大气边界层白天温度测量用转动拉曼激光雷达

Rotational Raman Lidar for Daytime-Temperature Profiling of the Atmospheric Boundary Layer

设计了一个转动拉曼激光雷达系统,对大气边界层温度进行全天候高精度测量。系统选用波长355 nm的紫外激光作光源,采用高光谱分辨力光栅,将雷达接收到的散射信号以及太阳背景光从空间上分离,配合边缘反射镜,反射转动拉曼信号,去除大部分米氏-瑞利散射和太阳背景光噪声信号,并用两个窄带干涉滤光片,分离中心波长为353.9 nm和353.1 nm转动拉曼散射信号,同时对噪声信号进行2次高精度剔除,以保证白天测量的需要。对系统进行了分析及数值计算,结果表明在激光脉冲能量300 mJ,望远镜有效口径25 cm,测量时间10 min的条件下,可以在白天太阳背景光辐射度为3×108W/(m2.sr.nm)的边界层内测量高度2.5 km以下的大气温度分布,并在大气散射比低于2.5的条件下,温度测量精度可达到1 K。

A high-accuracy rotational Raman lidar system has been designed for daytime temperature profiling of atmospheric boundary layer. An ultraviolet laser with wavelength at 355 nm is selected as light source. A highresolution grating is employed to separate scattering signals that the lidar receives and solar background signals according to wavelength spatially, and an edge mirror is then used to reflect the rotational Raman signal and block the majority of interference signals including solar background and Mie-scattering and Rayleigh-scattering signals. Two signal, whose central wavelengths are located at 353. 9 nm and 353. 1 nm, respectively, are filtered by two narrowband interference filters. The two filters also block the leakage of interference signal accurately, which ensures the requirement of daytime measurement. The lidar system is simulated by using a numerical calculation, and the result shows that the system is capable of measuring temperature profile of atmospheric boundary layer in daytime with a temperature errors of less than 1 K up to a height of 2.5 km under conditions of laser energy of 300 mJ, 25 cm diameter telescope, observation time of 10 min, solar radiance of 3 ×10^8W/（m^2·sr·nm） and atmospheric backscattering ratio less than 2.5.