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The Hong Kong Observatory was established in 1883, mainly to provide
scientific information for the safe navigation of ships. Since then, it
has evolved in line with community needs providing services in and studies
on weather forecasting, hydrometeorology, climatology, physical oceanography,
aviation and marine meteorology, and radiation monitoring and assessment.
The Observatory also administers the official time standard for Hong Kong,
provides basic astronomical information and maintains a seismological
monitoring network.
The Observatory issues weather forecasts and warnings
of hazardous weather to the public, mariners, the civil aviation community
as well as special users such as port and container terminal operators.
Whenever Hong Kong is threatened by tropical cyclones,
frequent warnings are widely 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.
To promote public education and awareness regarding
hazardous weather, the Observatory began in 2003 to run basic meteorological
courses for members of the public and government personnel, and organised
guided tours of the Observatory, exhibitions, popular scientific lectures
and Open Days.
Besides presenting regular weather programmes on television,
the Observatory's meteorologists also give interviews and briefings on
the radio and television during adverse weather.
While the Dial-a-Weather service provides recorded
weather messages to the public, the Telephone Information Enquiry System
serves as an interactive means for the public to obtain a variety of meteorological,
geophysical and time information by phone or by fax.
The Observatory operates a website displaying a great
variety of information. The website also features an audio version for
the visually impaired and a WAP (Wireless Application Protocol) version
for mobile phone users. In 2003, weather information at Victoria Peak
and at Ngong Ping on Lantau Island was added to the website to enhance
the coverage of regional weather information for the public and tourists.
The Observatory website recorded over 330 million hits in 2003. The Observatory
also manages two websites set up on behalf of the World Meteorological
Organisation to make available official weather warnings and forecasts
around the world to the international community.
The Observatory exchanges weather observations and forecasts with the
rest of the world under the framework of the World Meteorological Organisation.
In addition, it exchanges weather radar imageries and observations of
automatic weather stations with the meteorological bureaux of Guangdong
and Macau. The Observatory monitors the weather using a wide range of
equipment including meteorological satellites ground stations, Doppler
weather radars, automatic weather stations, weather buoys, radiosondes
carried by balloons as well as wind profilers. These are augmented by
observations from aircraft and Voluntary Observing Ships. The Observatory
also operates tide gauges to monitor raised sea levels and coastal flooding
caused by tropical cyclones.
To mitigate damage due to floods and landslips, rainstorm
and landslip warnings are issued based on the objective guidance provided
by a 'nowcasting' system developed by the Observatory. This system automatically
analyses radar and 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.
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.
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.
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.
To monitor earthquake activities in the vicinity
of Hong Kong, the Observatory operates a network of eight short-period
seismograph stations. Long-period seismographs at the Observatory's headquarters
detect tremors world-wide and information on significant tremors is made
public through the media. On average, Hong Kong experiences about two
minor earth tremors every year.
The Hong Kong Time Standard is provided by a caesium
beam atomic clock. Accuracy within fractions of a microsecond a day is
maintained. A six-pip time signal is sent to Radio Television Hong Kong
for broadcast at quarter-hour intervals. The time checking service is
also available to the public through the Observatory's Telephone Information
Enquiry System as well as through a Network Time Service at its home page.
The Network Time Service provided about 270 million checks in 2003.
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