ENG-2003 — Page 366

THE ENVIRONMENT

306

raingauge data and forecasts the rainfall distribution within Hong Kong in the next few hours.

High-resolution numerical weather prediction models operated by the Observatory as well as those of meteorological centres overseas are the backbone of weather forecasting. Taking advantage of the improvement in forecasting techniques, the five- day forecast issued by the Observatory was extended to seven days in December. The Observatory also enhanced its tropical cyclone warning service during the year, by extending the forecast period from 48 to 72 hours.

Aviation Weather Services

The Observatory's Airport Meteorological Office at the Hong Kong International Airport provides weather services for civil aviation for a designated airspace over the northern part of the South China Sea. It provides aviation users with flight documents, aerodrome forecasts and warnings, and other information such as radar and satellite pictures.

A Light Detection and Ranging System and a terminal Doppler weather radar help to monitor windshear around the approaches to the airport under fine and rainy conditions, respectively.

Radiation Measurement and Assessment

The Observatory operates a network of 10 radiation monitoring stations to continuously monitor radiation levels in Hong Kong. Samples of air, water, soil and food are regularly collected over various parts of Hong Kong and their radiological contents measured.

In 2003, a review of data obtained since 1987 showed no significant difference in Hong Kong's environmental radiation levels before and after the operation of the nuclear power station at Daya Bay.

If a nuclear emergency occurs or is likely to occur, the Observatory will immediately intensify radiation monitoring, collect relevant information for assessing the radiological consequences and provide technical advice to the relevant government policy bureaux regarding the appropriate protective actions to take.

To promote public understanding of environmental radiation and preparedness for nuclear emergencies, the Observatory produced a video and launched an educational web page on the Daya Bay Contingency Plan in 2003.

Climatological, Oceanographic and Geophysical Services

The Hong Kong Observatory provides climatological information to meet the needs of users in various activities ranging from recreation through engineering design and environmental impact analysis to litigation. It also conducts research on short-range climate forecast and long-term climate change in Hong Kong. A forecast of the annual rainfall and number of tropical cyclones affecting Hong Kong is issued early in the year.

The Observatory produces an annual tide table for Hong Kong. It also provides assessments of the probabilities of occurrence of extreme storm surges and advice on oceanographic matters to other government departments and the engineering community.