engleski

The complex bora flow in the lee of Southern Velebit

The complex flow structure in the lee of the Southern Velebit is investigated by means of very high-resolution numerical simulations carried out with the NRL COAMPS model. The focus is placed on a wintertime severe bora episode. The spatially complex and temporally highly variable 3D flow structure is characterized by a hydraulic jump over the lee slope and a pronounced wake over the Zadar area. The wake structure appears very sensitive to the upstream flow evolution and is highly non-stationary. The reversed flow along the wake centerline as well as flow separation and rotor formation are observed during different stages of the bora evolution. Sensitivity experiments show the height of Velebit exerting a strong influence on the flow structure, including the onset and strength of the bora flow and the structure of the wake. The terrain of the Zadar peninsula, although significantly lower than that of Velebit, is shown to influence the characteristics of the fully developed bora flow.

bora; critical level; orography; rotors; upstream conditions; wake

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