【作者】 刘君；

【导师】 华灯鑫； 李言；

【作者基本信息】 西安理工大学 ， 机械工程， 2008， 博士

【摘要】 边界层是最接近人类活动的地表层的气层,人类的日常活动直接影响到底层边界层的大气状态,边界层的物性又影响着人类的生存环境。因此研究边界层内的大气状态变化,对研究太阳辐射,地球动力学上的热量传递,解释地球温暖化现象,提高局部气象预报的准确度,进行大气污染的防治,特别对城市气象变化等研究有着很重要的意义。激光雷达作为一种主动遥感探测工具,具有探测范围大、空间分辨率高、能实时连续监测和测量精度高等特点,已广泛用于激光大气传输、全球气候预测、气溶胶辐射效应及大气环境等研究领域。论文的研究工作主要以边界层内的大气温度剖面及对流层内气溶胶剖面的光学特性精细探测技术为研究对象,重点探讨了利用转动喇曼散射激光雷达实现白天低层大气温度高精度探测的方法和关键技术;利用米散射激光雷达观测西安城区大气气溶胶时空变化特性及数据反演技术的研究;提出了高光谱分辨率激光雷达系统精确探测大气气溶胶光学特性的技术。为解决白天强烈太阳背景光及低层大气中的高密度气溶胶对激光雷达温度探测的影响,提高系统的信噪比,提出了一种新的紫外域波长转动喇曼散射测温激光雷达系统的分光方案。结合一个高光谱分辨率光栅和一个边缘反射镜有效滤除了大部分噪音信号;在2个喇曼通道中设置窄带干涉滤光片分别提取2个转动喇曼信号波长,并对剩余的米—瑞利散射光进行再次剔除,实现对噪音信号的高抑制率。理论分析与实验结果表明,所研究的系统和测试方法可以有效抑制系统噪音信号,能够实现白天低层大气温度分布的高精度测量,在激光输出功率250mJ,探测时间4分钟的情况下,温度探测误差小于1K时的探测高度白天可以达到1.8km,夜晚可以达到2.3km。针对西安城区大气气溶胶分布及变化规律的研究需要,以及沙尘暴的预警预测需求,开展米散射激光雷达大气气溶胶观测实验及光学特性的数据反演技术的研究,首次获得西安城区低层大气气溶胶浓度的高度分布数据。为实时观测气溶胶三维剖面特性,提出便携式小型可扫描的米散射激光雷达系统设计方案,用于探测对流层内大气气溶胶及卷云的光学特性以及大气水平能见度等。在分析研究现有气溶胶探测及数据反演技术的基础上,针对大气气溶胶高精度探测的难题,提出并建立了一种紫外域高光谱分辨率激光雷达系统方案。该系统利用高光谱分辨率光栅分离太阳背景光,以满足系统白天探测的要求;利用一个Fabry-Perot标准具分离出多普勒增宽的瑞利散射信号,因而气溶胶的浓度对探测结果不会产生影响;借助光栅的分光效应,该系统还能实现水蒸气的同时探测。更多还原

【Abstract】 Atmospheric boundary layer, which is closest to the surface of the earth, influences the activity of human being. The human activities in day-to-day directly affect the state of the atmospheric boundary layer. Therefore the study of atmospheric boundary layer is though of very importance for the solar radiation and heat transfer geodynamics, explanation of global warming phenomenon, improvement of local weather forecast accuracy, prevention and treatment of air pollution, especially for urban meteorological change. Atmospheric lidar, as an active remote sensing tool, has been proved to be powerful in atmospheric measurement, with a large detection range, high spatial resolution, continuous monitoring with high accuracy and real-time. It has been widely used in the research fields of laser atmospheric transmission, global climate prediction, radiation effect of the atmospheric aerosol and environment monitoring.This thesis mainly focuses on the fine detection of atmospheric temperature profiles in the boundary layer and the aerosol profiles in the troposphere. Methods and key techniques of rotational Raman scattering lidar with high-accuracy detection of lower atmospheric temperature during daytime are studied. Characteristics of Xi’an urban aerosol spatial variations are also observed and analyzed with Mie scattering lidar. A kind of high-spectral-resolution lidar for accurate profiling of atmospheric aerosol optical properties is proposed.In order to eliminate the strong solar background during daytime and high-density aerosol influence on the temperature detection in the lower atmosphere, a new spectroscopic filter is proposed for the UV temperature lidar system based on rotational Raman scattering. With the help of combination of high-spectral-resolution grating and an edge-mirror, the major portion backgrounds yielded from the solar and Mie and Rayleigh scattering are blocked. To achieve a high noise suppression rate, narrow-band interference filter is used to reject the remaining Mie-Rayleigh scattering signal in each Raman scattering channel. Theoretical analysis and experimental results show that the lidar system and the detection methods can suppress system noise effectively. And the accurate profiling of the lower atmospheric temperature during daytime can be achieved. The temperature error less than 1K is obtained up to 2.3 km for nighttime and 1.8 km for daytime measurement with 250 mJ laser pulse energy and 4 minutes observation time.For the needs of urban aerosol profiling in Xi’an and sand storms forecasting, the research of the aerosol observation experiment by Mie lidar and corresponding data procession of aerosol optical properties has been developed. The aerosol distribution data in Xi’an was given firstly. For real-time observing three-dimensional profiles of aerosol, a small portable scanning lidar system was designed to detect the optical properties of atmospheric aerosols and cirrus, horizontal visibility and so on.For fine detection of atmospheric aerosol profiles, an UV high-spectral-resolution lidar system was proposed and established on the basis of analyzing the existing technique of aerosol detection and data inversion. The system uses a high-spectral resolution grating to split solar background spatially to meet the requirement of daytime detection. Since the system uses a Fabry-Perot etalon to split out the Doppler broadened Rayleigh scattering signal, the concentration of aerosols have no influence for the detection results. By use of the diffraction effect of the grating, the system may detect the water vapor profiles simultaneously.更多还原