共查询到17条相似文献，搜索用时 93 毫秒
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介绍了激光雷达在气象上的作用,并在使用光子计数法的基础上利用激光雷达方程计算出了在不同高度处大气的后向散射光子.为进行激光大气探测奠定理论基础. 相似文献
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本文介绍了一台三波长米散射激光雷达系统，并用数值模拟计算的方法研究其性能。计算结果表明此系统可进行大气边界层和平流层探测。文中介绍的数值模拟方法，适用于各种米散射激光雷达性能的研究。 相似文献
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本文提出了一个参数化的多次散射激光雷达方程,该方程基于本文引出的四个因子,即几何消光因子、消光分布因子、前向散射因子和后向散射因子.前两个因子表征多次散射成分对大气消光系数分布、激光的发散角和接收视场角以及接收孔径的依赖关系,后两个因子表征多次散射成分对散射相函数的依赖关系.这个参数化多次散射雷达方程在241个数值试验中得以检验,这些试验包含很宽的大气条件和雷达几何参数,包括14个大气散射相函数,均匀和不均匀的大气消光系数分布,0.5至1之间变化的一次散射反照率,地基和空间站激光雷达两种情形.数值试验表明,在小于4的光学厚度内参数化的解和Monte-Carlo解之间的标准偏差小于27％,而本模式的计算时间比Monte-Carlo方法偏小4个数量级左右.本模式不仅适合于研究多次散射对激光回波信号和激光大气遥感的效应,而且对于考虑多次散射的激光大气探测而言,是一个合适的应用模式. 相似文献
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气象激光雷达的发展现状 总被引：8，自引：0，他引：8
激光雷达能用来测量云、雾、能见度、空中风场、大气密度和大气温度,也可以用来监测空气中的有害气体。该文介绍了用于气象探测的半导体激光雷达、微脉冲激光雷达、一般弹性散射激光雷达、多普勒激光雷达、差分吸收激光雷达和Raman激光雷达的发展现状和趋势,认为人眼安全、高重复频率和宽探测范围是气象激光雷达的发展方向。固体激光雷达的气象应用最广泛,微脉冲激光雷达能同时测量云底高度、能见度和获得大气气溶胶消光廓线,有比较好的应用前景,半导体激光雷达是测量云底高度的理想工具。 相似文献
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近红外波段凝结核性质对雨滴散射特性的影响 总被引：1，自引：0，他引：1
用M ie散射理论,在已知大气气溶胶粒子的折射率基础上,计算并讨论大气气溶胶以及在其上凝结形成的雨滴的散射相函数、散射效率因子等散射特性。结果表明,对流层中气溶胶粒子的散射能力依次为水滴,冰晶,海洋性粒子,沙尘性粒子,水溶性粒子,煤烟。对于在可溶性核上凝结形成的雨滴,海洋性核的散射能力强于水溶性核的散射能力。由不可溶性核凝结形成雨滴的散射能力依次为煤烟核、冰晶核和沙尘性核。纯水雨滴的散射能力介于沙尘性核和冰晶核之间,强于海洋性核。该结论可以为光学测雨仪器在不同地区条件下的参数设置提供依据。 相似文献
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本文提出了一个参数化的多次散射激光雷达方程,该方程基于本文引出的四个因子,即几何消光因子、消光分布因子、前向散射因子和后向散射因子.前两个因子表征多次散射成分对大气消光系数分布、激光的发散角和接收视场角以及接收孔径的依赖关系,后两个因子表征多次散射成分对散射相函数的依赖关系.这个参数化多次散射雷达方程在241个数值试验中得以检验,这些试验包含很宽的大气条件和雷达几何参数,包括14个大气散射相函数,均匀和不均匀的大气消光系数分布,0.5至1之间变化的一次散射反照率,地基和空间站激光雷达两种情形.数值试验表明 相似文献
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Lidar methods for observing mineral dust aerosols are reviewed.These methods include Mie scattering lidars,polarization lidars,Raman scattering lidars,high-spectral-resolution lidars,and fluorescence lidars.Some of the lidar systems developed by the authors and the results of the observations and applications are introduced.The largest advantage of the lidar methods is that they can observe vertical distribution of aerosols continuously with high temporal and spatial resolutions.Networks of ground-based lidars provide useful data for understanding the distribution and movement of mineral dust and other aerosols.The lidar network data are actually used for validation and assimilation of dust transport models,which can evaluate emission,transport,and deposition of mineral dust.The lidar methods are also useful for measuring the optical characteristics of aerosols that are essential to assess the radiative effects of aerosols.Evolution of the lidar data analysis methods for aerosol characterization is also reviewed.Observations from space and ground-based networks are two important approaches with the lidar methods in the studies of the effects of mineral dust and other aerosols on climate and the environment.Directions of the researches with lidar methods in the near future are discussed. 相似文献
