【作者】 陈阳；

【导师】 吴松华；

【作者基本信息】 中国海洋大学 ， 摄影测量与遥感， 2011， 硕士

【摘要】 大气风场是气象研究的必要参数之一,多普勒激光雷达能以较高的空间、时间分辨率探测大气三维风场,目前已成为风速测量的最有效途径之一。多普勒激光雷达通过对大气分子运动——风所引起的多普勒频移的测定,从而反演获得风场数据。主要采用相干和非相干两种方法,相干探测法只能应用于气溶胶含量较高的低空区域;非相干即直接探测技术不受此限制,直接测量回波能量鉴别频移,但它需要获取气溶胶与大气分子的成分比——气溶胶后向散射比用以标定灵敏度。当前的测量方法中气溶胶后向散射比与风速分时测量,然而实际大气中气溶胶状态变化剧烈,非同步测得的数据无法准确描述测风时的大气情况,故必然引入误差。本文分析了当前多普勒激光雷达灵敏度测量存在的问题,提出了解决方案。从激光雷达的后向散射光谱出发,在接收系统中增加新的接收通道,采用分光片与干涉滤光片提取非弹性散射谱——拉曼谱。基于拉曼谱为纯大气分子散射的特性,实时测算气溶胶后向散射比廓线,同时又能借助其本身的光谱性质反演气溶胶后向散射系数、消光系数或者温度等大气参量,拓展激光雷达的功能。拉曼散射包括振动拉曼和纯转动拉曼两种散射,文中分别设计了振动拉曼和纯转动拉曼两套方案进行标定方法研究。对振动拉曼方案进行实验论证,描述了系统的搭建,开展实验。结果表明,系统可在测风的同时获取低空对流层(6、7km)以内的气溶胶后向散射比廓线,以进行多普勒激光雷达灵敏度的标定,并可获取气溶胶的消光系数、激光雷达比等参量。同时改进了气溶胶后向散射比的算法,并通过对新旧算法的反演结果比较验证了改进的意义。对纯转动拉曼方案进行模拟分析,描述了系统的构造,计算结果表明纯转动拉曼系统具备了可行性,为后续多普勒激光雷达的性能升级与气象应用奠定了理论基础。更多还原

【Abstract】 Wind field is one of the necessary parameters for meteorology research. Doppler lidar is able to detect wind field in high spatial and temporal resolution.By detecting the Doppler frequency shift caused by atmosphere movement, Doppler lidar can retrieve the wind velocity. The technologies of Doppler wind lidar include coherent method and incoherent method (also called direct detection technique). Coherent method is only applied to aerosol scattering but not molecular scattering due to the broadened scattering spectrum. On the other hand, incoherent method can detect both of aerosol and molecular scattering by measuring the energy of returning signal and is one of the most effective way of wind measuring in clear air. In direct detection method, aerosol backscattering ratio is essential to define the measuring sensitivity of the wind speed. However, the measurements of aerosol backscattering ratio and wind are asynchronous among the state of the art Doppler lidars so that the uncertain error could be brought by the temporal and spatial variation of aerosol particles.The article analyses the problem of Doppler lidar sensitivity measurement and proposes the solution. Basing on the backscattering spectrum, a new receive channel of inelastic scattering is added to acquire Raman scattering with beam splitters and interference filters. With the pure molecular scattering, Raman scattering, the novel system probes aerosol backscattering ratio in real time with wind measurement. Meanwhile, it is capable of retrieving the extra parameters of aerosol backscattering coefficient, extinction coefficient and atmosphere temperature profile to develop a multi-function meteorology lidar.The article designs tow blue prints of vibrational Raman method and pure-rotational Raman method for calibration research, respectively. The vibrational Raman method is testified with experiment. The results show that this method is capable of measuring aerosol backscatter ratio profile of low-altitude troposphere (below 7km) at the same time as wind measurement, which can define the wind measurement sensitivity. Aerosol extinction coefficient and lidar ratio are additional parameters acquired in measurement. A new arithmetic of aerosol backscatter ratio is proposed and proved to be more effective. The pure rotational Raman method is assessed by simulation. The results of calculation testify the feasibility of system and establish the theory foundation of developing the multi-function meteorology lidar.更多还原