Mid‐ and Low‐Altitude Raman Lidar to Simultaneously Measure Nighttime Water Vapor and All‐Day Temperature

Abstract Conventional Raman lidar is constrained by the low signal of Raman backscattering, rendering it incapable of measuring the atmospheric parameters in high‐altitude regions. This paper presents a powerful Raman lidar that employs a multi‐receiver system, enabling simultaneous measurements of optical properties of aerosols, atmospheric temperature, and water vapor. Based on the single‐line‐extracted pure rotational Raman scattering, the system can make temperature measurements from 1 up to 40 km at night and 20 km during the day by utilizing a high‐precision Fabry‐Perot Interferometer. The water vapor channel detects the vibrational Raman scattering of water vapor and performs water vapor mixing ratio (WVMR) measurements from 0.3 to 5 km. The measurement comparisons between the lidar and the microwave radiometer and radiosonde demonstrate the capability of the lidar system. In the case of 1‐hr lidar measurement data integration, the statistical errors of the temperature are within 1 K under 300 m resolution, while the WVMR errors are within 0.5 g/kg under 30 m resolution. This indicates that the lidar data inversion results are effective. Moreover, the 24‐hr continuous observations demonstrate the performance of the lidar system during the daytime, also further substantiating the stability of the Raman lidar system. The high‐resolution atmospheric temperature and water vapor measurements reveal the negative correlations of their perturbations in the case observation.