ENG-1985 — Page 342

THE ENVIRONMENT

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Airport Meteorological Office. The system also produces objective short-term rainfall estimates at selected locations.

High resolution satellite cloud pictures from the Japanese Geostationary Meteorological Satellite are received in Hong Kong. The pictures, recorded in digital form, are processed by microprocessors to give special displays for such a purpose as estimating maximum winds in a tropical cyclone. When necessary, satellite pictures transmitted by polar-orbiting meteorological satellites are also received, supplementing information from the geostation- ary satellite.

During the year, plans were made to acquire a bigger computer to cater for various applications in the department including automatic weather chart plotting, improved quality control and processing of weather data, and numerical modelling for forecasting and warning services.

In order to monitor local earthquakes, a network of three short-period seismometers at Cheung Chau, High Island and Tsim Bei Tsui is operated by the Royal Observatory. Long-period seismographs record tremors from all over the world. Strong motion accelero- graphs are installed at two locations with different soil properties. While on average only two or three earthquakes are felt by the public each year, hundreds are detected by the seismometer network. In recent years, about 150 earthquakes have been detected annually within 320 kilometres of Hong Kong.

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Measurements of Beta and Gamma radioactivity in airborne dust and rain-water are made at King's Park. The observatory co-operates with the UK Atomic Energy Research Establishment and the International Atomic Energy Agency in making these measure- ments. Plans are in hand to implement a more comprehensive programme of background radiation monitoring.

The observatory operates a caesium beam atomic clock which provides time signals accurate to about one micro-second. A six-pip signal is broadcast on 95 mHz every quarter hour and is also relayed to Radio Television Hong Kong for broadcast to the public. The Royal Observatory time standard was calibrated with the primary standard at the Radio Research Laboratories in Japan in May.

Research

The Royal Observatory carries out investigations on weather systems affecting Hong Kong with a view to improving the standard of weather services. The performance of existing objective methods of forecasting tropical cyclone movement was assessed and new methods were introduced. Several recent tropical cyclones were analysed in detail. The first annual joint technical review of severe weather events with the Guangdong Meteorological Bureau was held in Shenzhen in April.

During the year, a trial of a numerical method of weather prediction was undertaken and this method was refined. Several computer models for flood forecasting were also studied. Under the auspices of the Environmental Monitoring Research Programme of the World Meteorological Organisation, a station of the Background Air Pollution Monitoring Network (BAPMON) was set up at the Sai Kung East Country Park to collect data required for research into the long range transport of pollutants in the atmosphere.

Research is also directed at meeting the demand for meteorological analyses by industry and for engineering projects. Other projects during the year included work on design wind and rainfall parameters and modelling of sea waves and tides by using computers. The analysis of meteorological data collected in western Victoria Harbour as part of a study to investigate local conditions which might affect new developments was completed.