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Characteristics of bora wind at the Dubrovnik airport

Dubrovnik airport (DA, 42.56°N, 18.27°E) is settled approximately 20 km southeast of the town of Dubrovnik on the 160 m ASL plateau. The runway is 3.3 km long and is oriented parallel to the coast (NW-SE), 1.5 km away from the sea to the southwest and 1 km away from the Sniježnica Konavoska ridge (≈1200 m ASL) to the northeast. Due to this kind of geographical setup, the runway is directly impacted by bora wind which causes many difficulties in the air traffic flow at DA. Therefore, accurate and precise forecasts of bora wind for DA are of the essential importance, primarily for safety reasons and overall tourism. In this work we analyze METAR reports data logged at the Dubrovnik airport in the period from 28 November 2007 to 30 April 2014 and outputs from the numerical model ALADIN for the same period. We report occurrence of two types of bora wind at DA: 1. standard type (ST) in which bora flow exists only in the lower troposphere and 2. opened type (OT) in which bora flow extends throughout the whole troposphere. The ST bora mostly follows the hydraulic theory which makes it much more predictable than the OT bora whose behavior is more erratic and less understood. In the observed period we found 209 ST and 88 OT bora events. We investigate relationships between the measurements and numerical simulations in order to improve forecasts of bora at DA. We also compare the wind measurements between NW and SE end of the runway in order to investigate which of the two points would be more suitable for taking off/landing during a bora event.

Bora wind; Dubrovnik airport; METAR; ALADIN

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