Marine Meteorological Services
Introduction: In 1884, soon after the establishment of the Hong Kong Observatory, a "drum, ball and cone" system of symbols was introduced to warn ships in port of tropical cyclones in the South China Sea. This was the earliest marine meteorological service provided by the Observatory in Hong Kong. In 1915, marine weather forecasts for ships were broadcast using radio telegraphy for the first time.
A rudimentary port meteorological service also existed in the early years of the Hong Kong Observatory. Clocks carried by ships were checked and calibrated. An officer with the specific duty of visiting ships in port was appointed in 1892.
With the progress of time, Hong Kong has become one of the busiest ports in the world with over 100 ocean going vessels entering the harbour every day. The prosperity of Hong Kong depends heavily on the safe operation of these ships in all weather conditions. There are busy ferry and barge operations and a growing population engaged in recreational sailing and other water sports. The marine meteorological services provided by the Hong Kong Observatory today have the functions of serving international shipping on the high seas, fishing and oil drilling activities in coastal waters as well as water transport and recreation offshore.
Marine Weather Forecasts and Warnings: Marine weather forecasts for shipping are issued twice a day by the Central Forecasting Office of the Hong Kong Observatory. They contain warnings of winds of gale force or above, a synopsis of significant meteorological features and 24-hour forecasts of weather and sea state for ten marine areas in the South China Sea and the western North Pacific. The forecast areas are shown in Figure 1. These forecasts are broadcast via NAVTEX, an international broadcast system for disseminating navigational information by the coastal radio station for ships plying in the region.
Weather bulletins for the south China coastal waters are prepared six times a day and broadcast by local radio stations. They contain warnings of strong winds, fog and hazardous weather, 24-hour forecasts of wind, significant weather, sea state as well as a further outlook for the next 24 hours for seven fishing areas along the coast of south China (Figure 2). Latest weather reports from selected coastal and island stations are also included in the bulletins.
Special weather bulletins for Hong Kong waters are issued on Saturdays, Sundays and other general holidays except when tropical cyclone signals are issued in Hong Kong. These bulletins provide weather information including winds for various locations in the Hong Kong waters. They are issued specially for sailing boats and small craft.
Forecasts tailored to meet the needs of special users are issued. Specialized forecasts of weather and sea state up to seven days ahead are issued, on request, to oil rigs operating in the offshore waters of southern China. Since 1985 the Hong Kong Observatory has been using numerical models to forecast wave conditions over the China Seas and the western North Pacific in support of such specialized service.
When a tropical cyclone is located within the area bounded by latitudes 10N and 30N and longitudes 105E and 125E, the Hong Kong Observatory issues additional warnings for shipping at 3-hourly intervals giving detailed information on the location, intensity and forecast movement of the tropical cyclone, and also wind and wave conditions associated with it. These are also broadcast by NAVTEX.
In addition, meteorological forecasts and warnings for shipping on the high seas over western North Pacific and South China Sea are broadcast via INMARSAT-C as part of the Global Maritime Distress and Safety System (GMDSS) of the International Maritime Organization (IMO). The bulletin prepared by the Hong Kong Observatory contains warnings of winds of gale force or above, as well as a synopsis and forecast over the South China Sea and adjacent areas. Whenever one or more tropical cyclones are located within the area bounded by the Equator and latitude 30N and longitudes 100E and 125E, four additional bulletins will be issued everyday, giving detailed information on the location, intensity and forecast movement of the tropical cyclones, and also winds and wave conditions associated with it.
Specialized advice is given to pilots and ferry companies as required and special purpose forecasts are also supplied to support boat races by arrangement. The Central Forecasting Office is also responsible for supplying meteorological information on request to rescue co-ordinating centres in support of maritime search and rescue operations.
When oil spills occur in Hong Kong, special 12-hour forecasts of wind, weather, state of sea, wave height, sea surface temperature, storm surge and abnormal tidal currents will be issued and despatched to the Marine Department when required.
Voluntary Observing Ships and Port Meteorological Services: Ships' weather observations provide vital information needed to identify the prevailing weather systems and are especially important for the preparation of forecasts for the sea areas and the timely preparation of warnings of hazardous weather conditions. Under the Voluntary Observing Ships' Scheme of the World Meteorological Organization, the Hong Kong Observatory started in 1949 to recruit a fleet of locally based voluntary weather observing ships. Presently a fleet of about 70 merchant ships which ply between Hong Kong and various ports of the world is maintained. They are equipped with meteorological instruments supplied by the Hong Kong Observatory. Ship officers on board make regular weather reports and send them to nearby coastal radio stations or coast earth stations for onward transmission to meteorological centres.
Port meteorological services are provided to all Hong Kong voluntary weather observing ships. When they call at Hong Kong, the Port Meteorological Officer (PMO) visits these ships, checks the instruments and advises ship officers on meteorological matters. Relevant publications are supplied. The PMO is also responsible for maintaining close liaison with shipping companies.
Weather observing ships recruited by other nations can also contact the PMO when they are in Hong Kong. Copies of ship codes for reporting weather observations at sea and various publications of the Hong Kong Observatory are supplied on request, and barometer checks can be arranged.
Beginning in 1989, annual surveys are conducted amongst masters of ships to obtain feedback on the marine meteorological services provided by the Hong Kong Observatory. A newsletter was also started in 1993 to address the issues raised in the surveys and to give information on any new marine meteorological services the Hong Kong Observatory has initiated.
Marine Climatological Summaries: Ship observations are invaluable for the study of climatic conditions in the ocean areas.
The Hong Kong Observatory is one of the eight centres in the world designated by the World Meteorological Organization (WMO) to collect marine meteorological data and to compile marine climatological summaries. The area of responsibility of Hong Kong is the South China Sea from the Equator to 30N and from 100E to 120E.
Under the WMO Marine Climatological Summaries Scheme, weather observations recorded by Hong Kong voluntary observing ships are quality checked by the Observatory and then exchanged among members under the coordination of the Global Collecting Centres in the United Kingdom and Germany. From 1955 till now, over 1.9 million ship weather observations have been collected by the Hong Kong Observatory.