Ultraviolet Raman lidar for high-accuracy profiling of aerosol extinction coefficient

Abstract

An ultraviolet (UV) Raman lidar system at 354.7 nm has been developed for accurately measuring the aerosol extinction profiles. A spectroscopic filter combining a high-spectral-resolution grating with two narrowband mirrors is used to separate the vibrational Raman scattering signal of N2 at a central wavelength of 386.7 nm and the elastic scattering signal at 354.7 nm. The aerosol extinction is derived from the Raman scattering of N2 and the elastic scattering by the use of Raman method and Klett method, respectively. The derived results of aerosol extinction are used to compare the difference of two retrieval methods, and the preliminary experiment shows that the Raman lidar system operated in analog detection mode has the capability of measuring aerosol profiles up to a height of 3 km with a laser energy of 250 mJ and an integration time of 8 min.

Observations and Analysis of Relationship between Water Vapor and Aerosols by Using Raman Lidar

“…k N =k H is the system constant, which can be calibrated by comparison with radiosonde data at the same height. The aerosol extinction coefficient can be retrieved by using the vibrational Raman scattering signal of N 2 and is given as 15) …”

“…The aerosol extinction coefficient can be retrieved by using the vibrational Raman scattering signal of N 2 and is given as 15) 0 ;aer ðzÞ ¼…”

“…13,14) The intensity of the N 2 vibrational Raman scattering signal can be used to determine aerosol extinction profiles accurately without the need for arbitrary assumptions. 15) A UV vibrational Raman lidar at a wavelength of 354.7 nm has been built for daily observations of water vapor and aerosol optical properties over Xi'an, China. Continuous observations have been made of the temporal and spatial variations of atmospheric water vapor and aerosol profiles.…”