Incoherent Scatter Radar Probing of the 60-100-km Atmosphere and Ionosphere

All current incoherent backscatter radars can make mesospheric or D region measurements (60-90-km altitude) under at least some conditions. This paper, which is tutorial in nature, develops the basic concepts of incoherent scatter radar measurements in the D region and the conditions under which measurements are possible are derived and shown for each radar. Conditions examined include overall system sensitivity, electron and ion spectral line widths and power distributions, and time/height averaging effects. The appropriate form of the radar equation is derived and calibration of the radar system is discussed along with the various aspects of signal processing involved. Total power only and combined total power and ion line spectral measurements are described in terms of ease of use, applicability to various radars, and parameters of aeronomic interest derivable from the measurements.