纯转动拉曼激光雷达探测对流层中底部大气温度

发布时间：2018-03-05 00:36

本文选题：纯转动拉曼激光雷达　切入点：大气温度　出处：《中国科学技术大学》2017年博士论文　论文类型：学位论文

【摘要】：大气温度是表征大气能量平衡的重要参数之一,高精度探测大气温度的时空变化规律具有重要的应用价值和科研价值。激光雷达虽然是新兴技术,但由于其具有高时空分辨的优势,激光雷达已经成为探测大气温度以及其他大气参数的一种不可缺少的工具。在863项目"多源光谱层析及三维数值大气关键技术"的支持下,我们研制了一台多功能多通道激光雷达系统,能够同时、连续、高精度观测近地面至对流层范围的大气温度、水汽和气溶胶,并且在合肥和北京两地分别进行了观测实验,两地观测实验都取得了与无线电探空气球较一致的结果,主要研究内容如下:(1)首先论述了激光雷达大气遥感的理论背景和系统构造,以及各类激光雷达探测技术。对大气温度的分布特征和常见的探测方法进行了概述,列举了国内外典型的大气温度探测激光雷达,简述了最新测温激光雷达的发展动态。(2)本文主要完成了一套能够同时探测大气温度、水汽和气溶胶的多功能多通道的集成式纯转动拉曼激光雷达。激光发射单元采用美国Continuum公司的Nd:YAG固体激光器,激光器输出基频波长为1064nm,经由二倍频和三倍频分别输出532nm和355nm的激光,355nm单脉冲激光输出能量约为300mJ,脉冲频率20Hz。卡塞格林式望远镜具有焦距长、结构紧凑的优点,分别采用450mm 口径大望远镜接收温度和水汽的拉曼散射回波信号,300mm小口径望远镜接收气溶胶的米散射回波信号。利用干涉滤光片以一定的倾斜角度安装在光学平台上,可以实现对大气回波信号的有效分光。数据采集单元采用瞬态记录仪,它能同时收集数模信号。(3)分光系统的核心是干涉滤光片,模拟计算了干涉滤光片参数中心波长和带宽与温度测量不确定度的关系。用于探测大气温度的激发发射波长选为355nm的紫外光,激发光波长越短,后向散射微分截面越大,转动拉曼信号越强,并且355nm处于可见光范围外,更容易实现白天探测。模拟计算表明,高阶转动量子数拉曼通道的干涉滤光片中心波长对温度探测精度更敏感。(4)激光雷达系统研制成功后分别在合肥和北京部分地域开展了近地面大气温度的观测与分析,选用同时间点释放的无线电探空气球验证仪器的可靠性。观测资料表明了对流层温度具有较明显的时空分布特征。(5)本文重点分析了测量信号不确定度、不同时空分辨率和标定常数对温度探测精度的影响。累积发射脉冲数越多,噪声越小信噪比越大,测量信号不确定度越小。在累积激发脉冲数为10000发(5000发)时,对应30m、60m、120m和240m的空间分辨率,近地面至8km高度处温度测量不确定度的均值分别为 1.09K(1.33K),0.83K(0.85K),0.78K(0.79K)和0.88K(0.89K)。标定常数a和b不仅影响温度廓线的平移,还对温度廓线的形状有影响,标定常数c只影响温度廓线的平移。根据观测数据可知,a和c有相同的变化趋势,b变化趋势相反。当a、b和c变化趋势相同时,利用公式反演温度带来的误差较小,误差有互相抵消的趋势;当a、c变化和b变化趋势相反时,利用公式反演温度带来的误差较大。
[Abstract]:Air temperature is one of the important parameters characterizing the atmospheric energy balance, has important application value and research value of high precision detection of temporal and spatial variation of atmospheric temperature. Although the laser radar is a new technology, but because of its high spatial and temporal resolution, laser radar has become an indispensable measurement of atmospheric temperature and other atmospheric parameters of the tool in the 863 project "multi spectral tomography and 3D numerical atmospheric" key technology support, we developed a multi-function laser radar system, which at the same time, continuous, high precision measurement of atmospheric temperature near the ground surface to the troposphere range, water vapor and aerosol, and in Hefei and Beijing respectively were observed. The two observations are made is consistent with the results of the air ball on the radio, the main contents are as follows: (1) first, the laser radar Gas sensing theoretical background and system structure, and various types of laser radar technology. The distribution characteristics of the atmospheric temperature and the common detection methods are summarized, enumerates the atmospheric temperature detection laser radar at home and abroad, introduces the latest development of lidar. (2) this paper completed a at the same time, the detection of atmospheric temperature, the pure rotational Raman lidar integrated multiple channels of water vapor and aerosol. The laser emitting unit by Nd:YAG laser Continuum in the United States, the laser output wavelength of 1064nm laser frequency, frequency and frequency respectively by two three output 532nm and 355nm 355nm, the single pulse output energy is about 300mJ pulse frequency, 20Hz. Cassegrain telescope with long focal length, the advantages of compact structure, using the 450mm large aperture telescope receiving temperature and water vapor tension Raman scattering echo, Mie scattering echo signal receiving aerosol 300mm small caliber telescope. The interference filter with a skew mounted on the optical platform, can achieve effective light on the atmospheric echo signal. The data acquisition unit adopts transient recorder, it can simultaneously collect analog signals. (3) the core optical system the interference filter, simulated interference filter parameters of center wavelength and bandwidth and temperature measurement uncertainty. For the excitation emission wavelength is 355nm UV detection of atmospheric temperature, excitation wavelength is shorter, the backscatter differential cross section of the greater rotational Raman signal is strong, and 355nm is in the range of visible light during the day, easier to achieve detection. Simulation results show that the interference filter center wavelength high order rotational quantum number Raman channel is more sensitive to temperature detection accuracy. (4) Ji Guanglei The system was successfully developed in Hefei and Beijing regions to carry out observation and analysis of the near surface atmospheric temperature, the reliability of radiosonde verification instrument at the same time release. The observation data show that the tropospheric temperature has obvious spatial distribution characteristics. (5) this paper focuses on the analysis of measurement uncertainty and the effects of different spatial and temporal resolution and calibration constant on temperature detection accuracy. The cumulative pulse number, the smaller the noise signal-to-noise ratio is larger, the uncertainty of the measurement signal is small. The cumulative excitation pulse number is 10000 (5000), corresponding to 30m, 60m, 120m and 240m spatial resolution, near at the height of 8km to ground temperature measurement uncertainty values are 1.09K (1.33K), 0.83K (0.85K), 0.78K (0.79K) and 0.88K (0.89K). The calibration constants A and B not only affects the temperature profile of the horizontal movement, but also on the temperature profile shapes Affect the translation calibration constants of C only affects the temperature profile. According to the observation data shows that a and C have the same trend, the change trend of B was opposite. When a, B and C in the same trend, using the formula of temperature inversion error caused by errors tend to cancel one another; when a, C the changes of B and the opposite trend, using the formula of temperature inversion error is large.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN958.98

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