ENG-1999 — Page 485

THE ENVIRONMENT

while observations from Voluntary Observing Ships provide valuable information on weather at sea.

Rainfall information is important because of the occurrence of flood and landslips during heavy rain. A dense network of about 70 automatic reporting rain-gauges provides real-time information on rain distribution and intensity for the operation of rainstorm and landslip warnings. An operational forecasting system has been developed to assimilate relevant information for rainstorm monitoring and prediction. The first phase, focusing on rainfall forecasts based on combined radar and rain-gauge analysis, was put into operation in April.

To further enhance the capability of rainstorm forecasting, a super computer was installed at the Observatory for running high-resolution numerical weather prediction models. Using guidance from numerical products from both global and limited area models, forecasters can now issue weather forecasts several days ahead with reasonable confidence.

The Observatory operates tide gauges to monitor coastal flooding and raised sea levels caused by tropical cyclones. To probe the upper atmosphere, radiosondes. carried by balloons are launched three times a day at King's Park to measure weather conditions aloft.

The Observatory exchanges weather radar images with the Guangdong Meteorological Bureau and operates jointly with them four solar-powered automatic weather stations at Huangmao Zhou, Tuoning Islands, Neilingding Islands and Wailingding Islands to provide better timing of the approach of hazardous weather such as fronts, squall lines and tropical cyclones.

Aviation Meteorology

The Observatory operates the Airport Meteorological Office (AMO) at the Hong Kong International Airport to provide weather services for civil aviation. Besides keeping watch and issuing warning of hazardous weather over the Hong Kong Flight Information Region, the AMO provides flight documentation to aircraft departing from Hong Kong. This includes weather forecasts for destination airports, prognostic charts of significant weather en-route and forecast wind and temperature data appropriate to cruising levels. Messages on meteorological conditions at the Hong Kong International Airport are also supplied to airline operators through a dedicated web server for pre-flight planning.

In 1999, additional meteorological equipment for the second runway was installed. Acquisition of meteorological equipment for an ancillary AMO at the back-up Air Traffic Control Complex was near completion. A contingency plan was prepared for switching operation from the existing AMO to the back-up facility in an emergency.

Radiation Measurement and Assessment

The Observatory operates an Environmental Radiation Monitoring Programme to monitor radiation levels in Hong Kong. The programme entails the collection and measurement of samples of air, water, soil and food regularly at several sites. A network of stations monitor the ambient gamma dose rate continuously and warn of any deviation from normal levels. Data are disseminated to the media daily and released in a bulletin every month. The prevailing radiation levels are also published annually.

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