Estimating Turbulence Intensity along Flight Paths in Terrain-disrupted Airflow using Anemometer and Wind Profiler Data

Turbulent airflow arising from terrain disruption of the prevailing winds may occur over the arrival and departure flight paths of the Hong Kong International Airport (HKIA) under certain weather conditions, such as strong east to southeasterly winds in stable boundary layer in spring, intense southwest monsoon in summer, and high winds associated with tropical cyclones.

Timely alerting of significant turbulence, which is quantified in terms of Eddy Dissipation Rate (EDR) following international aviation practice, is crucial in assuring flight safety. In the existing Windshear and Turbulence Warning System (WTWS) operated by the Hong Kong Observatory (HKO), EDRs along flight paths are estimated from the data of surface anemometers in the vicinity of the airport and on the hills nearby based on correlation equations established from a limited number of turbulent flow events collected by a research aircraft before the opening of HKIA in 1998.

This study aims at enhancing these equations by using a larger dataset, namely, EDR derived from Quick Access Recorder (QAR) data collected onboard transport category commercial jets over all seasons in a 2-year period at HKIA. Results of using additional data sources to establish the correlation equations, such as wind data from the newly installed anemometers at the valleys near the airport and the EDRs in the upper air as estimated from wind profilers, are also presented.