THE ENVIRONMENT
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Hourly cloud pictures received from the Geostationary Meteorological Satellite of the Japan Meteorological Agency give general indications of tropical cyclones, severe storms and frontal systems approaching the south China coast. The Observatory's weather radar system at Tate's Cairn detects rain within about 500 km of Hong Kong and gives estimates of rain intensity and movement. Information on thunderstorms as detected by a lightning location system is also available to forecasters."
Weather observers and automatic weather stations at about 40 locations in Hong Kong provide comprehensive and real-time coverage of regional weather variations, while observations from Voluntary Observing Ships provide valuable information on weather at sea.
Rainfall information is important because of Hong Kong's vulnerability to floods and susceptibility to landslips during heavy rain. A dense network of about 70 automatic reporting rain-gauges provides real-time information on rain distribution and intensity over Hong Kong for the operation of rainstorm, flood and landslip warnings.
The Observatory operates tide gauges for monitoring coastal flooding and raised sea levels caused by tropical cyclones. To probe the atmosphere aloft, radiosondes carried by balloons are launched four times a day at King's Park to relay weather information from the upper air.
The Observatory exchanges weather radar images with the Guangdong Meteorological Bureau and operates four solar-powered automatic weather stations at Huangmao Zhou, Neilingding Island and Wailingding Island west of Hong Kong, and the Tuoning Islands to the east, to give earlier indication and better timing of the approach of hazardous weather such as fronts, squall lines and tropical cyclones. Using guidance from numerical products from both global and limited area models, forecasters can now issue weather forecasts several days ahead with reasonable confidence.
Aviation Meteorology
The Observatory operates the Airport Meteorological Office (AMO) at the Hong Kong International Airport to provide services for civil aviation. Besides keeping watch and warning of hazardous weather over the Hong Kong Flight Information Region, the AMO provides flight documentation to aircraft departing Hong Kong. This includes weather forecasts for destination aerodromes, prognostic charts of significant weather en route and forecast wind and temperature data appropriate to cruising levels.
Good progress was made in establishing meteorological facilities and services for the new airport at Chek Lap Kok. Major meteorological systems were installed during the year and put into trial operations to collect data. Weather observations at Chek Lap Kok continued throughout 1997 and the data were transmitted to aviation forecasters at AMO, enabling them to become familiar with the conditions at Chek Lap Kok in preparation for operations there.
Radiation Measurement and Assessment
The Observatory operates an Environmental Radiation Monitoring Programme to monitor radiation levels in Hong Kong. The programme, begun in 1987, entails the collection and measurement of samples of air, water, soil and food regularly at