Analysis and Results from ISR Observations of Lower Ionosphere

The D and E regions lie in the lower ionosphere region of 60～110km height. This region is influenced by solar radiation, cosmic noise radiation, atmospheric electrodynamics and many factors, and there exists a variety of incredible variation characteristics. Even in the magnetically quiet day, atmospheric electrodynamics can make a significant effect on this region except solar radiation. In the D region, there exists radio waves strong absorption, which can influence the transmission of high frequency radio waves. Electron and ion density can be obtained from the Incoherent Scatter Radar (ISR) Arecibo, located at Puerto Rico. ISR data can be used to study the movement characteristics of the lower ionosphere in mid-latitude, and get the electron density curves changing with time and height, which present obvious diurnal changing phenomenon. The spectrum of the data is analyzed to probe diurnal effects of electron density changes. Besides the electron density height profiles have been drawn, and observe obvious plasma descending from the base of F-layer to E region. The layer structure characteristics of the lower ionosphere and electron density changing show that there exists different degree of disturbance. By analyzing the influencing factors it is concluded that the atmospheric tides and the acoustic gravity waves can cause disturbance to lower ionosphere, which is coupled with the atmosphere in certain degree.