INTERFACE

The surface energy balance, i.e. the partitioning of the energy exchange between the Earth’s surface and the atmosphere, plays an essential role in determining meteo-climatological conditions in the atmospheric boundary layer. An accurate assessment of its components is therefore crucial for a variety of applications. However, measurements of the surface energy balance terms are still affected by uncertainties. In particular, turbulent heat fluxes measured with the eddy-covariance technique generally do not balance the available energy. Several studies claim that the main reason for this gap is connected to the advection induced by secondary circulations, which can be present even over homogeneous surfaces in convective conditions, but are more common over heterogeneous and complex terrain, as a consequence of differential heating.

Objectives 

The INTERFACE project will evaluate the uncertainties connected to the measurement of the surface energy balance at different sites in the Alpine environment, where processes related to the lack of closure are expected to be particularly significant. Measurements at sites located in different contexts and climatic settings, thus differently influenced by advection, will allow to investigate the relationship between the non-closure of the surface energy balance, the surface heterogeneity and the consequent development of different types of local and mesoscale circulations. 

Methods 

The above objectives will be addressed by combining ground-based and UAV measurements, integrated by high-resolution numerical simulations. The use of UAV will allow spatially-distributed measurements around the eddy-covariance sites, crucial for the estimation of advection, while numerical simulations will be used to complement and interpret the results of the experimental activities. 

Innovation 

The present project will provide, for the first time, a systematic quantification of the non-closure of the surface energy balance at several Alpine sites, investigating in detail the role of local and mesoscale circulations at locations where such phenomena are a well-known and well-researched characteristic of the local flow conditions. The project will benefit from an unprecedented combination of advanced methodologies in different fields, from the analysis of turbulence data, to the adoption of a sophisticated UAV platform, and the use of large-eddy simulations over complex terrain. 

EURAC (Center for Sensing Solutions) undertakes tasks into these phases: 

Phase 1 (months 13-20: Jul 2023 to Feb 2024) involves a literature review on meteorological parameters measurement techniques using UAVs, identifying their challenges, selecting the best CFD methods and turbulence models, choosing the appropriate software, and simplifying the setup. 

Phase 2 (months 13-28: Jul 2023 to Oct 2024) includes selecting suitable sensors for measuring meteorological parameters with EURAC's UAV, preparing the data logger and coding for sensor integration and data collection, and mounting the sensors, data logger, and necessary accessories onto the UAV. 

Phase 3 (months 13-28: Jul 2023 to Oct 2024) focuses on creating the UAV geometry in CAD software, generating grids and meshes in fluid dynamics software, conducting CFD simulations in ANSYS FLUENT, running simulations on HPC cluster, and post-processing the numerical results using ANSYS CFD-POST. 

Phase 4 (months 25-29: Jul 2024 to Nov 2024) emphasizes wind tunnel testing of the UAV and sensors, including designing the required tests, preparing the wind tunnel, and conducting the experiments. 

Phase 5 (months 29-32: Nov 2024 to Feb 2025) covers analyzing the results from the wind tunnel tests and CFD simulations, refining the UAV's sensor data, and preparing for field data collection. 

Phase 6 (months 29-33: Oct 2024 to Mar 2025) focuses on conducting preliminary field tests of the UAV and sensors in outdoor environment close to an ECT to assess the data collection process and evaluate the results. 

Phase 7 (months 34-36: Apr 2025 to Jul 2025) involves planning and conducting field campaigns in collaboration with INTERFACE partners. 

Phase 8 (months 35-36: May 2025 to Jul 2025) includes preparing detailed and comprehensive reports.