310 The Environment
was the fourth wettest June and August the second wettest August since records began in 1884.
It was also a hazy year. For some 28 per cent of the time, reduced visibility of 8 kilometres or less was observed at the Hong Kong International Airport, breaking the previous record of about 24 per cent set in 2004. Only three tropical cyclones affected Hong Kong, roughly half the normal figure. The first tropical cyclone warning signal of the year was issued on 12 August, the latest in post-war years.
Meteorological Services
Hong Kong Observatory
The Hong Kong Observatory was established in 1883, mainly to provide a time service and weather information for the safe navigation of ships. Since then, it has evolved in line with community needs, providing services in weather forecasting, climatology, hydrometeorology, physical oceanography and radiation monitoring and assessment. The Observatory also administers the official time standard for Hong Kong, provides astronomical information, maintains a seismological monitoring network and operates the tsunami warning system in Hong Kong.
The Observatory issues weather forecasts and warnings of hazardous weather to the public, mariners and the aviation community as well as special users such as container terminals and transport operators.
Whenever Hong Kong is threatened by tropical cyclones, warnings are disseminated through the mass media. A colour-coded rainstorm warning system warns people of heavy rain. The Observatory also issues warnings on thunderstorms, landslips, fire danger, strong monsoon, cold and very hot weather and frost. An advisory service on the ultraviolet (UV) index is also provided. In 2005, the thunderstorm warning service was strengthened by additional lightning information generated by a newly installed lightning location system. A service to alert container terminal operators and related sectors to the occurrence of severe gusts was also introduced.
The Observatory exchanges weather observations and forecasts with the rest of the world under the framework of the World Meteorological Organisation. Weather radar images and observations of automatic weather stations are exchanged with the meteorological authorities of Guangdong and Macao. Weather is also monitored using weather buoys, an upper-air sounding system and wind profilers. These observation systems are augmented by observations from aircraft and Voluntary Observing Ships.
Objective guidance for the issuance of rainstorm and landslip warnings is provided by a computer-based nowcasting system developed by the Observatory itself. This system automatically analyses radar and raingauge data and forecasts the rainfall distribution in the territory within a few hours.
Page 360Page 361