气溶胶激光雷达比的迭代反演

Retrieve of Lidar Ratio of Aerosols by Iteration

基于Fernald法研究了激光雷达比设定值与激光雷达有效探测范围内气溶胶光学厚度之间的函数关系。针对函数的连续性,提出了以光学厚度为收敛判据,采用二分法反演低层气溶胶激光雷达比的新方法。2014年7月下旬,利用太阳光度计和西安理工大学自主研发的拉曼-米氏激光雷达对西安局部地区大气进行了实验观测,并利用所提出的方法进行了数据反演。实验结果表明,西安局部地区气溶胶激光雷达比在观测期间比较平稳,基本为44或45。降雨当天,受大气湿度影响,激光雷达比值较大为51。利用激光雷达米氏散射回波信号和太阳光度计探测数据,提出了采用迭代反演算法开展气溶胶激光雷达比精细反演新方法,对研究气溶胶光学特性的精细反演算法具有重要的意义。

Based on Fernald method, the function relation between the set value of the lidar ratio and the optical depth of aerosols within the lidar detection range is studied. In view of the continuity of the function, the new algorithm for retrieving low layer arosol slidar ratio is proposed, in which the dichotomy is used and the optical depth of aerosols is the convergent criterion. In late July 2014, the sun photometer and the self-developed Raman-Mie lidar are used to detect the atmosphere in Xi′an. Then the proposed algorithm is used to retrieve the lidar ratio and the extinction coefficient. The experimental results show that, the lidar ratio of aerosols in Xi＇an is relatively stable during the observation period, the value is 44 or 45. Due to the impact of atmospheric humidity the lidar ratio is larger in the day of rain, the value is 51. The fine retrieving of aerosols lidar ratio is accomplished by iteration, and in the iteration only the Mie scattering signal of lidar and the detection data of sun photometer are used. This is very important for studying the fine retrieve algorithm of aerosol′s optical characteristics.