Compact Automatic Rotational Raman Lidar System for Continuous Day- and Nighttime Temperature and Humidity Mapping

Water-vapor and temperature profiles with high accuracy and vertical resolution from the surface to the lower troposphere are fundamental for accurate weather forecasts, process studies, and validation of satellites. Within the MOSES project (Modular Observation Solutions for Earth Systems) of the Helmholtz Alliance, a new Water-Vapor and Temperature Rotational Raman Lidar system (WVTRL) fulfilling these requirements has been developed and tested by the Institute of Physics and Meteorology (IPM) at the University of Hohenheim (UHOH).

This new remote sensing system is a robust, portable, high-power Rotational Raman lidar. It is based on the knowledge acquired at the IPM in the development of different generations of rotational Raman lidar systems in the recent years. The system measures atmospheric temperature and humidity profiles with high resolution, even in daytime conditions due to the use of a strong UV laser radiation and an optimized receiving chain in each one of the implemented channels.

It is well known that different parts of a pure rotational Raman backscatter spectra show different temperature dependence. Therefore, the ratio from two backscattered signals from two of this parts can be used to obtain a temperature profile of the atmosphere. Besides, an elastic and water-vapor profile can be measured, so the water vapor mixing ratio, backscatter coefficient and extinction coefficient can also be obtained.

First atmospheric measurements have been obtained during the Land-Atmosphere Feedback Experiment (LAFE) at the Southern Great Plains (SGP) central facility in August 2017. The system has been also tested at the new UHOH Land-Atmosphäre Feedback Observatorium (LAFO) between August and November 2018. During May - June 2019, it participated in the ScaleX campaign (organized by the MOSES project) in southern Germany. There are two field campaigns planned for the next months. Measurements taken during these field campaigns will be shown.

Our new lidar will enhance the MOSES project, showing the potential of remote sensing systems gathering ground-truth information about the land-surface-atmosphere feedback, the behavior of the atmospheric boundary layer and the lower troposphere.