Analysis and numerical simulation of a waterspout at the Hong Kong International Airport

Abstract

The wind field of a waterspout that occurred near the Hong Kong International Airport was documented using dual-Doppler analysis from a dense network of Doppler Light Detection and Ranging (LIDAR) systems operated at the airport, and nearby surface weather station observations. The dual-Doppler winds are used in tandem with surface observations to analyze the wind structure of the waterspout. The performance of a numerical weather prediction system simulating the windshift line and the associated vortices is compared to the observations. The waterspout and the other vortices formed along a windshift line (convergence between the arriving northeast monsoon and background westerly/sea breeze) and were rather weak, with the surface wind gusting to about 10 m/s. However, the dense network of meteorological sensors at the airport provided unprecedented surface sampling of these vortices. The numerical model captured the convergence line and the vortices reasonably well and may provide earlier alerting to the aviation weather forecasters about the possible occurrence of small waterspout-type vortices near the airport, which may have implications to aviation safety.