engleski

Systematic differences in moderate to severe Bora upwind and downwind turbulence

Turbulence statistics are analyzed for Bora wind episodes that occurred simultaneously in the town of Senj and at the Vratnik pass at the northern Croatian Adriatic coast, for a large dataset spanning over nine months and 800 hours of moderate to severe bora wind record. Our goal is to address the systematic differences in characteristics of the near-ground turbulence statistics between Senj, located at the shoreline leeward of the main mountain peaks and Vratnik, located at the mountain ridgeline "above", approximately 7.5 km away from Senj. Special focus was on the difference in turbulence kinetic energy (TKE) and its dissipation rate between those two sites. Through these two quantities, we explore how well the TKE balance at either site adheres to a simple shear-dissipation model. Finally, turbulence intensity is compared to values measured elsewhere at the Croatian coast and to the values recommended in various engineering codes. Such patterns of turbulence, which affect the onset, duration and cessation of Bora wind, are often not adequately parametrized in operational numerical model.

Bora ; field measurements ; TKE balance ; turbulence ; surface-layer scaling

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