新近研制了一台基于532和1 064 nm的双波长米散射激光雷达(dual-wavelength lidar, 简称DWL), 用于探测对流层大气气溶胶可见和红外波段的消光特性及其时空分布, 同时用于粒子尺度谱垂直分布特征的研究。 系统采用4个通道分别用于接收对流层下部和中上部532及1 064 nm的大气回波信号, 有效地缩短了获取大气信息的时间。 采用窄带滤光片, 并借助光阑, 将接收的激光大气回波信号谱线(米散射和瑞利散射光谱)从天空太阳背景噪声中分离, 提高系统的白天探测能力。 叙述了雷达系统的总体结构和技术参数以及数据处理方法。 利用该雷达对合肥地区(117.16°E, 31.90°N)上空的气溶胶进行了探测。 给出了对流层大气气溶胶532及1 064 nm消光系数的垂直廓线及其时空分布典型探测结果。 分析了气溶胶波长依赖指数的空间垂直分布。 讨论了对流层大气气溶胶光学厚度月变化。 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, 可以很好的反映气溶胶粒子的时间和空间分布特征。

A new dual-wavelength Mie lidar (DWL) is introduced. The DWL can be used to monitor the optical properties of tropospheric aerosol at 532 and 1 064 nm wavelength and their spatial and temporal variations, and to research aerosol size distribution with altitude. This lidar adopted four channels to receive the far and near range backscattering signal at 532 and 1 064 nm wavelength respectively. In order to enhance the capability of daytime measurement, the system employed a narrow band interference filter to separate the main backscattering signal of lidar return, including Mie backscattering signal and Rayleigh backscattering signal from the total backscattering signal including non-elastic scattering signal and solar spectrum, by cooperating with an iris to depress the majority of sky background noise. Overall structure and specifications of the lidar, as well as data processing method, were described. The lidar system has been operated in Hefei (117.16°E, 31.90°N). The profile of extinction coefficient of tropospheric aerosol and its temporal-spatial distribution were obtained. Angstrom exponent and optical depth of aerosol were also discussed. The observational results have shown that this lidar works well both during the day and at night and has the ability to measure the tropospheric aerosols and to manifest the temporal and spatial distributions of the aerosols with high precision.