Study of the Atmospheric Boundary Layer and Land-Atmosphere Interaction with Lidars

Investigating the dynamics of the atmospheric boundary layer (ABL) is essential for studies of air quality, the energy and water cycles and for the improvement of weather and climate models. During daytime in convective conditions, the convective boundary layer (CBL) is formed. Here, we present our approach of how to continuously study CBL characteristics with an improved algorithm including fuzzy logic. The Land-Atmosphere Feedback Observatory (LAFO) of University of Hohenheim consists of two Doppler lidars, a Doppler Cloud Radar, the Atmospheric Raman Temperature and Humidity Sounder (ARTHUS), and Eddy covariance stations. These are excellent tools for observing high resolution atmospheric wind profiles, clouds and precipitation events, as well as thermodynamic profiles and surface fluxes. The data are collected at LAFO by operating continuously two Doppler lidars, one in vertical and one in six-beam scanning mode, to obtain vertical and horizontal wind profiles. Both Doppler lidars are operated with resolutions of 1 s and 30 m. The six-beam staring Doppler lidar is used for obtaining time series of turbulent kinetic energy (TKE), momentum flux, TKE dissipation rate and horizontal wind profiles statistics. The vertically staring Doppler lidar is used to compute statistics of higher-order moments of vertical wind fluctuations, the CBL height, and cloud base height. With these data, the land-atmosphere coupling processes and the associated nonlinear feedbacks are investigated as well as their impact on the turbulent structure of the CBL.

We will present analyses of two three-month periods covering different weather conditions: 1 May to 31 July 2021 and 2022.