engleski

Measurements and forecasts of bora turbulence at the Dubrovnik airport (LDDU), Croatia

Bora flows cause huge problems during taking off and landing at the Dubrovnik airport (LDDU). Therefore, in the period from 08 December 2017 to 31 March 2018, a 10 m high tower, with ultrasonic anemometers at 3 m level and on its top, was installed at the LDDU to measure structure of the mean airflow and turbulence in the immediate vicinity of runway. These measurements are used for comparison of the simulated airflows using an operational numerical weather prediction (NWP) model for the LDDU. Information about the mean wind speed, wind gusts and wind shear that pilots get prior to taking off and landing greatly relies on such data and dedicated numerical simulations ; therefore, it is of utmost importance that crucial parameters predicted numerically describe the real state of the airflow of interest as good as possible. Through the comparisons of numerical simulations with tower measurements, relationship between simulated parameters and measured turbulence is investigated. For estimation of turbulence kinetic energy and its dissipation rate (EDR) from measurements, Fourier spectral analysis is used. Concerning the bora flows, our results indicate a great difference in turbulence structure between so called standard (or shallow) bora flow and so called opened (or deep) bora flow. Furthermore, we showed at another location that the peak value of the cube root of EDR for bora surface layer turbulence easily exceeds its severe threshold of 0.7 m2/3s-1, which is an aircraft-independent objective measure of turbulence intensity in civil aviation according to International Civil Aviation Organization, 2007. We want to map out EDR near the LDDU as much as possible and then look for its acceptable forecast. The final product of this work should be a declaration of relevant parameter(s) from NWP operational model that is most correlated with the observed (measured) turbulence. This(these) parameter(s) should contribute to the quality of information about hazardous airflow situations during taking off/landing at the LDDU ; moreover, it should be, in principle, adaptable to other airports.

bora flows ; turbulence ; ALADIN model

nije evidentirano