Barium Ion Lidar: Analysis of a lidar system for measuring temperatures in the middle thermosphere (200-500 km)

Resonance scattering techniques have enjoyed considerable successes in probing the upper atmosphere. Temperature lidars have used the hyperfine structure of the sodium resonance lines to measure temperatures at high resolution in the mesospheric sodium layer (80-100 km) [Fricke and von Zahn, 1989; Senft et al., 1994]. An iron lidar has been proposed to use the Maxwell-Boltzmann distribution of electronic states in two resonance lines to measure temperatures in the same altitude region [Gelbwachs, 1994], However, higher altitudes remain inaccessible due to the lack of a suitable naturally occurring resonance scattering target. In this paper we examine the hyperfine structure of the barium ion (Ball) and consider lidar probing of an artificial barium ion cloud as a method of measuring temperature in the middle thermosphere (200-500 km).