INTERFACE

.

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 investigation of 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.
The above objectives will be addressed by combining ground-based and UAV measurements, integrated by high-resolution numerical simulations. The use of UAVs 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.
EURAC’s Center for Sensing Solutions has been responsible for the complete technical development of the UAV-based measurement system and associated modeling activities. The team carried out an extensive literature review and published a review paper titled “A Review of Methods and Challenges for Wind Measurement by Small Unmanned Aerial Vehicles,” along with two conference presentations. A detailed CFD study of an octocopter platform was performed using ANSYS Fluent on the Vienna HPC cluster to analyze the airflow around the drone. EURAC also led the selection and purchase of suitable sensors (including sonic anemometers, solar radiation, temperature, and humidity sensors), the design and programming of customized data loggers with microcontrollers, and the integration of these components onto the drone.
To validate the system, EURAC conducted wind tunnel experiments in Geneva, Switzerland, to compare CFD results with measured data, followed by laboratory tests to assess the real-time response of the sensors under flight conditions. A field campaign was successfully carried out around the eddy covariance tower at Mezzocorona, during which data were collected and preliminarily analyzed. In the coming months (Nov–Dec 2026), EURAC plans to perform a full analysis of the flight data, submit a journal paper on the CFD and wind tunnel results, and present a conference dissemination describing the UAV instrumentation and calibration process. Between Jan–Apr 2026, planned activities include CFD analysis of a hexacopter, a possible second field campaign (pending collaboration with the University of Trento), preparation of a paper on sensor calibration and real field flight data, and finally, the joint preparation of the project’s final report with partners from the University of Innsbruck and the University of Trento.
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.