Observation and investigation of the land-atmosphere system, atmospheric boundary layer processes, and fluxes

• Applicants: Dr. Frank Beyrich; Dr. Thomas Jagdhuber; Dr. Angelika Kübert; Professor Dr. Matthias Mauder; Professorin Natalie Orlowski; Dr. Verena Rajtschan; Professor Dr. Thilo Streck; Professor Dr. Christoph Thomas; Professor Dr. Volker Wulfmeyer
• Subject Area: Atmospheric Science
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 514721519

The characterization of Land-Atmosphere (L-A) feedback requires detailed studies of the soil, the land cover, and the atmosphere up to lower free troposphere encompassing the atmospheric boundary layer. Almost all current observatories and observational networks focus only on subcomponents of the L-A system. The objective of project P1 of the Research Unit Land-Atmosphere Feedback Initiative (LAFI) is to realize a comprehensive field program over heterogeneous farmland at the Land-Atmosphere Feedback Observatory (LAFO) of the University of Hohenheim that closes these observational gaps. At the LAFO, we will realize the simultaneous profiling of key variables in all three compartments and the characterization of their horizontal distributions in a heterogeneous landscape. Moreover, we will analyze a 20-year data set collected at the MOL-RAO of the DWD covering the most relevant L-A system variables for the derivation of statistical L-A feedback metrics, surface fluxes, and the energy-budget closure with special emphasis on extreme conditions such as exceptionally wet and dry years. At LAFO, over at least one vegetation period (spring–fall 2025), we will perform a General Operations Period (GOP) in combination with a series of five Intensive Observations Periods (IOPS) to characterize L-A feedback processes. Besides well-established measurement techniques such as flux chambers and eddy covariance systems as well as Doppler lidar systems we will further employ new techniques. These include water stable isotope sensors for differentiating between evaporation and transpiration, fiber-optic distributed sensing in the soil, in the canopy, and in the surface layer for temperature and wind measurements, canopy profiling of radiation, temperature, and moisture, unmanned aerial vehicles to map land surface properties, and high-resolution scanning Raman- and differential absorption lidar systems together with Doppler lidars to derive 3D turbulent properties of the surface layer and the atmospheric boundary layer with special emphasis on entrainment processes. P1 is of immediate relevance to all other projects and serve as a focal point of LAFI. P2-P6, and P11 will contribute to the sensor synergy and analyze the data collected under different scientific aspects. P7-P9 will model the whole GOP and use the P1 data for comparisons of feedback metrics and process representations as well as model evaluation. P10 will analyze the MOL-RAO long-term and the LAFI GOP and IOP data using deep learning methods. The measurements performed in P1 provide the essential basis to reach the all six objectives and to address all the hypotheses of LAFI. Similarly, all cross-cutting working groups rely on the observations of P1. By means of the design and the performance of the LAFI GOP and IOPs we expect new insights in L-A feedbacks and processes over agricultural landscapes.

• DFG Programme: Research Units
• Subproject of: FOR 5639: Land-Atmosphere Feedback Initiative (LAFI)
• International Connection: Luxembourg
• Major Instrumentation: 2 Open Path Eddy Covariance System ; 2 Sap Flow Measuring Systems ; Distributed Temperature Sensing Unit ; Doppler Lidar ; Water Isotope Analyzer
• Partner Organisation: Fonds National de la Recherche
• Co-Investigators: Dr. Andreas Behrendt, Ph.D.; Dr. Oliver Branch, Ph.D.; Dr. Joachim Ingwersen
• Cooperation Partner: Dr. Stanislaus Josef Schymanski