The method of retrieving aerosol extinction coefficient by ultraviolet lidar

Abstract

Aerosol is the main component of air pollutants. Lidar is a powerful tool to detect atmospheric aerosols. 355 nm in ultraviolet, visible spectrum and 1064 nm in near infrared are commonly used in detection, while the ultraviolet spectrum with wavelength less than 320 nm is less used. The main reason is that ozone has a certain content in the atmosphere and is strongly absorbed in the ultraviolet spectrum. Retrieving aerosol extinction coefficient from ultraviolet lidar equation is more complex than from 355 nm, visible spectrum and 1064 nm lidar equation because of the interaction of aerosol absorption, ozone absorption and atmospheric molecular absorption.The method of detecting aerosol extinction coefficient is proposed by emitting two ultraviolet lasers into the atmosphere at the same time. An iterative inversion method is designed to retrieve the aerosol extinction coefficient profile from two ultraviolet lidar equations with the ozone concentration profile as the constraint condition. In order to verify the correctness of the inversion method, the test is arranged by simulation signal.Two simulation ultraviolet lidar signals are obtained from supposed aerosol extinction coefficient and ozone concentration profiles, then, the aerosol extinction coefficient profiles in the ultraviolet spectrum are retrieved from the simulated signals by the inversion method. The results indicate that the inversion method is feasible and reliable.