AN INTRODUCTION TO THE DEPARTMENT
The Hong Kong Observatory (the Observatory) is a department of the Government of the Hong Kong Special Administrative Region. It forecasts weather and issues warnings on weather-related hazards. The Observatory also monitors and makes assessments on radiation levels in Hong Kong and provides other meteorological and geophysical services to meet the needs of the public and the shipping, aviation, industrial and engineering sectors.
History: More than a century has elapsed since the establishment of the Hong Kong Observatory in 1883. Early operations included meteorological and magnetic observations, a time service based on astronomical observations and a tropical cyclone warning service.
Tropical Cyclone Warnings: The tropical cyclone warning service is an important function of the Observatory. Warning bulletins with recommended precautionary actions are broadcast at frequent intervals to the public, shipping and aviation sectors. Media briefings are conducted during the approach of tropical cyclones to provide the public with timely updates on latest tropical cyclone information.
Weather Services: The Central Forecasting Office routinely issues local weather forecasts to the press, radio and television stations and relevant government departments. Warnings for hazardous weather such as typhoon, thunderstorm, heavy rain, landslip, flooding, strong monsoon, fire danger, low temperature and frost as well as very hot weather are issued to alert the public.
During tropical cyclone and rainstorm situations, some advance indication of the issuance or cancellation of signals and warnings will be given to the public to the extent possible to let people take early precautions against severe weather.
Specialised weather forecasts are prepared for utility companies, public transport operators, engineering contractors and information providers. Forecasts of up to a week ahead can be made to meet the needs of these special users.
The Dial-a-Weather service operated by the Observatory, which provides recorded weather messages, remains popular. In 2001, the total number of handled calls was over 20 million. The Telephone Information Enquiry System, an interactive enquiry system through which the public could obtain a variety of meteorological and geophysical information by phone or by fax, also attracted around one million enquiries in 2001. Weather messages and information are available in Cantonese, Putonghua and English.
The Observatory maintains a website on the Internet. Apart from a variety of forecasts, the website provides a wide spectrum of information such as satellite pictures, weather maps, weather of other cities, TV weather programmes, tropical cyclone warnings for shipping, rainfall distribution maps, tropical cyclone tracks, newsletters for the Friends of the Observatory, information on El Nino and the greenhouse effect, and near real-time weather information over various places in Hong Kong. In 2001, page visits topped 100 million, an increase of more than 70 folds since its first year of launch in 1996. The Observatory website is continuously enhanced with new features. For example, UV index, aviation and environmental radiation monitoring information were added to the website in recent years. To enable the accessibility of the Observatory's website for the visually impaired, the Observatory provided text-based web pages to facilitate their use. In addition, an audio web page was also launched in 2001 with weather information in audio format. To provide mobile phone users with timely update forecasts, warnings and current weather, WAP version of the website was launched in
2001.
Regular TV weather programmes are presented by professional officers of the Observatory and broadcast by local TV stations. These weather programmes are produced in a studio at the Observatory.
Since the establishment of the Friends of the Observatory in 1996, the number of members has grown to more than 3,800. Comments and ideas of members have been useful in identifying the needs of the public, resulting in the improvement on the effectiveness of our services. Activities of the Friends of the Observatory include regular science lectures, visits to Observatory facilities and publication of newsletters.
The Observatory contributes to the Global Maritime Distress and Safety System of the International Maritime Organization by preparing weather bulletins and severe weather warnings for the China Seas and the western North Pacific regions. These messages are broadcast via INMARSAT communication satellites four times a day to ships on the high seas. When there are tropical cyclones nearby, tropical cyclone weather information will also be sent to ships via INMARSAT communication satellites. The 24-hour marine weather forecasts issued twice daily are broadcast in NAVTEX by coastal stations to ships plying in the region. For the south China coastal waters, the Observatory also prepares weather bulletins which are broadcast via local radio and coastal stations.
The Hong Kong Observatory maintains close cooperation with a fleet of voluntary observing ships. Meteorological instruments are supplied to these ships for seafarers to observe the weather en route and send weather reports to the Observatory and other meteorological centres. Surveys on marine meteorological services provided by the Observatory are conducted annually. Newsletters are published to address questions raised by the fleet and to provide them with information on new marine meteorological services.
The Observatory provides weather services for a designated airspace over the northern part of the South China Sea and issues warnings on hazardous weather such as thunderstorms, icing, windshear and turbulence. It operates an automatic information service to provide aviation users with flight documents, latest weather forecasts and warnings, and other relevant information. Weather briefings are provided to pilots and other users as needed.
Close contact with airline operators and aviation users is maintained through regular meetings of a liaison group on aviation weather service. A newsletter on the latest development in aviation weather service is published on a regular basis.
Meteorological Observations: Surface observations of various meteorological elements are made by trained observers at the Hong Kong Observatory Headquarters, Airport Meteorological Office and King's Park Meteorological Station. A network of 67 automatic weather stations located at various places in Hong Kong is operated by the Observatory. With co-operation between the Guangdong Meteorological Bureau and the Hong Kong Observatory, four solar-powered automatic weather stations are now in operation at Huangmao Zhou, Tuoning Islands, Neilingding Island and Wailingding Island.
