利用激光雷达测量重力波三维结构

激光雷达观测得到的密度、温度等数据被广泛应用于大气重力波研究.瑞利激光雷达可以获取激光路径上的大气密度、温度数据.对于大气中的三维波动而言,单条路径上的观测参量能提取得到的波动信息有限.本文首先以单色重力波为例,分析了利用激光雷达直接观测三维波动结构的可行性.激光雷达垂直观测即可得到重力波的垂直波长,当激光雷达以一定的天顶角斜向测量时,所得到的波长包含了重力波的垂直波长以及水平波长信息.因此,利用激光雷达同时以三个方向(垂直、向南(天顶角30°)以及向西(天顶角30°))测量,可以提取得到重力波的垂直波长和水平波长.本文利用中国科学院国家空间科学中心研制的车载532nm瑞利激光雷达的经向系统和纬向系统同时以不同的指向角观测大气重力波,对利用激光雷达获取三维波动结构的方法进行了分析研究.本文给出了北京地区激光雷达观测重力波的诸多案例,分析了30~60km高度范围内北京地区大气重力波的垂直及水平波长信息.并以2017年11月7日观测的准单色重力波为例,结合再分析资料的风场数据,分析了该重力波的水平波长,垂直波长及传播方向等信息.

Measuring the three-dimensional structure of gravity waves by Lidar

The density and temperature data obtained by Lidar are widely used in research of atmospheric gravity waves. Rayleigh Lidar can obtain atmospheric density and temperature data on the laser path. But for three-dimensional gravity waves in the atmosphere, the observational parameters on a single path can only extract limited fluctuation information. In this paper, the monochromatic gravity waves are taken as an example to analyze the feasibility of using Lidar to directly observe three-dimensional wave structure. The vertical wavelength of the gravity waves can be obtained directly by the vertical observation of the Lidar. When the Lidar measures obliquely at a certain zenith angle, the obtained wavelength includes both vertical wavelength of the gravity waves and horizontal wavelength information. Therefore, the vertical and horizontal wavelengths of the gravity waves can be extracted by using Lidar to measure simultaneously in three directions (vertical, southward (zenith angle 30°), and westward (zenith angle 30°)). Under the existing conditions, this paper uses the meridional system and the zonal system of the 532 nm Rayleigh Lidar developed by the National Space Science Center of the Chinese Academy of Sciences to simultaneously observe atmospheric gravity waves at different pointing angles. The method of using Lidar to obtain the three-dimensional wave structure is analyzed. This paper gives a number of cases of gravity waves observed by Lidar in Beijing, and analyzes the vertical and horizontal wavelength information of atmospheric gravity waves in the height range of 30~60 km. Taking the quasi-monochromatic gravity waves observed on November 7, 2017 as an example, combined with the wind data of National Centers For Environmental Prediction, the horizontal wavelength, vertical wavelength and propagation direction of the gravity waves are analyzed.