P35 - Investigating the Mechanism of a Local Windstorm in the Swiss Alps Using Large-Eddy Simulations
DescriptionThe Laseyer windstorm is a local and strong wind phenomenon in the narrow Schwende valley in northeastern Switzerland. The phenomenon has raised the interest of meteorologists as it has - in the past - led to derailments of the local train. It is characterised by easterly to southeasterly winds during strong northwesterly ambient wind conditions, thus the wind in the valley reverses compared to the flow further aloft. We use a newly developed large-eddy simulation (LES) configuration of the FVM atmospheric model based on Python and GT4Py to gain a better understanding of the Laseyer windstorm. The LES are performed in the very steep and highly complex terrain using idealised initial and boundary conditions. With this numerical tool we can study the sensitivity to ambient flow parameters in a controlled environment. As a result, we are able to shed light on the mechanism of the Laseyer by revealing the flow structure and variability in the narrow Schwende valley. A set of idealised LES with carefully selected ambient flow parameters allows us to identify the wind direction and wind speed conditions needed for the occurrence of the Laseyer and its response to changing ambient flow conditions.
TimeTuesday, June 2710:06 - 10:07 CEST