Numerical Simulation of Wind Gusts in Terrain-disrupted Airflow at the Hong Kong International Airport

The Hong Kong International Airport (HKIA) is located in an area of complex terrain. To its south is the hilly Lantau Island with peaks rising to about 1000 m above mean sea level with valleys as low as 400 m in between. Winds from the east to southwest could become turbulent and gusty after flowing over the Lantau terrain. The development of objective forecast guidance for forecasting gust will be beneficial to aviation forecasters in support of their preparation of the aerodrome forecast (TAF), take-off and landing forecasts, as well as aerodrome warning of strong wind and gusts.

This study explores the feasibility of using a high-resolution numerical weather prediction (NWP) model to forecast gusts associated with terrain-disrupted airflow in two typical weather conditions of gusty winds at HKIA, namely, southwesterly flow, and east to southeasterly flow. Nested numerical simulations with a spatial resolution down to 200 m are employed to resolve the complex terrain near HKIA and simulate orographically enhanced high wind events. The simulation results are compared with surface anemometer observations in the vicinity of the airport. The effect of turbulence parameterization schemes on gust forecasting is also examined.