北京地区大气气溶胶的激光雷达观测及反演算法研究

A Micro-Pulse Lidar Observation of Aerosol in Beijing and Retrieval Algorithm Research

利用微脉冲激光雷达在北京地区的观测,研究两种避开利用高空信号的反演算法。算法一,根据Fernald的反演算法把边界取在混合层中间某处,并结合太阳光度计的观测进行反演。通过激光雷达与同一地点自动气象站的地面观测比较验证了反演结果,表明该方案用于激光雷达的气溶胶消光系数反演是可行的。算法二,由于激光雷达近端处的信号和地面气溶胶消光系数线性相关,从而利用地面气溶胶观测数据反演雷达常数和观测期间气溶胶平均后向散射比,结果与第一种方案一致,表明利用该方法反演是可行的。最后利用这次激光雷达的观测,分析北京地区冬季一次西伯利亚高压过境时的气溶胶演变过程,将激光雷达观测与南郊观测站地面观测进行比较,并验证了激光雷达的反演结果和算法的可靠性。

The MPL observation data in Beijing is used to develop two new algorithms which will not need to refer to the low SNR signal in high altitude.In the first algorithm,the boundary in mixing layer is chosen in the Fernald’s theory.Then the lidar constant can be retrieved by combining AOD.Compared with the data from the automatic meteorological station locates in the same place,this algorithm seems viable for lidar’s extinction coefficient retrieval.In the second algorithm,since the range corrected lidar data near the surface is linear relate to the surface extinction coefficient,the visibility data in the surface could be used to calculate the lidar constant.The result of the lidar constant and the average extinction-to-backscatter ratio during the experiment period are similar to the first algorithm.In these two algorithms,the lidar constant is retrieved without using the high altitude signal.In the end,the lidar observation of a classic aerosol case when a Siberian High passes through Beijing is analyzed.By comparing the lidar observation with the Nanjiao Observation Station data,the lidar retrieval and the new algorithm are considered to be reliable.