Properties of the Neutral Density in the Polar Lower Thermosphere Determined byIncoherent Scatter Radar

摘要

The properties of the lower thermospheric neutral density are investigated usingincoherent scatter radar technique. The data examined include 52 days of radar measurements from Chatanika, Alaska taken during the period 1976-1982, and one 6-day continuous period from Sonderstrom, Greenland taken during the Lower Thermospherica Coupling Study (LTCS-1) in September, 1987. The data analyzed to determine average vertical profiles of the neutral density and to characterize the tidal oscillations of the neutral density in the lower thermosphere. Techniques and software have been developed to process incoherent frequency is the received on magnetic tapes in a standard output format. The ion-neutral collision frequency is the radar-derived parameter from which one can derive neutral density in the lower thermosphere. The complicated interaction of the radar with the plasma makes it possible for so many parameters of the plasma to be determined from the backscattered spectrum of radiation. In the E-region, the ion-neutral collision frequency is fit from the autocorrelation function (ACF) under the assumption that the ion and electron temperatures are equal. But in the polar lower thermosphere, there are processes that can cause thermal disequilibrium among the ions and electrons. The dominant interaction between ions and neutrals in the lower thermosphere is and induced dipole interaction. Total neutral number densities are derived from the ion-neutral collision frequencies using this theory. Keywords: Theses. (Author) (jd)