Maruška Mole (Author), Longlong Wang (Author), Samo Stanič (Author), Klemen Bergant (Author), William Eichinger (Author), Francisco Ocaña (Author), Benedikt Strajnar (Author), Primož Škraba (Author), Marko Vučković (Author), William B. Willis (Author)

Abstract

The Vipava valley in Slovenia is well known for the appearance of strong, gusty North-East Bora winds, which occur as a result of air flows over an adjacent orographic barrier. There are three revealing wind directions within the valley which were found to give rise to specific types of atmospheric structures. These structures were investigated using a Mie scattering lidar operating at 1064 nm, which provided high temporal and spatial resolution backscatter data on aerosols, which were used as tracers for atmospheric flows. Wind properties were monitored at the bottom of the valley and at the rim of the barrier using two ultrasonic anemometers. Twelve time periods between February and April 2015 were selected when lidar data was available. The periods were classified according to the wind speed and direction and investigated in terms of appearance of atmospheric structures. In two periods with strong or moderate Bora, periodic atmospheric structures in the lidar data were observed at heights above the mountain barrier and are believed to be Kelvin–Helmholtz waves, induced by wind shear. No temporal correlation was found between these structures and wind gusts at the ground level. The influence of the wind on the height of the planetary boundary layer was studied as well. In periods with low wind speeds, the vertical evolution of the planetary boundary layer was found to be governed by solar radiation and clouds. In periods with strong or moderate Bora wind, convection within the planetary boundary layer was found to be much weaker due to strong turbulence close to the ground, which inhibited mixing through the entire layer.

Keywords

downslope wind;lidar observations;Kelvin-Helmholtz waves;Bora;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UNG - University of Nova Gorica
UDC: 53
COBISS: 4626939 Link will open in a new window
ISSN: 0022-4073
Views: 4552
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Other data

URN: URN:SI:UNG
Type (COBISS): Not categorized
Pages: str. 39-45
Issue: ǂVol. ǂ188
Chronology: Feb. 2017
DOI: 10.1016/j.jqsrt.2016.05.020
ID: 9246600