engleski

Multiscale simulations of bora downslope windstorm events

Bora events over the eastern Adriatic coast are well known for exceptional spatial and temporal wind variability. Such a wind climate is a challenge for wind studies which require knowledge of wind conditions in a relatively small area (e.g. 10 km x 10 km). The aims of this work are i) to perform realistic simulations of bora events using multiscale simulation which resolves large eddies (LES approach) and ii) to study sub-mesoscale pulsations, sources and sinks of bora turbulence through the analysis of the turbulence kinetic energy (TKE) budget. Numerical analysis of the event used the WRF model with realistic initial and boundary conditions and multiple nested computational domains in two configurations. The first used a mesoscale model setup at a grid spacing reaching 333 m in the highest resolution domain and a Mellor-Yamada type of the Planetary Boundary Layer (PBL) scheme while the second used a LES setup at a grid spacing as fine as 37 m using explicit simulation of large turbulent eddies. First, multiscale simulations show more successful in simulating the evolution of the tested bora events. While mechanical production and dissipation of TKE are the dominant terms of the TKE budget, other terms such as turbulent transport and advection play an important role in the budget as well. Results show potential to use WRF-LES framework for wind studies when a detailed knowledge of wind conditions is required.

bora, pulsations, observations, numerical simulations

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