Several terrain-induced processes in the atmospheric boundary layer over mountains affect the transport and exchange of heat, momentum, moisture, aerosols, and trace constituents between the surface and the atmosphere and within the atmosphere. TEAMx (Multi-scale transport and exchange processes in the atmosphere over mountains – programme and experiment) is an international research program that aims at improving our understanding of these processes and their representation in numerical weather and climate prediction models. Measurements were collected in a north–south transect through the Alps using a range of different instruments as part of the 1-year-long TEAMx Observational Campaign between September 2024 and September 2025. To sample the mountain boundary layer at multiple spatial and temporal scales, observations from various platforms were combined: surface weather and eddy-covariance stations, surface-based remote sensing instruments, radiosoundings, drone-based measurements, and aircraft flights. The observational data were complemented by numerical modeling for process understanding and model development. This special issue collects observational, modeling, and theoretical studies originating from the TEAMx research programme.

Review process: This inter-journal special issue co-lists papers of different journals. Thereby, each paper was submitted to 1 particular journal and underwent the regular interactive peer-review process of that journal. Depending on the journal, the peer review was handled by regular members of the editorial board and/or by guest editors designated by the journal’s chief/executive editors.