A New Land-Atmosphere Feedback Observatory (LAFO)

Studies of land-atmosphere (L-A) feedbacks are essential for understanding the Earth system. These feedbacks are the result of an interaction of processes related to exchanges of momentum, energy, and mass in the soil-vegetation-surface layer (SL)-atmospheric boundary layer (ABL) continuum. Quantification of feedbacks are often made using L-A feedback metrics. Inaccurate representation/parameterization of feedbacks are a weakness of current weather models, and their improvement will thus contribute to better simulations over all spatiotemporal scales. Improving feedback representation requires simultaneous measurements in all L-A compartments using a synergy of in-situ and active remote sensing instruments. To that end, a new Land-Atmosphere Feedback Observatory (LAFO) was established at the University of Hohenheim, Stuttgart, Germany funded by the Carl Zeiss Foundation. It was developed as a prototype for a future network of GEWEX LAFOs (GLAFOs), proposed by the Global Energy and Water Exchanges (GEWEX) program and GEWEX Global Land/Atmosphere System Study (GLASS) panel (Wulfmeyer et al. 2020). The main goals are to: 1) investigate the diurnal cycle and statistics of ABL temperature, humidity and wind profiles, 2) characterize L-A feedback by suitable metrics. 3) improve parameterizations of vegetation, surface and ABL fluxes, 4) verify mesoscale and turbulence permitting models, LAFO brings together a sensor synergy with fine spatiotemporal resolution. An extended set of soil physical, plant dynamic as well as meteorological variables throughout the ABL are measured, focusing on evapotranspiration and other exchanges over agricultural landscapes. The LAFO observations with current instruments are continuously archived, according to FAIR data principles (Findable, Accessible, Interoperable, Reusable) and are complemented by additional field campaign measurements. The first key component of the current LAFO sensor synergy consists of four 3D scanning lidar systems: A scanning water vapor Differential Absorption Lidar (DIAL, Muppa et al. 2016, Späth et al. 2016) and the Atmospheric Rotational-Raman Temperature and Humidity Sounder (ARTHUS, Lange et al. 2019), both developed at the Institute of Physics and Meteorology. Both these systems are unique and provide water vapor and temperature profiles from the surface layer to the free troposphere with fine resolution down to turbulence scales (Behrendt et al. 2015, Wulfmeyer et al. 2015). These lidars are complemented by a scanning Doppler cloud radar and two Doppler lidars for measuring horizontal and vertical wind profiles and turbulent fluctuations. This combination allows determination of sensible and latent heat flux profiles. The second key component is a soil moisture and temperature sensor network distributed over agricultural land and two 10-m towers, measuring turbulent fluxes at two heights. LAFO will soon form part of a new Research Unit, funded by the German Research Foundation (DFG), called the Land-Atmosphere-Feedback-Initiative (LAFI) which begins in 2024, and incorporates novel crop, hydrology and atmospheric instruments, operated by several research partners within Germany. Here, we present measurement examples from the LAFO and show how these can be used to reach our research goals.   References Wulfmeyer et al. 2020, GEWEX Quarterly Vol. 30, No. 1. Behrendt et al. 2015, doi:10.5194/acp-15-5485-2015 Wulfmeyer et al. 2015, doi:10.1002/2014RG000476 Muppa et al. 2016, doi:10.1007/s10546-015-0078-9 Späth et al. 2016, doi:10.5194/amt-9-1701-2016 Lange et al. 2019, doi:10.1029/2019GL085774