Abstract
Methods for now-casting adverse weather conditions with the potential to cause disruption to aircraft landings often make use of real-time measurements at high temporal resolution. This paper describes processing methodologies developed to derive meteorological parameters from such measurements recorded in the vicinity of Hong Kong International Airport, specifically a radiometer in King’s Park, a wind profiler and surface anemometer on Cheung Chau Island and weather buoys in the Pearl River estuary. These parameters are suitable for use as input to a now-casting application of the computationally efficient airflow model, FLOWSTAR, which has previously been shown to predict mountain waves generated by flow over Lantau Island to the southeast of the airport. Radiosonde data from King’s Park have been used to test the radiometer processing method; the novel approach of using minimum and maximum potential temperature deviations from a series of height-dependent linear profiles to derive radiometer inversion layer parameters generates data that compares well with values derived from corresponding radiosonde profiles. Mountain wave strength depends on the magnitude of wind speed in the inversion layer; wind profiler data can be used to estimate typical and maximum wind speeds and associated wind directions using estimates of inversion layer depth derived from the radiometer data. With estimates of surface sensible heat flux appropriate for the airport’s coastal location calculated using a marine boundary layer scheme, a dataset of meteorological parameters at 20-min resolution has been derived for input into the FLOWSTAR model. The combination of automated meteorological data processing methods and flow field modelling has the potential to form part of a now-casting system for determining strong wind shear conditions at the airport.
Highlights
Aircraft landing at airports located in the vicinity of significantly elevated terrain may experience less than ideal meteorological conditions due to the influence of mountains on air flow and turbulence
For temperature-related parameters, an inter-comparison of datasets derived from the radiometer and radiosonde has been undertaken for the subset of hours where radiosonde soundings are available (27 h); wind profiler measurements can be compared to radiosonde soundings, and a comparison of hourly marine and land surface sensible heat flux values is presented
Within the set of radiometer measurements made at times that coincide with radiosonde soundings, the purpose of this work is to identify a further subset of cases that corresponds to stronger inversions, which can be defined in terms of sharp changes in potential temperature profiles
Summary
Aircraft landing at airports located in the vicinity of significantly elevated terrain may experience less than ideal meteorological conditions due to the influence of mountains on air flow and turbulence. 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].
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