Study On The Characteristics Of Conductivity And Scintillation Of Radio Wave In High-latitude Ionosphere

On the basis of theoretical study on ionospheric electrodynamic, and electromagnetic wave propagation in random media, space weather parameters, such as solar activity index and geomagnetic index, effects on the characteristics of the ionospheric conductivities and scintillation, have been studied in this dissertation. The main works are as follows:Firstly, the expression of conductivities is derived by using the current density equation and momentum equations. So the Pedersen conductance and Hall conductance(perpendicular to the direction of the magnetic field) are simulated on theory. Then, the characteristics of conductivities with the change of space weather parameters and the global morphological characteristics of the height-integrated conductivities are analyzed.Secondly, the height-integrated conductivities of the polar ionosphere are calculated, based on a self-consistent model of the polar ionosphere, which takes into account the ionization of the precipitation electrons with different energy spectrums. Maxwellian distribution and corrected Maxwellian distribution are assumed for the energy spectrum of the precipitating particles. The results show that the relative magnitude of the conductivity deduced using the different energy spectrum of the electrons also depends on the average energy.Thirdly, based on the weak scintillation phase screen theory and signal intensity power spectra theory, which have been studied by Rino and Fremouw, we present a scintillation climatological model for high-latitude ionosphere, which makes use of IRI model, irregularity anisotropy model and the phase screen propagation model. As a result, the diurnal and seasonal variations of the scintillation intensity index 4S are simulated on theory and discussed successfully. Meanwhile, to speculate in the cause-effect mechanisms producing scintillations over high latitudes, The limited data from GISTM(GPS ionospheric Scintillation and TEC Monitor) receivers at hight latitude regions over northern hemisphere are got. And the method adopted is the ground based scintillation climatology statistical algorithm which produces maps of scintillation occurrence to investigate ionospheric scintillations scenario in terms of geomagnetic coordinates. The results show that, at high latitudes, the scintillation strength is relatively weak, and less incidence. In the disturbed days, the response of amplitude scintillation is more sensitive. In addition, the study of total electron content relative variation shows more important significance scintillation of radio wave.