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A state-of-the art Rayleigh and Mie backscattering lidar was set up at Gadanki (13.5N, 79.2E) in the Tropics in India. Using this system, regular observations of upper tropospheric clouds, aerosols at stratospheric heights and atmospheric temperatures in the range from 30 to 80 km were made. In this paper, the data collected during the period of 1998–99 were selected for systematic investigation and presentation. The Mie scattering lidar system is capable of measuring the degree of depolarization in the laser backscattering. Several tropical cirrus cloud structures have been identified with low to moderate ice content. Occasionally, thin sub-visible cirrus clouds in the vicinity of the tropical tropopause have also been detected. The aerosol measurements in the upper troposphere and lower stratosphere show low aerosol content with a vertical distribution up to 35 km altitude. Rayleigh-scattering lidar observations reveal that at the tropical site, temperature inversion occurs at mesospheric heights. Atmospheric waves have induced perturbations in the temperatures for several times at the upper stratospheric heights. A significant warming in the lower mesosphere associated with a consistent cooling in the upper stratospheric heights is observed particularly in the winter season during the events of sudden stratospheric warming (SSW). 相似文献
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Lidar has been used extensively in the area of atmospheric aerosol measurement. Two unknowns at the reference altitude, the lidar ratio and the backscatter coefficient, need to be resolved from the lidar equation. In the actual application, these two values are difficult to obtain, particularly the backscatter coefficient. To better characterize the optical properties of aerosols, optical thickness, and attenuated backscatter obtained by other instruments are usually used as the input for joint inversion. However, this method is limited by location and time. In this study, the authors propose a new method for aerosol retrieval by using Mie scatter- ing lidar data to solve this problem. The authors take the horizontal aerosol extinction coefficient as the con- straint to begin the iteration until a self-consistent aerosol vertical profile was obtained. By comparing their results with Aerosol Robotic Network （AERONET） data, the authours determine that the aerosol extinction coefficient obtained by combining horizontal and vertical lidar observations is more pre- cise than that obtained by using the traditional Fernald method. This new method has been adopted for re- trieving the extinction coefficient of aerosols during the observation days. 相似文献
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非球形气溶胶粒子散射特性及其等效Mie散射误差分析 总被引：3，自引：2，他引：1
为分析形状对气溶胶粒子散射特性的影响,采用T矩阵法计算了0.633μm波段(自然光)不同种类、形状的气溶胶单粒子与体散射的散射相函数,并讨论了气溶胶粒子形状畸变与等效Mie散射误差的变化规律。结果表明:粒子形状畸变对气溶胶粒子散射能量空间分布影响较大。对于单粒子,各散射角上的等效Mie散射误差并不随粒子形状畸变程度单调变化。从相对误差量级上看,形状畸变对180°散射的影响强于0°,对35°的散射影响相对较弱。对于两种非球形粒子等效方法,等表面积法优于等体积法。不同类型的非球形气溶胶粒子体散射存在显著差异,沙尘性与海洋性的等效Mie散射误差明显大于煤烟性与可溶性粒子;对于同一种气溶胶,形状的改变对侧向与后向散射影响显著,对前向散射影响不大。 相似文献
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激光雷达作为一种新兴的主动遥感探测工具,被广泛应用于大气遥感、环境监测等领域。星载激光雷达由于其较广的探测范围、较高的时空分辨率、可获得连续的廓线数据等优势,已经成为全球及区域气溶胶和云特性观测研究的强有力工具。本文总结了自2006年CALIPSO卫星发射以来,中国科学家在利用其开展沙尘气溶胶及污染研究方面的工作,重点阐述了沙尘气溶胶的时空分布、远距离传输、分类识别、光学特性、沙尘释放、辐射与气候效应,以及灰霾和烟尘特性等方面的最新研究成果。对以上研究成果的梳理,有助于深入理解中国在利用星载激光雷达开展沙尘与污染研究的水平,也为未来开拓中国自主研发星载激光雷达的遥感应用领域奠定了基础。 相似文献
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气溶胶激光雷达由于系统设计、观测场地气候条件、反演过程中参数选取等因素不同,每次测量反演得到的气溶胶光学参数质量不一致,可信度难以评估,进而极大地影响了其在气象、环保等领域业务化应用。为了解决该难题,本文分析了影响激光雷达气溶胶光学参数质量的因素,开发了一套气溶胶光学参数质量可信度评估算法。采用科学、合理的评分和权重分配方案对激光雷达每次测量反演得到的气溶胶光学参数质量可信度进行评估。本文主要讨论对偏振、米散射激光雷达气溶胶光学参数的质量评估,以中国气象局气象探测中心的波长为532 nm的偏振、米散射激光雷达为例,对所提出的质量可信度评估算法进行验证和分析。结果表明:该算法能够有效地区分出不同激光雷达在不同观测场景下每次测量反演得到的气溶胶光学参数质量可信度,具备为气溶胶激光雷达业务化应用提供可靠性评估的能力。 相似文献