System Simulation of Spaceborne and Airborne High Spectral Resolution Lidar for Aerosol Monitoring

Atmospheric aerosols play very important roles in climate change and air particulate pollution. Due to their highly variable optical and physical properties as well as to short atmospheric lifetimes and large spatial and temporal gradients, the aerosol impact on climate models and air pollution is really a complex task. Lidars based on elastic scattering have been largely used to measure aerosol spatial distribution and to derive their properties, but elastic backscatter Lidar data require the assumption of the aerosol extinction-to-backscatter ratio to retrieve aerosol optical properties profiles. To overcome this disadvantage, two main methods, High Spectral Resolution Lidar (HSRL) and Raman lidar, can be used to measure aerosol optical properties without a-priori hypotheses. Compared to Raman lidar, HSRL has the advantage of day and night measurements and can be adapted to many kinds of carrying platforms. HSRL can provide the vertical profile of aerosol extinction by separating the Mie signal by atmospheric aerosol and the Rayleigh signal by atmospheric molecules. Due to small spectral difference between Mie and Rayleigh signals, there are three difficulties: firstly, the laser source must have a narrow bandwidth, high energy and stable center wavelength; secondly, the receiver should have a very narrow spectral filter to separate aerosol scattering and molecular scattering; thirdly, the center wavelength of the receiver must be real-time locked to laser source. In order to study the influence of system parameters and to optimize their values, a system simulation of high spectral resolution lidar for aerosol monitoring has been done and will be presented in this paper. XXXVIII Meeting of the Italian Section of the Combustion Institute