Measurement of Atmospheric NO2 Profile Using Three-wavelength Dual-Differential Absorption Lidar

Lidar instruments are efficient detectors of air pollutants such as nitrogen dioxide (NO2). However, the measurement errors are not negligible due to the influence of the aerosol in the atmosphere. We present a novel lidar for measuring tropospheric NO2 vertical profiles. For improving the received powers, the emitter unit consists of two pulsed pump laser -dye laser combination, and use three wavelengths of 448.10nm, 447.20nm and 446.60 nm corresponding to the strong, medium and weak absorption of NO2 respectively. The effects of aerosol on tropospheric NO2 measurements by three wavelength (448.10 -447.20 -446.60 nm) dual differential absorption lidar (dual-DIAL) and conventional two - wave length (448.10-446.60nm) differential absorption lidar (DIAL) are theoretical analyzed, and their system err are computer simulated. Experimental results show that the three - wavelength dual - DIAL method is more effective to reduce the effects of aerosol than the two - wavelength DIAL method, and its system error is no more than 4% without correcting the aerosol effect.