Some observations of low level wind shear at the Hong Kong International Airport in association with tropical cyclones

Abstract

In summer, Hong Kong is affected by tropical cyclones moving northwestwards over the northern part of the South China Sea. They may bring strong southeasterly airflow to the territory. The wind is disturbed by complex terrain to the south of the Hong Kong International Airport, resulting in turbulent airflow in the airport area and leading to the occurrence of low level wind shear and turbulence. This study documents the observations of wind shear at the airport in some recent cases of tropical cyclones in Hong Kong. The alerts from three operational wind shear algorithms are described, based on anemometers, the light detection and ranging system and microwave radar. The situations at the maximum wind shear magnitudes are presented. This is followed by a statistical analysis of the occurrences of wind shear against the wind shear magnitude and sign. A logarithmic relation between the two is found, and it is applicable for all tropical cyclone cases under study and different wind shear algorithms. However, there is no uniform equation for the logarithmic distribution, apart from the case of laser radar wind shear alerts for headwind loss.Finally, the accuracy of wind shear alerts of one tropical cyclone case is presented by comparison with pilot wind shear reports. It is hoped that the documentation in this study could serve as a useful reference to aviation weather forecasters at other airports with similar wind shear situations, as well as contributing to an improved understanding of the statistical behaviour of the wind shear phenomenon. K E Y W O R D S aviation, tropical cyclone, wind shear

Historical analysis (2001–2019) of low‐level wind shear at the Hong Kong International Airport

“…The emergence of power law, or scale free, statistics is a sign of critical behaviour in complex systems, and has been reported in different fields such as finance (Mandelbrot, 1963), online social networks (Liu et al, 2011) and meteorology (Peters & Neelin, 2006). On a separate front, Chan and Li (2020) recently investigated the characteristics of wind shear at HKIA during four tropical cyclone episodes. By analysing the automatic alerts of wind shear based on remote sensing detection, they found an exponential relation between the frequency and the magnitude of the detected shear.…”

Low-level wind shear of wind field modeling and simulation

“…The characteristics of the numerical wind shear wind field model is divided into three-dimensional space which must be a certain density of grid points to solve by the computer. In order to improve the resolution, It needs to provide a large number of grid point data, a large capacity computer at a high speed should be adopted [11][12][13] .…”

Derivation of High-Resolution Meteorological Parameters for Use in Airport Wind Shear Now-Casting Applications

“…If pilots have advance warning of adverse conditions, with the assistance of air traffic control personnel, appropriate action can be taken to avoid dangerous landings, for instance, use of alternative runways or airports [2]. Such warning systems can be developed through application of a variety of methods, such as deployment of instrumentation near the airport [3] or use of numerical weather prediction (NWP) models to calculate flow and turbulence fields [4]; systems may use a combination of both of these approaches [5]. Alternative solutions to similar complex, non-linear problems involving multiple variables may be found through the application of machine learning, for instance, using neural networks to optimize aerodynamic parameters in relation to unmanned aerial vehicles [6].…”

“…LiDAR and weather buoy observations have been used to evaluate high-resolution NWP model performance for particular adverse conditions [4], and the same system was further evaluated for a two-year period by comparison with pilot wind shear reports in [11]. A methodology for the use of anemometer, LiDAR and microwave radar data in operational wind shear algorithms has been developed [3]. In addition to these literature studies, Hong Kong Observatory publishes accessible information on wind shear and turbulence for pilots and air navigators, including details of the Hong Kong aviation weather alerting service [12].…”