Sub-kilometer simulation of terrain-disrupted airflow at the Hong Kong International Airport – Aviation applications and inter-comparison with LIDAR observations

The Hong Kong International Airport (HKIA) is situated on an artificial island surrounded by complex orography. Interaction of background easterly or southerly winds with the mountains upstream of HKIA often lead to development of terrain-disrupted flow features which, when propagating across the airport runway corridors, are capable of impacting on landing/departing aircraft in the form of windshear and/or turbulence encounters.

To better resolve and forecast such fine-scale local flow phenomena, the Hong Kong Observatory has begun trial operation of a sub-kilometer numerical prediction system, the Aviation Model (AVM), based on the WRF (Weather Research and Forecast) Model, since late 2013. At a horizontal resolution down to 200 m, the inner domain of the AVM provides detailed, hourly-updated forecasts in the immediate vicinity of HKIA up to 6 – 9 hours ahead and is driven by a 600-m resolution outer domain focusing on the surrounding Pearl River Estuary region.

This study presents initial performance of the AVM in capturing these terrain-induced disturbances through verification against pilot reports of low-level windshear and/or turbulence at HKIA, aircraft Quick Access Recorder (QAR) data, as well as measurements by high-resolution remote-sensing instruments e.g. scanning Doppler LIDAR. The application of model-derived boundary layer turbulence intensity (in the form of eddy dissipation rate) in alerting of low-level turbulence at HKIA will also be explored together with comparison against calculated values using LIDAR data.