Iron Boltzmann factor LIDAR: proposed new remote-sensing technique for mesospheric temperature.

We describe a new LIDAR technique for middle atmospheric temperature measurement. The proposed LIDAR exploits the Fe layer in the 80-100-km altitude region. Absolute temperatures are inferred by the use of the Maxwell-Boltzmann relationship from the ratio of LIDAR returns from mesospheric Fe atoms excited at 372 and 374 nm, corresponding to the ground-state resonance line and a thermally populated resonance line, respectively. The wavelengths of the new LIDAR are favorable for capturing Rayleigh signals from the middle atmosphere. A simulation indicates that a complete temperature profile from 30 to 100 km can be acquired with the proposed LIDAR by monitoring simultaneously the Rayleigh signals and the Fe fluorescence returns excited by the same transmitter pulse.