Hong Kong's New Airport at
Chek Lap Kok (CLK) is located on partly reclaimed land adjacent to Lantau Island, whose
rugged terrain has a maximum elevation of nearly 1,000 meters (Fig. 1). Consequently,
aircraft operating at the new airport may be affected by significant terrain-induced
windshear and turbulence under certain meteorological conditions. In order to enhance
safety and operational efficiency at the airport, Weather
Information Technologies Inc. (WITI) has developed a Windshear and
Turbulence Warning System (WTWS) which was installed, tested and has been
operational since the airport's opening day, 6 July 1998.
The 44-month project was
under the sponsorship of the Hong Kong
Observatory. The WTWS development team included WITI, the National Center for Atmospheric Research (NCAR), Hong Kong University of Science and Technology (HKUST), and
the University of Wyoming.
Components include basic and applied research
on wind flow over Hong Kong's terrain, a scientific field study, warning system concept
and feasibility studies, system design, development, testing, implementation and training.
The WTWS provides real-time hazardous weather information to air traffic controllers and
pilots to enhance safety in the terminal area and improve predictions of hazardous weather
to support strategic decision making by air traffic managers.
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 Figure 1. Topographical map
of the region near Hong Kong's new airport. The highest elevations are above 800 meters.
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The WTWS is the first system worldwide to
provide real-time alerts of terrain-induced turbulence and alerts for both convective and
terrain-induced windshear, the WTWS also provides predictions of turbulence caused by
terrain and airport surface wind as well as numerical weather prediction guidance. For
detection of convective windshear, the WTWS relies partly on the output from a Terminal Doppler Weather Radar (TDWR)
at Tai Lam Chung, about 12 kilometers from CLK. The windshear warning system ingests TDWR
products including gust front, precipitation intensity, and storm motion, providing an
integrated alert system. It generates graphics and text designed for easy interpretation
by pilots, controllers, traffic managers and aviation forecasters. It also
interfaces with other airport systems, reaching a broader user community including airport
authority staff and airline offices.
Prior to the development of
the windshear warning system, several studies were conducted in Hong Kong to gain insight
into the meteorological conditions near the location of the new airport. These studies
included analysis of routine weather observations, special observing programs and
meteorological modeling of the differences between the existing Kai Tak Airport and the
new airport. Variables that were analyzed included wind direction and speed, temperature,
clouds, visibility, rainfall, thunderstorms and fog. Methods used to conduct these studies
included investigative flights by light aircraft and water tank and wind tunnel
experiments.
The probability of
significant turbulence and windshear at Chek Lap Kok during specific meteorological
conditions prompted the Hong Kong government to create the WTWS program. It was designed
to investigate the detailed wind flow environment near the airport site and based on the
scientific results, build and implement an operational windshear and turbulence warning
and forecasting system. Following a competition, the project was awarded to Weather
Information Technologies Inc. in October 1993.
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