Mesoscale airflow structure over the northern Croatian coast during MAP IOP 15 – a major bora event

Abstract

We have investigated a strong Bora event over the Northern Adriatic, which occurred on 7 November 1999 during MAP IOP 15. The wind field, potential temperature, vertical component of relative vorticity, and turbulent kinetic energy in the lower troposphere were simulated by a nonhydrostatic mesoscale model (MEMO), which was run at a very fine horizontal resolution with the grid spacing of 1 km. Our model simulation accurately reproduced the timing of the Bora event, and the modeled fields exhibited a good agreement with routinely measured winds along the Croatian coast as well as a large degree of consistence with the MAP measurements offshore. The model results also provided a detailed view of the hydraulic airflow structure and thermodynamic conditions during the Bora event. Our simulation results confirm the existence of topographically induced vorticity filaments originating in the turbulent regions near the coastal mountains, where these turbulent zones are collocated with the hydraulic jump-like flow features. All of the above processes have the highest intensity in the region of Senj.