Simultaneous profiling of O_3 and NO_2 in the lower troposphere by multiwavelength differential absorption lidar

摘要

Vertical concentration profiles of O_3 and NO_2 in the lower troposphere were measured simultaneously using a multiwavelength differential absorption lidar (DIAL) system based on a pair of Nd:YAG pumped dye lasers each capable of emitting two wavelengths on alternate pulses. A mixture of Rhodamine 590 and Rhodamine 610 dyes and second harmonic generation was used to generate wavelengths 288.2 nm (on) and 293.5 nm (off) for O_3 measurement, and sum frequency mixing of LDS765 dye laser radiation with Nd:YAG fundamental was used to generate wavelengths 448.1 nm (on) and 446.8 nm (off) for NO_2 measurement. O_3 profiles of approximately 30-50 ppb and NO_2 profiles of 0-20 ppb were obtained for vertical range 1500-2500 m. The measurement error was estimated to be <6 ppb for 150 m range resolution, or <0.9 ppm-m, for both O_3 and NO_2.