Downbursts are negatively buoyant descending winds coming from thunderstorm clouds that spread on the horizontal upon impinging the ground. Surface roughness is known to govern the characteristics of synoptic-scale atmospheric boundary layer (ABL) winds. This study assesses whether the same holds for downburst outflows and to which degree. The downburst winds are experimentally reproduced as a large-scale impinging jet at the WindEEE Dome, at Western University (Canada). Three different surfaces were tested and the equivalent full-scale roughness length is quantified through a best-match approach between experimentally produced ABL winds and ESDU profiles. The highest roughness produces an outflow vertical profile with maximum velocity reduced in magnitude and occurring at higher elevation with respect to the smaller-roughness cases.

Effect of surface roughness on large-scale downburst-like outflows

Federico Canepa;Massimiliano Burlando;Horia Hangan;
2022-01-01

Abstract

Downbursts are negatively buoyant descending winds coming from thunderstorm clouds that spread on the horizontal upon impinging the ground. Surface roughness is known to govern the characteristics of synoptic-scale atmospheric boundary layer (ABL) winds. This study assesses whether the same holds for downburst outflows and to which degree. The downburst winds are experimentally reproduced as a large-scale impinging jet at the WindEEE Dome, at Western University (Canada). Three different surfaces were tested and the equivalent full-scale roughness length is quantified through a best-match approach between experimentally produced ABL winds and ESDU profiles. The highest roughness produces an outflow vertical profile with maximum velocity reduced in magnitude and occurring at higher elevation with respect to the smaller-roughness cases.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11567/1095182
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