Wind, temperature, pressure and humidity soundings in the atmosphere up to a height of about 30 kilometres are made at the King's Park Meteorological Station at regular intervals using balloon-borne instruments.
The Doppler weather radar at Tai Mo Shan, in operation since 1999, detects severe weather within some 500 kilometres of Hong Kong. Combining with the data of the weather radar at Tate's Cairn, winds at various heights above Hong Kong can be determined.
The satellite ground reception system of the Observatory receives cloud pictures from both the Japanese Geostationary Meteorological Satellite and the Chinese Fengyun-2 Satellite. These cloud pictures provide useful information on such severe weather as tropical cyclones, fronts, thunderstorms and heavy rain over Asia, the western Pacific and Indian Ocean.
The Observatory operates a suite of equipment, including wind sensors, ceilometers and runway visual range transmissometers, to monitor the weather in and around the Hong Kong International Airport. A terminal Doppler weather radar at Tai Lam Chung provides alerts of microbursts and other thunderstorm-related windshear.
Communications and Data Processing: The Observatory is connected to meteorological centres in Tokyo and Beijing by point-to-point links for the exchange of real-time meteorological observations. The Observatory also uses the Internet extensively for exchange of other meteorological information with overseas meteorological organisations. A UNIX-based computer system in the Observatory processes the data collected from the Global Telecommunication System, the Aeronautical Fixed Telecommunication Network, the World Area Forecast System and automatic weather stations in Hong Kong. The computer system also plots charts, produces objective weather forecasting aids as well as disseminates local weather information and warning messages. Archives of meteorological data for climatological research are kept on disks and tapes.
Climatological Services: Summaries of weather observations and analysed climatological data are published for local and overseas researchers on planning, engineering, etc. Official documents pertaining to weather information are regularly issued for litigation purposes.
The Hong Kong Observatory is designated by the World Meteorological Organization (WMO) as the centre for marine meteorological data for the South China Sea region. Marine climatological information can be provided to companies involved in activities in offshore waters.
Climate Change: The Observatory participates in local and international scientific programmes in global climate change. It makes observations of ozone profiles over Hong Kong as Hong Kong's contribution to WMO's Global Atmospheric Watch Programme. An UV Index advisory service has also been provided to the community since October 1999. Furthermore, the Observatory monitors developments in climate phenomena such as El Nino and La Nina, identifies their impacts on Hong Kong and provides experimental long range forecast.
Hydrometeorology: The Observatory manages a network of manned and automatic rainfall stations. The real-time rainfall data from 111 automatic rain gauges are used in the operation of rainstorm, flood and landslip warnings. The Hong Kong Observatory, Drainage Services Department and Water Supplies Department jointly operate an automatic water-level and rainfall reporting system for flood monitoring and basin management of the northern New Territories. In addition, the Observatory also carries out computation on the Probable Maximum Precipitation in Hong Kong.
Oceanography: The Observatory maintains a network of tide gauges to provide information on tides, mean sea levels and storm surges. Storm surges are also forecast via a numerical model. The Observatory also publishes annual tide tables for Hong Kong.
Time Service: The Hong Kong time standard is maintained with a Caesium Beam Atomic Clock kept in the Observatory. The accuracy of the clock is within fractions of a microsecond a day of the international time standard kept by the International Bureau of Weights and Measures in France. Time checking services are provided through the Internet, the Telephone Information Enquiry System and local radio stations. The public can synchronize, through the Internet, the clocks on their personal computers with the Observatory's atomic clock.
Seismology: To monitor earthquake activities in the vicinity of Hong Kong, the Observatory operates a network of eight short-period seismograph stations. In addition, three strong motion accelerographs have been installed on different geological sites and ground acceleration data are collected for use in structural design.
Astronomy: The results of astronomical computations are published annually in the Hong Kong Observatory Almanac. The Observatory also issues press releases on significant astronomical events.
Radiation Monitoring and Assessment: Monitoring of radioactivity in the atmosphere, rain and drinking water began in the 1960s. This was expanded into the Environmental Radiation Monitoring Programme in 1987, with the objective of measuring the environmental radiation levels in Hong Kong prior to and after the operation of the Guangdong Nuclear Power Plant at Daya Bay. Air, water, soil and food samples are regularly collected for radioactivity measurement. A report on measurement results between 1987 and 1991 was published in 1992. Annual reports have been published since 1992.
A Radiation Monitoring Network reporting real-time ambient gamma radiation levels in Hong Kong is in operation. Averaged 24-hour values at various locations in Hong Kong are released to the mass media daily and published in monthly bulletins and annual reports.
Training and Education: Meteorological courses are provided to staff of the Observatory and some overseas meteorological organisations. Courses on radiation measurement and radiological protection are also conducted to the Observatory and other Government staff. A conveniently located resource centre is open to the public for easy access of information provided by the Observatory.