Learning by Research

Thesis title: In-situ study of katabatic flows over a steep alpine slope during anticyclonic conditions

Katabatic winds develop close to the surface when a slope, even a small one, is cooled by an unfavourable night-time radiation balance. Their presence takes a particular importance in inhabited mountainous regions. Indeed, in winter anticyclonic conditions, the cold air brought by these winds into the valleys amplifies the thermal inversions, which are then persistent for several days and block the vertical mixing. Horizontal transport, on the other hand, is limited by the restricted space created by the valley's confinement. The result is a stagnation of the air over a few hundred meters of thickness. This configuration is conducive to the development of strong pollution episodes as we know them in the Grenoble area.
Very few experimental studies have been carried out on steep slopes, and the characterization of the key flow parameters is limited to a maximum of 4 measurement levels, making it difficult to understand katabatic winds. The objective of this PhD is to bring elements of understanding on the development of these winds on steep slopes, by shedding light on the link between the physics of the flow and the cooling of the air near the surface, as well as on the vertical transfers of heat and momentum.

Key words: Katabatic winds, Steep alpine slope, Turbulence kinetic energy, Atmospheric boundary layer

Doctoral School: ED STEP - Sciences de la Terre, de l’Environnement et des Planètes
Research Laboratory: Laboratoire des Écoulements Géophysiques et Industriels (LEGI – CNRS, Grenoble INP-UGA/UGA)
Thesis Supervision: Christophe BRUN, Jean-Martial COHARD and Jean-Emmanuel SICART

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