Application of Short-Range Lidar in Wind Shear Alerting

Abstract

ong-range lidar systems have been used operationally at the Hong Kong International Airport for wind shear alerting. They are used for monitoring the headwinds over the last 3 n mi of all of the runway corridors of the Hong Kong International Airport (HKIA). This paper discusses the results of a trial of using short-range lidar (SRL) in the alerting of wind shear over a particular runway corridor by performing more frequently updated wind measurements over a specific section of this corridor in which many wind shear reports are received. The radial resolution of the lidar is 75 m and the data are updated every 20 s. Three different ways of wind shear alerting based on SRL?s data are studied, namely, the deviations of the measured radial velocities from the uniform background flow (the ?velocity fluctuation?), eddy dissipation rate (EDR), and autocorrelation of radial velocity. The performance of these methods is studied by comparing with the pilot wind shear reports. The velocity fluctuation has the best skill in capturing the wind shear reports. By combining the wind shear alerts from SRL with those from the Wind Shear and Turbulence Warning System (WTWS), it is possible to achieve a probability of detection (POD) of pilot wind shear reports of about 90%, with a percentage of time on alert (PTA) of about 10% only. This even outperforms the existing overall wind shear alerting service (WTWS plus subjective wind shear warnings issued by aviation weather forecasters) by significantly reducing PTA. As such, the present study shows that it is possible to combine wind shear alerts from SRL and WTWS for automatic wind shear alerting without the need of human intervention, at least for a particular runway corridor of HKIA.