Simulation And Statistic Analysis On Mid-Latitude Sporadic E-Layers

Sporadic E-layer always attracts the attention of lots of experts. This paper does research on the characteristics and the forming mechanism of the mid-latitude sporadic E-layer from statistics of observed data and numerical simulation. Therefore we firstly build a theoretic model of the mid-latitude ionospheric E layer as the background of Es, and the diurnal, seasonal and solar variation tendencies of electron and ion densities in the ionospheric E layer are obtained. Through comparing the Es data from more than twenty stations in East Asia year by year, month by month and station by station, we attain the temporal and spatial variation tendencies of the peak of the Es occurrence. Using the mechanism of vertical and horizontal wind shear, we simulate the forming process of the mid-latitude sporadic E led by tides and planetary waves. Furthermore, the forming process of the sporadic sodium layer, which is closely correlated with Es, is also simulated.The major work in this paper has been carried out in the following three aspects: The first part deals with theoretic model of the mid-latitude ionospheric E layer. To research into the background of Es, we build a theoretic model of the mid-latitude ionospheric E layer. Through computer numerical simulation, the temporal and altitudinal variation tendencies of electron and ion densities can be obtained from the continuity equations of the four main component ions i.e. NO+, O2+, O+ and N2+. Considering the disadvantages of the previous models, we further discuss the influence of some important factors such as secondary ionization, fluxes at wavelengthsλ<150?, photoabsorption cross section and distribution of NO upon the model's results.The second part deals with the mid-latitude sporadic E layer. This part is important in the whole paper and contains three aspects of work. Firstly, through comparing the Es data from more than twenty stations in East Asia year by year, month by month and station by station, we attain the temporal and spatial variation...