Study on low-level windshear and turbulence at Hong Kong International Airport by coupling large eddy simulation with mesoscale model

Terrain-induced windshear and turbulence are known to be serious threats to airplanes during takeoff and landing. However, it is less known that low-level windshear and turbulence induced by buildings/manmade structures situated near the airport runway may also be an important danger under fair weather conditions. To elucidate the structure and physics of microscale anticyclones observed at the Hong Kong International Airport (HKIA) and their impact on aviation safety, an investigation using a multiscale modelling framework by coupling large eddy simulation with mesoscale model is carried out under realistic weather conditions with tiny anticyclic vortices being observed. After validation with field observations, the multiscale model (MM) successfully predicts the microscale anticyclones generated from both the Passenger Terminal Building (PTB) and the AsiaWorld-Expo (AWE) located at HKIA. It is found that the microscale anticyclones from the east side of the PTB and the west side of the AWE interact with a flight glide path, causing low-level windshear and turbulence and posing potential aviation risks. By simulating another scenario without the AWE, it is revealed that the microscale anticyclones interacting with the flight glide path are significantly reduced, confirming that the increase in microscale anticyclone events is closely related to the presence of the AWE. Furthermore, the simulation without the PTB indicates a further reduction of the tiny anticyclonic vortices near the AWE and under the prevailing southwesterly flows; the interaction between the wakes of the PTB and the downstream AWE is likely to contribute to the generation of these microscale anticyclones. Our study adds evidence that the tiny anticyclonic vortices are a result of the interaction between the southwesterly background flows and major buildings (i.e., the PTB and AWE) at HKIA; this understanding could help enhance sustainability and resilience of the airport and meet the city’s growing demand for safe aviation services.