Weather Reports
Types of weather services for shipping, Meteorological Offices
Marine Meteorological Services have two functions:
(a) To serve international shipping, fishing and other marine activities on the high seas; and,
(b) To serve the various activities which take place in coastal and offshore areas and on the coast itself
GMDSS, NAVTEX, VHF DSC, HF DSC and MF DSC.
Digital Selective Calling (DSC) alerting is available. DSC is a technique using digital codes enabling a radio station to
establish contact with, and transfer information to, another station or group of stations, and complying with the
relevant recommendations of the International Radio Consultative Committee (CCIR)
GMDSS
Sea area A2 is an area, excluding sea area Al, within the radio-telephone coverage of at least one MF coast
station in which continuous DSC alerting is available;
Sea area A3 is an area, excluding seas areas Al and A2, within the coverage of an INMARSAT geostationary satellite in
which continuous alerting is available;
Sea area A4 is an area outside sea areas Al, A2 and A3, which are areas are in polar regions. Ships are required
to carry the appropriate equipment for the sea area(s) in which they will be travelling.
Most of the high seas areas of the world are in sea area A3
Under the GMDSS, high seas, weather and sea bulletins are broadcast by satellite, using the INMARSAT Safety Net
service with the Enhanced Group Calling System (EGC). The EGC allows a bulletin to be broadcast to all ships with the
relevant receiving equipment in:
(a) A standard area, or,
(b) A rectangular area delineated by latitude and longitude by the sender, or
(c) A circular area delineated by a central point and radius by the sender.
Forecasts are broadcast in English to standard areas. Warnings may be broadcast to rectangular or circular areas to
ensure that ships receive only warnings relevant to them.
NAVTEX
Sea area A2 is serviced in some parts of the world (mostly in the northern hemisphere) by the NAVTEX service. This
service is the coordinated broadcast and automatic reception on 518 kHz of maritime safety information by means
of narrow-band direct-printing telegraphy using the English language. As a common frequency is used, a group of
(say) six stations will broadcast sequentially for five-minute periods over the course of each half-hour. The messages
are printed out automatically on receiving equipment on the bridge of a ship.
Other radio communications
Provision is made for broadcast and reception by means of VHF DSC, HF DSC and MF DSC. Full details of the radio
communications required internationally in the various sea areas can be found in Regulations 6 to 11 of Chapter IV
of the SOLAS Convention. An NMS may have to prepare and/or issue warnings and routine forecasts for transmission
by an HF-direct-printing telegraphy maritime safety information service for areas where such a service is provided
for ships engaged exclusively on voyages in such areas
Other services
While weather and sea bulletins constitute the basic service for the high seas, other forms of services have been
introduced on an international basis to meet the requirements of various marine interests.
These services include:
- special information in support of maritime search and rescue operations;
- broadcasts of weather charts by radio facsimile;
- provision of marine climatological information, including summaries;
- provision of services to high seas fishing;
- combatting marine pollution;
- provision of expert meteorological advice, and;
- information in marine meteorological matters.
Utilities of ship data :
India is providing weather services to shipping communities since 1864, much before formal establishment of India
Meteorological Department in 1875. There is a large data gap over the oceanic areas and ship data are one of the
major source and provide important support to our forecasting systems both conventional and numerically based
dynamic systems. Such data are being collected and archived in IMD and climatology of sea state are derived.
Major utilization of ship data are as follows:
1. To issue Weather and sea bulletins both for shipping on the high seas and those plying in coastal waters
(twice daily in undisturbed weather and 6 bulletins per day during storm periods).
2. To issue Bulletins for Indian Navy also called Fleet forecasts (twice daily), GMDSS bulletins, Port Warnings
(daily once and more often as and when necessary), Fisheries warnings (4 times daily).
3. To issue warnings and bulletins to the various interests in the maritime states of India, coastal shipping
and ships in the high seas for their specified areas of responsibility. These bulletins, include the 4 stage warnings viz.
pre-cyclone watch, cyclone alert, cyclone warning and post land-fall outlook during cyclone situations.
4. To issue routine weather forecasts for shipping, fishermen, off-shore oil exploration etc. and issue of
special weather warnings for severe weather phenomena like tropical cyclones over the Indian seas.
5. To watch over the weather developments in the Indian Seas and advise ships, ports, fishing vessels, the
government agencies and other concerned officials, general public etc., in time, regarding adverse weather
associated with cyclonic storms and depressions.
6. For archiving of surface marine data and preparation of Marine climatological summaries on
yearly/decadal/30 year basis in the Indian Ocean, north of latitude 15S and between 20E to 100E, which are
exchanged with International marine centres.
