ENG-1985 — Page 341

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THE ENVIRONMENT

Following the successful completion of two Typhoon Operational Experiments in 1982 and 1983, organised under the auspices of an international Typhoon Committee, the use- fulness of enhanced exchange of observational data and forecasts among meteorological services in the region during tropical cyclone situations was generally recognised. In 1985, the Royal Observatory continued to participate in the programme of enhanced information exchange.

Services for aviation are provided by the Airport Meteorological Office. About 90 aircraft each day are supplied with prognostic weather charts and landing forecasts. Special warnings are issued for adverse weather. Wind conditions at the airport and its vicinity are monitored continuously using a network of anemometers and a doppler acoustic radar at Lei Yue Mun on the southeastern approach to the airport.

In order to provide these services, meteorological data are received from other countries through a computerised telecommunication system. This information is regularly analysed and supplied to forecasters while the coded messages are also transmitted to neighbouring countries.

Weather observers at the Royal Observatory headquarters, Hong Kong International Airport and Cheung Chau keep a continuous watch on local conditions. Additional observations are made by the Marine Department at Waglan Island and Green Island, by the Royal Navy at Tai O and by the Royal Air Force at Sek Kong. Eighteen anemometers are operated by the observatory in different locations. Winds recorded at the Star Ferry Pier, Kowloon, and at Waglan Island, representing conditions in Victoria Harbour and offshore respectively, are telemetered to the Central Forecasting Office. A spherics recorder is used to register thunderstorm activity within a range of about 100 kilometres, and a lightning location system provides information on lightning within about 130 kilometres. The observatory also has a network of more than 100 rain gauge stations, mostly operated by voluntary observers. Implementation of the plan to supply more up-to-the-minute information to the Central Forecasting Office continued.

During the year, three purpose-built automatic weather stations were added to the local network which now comprises Ta Kwu Ling, Lau Fau Shan, Chek Lap Kok, Tsing Yi and Sha Tin. All these stations send weather data to the observatory headquarters through telephone lines. Another automatic weather station was set up in 1985 on Huangmao Zhou, an island 40 kilometres to the south of Lantau Island, in collaboration with the Guangdong Meteorological Bureau. The network of automatic rain gauges, which report rainfall amounts instantaneously to the observatory through a microprocessor system, was expanded further during the year.

The network of tide gauges sending instantaneous information back to the Royal Observatory headquarters comprises stations at Tsim Bei Tsui, HMS Tamar, Tai Po Kau, North Point and Lok On Pai. In addition, tide information is also gathered at Tai O. A wave data processing system was installed at Waglan Island in 1985. Aided by these networks, weather forecasters keep a close watch on the latest developments in weather and issue warnings accordingly.

Upper-air atmospheric conditions are measured by radiosondes carried by balloons launched at King's Park Meteorological Station. Signals transmitted by the radiosondes are processed by a minicomputer on the ground. A tethered balloon and radiosonde sys- tem is also used at selected locations to obtain data up to a few hundred metres above the ground.

A digital radar system which employs a minicomputer to process radar signals supplies information on rain distribution to forecasters at the Central Forecasting Office and the