Open AccessModelling of wind shear downwind of mountain ridges at Hong Kong International Airport
Author(s) -
Carruthers David,
Ellis Andrew,
Hunt Julian,
Chan P. W.
Publication year - 2014
Publication title -
meteorological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 59
eISSN - 1469-8080
pISSN - 1350-4827
DOI - 10.1002/met.1350
Subject(s) - froude number , wind shear , wind gradient , geology , meteorology , wind speed , boundary layer , inversion (geology) , wind direction , shear velocity , flow (mathematics) , geodesy , atmospheric sciences , seismology , mechanics , turbulence , geography , physics , tectonics
A theoretical and computational study is presented of the wind flow over the mountain ridges to the south of Hong Kong International Airport given the upwind profiles of ‘mean’ velocity and temperature. A sensitivity study shows how large variations in wind speed, wind shear and wind direction occur on the approach path when the upwind flow from the southeast is stably stratified above the boundary layer with a significant inversion no more than a few hundred metres above the ridge (height about 450 m). The Froude number is close to unity. The effects of vertical wind shear across the inversion layer reduce the speed‐up, and directional wind shear changes the surface flow direction. The observed horizontal length scales along the approach are about equal to the projected widths of the predominant features of the ridges and valleys. For an extreme wind event there was found to be satisfactory agreement between the wind speed measured by a landing aircraft and the predictions of the fast quasi‐linear analytically based computer model FLOWSTAR. This suggests that near real time application of the model and near real time monitoring with remote and in situ instruments can be used to predict these extreme flow events and hence give warnings about them. Conclusions are drawn about how such predictive modelling could be developed.