Inversion Algorithm For Visibility Based On Backward Scattering Lidar

Visibility is an important meteorological factor to the meteorological, which reflect the degree of opacity of the atmosphere. Accurate detection of visibility is significant for ensuring civil aviation safety, even for the people travel safety Due to the characteristics of remote probing technique and high spatiotemporal resolution of lidar, it has become a powerful tool for the atmosphere sounding like visibility and aerosol distribution. With the low visibility weather(fog, haze, cloud) occurs more frequently, accurate detection of low visibility is of great significance of ensuring safety in civil aviation. In this paper, we propose inversion algorithms for determining visibility, and lidar ratio based on multiple scattering lidar equation starting from the actual demand of civil aviation. The effectiveness of the two algorithms is verified by real signals, and the study has important application value. The specific contents are mainly in the following aspects.1. The relevant background and research status of research at home and abroad of this topic are briefly described, and then visibility detection instruments and inversion methods are discussed. Focusing on current commonly inversion algorithms for example Klett and Fernald integral method and multi-elevation angles for measuring atmospheric slant integral visibility and so on, which are all based on a scattering lidar equation and these algorithms are not applied to the low visibility weather. And then we propose the key problem of the low visibility inversion, that is to solve multiple scattering effects, and the influence of multiple scattering on the results used this inversion are analyzed.2. The paper establishes and optimizes the multiple scattering transfer mode, and so a hybrid algorithm for determining the slant-range visibility in the low-visibility atmosphere is proposed, considering multiple-scattering effects. The proposed algorithm has been used for retrieving the slant-range visibility from returns of lidar under weather of fog, mist and haze.The results reflect that the method has higher precision and especially for the condition of low-visibility atmosphere the multiple-scattering effects have to be considered3. In this paper, the properties of cirrus cloud with multiple scattering are studied and the retrieval methods of cirrus lidar ratio are improved. We propose an approach for determiningcirrus lidar ratio based on multiple scattering factors and the extinction coefficients of cirrus are corrected by the factors. The experiment is carried on based on this method, using the real echo signals of lidar. It's turned out that the prosed technique has the advantages of high accuracy. Therefore, it has a promise future.