探测气溶胶消光特性的双波长米散射激光雷达

Dual-wavelength Mie Lidar for Measuring the Whole Tropospheric Aerosols

研制了一台双波长米散射激光雷达,用来探测对流层大气气溶胶532 nm和1064 nm两个波段的消光特性及其时空分布。该雷达系统采用四个通道分别用于对流层下部和中上部532 nm及1064 nm的大气回波信号,并采用窄带滤光片,借助小孔光阑,有效压制背景,以提高系统白天探测能力。描述了该雷达系统的总体结构和技术参数以及数据处理方法。给出了合肥地区(N31°54′,E117°10′)对流层大气气溶胶532 nm及1064 nm大气气溶胶消光系数的垂直廓线及其时空分布的典型探测结果,分析了气溶胶的波长依赖指数和532nm波段的光学厚度。观测和分析结果表明,双波长具备昼夜连续观测对流层大气气溶胶的能力,可以很好地反映气溶胶粒子的时间和空间分布特征。

A new dual-wavelength Mie lidar （DWL） was developed for measuring the optical properties and their spatial and temporal variations of tropospheric aerosol at 532 nm and 1064 nm wavelength. Four channels are adopted to receive the far and n^ar range backscattefing signals at 532 nm and 1064 nm wavelength respectively. In order to enhance the capability of daytime measurement, the system employs a narrow band interference filter to separate the main backscattering signal of lidar return, including Mie backscattering signal and Rayleigh backscattering signal from all the backscattering signals including non-elastic scattering signal and solar spectrum, by using an iris to block the majority of sky background. Overall structure and specifications of the lidar are described. Lidar data processing method is also presented. The lidar system was operated at Hefei（N31~54~i EllT^10~）. The profile of extinction coefficient of tropospheric aerosol and its temporai-spatiai distribution were obtained. Optical depth and Angstrom exponent of aerosol are also discussed. The observed results show that this lidar works well day and night, and it has ability to measure the tropospheric aerosols and to manifest the temporal and spatial distributions of the aerosols with high orecision.