Scanning Measurements With an Automated Temperature and Moisture Lidar in the Atmospheric Boundary Layer

Despite significant advancements in atmospheric observation techniques, the thermodynamic structure of the atmospheric boundary layer (ABL) remains largely unexplored due to the scarcity of suitable high-resolution remote sensing measurements. Over the past six years, the Atmospheric Raman Temperature and Humidity Sounder (ARTHUS), an automated profiler based on the Raman lidar technique (Lange et al., 2019), has participated in several ground- and ship-based measurement campaigns (Stevens et al., 2021; Flamant et al., 2021). These campaigns have demonstrated ARTHUS's capability to resolve critical atmospheric features, such as turbulent fluctuations and their statistics with high temporal and spatial resolution.

In combination with Doppler lidars, ARTHUS enables profiling of sensible and latent heat fluxes within the convective ABL, thereby supporting the investigation of flux-gradient relationships (Wulfmeyer et al. 2016, Behrendt et al., 2020). These capabilities make ARTHUS a powerful tool for advancing process studies of land-atmosphere interactions, enhancing weather and climate monitoring, validating atmospheric models, and improving data assimilation techniques. We present examples from several field campaigns with respect to the observation of diurnal cycles of profiles of mean and turbulent variables.

An eye-safe Nd:YAG laser with 20 W at 355-nm is used as transmitter. A 40-cm receiving telescope collects backscattered light providing independent measurements of temperature (T), water vapor mixing ratio (WVMR), CO2 concentration, particle extinction coefficient, and particle backscatter coefficient.

ARTHUS has proven its reliability during extended operations at the Land Atmosphere Feedback Observatory (LAFO) at the University of Hohenheim and across various field campaigns under diverse atmospheric conditions. As part of the Land-Atmosphere Feedback Initiative (LAFI, Wulfmeyer et al. 2024), ARTHUS will extend its capabilities to include scanning measurements from the surface through the ABL, capturing three-dimensional turbulent structures with a focus on entrainment processes. The campaign will take place between March and August 2025 at the LAFO site. For the first time, ARTHUS will deliver comprehensive maps of T, WVMR, and CO₂, especially near the surface and canopy but also up to the top of the ABL offering unprecedented insights into land-atmosphere feedback. At the conference, highlights of the first LAFI measurements will be shown.

References:

Lange et al. 2019, https://doi.org/10.1029/2019GL085774

Stevens et. al. 2021, https://doi.org/10.5194/essd-2021-18

Flamant et al. 2021, https://doi.org/10.1007/s42865-021-00037-6

Behrendt et al. 2020, https://doi.org/10.5194/amt-13-3221-2020

Wulfmeyer et al. 2016, https://doi.org/10.1175/JAS-D-14-0392.1

Wulfmeyer et al. 2024, https://doi.org/10.5194/egusphere-egu24-10102