大气不均匀性对星载多普勒激光雷达测风的影响研究

A global-coverage three-dimension wind field is necessary for global numerical weather prediction and climate reasearch. From 1980s, Europe and the United states have studied the feasibility and technology of spaceborne Doppler wind lidar to provide three-dimension wind field with global-coverage, high-resolution, high-precision. The critical technique of pulsed high-energy laser has broken down. The on-orbit demonstrator will be done. But the impact of atmospheric heterogeneity on yield,accuracy,representatives of the wind retrieved from spaceborne Doppler wind lidar has not been well discussed. In this project, the real atmospheric inhomogeneity within the small scale is firstly analyzed in order to clarify the characteristics of the vertical and horizontal inhomogeneity at typical regions, seasons, and altitudes. Secondly, the impact mechanism of atmospheric inhomogeneity on the wind retrieval of spaceborne Doppler wind lidar will be discussed, and the error impact model of the atmospheric vertical and horizontal inhomogeneity will be established. Finally, the wind retrieval algorithms and quality control methods considering the impact of atmospheric heterogeneities are developed according to the theoretical analysis and simulation of the relationship between the wind errors and veterical bin gate, horizontal reprsentative scale, wind assignment height.The validation and application of winds retrieved from future spaceborne Doppler wind lidar will be discussed.

全球三维风场资料是开展数值天气预报、气候研究的重要基础。从1980s开始，欧美就一直研究利用星载多普勒测风激光雷达进行全球三维高分辨率风场探测的可行性和技术，目前高能脉冲激光器等关键技术已取得突破性进展，即将开展在轨验证试验。然而由于大气气溶胶、云存在着较大的不均匀性，其对星载多普勒激光雷达测风数据获取率、准确性和代表性的影响研究还不深入。本项目从典型地区不同季节、不同高度小尺度内的大气垂直与水平不均匀性分析入手，建立不均匀特征参数数据集；开展大气不均匀性对星载多普勒激光雷达的测风影响机理研究，建立大气垂直与水平不均匀性影响测风误差分析模型，分析误差分布规律；开展实际不均匀大气条件下的仿真研究，弄清垂直分层厚度、水平代表性尺度、风速代表性高度与测风误差之间的统计关系，研究考虑大气不均匀性的星载多普勒测风激光雷达风速反演算法和质量控制方法；开展星载多普勒激光雷达风速资料比对验证与应用研究。

风是描述大气状态的基本参量之一，全球风廓线资料对于数值天气预报、气候研究和灾害天气预警具有重要应用价值。利用星载多普勒测风激光雷达进行全球风廓线探测将成为重要的技术手段，然而其风速反演准确性除了与激光雷达硬件参数有关外，还与大气状态、太阳背景辐射有较大关系，特别是与风速“观测值”代表性空间尺度范围内的大气不均匀性程度有关。本项目利用多种资料分析了不同地区、不同季节、不同高度的风、气溶胶、云的垂直不均性、水平不均匀性以及太阳背景辐射分布变化特点，建立了典型情况下的不均匀特征参数数据集，开展了大气垂直不均匀性、水平不均匀性、太阳背景辐射对星载多普勒激光雷达Mie通道和Rayleigh通道风速反演影响的理论与仿真统计研究，建立了相应的风速误差分析模型，分析了不同情况下的误差分布变化特点，开展了垂直分层厚度及透过率、水平代表性尺度、风速代表性高度、Mie通道条纹中心反演方法、Brillouin散射效应、Rayleigh散射回波对Mie通道的干扰、云的类型、地表类型等变化引起的风速误差敏感性试验研究，提出了相应的风速反演算法改进和质量控制方法。研究成果对开展星载多普勒测风激光雷达设计与风速反演算法改进研究具有重要应用价值。