基于粒子谱的多波长激光雷达近场大气光学参数校正方法

非同轴激光雷达由于存在发射激光与接收望远镜之间的不完全重叠区, 造成近场回波信号与真实大气信号不一致. 对于多波长激光雷达, 这种不一致更为突出和复杂. 然而, 近场大气是人类活动最集中的区域, 因此对多波长激光雷达近场信号进行校正, 对于了解和探究边界层大气具有十分重要的意义. 提出了一种利用粒子谱仪测量近地层气溶胶尺度谱分布并运用Mie 散射理论和低层大气指数衰减规律, 进而直接校正多波长激光雷达消光系数廓线近场信号的新方法. 通过对晴天、多云天气和雾天多波长气溶胶消光系数廓线近场信号的校正, 证明了该方法的可行性和实用性. 该方法着重考虑了多波长激光雷达比的波长依赖性和气溶胶粒子谱分布的天气相关性, 将该方法用于近地层大气消光系数廓线校正, 减少了由于不考虑这两个因素带来的消光系数廓线反演和校正的不确定性. 该方法对于研究不同天气情况下边界层内的大气气溶胶物理、光学特性具有一定的实用价值和借鉴意义.

Correction to near-range multiwavelength lidar optical parameter based on the measurements of particle size distribution

The lidar observations of aerosols under near range condition are distorted because of insufficient overlapping between the transmitting laser beam and the field of view of receiving telescope in non-coaxial lidar especially in multiwavelength lidar. However, the near-range atmosphere is closely related with human’s activity. So it is important to correct the near-range signal of multiwavelength lidar. This paper presents a novel method of correcting the near-range optical parameter of multiwavelength lidar based on aerosol particle size distribution measurements and Mie scattering theory. The near-range aerosol extinction profiles on fine day, cloudy day and foggy day are corrected. The results show that the method is convenient and feasible compared with the traditional methods. This method reduces the uncertainty of inversion and correction because the wavelength dependences of lidar ratio and the weather correlation of aerosol size distribution are taken into account. This method realizes the direct correction to near-range optical parameter of multiwavelength lidar. It is favorable and convenient to study physical and optical properties of boundary layer atmosphere by using this method. It will have a broad application and prospect.