Search

Results:

Vol. 6 (2003 year), No. 1

Namgaladze A.A., Namgaladze A.N., Fadeeva Yu.V., Goncharenko L.P. and Salah J.E.
Lower thermosphere and ionosphere behaviour during a strong magnetic storm of March 31, 2001: Modelling and comparison with the Millstone Hill incoherent scatter radar measurements

The numerical global Upper Atmosphere Model (UAM) has been used for studying the lower thermosphere and ionosphere behaviour during a strong magnetic storm of March 31, 2001. A comparison of the calculation results with the Millstone Hill IS radar data obtained during this magnetic storm has been carried out. A satisfactory agreement between the measured and calculated ion temperatures, electron and ion drift velocities has been obtained. The calculated electric field variation is similar to the observed one but is twice less in magnitude. As to the neutral horizontal wind velocities, there is a large difference between the calculated values and data obtained by the Millstone Hill IS radar, down to the different signs of the wind components. This difference can be bound up to distinctions in the frequencies of the ion-neutral collisions dependent on the neutral atmosphere parameters and the ion composition, and in the electric fields measured at Millstone Hill and theoretically calculated by the UAM. The reasons of the discrepancy of the thermospheric winds simulated by the UAM and calculated at Millstone Hill have been examined. The results of this examination show that the Millstone Hill wind results are very sensitive to the measured electric field values especially when the last are so large as they were in the case, and therefore even a moderate difference between the calculated and observed electric fields may cause a significant discrepancy of the thermospheric winds simulated by the UAM and calculated at Millstone Hill.

(in English, стр.6, fig. 11, tables. 0, ref 7, MS Word 95, MS Word 95 495 Kb)

Vol. 8 (2005 year), No. 1

Doronina E.N., Namgaladze A.A., Goncharenko L.P.
Variations of thermospheric parameters above incoherent dispersion stations during geomagnetic storms of 17-19 April, 2002

Study of the geomagnetic storm influence on the Earth's thermosphere behaviour has been performed by the mathematical modelling method. Thermospheric parameters have been calculated by two ways: by solving the continuity, momentum and heat balance equations (the theoretical model UAM) and using the empirical model of the thermosphere - MSISE2000. The calculations with the UAM have been conducted in two versions with various initial conditions: in the version UAM(TM) initial conditions have been taken from the MSIS, and in the version UAM(T5) they have been taken from the quasi-steady state UAM solution obtained by 5-day model runs. The time variations of the following thermospheric parameters have been analyzed: neutral temperature, molecular nitrogen and atomic oxygen concentrations, the ratio n(O)/n(N2) and the meridional component of the thermospheric wind. The comparison of the various calculation versions has shown that the geomagnetic storm effects in the UAM are larger than in the empirical model of the thermosphere, giving better agreement with the incoherent scatter data on the ionospheric electron density.

(in Russian, стр.12, fig. 6, tables. 0, ref 25, Adobe PDF, Adobe PDF 417 Kb)