Nocturnal winds in joining shallow valleys of different sizes - Observationaland numerical studies based on the field experiment KASCADE

Abstract : Cadarache is the largest research site of Commissariat à l'Energie Atomiques et aux Energies Alternatives (CEA) and is situated in the prealps of southeastern France. This centre comprises several facilities whose operationrequires impact assessment considering the emission of pollutants. The region is susceptible to stable stratification periods which, in combination with complex orography, affects the conditions for dispersion of pollutants. Theunderstanding and characterization of the local down-valley flows is thus a major issue for local and regional dispersion studies at Cadarache. KASCADE (KAtabatic winds and Stability over CAdarache for Dispersion ofEffluents) was focused on valley winds in two cross-oriented valleys (see Fig. 1) and has been conducted in the winter of 2013. The experiment revealed the existence and dominance of two down-valley winds. The studypresented here is based on both modeling and observations.