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Vol. 20 (2017 year), No. 1, DOI: 10.21443/1560-9278-2017-20-1/2
The photochemical theory of processes in the lower ionosphere is very complicated and up to now it is not completely developed. Therefore introduction of the effective coefficients determining the total speed of several important reactions has been widely adopted when modeling the D-region of the ionosphere. Experimental opportunities for obtaining effective recombination coefficients are rather limited. One of the methods to estimate effective recombination coefficients uses the phenomenon of a solar eclipse. The basis of this method is the idea of Appleton about similarity of the behavior of the linear inductive circuit and variations of the electron concentration in the ionosphere on a fixed height in the absence of the transport processes, the change in the rate of formation of electrons in time and the disappearance of free electrons due to recombination. By analogy with the time constant of the electric circuit Appleton called the reaction of the ionosphere on the process of ionization in the ionosphere as "sluggishness" with a characteristic time constant ?, which is also called the "relaxation time" or "time constant of the ionosphere". During 11 August 1999, 1 August 2008, 11 June 2011, 20 March 2015 solar eclipses at the partial reflection facility of the observatory "Tumanny" (69.0N, 35.7E) observations of the amplitudes of reflections of ordinary and extraordinary waves have been carried out. Using the obtained data the two-dimensional (time, height) distribution of the electron density ne at altitudes of the D-region ionosphere has been calculated. This has made it possible to obtain the behavior of the electron concentration in time at selected altitudes (temporal profiles of electron density at selected altitudes). Using the obtained experimental profiles, the effective recombination coefficients on the heights of the D-region ionosphere have been evaluated. Transport processes of plasma (for example, propagation of acoustic-gravity waves, vertical motion) during eclipses have influenced on the behavior of the temporal profiles of the electron concentration at altitudes of the D-region ionosphere. This has led to the fact that on some heights of the D-region ionosphere determination of effective recombination coefficient became impossible.
(in Russian, стр.12, fig. 10, tables. 2, ref 22, Adobe PDF, Adobe PDF 0 Kb)
Vol. 21 (2018 year), No. 1, DOI: 10.21443/1560-9278-2018-21-1
Tereshchenko E. D., Milichenko A. N., Rietveld M. T., Chernyakov S. M., Shvets M. V.
Change of the high-latitude ionosphere during heating by a powerful short radio wave of the EISCAT/Heating complex according to signals of the GLONASS satellite and the incoherent scattering radar
Results of observations of variations of temperature, electron concentration and total electron content of the high-latitude region of the ionosphere during its modification by powerful short radio waves of the heating complex EISCAT/Heating (Troms?, Norway) according to signals of the GLONASS satellites and the incoherent scattering UHF EISCAT radar (Troms?, Norway) have been provided. The geometry of passes of the GLONASS and GPS satellites for operating conditions of the heating complex in Troms? has been considered. It has been shown that during the experiments on the EISCAT/Heating complex for the study of the modified structure of the high-latitude ionosphere it is more convenient to use the GLONASS satellites. Parameters of orbits of these satellites allow researching changes of total electron content in the direction along the geomagnetic field line at the place of observation. It has been shown that during heating of the ionosphere by powerful short radio waves its structure is becoming an irregular one. Operation of the heating complex in the mode "switched on – switched off" has caused appearance of wavy variations of total electron content with the periods close to the heating period. The main features of behavior of the total electron content in the case of the continuous heating of the ionosphere in the direction of the magnetic zenith according to the GLONASS satellite are: reduction of total electron content in the central zone of the antenna diagram, i. e. in the direction of the magnetic zenith, and presence of the increased values of total electron content at the edges of the heating zone. According to the incoherent scattering radar the heating of the ionosphere by the powerful short radio wave has created the region of the increased electron temperature and electron concentration along the direction of the magnetic zenith. The behavior of total electron content according to the GLONASS satellite and the radar of incoherent scattering in many respects corresponds each other except the central part. Reasons of the mismatches have been considered.
(in Russian, стр.11, fig. 7, tables. 0, ref 12, adobe PDF, adobe PDF 0 Kb)