Climatology and Variability of the Ionosphere: Incoherent Scatter Radar Observations

摘要

Ionospheric climatology and variability studies are conducted using long-term incoherent scatter radar (ISR) observations from seven sites around the world. These studies result in an empirical model system, the ISR Ionospheric Model (ISRIM), which represents local and regional ionospheric climatology and variability of the ionosphere. This paper presents some results of the ISR-based climatology and variability. It is indicated that ionospheric variability changes with height significantly, being large in the F region and small in the E region and in the topside. These changes are dependent of locations. At high latitudes, variability in Ne and Ti in the E region is obviously larger than at midlatitudes and the corresponding percentage variability may become comparable with that in the F region. It is also indicated that in the seasonal variation of the F region electron density variability, the percentage variability is smaller in summer (later summer) than in winter and spring; in the diurnal variation, it is smaller during the day than during the night. Variability is also dependent of the solar flux level. A high F10.7 corresponds to the enhanced variability in summer; the sunrise induced variability is also enhanced.