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

Temperature is an important parameter in describing the atmospheric state. Large-scale temperature profile measurements with high temporal and vertical resolutions can provide a comprehensive understanding of the atmospheric dynamics and thermodynamics. Different from Rayleigh mechanism, a pure 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 1 m diameter telescope is built for high-precision temperature measurement from 10 similar to 40 km 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 3.0 K, 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 (10 min, 30 min and 60 min) 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. 3 K for altitudes of 10 similar to 20 km with 300 m spatial resolution; about 0. 8 K for 20 similar to 30 km with 600 m resolution; while with 900 m spatial resolution, it is about 3. 0 K for 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 similar to 80 km detection capacity, which provides a long-term effective method for the study of lower atmosphere to upper stratosphere.