|
|
 |
|
|
Ann. Geophys., 16, 1159-1168, 1998
www.ann-geophys.net/16/1159/1998/
© European Geosciences Union 1998
Ion composition measurements and modelling at altitudes from 140 to 350 km using EISCAT measurements
A. Litvin, W. Kofman, and B. Cabrit
Centre d'Etude des Phénomènes Aléatoires et Géophysiques, B.P. 46, F-38402 Saint Martin d'Hères, France
Fax: +33 04 76 82 63 84; e-mail: wlodek. kofman@lis.inpg.fr
Abstract. This work aims at processing the data of CP1
and CP2 programs of EISCAT ionospheric radar from 1987 to 1994 using the
"full profile" method which allows to solve the
"temperature-composition" ambiguity problem in the lower F region. The
program of data analysis was developed in the CEPHAG in 1995–1996. To improve
this program, we implemented another analytical function to model the ion
composition profile. This new function better reflects the real profile of the
composition. Secondly, 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
concentration and temperature, ion temperature, composition and bulk velocity.
The aim is to obtain models of the parameter behaviour defining the ion
composition profiles : z50 (transition altitude between atomic
and molecular ions) and dz (width of the profile), for various seasons
and for high and low solar activities. These models are then compared to other
models. To explain the principal features of parameters z50
and dz, we made an analysis of the processes leading to composition
changes and related them to production and electron density profile. A new
experimental model of ion composition is now available.
Key words. Auroral ionosphere · Ion chemistry and
composition · Instruments and techniques · EISCAT
Full Article in PDF (1092 KB) |
|
|
