Lidar measurements of Bora wind effects on aerosol loading
| Autor: | Klemen Bergant, Francisco Ocaña, Benedikt Strajnar, Primož Škraba, Marko Vučković, William E. Eichinger, Maruška Mole, Samo Stanič, William B. Willis, Longlong Wang |
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| Rok vydání: | 2017 |
| Předmět: |
Radiation
Wind gradient 010504 meteorology & atmospheric sciences Meteorology Planetary boundary layer Wind stress 010502 geochemistry & geophysics Atmospheric sciences 01 natural sciences Atomic and Molecular Physics and Optics Wind speed Wind profile power law Log wind profile Wind shear Physics::Space Physics Astrophysics::Solar and Stellar Astrophysics Physics::Atmospheric and Oceanic Physics Spectroscopy Geology 0105 earth and related environmental sciences Orographic lift |
| Zdroj: | Journal of Quantitative Spectroscopy and Radiative Transfer. 188:39-45 |
| ISSN: | 0022-4073 |
| DOI: | 10.1016/j.jqsrt.2016.05.020 |
| Popis: | 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 prevailing 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. |
| Databáze: | OpenAIRE |
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