Rocketborne Rayleigh lidar for in situ measurements of neutral atmospheric density.

We describe the design of a small Rayleigh scattering lidar for launch on a sounding rocket as well as the first, to our knowledge, in situ measurements of neutral number density performed with a rocketborne lidar in the mesosphere. The aim of the experiment is to study the dynamics of the neutral atmosphere with emphasis on turbulent structures and gravity waves. The altitude resolution of the density profile is better than 10 m. The uncertainty is 0.3% below 55 km and better than 1% to an altitude of 65 km. The lidar technique meets the requirement of measurement of total molecular density outside the shock front surrounding the supersonic payload, which is necessary for precision measurements of neutral atmospheric density. We have compared different component technologies and design approaches and show performance calculations for two electro-optical systems. The first system has laser and detector components that were available in 1993, the second has new solutions that became available in 1995. The second system has a signal-to-noise ratio that is five times higher than the first and employs a pulsed high-power laser diode array as the transmitter and a large-area avalanche photodiode as the receiver.