Upgrade of the YerPhI polarization Lidar System for using Polarization of the Elastic and Raman Backscattered Beams

Abstract

A powerful two-frequency lidar system using polarized beams has been developed at YerPhI. The system is completed with laser beam polarization changers and nitrogen and water Raman channels for investigation of the influence of atmospheric electric fields on the elastic and Raman backscattered beams polarization. At present, the system is being tuned for measuring vertical atmospheric backscatter profiles of aerosols and hydrometeors, analyze the depolarization ratio of elastic backscattered laser beams and investigate the influence of external factors on the beam polarization. Laser light that is reflected from the air and from clouds carries information on density profiles, aerosols and electrical fields. Applications of this system will be the investigation of the electrical state of the atmosphere during thunderstorms [1-3] on Mt Aragats, and, possibly the monitoring of the atmosphere at the site of the upcoming Cherenkov Telescope Array (CTA). CTA is expected to provide unprecedented sensitivity for gamma ray detection in the energy range of 30 GeV to 300 TeV. To fully exploit the potential of the telescope system it is important to characterize the optical and electrical properties of the atmosphere. A lidar system for the continuous monitoring of the atmosphere is the tool of choice.