What is TEAMx?

  • Vertical mixing of low-level air masses is often more effective in mountainous areas than over lowlands. On this autumn day, lower moisture and more effective vertical mixing kept the sky free of clouds over the Alps, creating a striking contrast with the low stratus covering the surrounding plains. Image credits: NASA Worldview.
  • Flow over mountains enhances stratiform and convective precipitation, drying up the atmosphere. Mountains are “water towers” for the surrounding plains. Precipitation maxima and minima are displayed in shades of blue and red, respectively. Image credits: Hydrological Atlas of Switzerland, Plate 2.6.
  • The First TEAMx Workshop took place in Rovereto, Italy, on 28-30 August 2019. The event was attended by 92 participants from 11 nations. Image credits: Ivana Stiperski.
  • The Second TEAMx Workshop took place online on 10-12 May 2021 and included more than 180 participants.
  • The Third TEAMx Workshop took place on 15&16 June 2023 in Zürich and online.
  • Flow over mountains can generate waves and downslope windstorms (Owens Valley, California, USA). Higher up, atmospheric flow decelerates because of gravity wave breaking. Orographic drag parameterizations alleviate systematic biases in general circulation models. Image credits: Robert Symons.
  • At daytime, mountains heat the atmosphere at high altitudes above sea level, generating breeze systems that favor horizontal and vertical transport and mixing. Converging slope winds over mountain tops lead to cumulus formation. Image credits: public domain.
  • At night, orography favors cold-air pooling. Stable layers may grow particularly deep in valleys, where they often persist until the next day (Valle Riviera, Switzerland). Image credits: Andreas Weigel.
  • Cold air pools may become persistent in the winter season, impeding vertical mixing and trapping pollutants for many consecutive days (Almaty, Kazakhstan, 12 January 2014). Image credits: Igors Jefimovs.


Every few decades the mountain meteorology community gets involved in large-scale international research programmes that culminate in a field campaign. Notable examples include ALPEX (Alpine Experiment, 1981-1982), PYREX (Pyrénées Experiment, 1990) and MAP (Mesoscale Alpine Programme, 1999). These programmes allowed to investigate atmospheric phenomena of progressively smaller scale, from lee cyclogenesis (ALPEX), to gravity wave drag (PYREX), potential vorticity streamers and gap flows (MAP). Preparations for TEAMx started with an informal meeting at the 33rd International Conference on Alpine Meteorology (2015).

Why a coordinated international programme?

Technological and scientific progress in the last decades made it possible to accurately observe processes at local scales, such as those that are responsible for earth-atmosphere exchange: the transfer of heat, momentum and mass between the ground, the planetary boundary layer, and the free atmosphere. In addition, advances in supercomputing made the high-resolution numerical simulation of these processes technically feasible.

Still, the interaction of the atmospheric flow with mountainous terrain remains one of the major sources of uncertainty in Earth-system modelling. Weather forecasts, be it for mountain-related extreme events or applications in air pollution, hydrology, energy meteorology, health or agricultural meteorology, remain very challenging over mountainous terrain.

In addition, mountains are a hot spot of climate change. A few of the most striking climate change impacts, like glacier melt or increased occurrence of flash floods, are directly tied to mountainous terrain. The limited horizontal resolution of climate models prevents them from accurately modelling a range of orography-dependent weather processes, ultimately causing climate change scenarios to be highly uncertain over mountains.

TEAMx is…

Scientific material

Scientific challenges related to TEAMx have been summarized in a series of peer-review articles published by Atmosphere in a special issue on Atmospheric Processes over Complex Terrain.

A journal article in Bulletin of the American Meteorological Society outlines the motivation behind TEAMx.

The TEAMx concept is concisely presented in an executive summary, while a detailed description of the scientific objectives of the programme is given in its white paper.


TEAMx is endorsed by the World Weather Research Programme (WWRP), as an Endorsed Project, and the World Climate Research Programme (WCRP), as a Crosscutting project within the Global Energy and Water Exchanges (GEWEX) Hydroclimatology Panel (GHP).