Geoscience Reference
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approximation (or tides can be assumed alternatively), and the temperature and
concentrations of the neutral components are taken from the empirical thermo-
spheric models (see foregoing). We also use these models to obtain the initial
spatial distribution of the neutral concentrations and temperature. As for wind, we
use zero velocity as the initial condition. To obtain a stationary solution we need
to integrate the modeling equation system until the results of integration remain
practically unchanged when containing the integration. Usually, to reach it, several
days (geophysical but not computing time) of integration are required.
Lower Ionosphere (D, E, and F1 Ionospheric Regions)
In this section the following parameters of D, E, and F1 ionospheric regions
are calculated: the total concentration of the molecular ions n (XY C ) D n (NO C ) C
n (O 2 C ) C n (N 2 C ), ion and electron temperatures T i and T e and the molecular ion
velocity V (XY C ) for the height range from 60 to 175 km (for T i and T e ) or 520 km
(for n (XY C )and V (XY C )). The following equations are solved:
@n XY C =@t D Q XY C L XY C
.3n i k=2/@T i =@t D P iQ C P iT C P iT
.3n e k=2/@T e =@t D P eQ C P eQ C P eT C P eT
n i m i g r .n i kT i / X
in in n. V i V / C en i . E C V i B / D 0 (4.11)
r .n e kT e / C en e . E C V e B / D 0
n e D n i D n XY C
In these equations Q (XY C ), L (XY C ) are the production and loss rates of the
molecular ions taking into account ionization by solar EUV direct and scattered
radiation, ionization by precipitating electrons, ion molecular reactions and dis-
sociative recombination; P iQ is the rate of the Joule heating of the ion gas;
P iT and P iT are the rates of the heat exchange between ion and electron and
neutral gases; n e is the electron concentration; P eQ and P eQ are the rates of
heating of the electron gas by photoelectrons and by precipitating magnetospheric
electrons, respectively; P eT D P iT ; P eT is the rate of the elastic and inelastic
exchange of heat between electron and neutral gases; m i is ion mass; g is the
vector of gravity acceleration; in n i D ni n n ; e is the electron charge; and E ,
B are the electric and magnetic fields. More information about the terms of
Eqs. 4.8 , 4.9 , 4.10 , 4.11 ,and 4.12 can be found in Namgaladze et al. ( 1988 )and
Brunelli and Namgaladze ( 1988 ).
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