleto
reconstruct the geoelectrical profile ρ g ( z ).

2

ρ S = T | Z | ≈

References

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