基于纯转动Raman激光雷达的中低空大气温度高精度探测

High-precision measurements of lower atmospheric temperature based on pure rotational Raman lidar

本文介绍了一套纯转动Raman测温激光雷达系统,通过高分辨光谱分光与滤光优化设计、收发精确匹配以及弱信号检测等技术,实现在武汉城市上空从10km至40km的中低空大气温度高精度探测.观测结果与同时段探空气球进行比对,在30km以下激光雷达探测温度与探空气球得到的温度数据吻合较好,最大偏差约为3.0K,表明了该激光雷达温度测量的可靠性.采用30min时间分辨率,在10～20km高度范围内温度统计误差约为0.3K（300m空间分辨）;20～30km统计误差约为0.8K（600m空间分辨）;30～40km统计误差约为3.0K（900m空间分辨）.通过整晚的温度廓线反演,为研究中低层大气中的波动现象提供依据.该转动Raman激光雷达实现了至40km高度的高精度大气温度探测,进一步可与Rayleigh测温激光雷达30～80km的高度衔接,为实现中低层大气连续观测研究提供了重要手段.

Temperature is an important parameter in describing the atmospheric state.Largescale temperature profile measurements with high temporal and vertical resolutions can provide a comprehensive understanding of the atmospheric dynamics and thermodynamics.Different from Rayleigh mechanism,apure rotational Raman（PRR）lidar is preferred for the lower atmospheric temperature measurements even with the aerosol and optically cloud layers.The PRR lidar system based on an injection-seeded laser source and a 1mdiameter telescope is built for high-precision temperature measurement from 10～40km over Wuhan.State of the art interference filters for light splitting and filtering are designed to extract the wanted PRR signals and suppress elastically backscattered light.With the optimum design of optical spectroscopy parameters,as well as exact light receiving and transmitting match,PRR scattering returns are detected by the weak signal detection technology.Lidar observation results are presented to investigate the overall lidar performance.The maximum deviation of temperatures measured by the PRR lidar and the local meteorological radiosonde below 30 km is about 3.0K,which shows good consistency and validates the reliability of the PRR lidar.Obvious deviation may occur because of balloon drifts,regional differences and special phenomena like the thermal inversion layer.Temperature profiles at different temporal scales（10min,30 min and 60min）are given for analysis of the wave properties and microstructures.The statistical temperature errors vary with the spatial resolutions in different detection ranges.For the lidar temperature profile of 30 min integration,the statistical error is about 0.3Kfor altitudes of 10～20km with 300 mspatial resolution;about 0.8Kfor 20～30km with 600mresolution;while with 900 mspatial resolution,it is about 3.0Kfor altitudes from 30 km up to 40 km.Besides,one night temperature profile with 30 min integration and varying spatial resolutions are given for the study of atmospheric thermal structure and dynamical fluctuations.Temperature measurement up to 40 km by the PRR lidar possesses great potential for the further combination with the Rayleigh lidar of 30～80km detection capacity,which provides a long-term effective method for the study of lower atmosphere to upper stratosphere.