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Gravity wave momentum flux

Atmospheric gravity waves can often be observed in wave clouds. They can propagate deep into the middle atmosphere and the associated momentum flux is a key driver of the circulation of the middle atmosphere.

©P. Preusse

Currently, global observational constraints on gravity wave momentum flux and gravity wave drag throughout the middle atmosphere are lacking, leading to large uncertainties in climate and weather prediction models.

CAIRT will provide information on the gravity wave momentum flux, propagation direction and drag through three-dimensional observation of temperature fluctuations at unprecedented scales.

Propagation of a gravity wave over the southern Andes from a model simulation.

The dots move with the background winds, the red and blue colours indicate the temperature perturbations due to the wave. Around 40km altitude the background wind vanishes and wave propagation to higher altitudes is inhibited. Here the waves break and accelerate the background winds, which is referred to as wave drag. Drag by gravity waves and global scale waves (Rossby waves) induces a global scale circulation, which ultimately influence weather and climate at the Earth surface.

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