纯转动拉曼激光雷达反演低层大气折射率廓线

大气折射率是影响光电探测领域测量精度的重要因素.为了提高光电测量精度,提出利用纯转动拉曼激光雷达信号反演低层大气折射率廓线的方法.通过接收N2和O2的纯转动拉曼回波信号,由双光栅单色仪分光后获得高低量子信号.根据高低量子信号的比值反演得出大气温度和大气压强廓线,从而获得大气折射指数垂直分布.通过与折射指数理论模型相比较,表明纯转动拉曼激光雷达反演对流层折射指数有较高的精度.给出了多组折射指数廓线的反演结果,得出多天夜晚不同时刻折射指数的特性.结果表明一天中不同时刻折射指数变化较小,7.5 km内最大相对误差约为0.4%;不同月份之间折射指数波动较为明显,4.5 km内相对误差可达3.5%左右.

Measurements of Refractive Profiles Using a Pure Rotational Raman Lidar in the Lower-Atmosphere

Atmospheric refractivity has a significant impact on measurement precision in the field of photoelectric detecting.To improve the detecting accuracy of photoelectric fields,a pure rotational Raman lidar technique for detecting tropospheric refractive index is discussed in detail.Higher-lower isolating two portions of the pure rotational Raman backscattering spectrum of N2 and O2 are obtained by separating from other singles using the double grating monochromator.By caculating ratio of the two return signals,atmospheric temperature and pressure profiles are derived,as well as the measurements of air refractivity.Compared with the theoretical model,the accuracy for detecting atmospheric refractivity using the pure rotational Raman lidar is convincingly illustrated by the results of laboratory experiments.Several atmospheric refractive profiles are shown and the characteristic of refractivity is acquired at different times and on different days.The results show that the changes of the refractivity are little during the night and reach only 0.4% below 7.5 km.The fluctuation of the refractivity between different days is obvious and reaches 3.5% below 4.5 km.