A. Litvine et al., ION COMPOSITION MEASUREMENTS AND MODELING AT ALTITUDES FROM 140 TO 350 KM USING EISCAT MEASUREMENTS, Annales geophysicae, 16(10), 1998, pp. 1159-1168
This work aims at processing the data of CPI and CP2 programs of EISCA
T ionospheric radar from 1987 to 1994 using the ''full profile'' metho
d which allows to solve the ''temperature-composition'' ambiguity prob
lem in the lower F region. The program of data analysis was developed
in the CEPHAG in 1995-1996. To improve this program, we implemented an
other analytical function to model the ion composition profile. This n
ew function better reflects the real profile of the composition. Secon
dly, we chose the best method to select the initial conditions for the
''full profile'' procedure. A statistical analysis of the results was
made to obtain the averages of various parameters: electron concentra
tion and temperature, ion temperature, composition and bulk velocity.
The aim is to obtain models of the parameter behaviour defining the io
n composition profiles : z(50) (transition altitude between atomic and
molecular ions) and dz (width of the profile), for various seasons an
d for high and low solar activities. These models are then compared to
other models. To explain the principal features of parameters z(50) a
nd dz, we made an analysis of the processes leading to composition cha
nges and related them to production and electron density profile. A ne
w experimental model of ion composition is now available.