Bora driven PV banners over the Adriatic

Bora is a severe wind commonly encountered along the Croatian coast of the Adriatic in winter months. On the northern Adriatic, this cold, gusty, northeasterly, downslope wind is associated with airflow over the coastal range of the Dinaric Alps---the southeast extension of the main Alpine massif. During the MAP SOP, on 8 November 1999, a dual aircraft mission with NCAR Electra and NOAA P-3 was flown over the northern Adriatic during an early stage of bora development that followed the advection of a deep low from the Bay of Genoa toward the central Adriatic.

The wind measured at multiple altitudes along two tracks flown parallel the main axis of the Adriatic, one adjacent to the Croatian coast and the other closer to Italy, reveals strong variation of bora speed and implies existence of multiple PV banners. The position of two encountered jets correlates well with gaps in the coastal mountains showing remarkable agreement with climatological profiles of wind speed along the Croatian coast. Additionally, in situ and remotely sensed data (lidar) from a cross-mountain flight track reveal the vertical structure of a shooting downslope flow. These observations as well as dropsonde data will be used to verify high resolution simulation of this event with the nonhydrostatic mesoscale model COAMPS. The model results will be explored to address the issue of potential vorticity generation in airflows over complex terrain.