Assessment of Surface Energy Balance Closure at eddy-covariance sites in Diverse Alpine Environments

The surface energy balance (SEB), which defines the partitioning of energy exchange between the Earth’s surface and the atmosphere, is crucial for characterizing the development and evolution of the atmospheric boundary layer. While an accurate assessment of SEB components is essential for numerous applications, eddy-covariance measurements remain affected by significant uncertainties. Specifically, turbulent heat fluxes typically fail to balance the available energy at the surface. Research suggests that this energy balance closure problem stems primarily from advection driven by secondary circulations, which are prevalent over heterogeneous and complex terrain due to differential heating.

This study assesses the relationship between SEB non-closure, surface heterogeneity, and the subsequent development of local and mesoscale thermally driven circulations. The analysis utilizes data from seven flux sites across diverse Alpine environments (both on flat and sloped terrain) - including vineyards, pastures, pre-alpine and continental forests - incorporating at least two years of data per site, with many exceeding four years. The results provide a systematic and robust quantification of SEB non-closure across several typical Alpine contexts, highlighting key similarities and differences between sites based on their topographic features, land cover, and prevailing meteorological conditions.

The present work is part of the INTERFACE project (INvestigating ThE suRFACe Energy balance over mountain areas), which is performed in the framework of the TEAMx research programme.