BORA IN REGIONAL CLIMATE MODELS: IMPACT OF MODEL RESOLUTION ON SIMULATIONS OF GAP WIND AND WAVE BREAKING

Sa？etak Bora, a mesoscale wind system on the eastern Adriatic coast, profoundly impacts the local weather conditions. During easterly inflow, wave breaking generates heavy downslope winds in the lee of the Dinaric Alps. Additionally, gap winds emerge in canyons like the Vratnik Pass near Senj and enhance the Bora to a jet-like flow. The representation of these processes in numerical models is highly dependent on the surface description and therefore on model grid spacing. This study evaluates two simulations with the regional climate model COSMO-CLM with grid spacing of 0.025° and 0.11° regarding Bora winds. Strong Bora events are discussed in detail using observations between December 1999 and November 2000. The model results show that a 0.025° high-resolution simulation can well reproduce both phenomena gap wind and wave breaking. The 0.11° simulation resolves gap winds surprisingly well but misses wave breaking events