CYCLONE OPERATION IN INDIA

For cyclone forecast and advance warning, the Government have strengthened the Meteorological Department, by providing Cyclone Surveillance Radars at Calcutta, Paradeep, Visakhapatnam, Machilipatnam, Madras and Karaikal in the east coast and at Cochin, Goa, Bombay and Bhuj in the west coast. Satellite picture receiving (APT) equipments at Delhi, Bombay, Pune, Madras, Visakhapatnam, Calcutta and Guwahati are receiving satellite pictures of the cyclones from the polar-orbiting Satellites of the U.S.A. and U.S.S.R. Since April 1, 1982 A.V.H.R.R. (Advance very High Resolution Radio-meter) ground receiving equipment is operative at New Delhi. At this Centre very High Resolution Cloud pictures (Resolution 1.1 km) in 5 channels as also T.I.P. data (Tiros Information Processor) are being regularly received and are being archived in Magnetic Tapes. Hard copies of the pictures in 2 or 3 channels are being obtained regularly. Distinct advantage of these pictures is due to their very High Resolution in all the 5 channels. Further improvements in the cyclone tracking and forecasting have taken place after the Meteorological application programme of the Indian Geo-Stationary Satellite INSAT-LB has become operational since October 1983. Monitoring of the cyclone by taking hourly pictures has helped the forecaster to improve his skill in issuing the timely warnings to the public. Satellite pictures received by the Meteorological Data Utilisation Centre (M.D.U.C.) at New Delhi are further disseminated to all the forecasting Offices through Radio Facsimile.

Cyclone operations are being done by the Meteorological Department through the Area Cyclone Warning Centres (ACWC) and the Cyclone Warning Centres (CWC). ACWC at Calcutta and Madras and the CWC at Bhubaneswar and Visakhapatnam are responsible for cyclone forecasting in the Bay of Bengal, ACWC at Madras and Bombay and CWC at Ahmedabad are responsible for the cyclones in the Arabian Sea - the National Forecast Centre or the WEATHER CENTRAL at Pune being the coordinator. Computerised Operational Advisory Forecasts on cyclone movements are being issued by the Numerical Weather Prediction (NWP) division of the Department at the H.Q. Office at New Delhi. Storm surge advisories are being issued to the ACWC/CWC by the Northern Hemispheric Analysis Centre (NHAC) at the H.Q. Office at New Delhi. Researches on scientific and operational aspects of Cyclones are being carried out at the Cyclone Warning Research Centre (CWRC) at Madras. Specialised researches on storm surges relating to surge height to storm intensity are done at the H.Q. Office at New Delhi.

It may be mentioned here that with the present knowledge about the cyclones and with the available aids, the average error in the predictions of the storm centre for a 24-hour forecast is about 200 km.

Cyclone warnings in appropriate formats are being disseminated to the various warnees (More).

Cyclone warnings issued to the Chief Secretaries, the Relief Commissioners and the District Collectors of the maritime states are the very basic information for cyclone distress prevention and mitigation. These are disseminated under "Two Stage Warning Scheme" i.e., in two stages whenever any coastal belt is expected to experience heavy rains, gales and tidal waves in association with a cyclonic storm or depression expected to intensify into a cyclonic storm. The first stage warning known as the "Cyclone Alert" is issued 48 hours in advance of the expected commencement of the adverse weather over the coastal areas. The second stage warning known as the "CycloneWarning" is issued 24 hours in advance. Both cyclone "Alert" and "Warning" messages are passed to the AIR stations for repeated broadcast. However, they are requested to broadcast cyclone warnings at hourly or half-hourly intervals, when the cyclone is nearer to the coast. It will be seen from the table that for dissemination of cyclone warnings, the Meteorological Department has to depend mostly on the Telecommunication channels of the Post and Telegraph Department consisting of landline telegrams, Teleprinter, Telex, Telephone, etc.. India Meteorological Department has been including some of the vital information like port signal advices in the cyclone warning bulletin issued to the AIR. Concerned warnees have also been advised to monitor the cyclone-warning bulletin on the AIR during cyclone seasons, which would help them to take appropriate action even in the case of not receiving the addressed warnings due to delay or failure of communications. During l987, INSAT based Cyclone Warning Dissemination System (CWDS) for south Andhra and north Tamil Nadu coasts was made operational, which is capable of circumventing failure of traditional communication Systems. Under this scheme, the cyclone warnings are directly sent to the users through INSAT. Such facilities have now been extended to all other cyclone prone areas.

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