Observed Properties of Planetary Ionospheres

Abstract

Information on the ionosphere of Earth has accumulated for the past four decades. Originally, electron density was the only primary quantity observable by groundbased radio techniques. During the last two decades information on other physical parameters of the ionosphere, such as charged particle temperature (T _e , T _i and ion composition (m _i ), as well as measurements of the ionizing radiations and the neutral atmosphere have become available. Satellites have provided a global picture of these parameters while at selected locations, groundbased incoherent backscatter radars have made possible the study of the time variations of these parameters as a function of altitude. In addition, sounding rocket experiments have provided direct measurements of many ionospheric parameters as a function of altitude, especially in the lower ionosphere.