Along-Coast Features of Bora-Related Turbulence

• Published in: Boundary-layer meteorology Vol. 143; no. 3; pp. 527 - 545
• Main Authors: Večenaj, Željko, Belušić, Danijel, Grubišić, Vanda, Grisogono, Branko
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-06-2012; Springer; Springer Nature B.V
• Subjects: Aerodynamics; Analysis; Atmospheric boundary layer; Atmospheric models; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Computational fluid dynamics; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Exact sciences and technology; External geophysics; Fluid flow; Kinetic energy; Kinetics; Mathematical models; Meteorology; Mountains; Numerical weather forecasting; Parametrization; Turbulence; Turbulent flow; Wind; Wind shear; Winds and their effects; Alps; Dinaric Alps; East Mediterranean; Mediterranean Sea; Adriatic Sea; Europe; MED, Adriatic Sea; WRF-ARW model; Bora wind; Turbulent kinetic energy; Turbulence averaging interval; Mesoscale Alpine Programme; Adriatic Sea; Dissipation rate; advection; Mountain gap; Measurement campaign; Dropsonde; digital simulation; Local wind; Mesoscale; parametrization; Aircraft observation; Turbulence energy; Wind shear; Turbulence structure
• ISSN: 0006-8314; 1573-1472
• DOI: 10.1007/s10546-012-9697-6

The along-coast, offshore turbulence structure of the Bora flow that occurred on 7 November 1999 during the Mesoscale Alpine Programme (MAP) Intensive Observation Period 15 is examined. In this analysis we employ the aircraft and dropsonde data obtained over the Adriatic Sea, where the turbulence structure is determined by estimating turbulent kinetic energy (TKE) and its dissipation rate along the flight legs. The turbulence characteristics of Bora in the lee of the Dinaric Alps is greatly influenced by the mesoscale Bora flow structure over the Adriatic Sea, which in the cross-wind direction features an interchange of jets and wakes related to mountain gaps and peaks. In order to establish the origin of turbulence, the Weather Research and Forecasting—Advanced Research WRF (WRF-ARW) numerical model is used and its results are compared to the measurements. All five TKE-prediction parametrization schemes available in the model show reasonable agreement with the measured values. Since these parametrization schemes do not have horizontal advection included, they suggest that the along-flight structure of the Bora turbulence is principally generated by the local vertical wind shear. Further evidence is needed to support this hypothesis.