Development of a multispectral Raman and fluorescence lidar to study the atmospheric aerosols chemical composition.

PAWELKO E; RISTORI P; SALVADOR J; OTERO L; PALLOTTA J; QUEL E

Workshop; VIII Workshop on Lidar Measurements in Latin America; 2015

The Lidar Division of CEILAP is developing a lidar (Light Detection and Ranging) to study the chemical composition of atmospheric aerosols in Argentinean Lidar Network. The instrument works with fluorescence, elastic and inelastic scattering in order to characterize the atmospheric particles in real time and with high spatial, temporal and spectral resolution. The transmission system is implemented by a Nd:Yag laser which emits in its first three harmonics (1064, 532 and 355 nm) at 10Hz. Reception is performed with two Newtonian telescopes. The main telescope has 50 cm diameter area and it is used to collect the fluorescence and Raman backscatter in coaxial arrangement with the laser beam. The second telescope has 20 cm diameter and it is used to recover Rayleigh and Mie backscatter in biaxial setup, with 532 nm orthogonal polarization. The Raman and fluorescence signals generated by laser interaction (532 or 355 nm) with the molecules composing atmospheric aerosols are processed with a multispectral acquisition system. The multispectral device consists of a Crossed Czerny-Turner spectrometer, a 32 channels hybrid photomultiplier and a photocount detection system which works at 15 m spatial and 4.5 nm spectral resolutions. This method allows to recover Raman and fluorescence spectrum within the atmospheric boundary layer and the first kilometers of the free atmosphere with temporal resolution better than an hour. The instrumental setup and the first aerosol studies in Buenos Aires region are presented and discussed.