Some novel observations of terrain-disrupted airflow at the Hong Kong International Airport based on range-height indicator and plan position indicator scans of the LIDAR and their numerical simulations

Abstract

Range-height indicator (RHI) scans from the Doppler Light Detection And Ranging (LIDAR) systems at the Hong Kong International Airport (HKIA) reveal vortices associated with Kelvin-Helmholtz (KH) instability, jump-like features and mountain waves associated with lower kills and a gap on Lantau Island nearby HKIA. These novel features of terrain-disrupted airflow at HKIA that has not been documented before. This paper analyzes such flow features by considering some parameters of the airflow based on the upper air sounding in Hong Kong, such as Richardson number, Scorer parameter, and Froude number. An attempt has also been made to simulate these novel flow phenomena at HKIA using a high resolution mesoscale numerical weather prediction (NWP) model. The modeling results are found to be a mixed success. Some features, such as mountain waves and jump-like feature, are readily reproduced. However, vortices associated with KH instability are difficult to reproduce, and the vortex shedding simulation does not fully reproduce the observational data based on the Doppler LIDARs. The results in this paper are considered to be useful for the study of mountain meteorology in Hong Kong and elsewhere in the world.