Background
For an introduction to windshear and turbulence, please look at the
Windshear and Turbulence pamphlet
(in pdf format).
Geographically, the Hong Kong International Airport (HKIA) was built on reclaimed land to the north of the rather
mountainous Lantau Island which has peaks rising to nearly 1,000 m with valleys as low as about 400 m in between.
To the northeast of HKIA, there are a number of smaller hills with peaks rising to between 400 and 600 m.
Under this coastal and hilly environment, a wide variety of weather phenomena can bring
windshear and turbulence to HKIA.
These include:-
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winds blowing across hilly terrain
microbursts and
gust fronts induced by thunderstorms
sea breeze
low-level jets
Weather Sensors for Monitoring of Windshear and Turbulence
Weather sensors for monitoring windshear and turbulence in and around HKIA include:-
a Terminal Doppler Weather Radar (TDWR)
strategically installed at about 12 km northeast of the airport
a network of automatic weather stations
on the surface, valleys and hilltops
three weather buoys
over the waters around the airport
two wind profilers over Lantau Island
a Doppler LIght Detection And Ranging (LIDAR) system at the airport |
Location map of weather sensors for windshear and turbulence monitoring
Click for a tour to the meteorological stations
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Windshear and Turbulence Alerts
Alerts for possible low-level windshear and turbulence within 3 nautical miles of runway ends
are automatically generated using data from a suite of weather sensors.
These alerts are updated at a frequency of at least once per minute for relay to aircraft.
The geographical distribution of windshear and turbulence is displayed on
graphical displays for air traffic control supervisors and aviation forecasters.
To supplement the automated alerts, actual pilot reports of windshear and turbulence
encountered below 500 m are also issued as alerts for broadcast on the Automatic Terminal
Information Service (ATIS) to ensuing aircraft. The aviation forecasters also
issue windshear alerts utilizing data from the suite of weather sensors.
With improved windshear alerting techniques and facilities put in place in the last
couple of years, the rate of successful detection of windshear events has been on the rise,
accompanied by a steady decrease in the false alarm rate. In 2002, over 85% of windshear
reports were covered by the Hong Kong Observatory's windshear alerts.
The figure reached 95% in the first half of 2003.
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Display of graphical windshear alerts
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