后向散射式激光雷达大气能见度反演方法研究

发布时间：2018-07-22 21:31

【摘要】：能见度作为较常规的气象观测要素,可以反映大气浑浊度,会给航空运输、环境监测甚至人们出行安全带来重大影响。激光雷达因其自身具备的远距离以及高分辨率探测等优势,已经成为大气探测(能见度、气溶胶分布等)领域强有力的工具。随着低能见度天气(雾、霾、云)频发,严重影响了航空飞行安全,这些天气下的能见度监测工作已成为近年来的研究热点。本文以民航实际需求为出发点,提出了基于多次散射激光雷达方程,适用于低能见度天气的斜程能见度反演方法和考虑多次散射的卷云光学特性的反演方法,并通过真实回波信号数据对提出的两种算法进行了仿真验证,给出了精确的数值解。其具体内容有以下几个方面。1.简要介绍了课题的研究背景和意义、能见度检测设备以及反演方法的发展历程。重点针对目前基于一次散射激光雷达方程的常用反演算法Klett和Fernald积分法以及多仰角法等进行了推导,并进行了仿真模拟,提出了目前低能见度天气下反演方法的不足,即忽略了对反演结果影响较大的多次散射参量的影响。2.针对上述不足,本文重点针对多次散射现象进行研究,建立并优化了多次散射传输模式,采用半解析蒙特卡洛模拟法计算多次散射分量。同时,针对比较复杂的斜程能见度的求解问题,提出了针对低能见度环境条件下的,考虑多次散射影响的组合算法。对浓雾、轻雾、霾三种天气下的真实回波信号进行了斜程能见度的反演,给出了数值解,实现了更为精准的探测。3.本文针对卷云激光雷达比等特性的反演进行了研究,提出了考虑多次散射的卷云光学特性反演方法,对受多次散射影响较大的卷云激光雷达比以及卷云消光系数曲线进行了修正,并对反演算法进行了仿真验证,表明该算法具有较高的准确度,更具应用价值。
[Abstract]:Visibility, as a relatively conventional meteorological observation element, can reflect the atmospheric turbidity, which will have a significant impact on air transportation, environmental monitoring and even people's travel safety. Lidar has become a powerful tool in the field of atmospheric detection (visibility, aerosol distribution, etc.) because of its advantages of long-range and high-resolution detection. With the frequent occurrence of low visibility weather (fog, haze, cloud), aviation flight safety is seriously affected. Visibility monitoring under these weather conditions has become a hot research topic in recent years. Based on the practical requirements of civil aviation, this paper presents an inversion method of oblique visibility based on multiple scattering lidar equations, which is suitable for low visibility weather, and an inversion method for the optical properties of cirrus cloud considering multiple scattering. The two algorithms are simulated and verified by the real echo signal data, and the exact numerical solution is given. Its specific content has the following several aspects. The background and significance of the research, visibility detection equipment and the development of inversion methods are briefly introduced. The inversion algorithms such as Klett and Fernald integration method and multi-elevation method based on the first scattering lidar equation are derived and simulated, and the shortcomings of the current inversion method in low visibility weather are proposed. That is to say, the influence of multiple scattering parameters, which has a great influence on the inversion results, is ignored. In view of the above shortcomings, this paper focuses on the study of multiple scattering phenomena, establishes and optimizes the multiple scattering transmission mode, and calculates the multiple scattering components by using semi-analytical Monte Carlo simulation method. At the same time, aiming at the more complex slant visibility problem, a combination algorithm considering the influence of multiple scattering is proposed for low visibility environment. The real echo signals of dense fog, light fog and haze are inversed in oblique range visibility, and the numerical solution is given to realize more accurate detection. 3. In this paper, the inversion of the cirrus lidar ratio is studied, and an inversion method for the optical properties of cirrus cloud considering multiple scattering is proposed. The cirrus lidar ratio and the curve of cirrus extinction coefficient which are greatly affected by multiple scattering are modified, and the simulation results of the inversion algorithm show that the algorithm has higher accuracy and more application value.
【学位授予单位】：中国民航大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN958.98

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