Original scientific paper
ON THE BORA BREAKTHROUGH NEAR A MOUNTAIN GAP
Alexander Gohm
; Institute for Meteorology and Geophysics, University of Innsbruck, Innrain 52, 6020 Innsbruck, Austria
Georg J. Mayr
; Institute for Meteorology and Geophysics, University of Innsbruck, Innrain 52, 6020 Innsbruck, Austria
Abstract
This study investigates the onset phase of a strong Adriatic bora on 04 April 2002 with high-resolution numerical modeling and observations. The airborne measurements were taken with the German Aerospace Center’s (DLR) Falcon aircraft within the framework of the EU-funded CAATER Programme 2001. The target area is a ~20-km wide mountain gap embedded in the Dinaric Alps, which favors strong jet-like winds. The model indicates a delay of the bora breakthrough at the coast of up to three hours between the center and the edge of the gap. During this period the wind field downstream of the gap is highly three-dimensional and transient. Near the gap center, a low-level jet is observed with winds exceeding
30 m s−1. Near the edge of the gap, the model shows flow separation and the formation of a low-level rotor with weak but
reversed surface winds underneath trapped gravity waves. This complex flow configuration with strong spatial variations in the wind field leads to horizontal and vertical wind shear in the vicinity of Rijeka airport on Krk Island, which represents a potential hazard for air traffic.
Keywords
CAATER; bora; gap winds; wind shear; hydraulic jump; rotor; gravity wave; modeling; airborne lidar
Hrčak ID:
64529
URI
Publication date:
15.12.2005.
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