TEAMx

Announcement: First TEAMx workshop, 28-30 August 2019

Multi-scale transport and exchange processes in the atmosphere over mountains – programme and experiment

Atmospheric processes specific to mountainous regions heavily affect the exchange of momentum, heat and mass between the Earth’s surface and the atmosphere. TEAMx is an international research programme that aims at improving our understanding of these processes.

  • Exchange processes govern the transfer of heat, momentum and mass between the ground, the planetary boundary layer and the free atmosphere. Over mountainous terrain, exchange processes include turbulent mixing, breeze systems, gravity wave propagation, and moist convection.
  • 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 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.
  • 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.
  • 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.

TEAMx targets

  • Numerical models and observational systems optimized for application over mountainous terrain.
  • Improved weather forecasts and climate change scenarios over mountains.
  • Accurate characterization of the global cycles of water, energy and trace gases.

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