Development of a high-spectral-resolution lidar for accurate profiling of the urban aerosol spatial variations

A high-spectral-resolution lidar system at a wavelength of 355nm has been developed to accurately profiling of spatial variations of optical properties of aerosols, particularly for urban aerosols, Asian-dust and cirrus clouds, at Xi'an, China. Rayleigh- and Mie-scattering components by atmospheric molecule and aerosol respectively are separated by use of a high-resolution Fabry-Perot etalon. A vibration Raman line of water vapor at 407.5nm is filtered by a high-resolution grating for measurement of water vapor density. The solar background is blocked by using the grating and narrowband filter. As a result, the water vapor density and the main aerosol optical properties, such as the extinction coefficient, backscatter ratio/coefficient and optical depth, are obtained accurately without needs of assumption condition. Preliminary experiment shows that the system has the capability of making measurement up to a height of 15km for aerosol optical properties.