THE ENVIRONMENT
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sunny spell persisted from December 10-27. Some frost was reported at Tai Lung Farm on December 3 and 20. The minimum temperature of 9.5°C at the Royal Observatory on December 20, as on February 27, was the lowest of the year. On Tai Mo Shan, temperatures dropped to 0.0°C. Fire danger warnings were in effect during 29 days of the month. According to newspaper reports some 30 000 people were made homeless by a succession of disastrous fires mostly in squatter areas.
The Royal Observatory
The Royal Observatory was established in 1883 mainly to provide scientific information for the safe navigation of sailing ships. The headquarters of the department has remained in the same building for 98 years and is now surrounded by high rise apartments. A new nine-storey office block is being built beside the original headquarters and is scheduled for completion in 1982.
The most important function of the department is the provision of weather information and tropical cyclone warnings for the public and for shipping and aviation. Forecasts for the public are prepared in the Central Forecasting Office and broadcast over radio and television at frequent intervals. Warnings of thunderstorms, heavy rain, fire danger and frost are issued whenever necessary. Special forecasts are issued for fishermen and yachtsmen in various marine areas.
Services for aviation are provided by the Airport Meteorological Office. About 80 aircraft each day are provided with meteorological prognostic charts and landing forecasts. Special warnings are issued for adverse weather. A micro-processor based system was built and installed by the Royal Observatory to provide a continuous display of wind shear in the approaches to the airport.
On average, 31 tropical cyclones form in the western North Pacific or China Seas every year and about half of them reach typhoon intensity (maximum winds of 33 m/s or more). Warnings and forecasts are issued every three hours for ships at sea, for shipping companies and airlines. Objective forecasts are made by computer and exchanged with neighbouring centres. Whenever tropical cyclones threaten Hong Kong, warnings and statements are issued at frequent intervals and widely distributed. In order to provide these services the observatory collects about 20 000 weather reports each day from land stations, islands, ships and aircraft. Coded messages are analysed by the observatory's computer and exchanged automatically with neighbouring countries. A large volume of historical weather records have been accumulated on magnetic tapes. These are used to answer climatological enquiries from a variety of organisations such as engineering consultants, universities, utilities, insurance and legal firms both in Hong Kong and overseas.
Instruments and Observations
1981 was the first full year in which high resolution satellite pictures from the Japanese Geostationary Meteorological Satellite (GMS) were available in Hong Kong. The pictures are recorded on magnetic tape in digital form and any area can be enlarged and enhanced by micro-processors to make it possible to locate the centre and estimate the maximum winds in a tropical cyclone.
Also during the year an order was made to replace the observatory's weather radar at Tate's Cairn. The new radar will be delivered in 1982 and will be able to print out rainfall rates over a wide area and also archive the data for climatological and research purposes. It will also provide remote displays on colour television sets. The old radar will still be maintained as a standby.