IMD announces new feature to help monsoon forecast

January 05, 2010 04:52 pm | Updated 04:52 pm IST - THIRUVANANTHAPURAM

India Meteorological Department is all set to introduce an additional feature to its forecasts during the monsoon season.

Secretary, Ministry of Earth Sciences, Shailesh Nayak, announced here on Tuesday that from this year on, farmers and other users would also get forecasts of active and break phases of monsoon 10 to 15 days in advance.

Till now, the IMD has been issuing forecasts for five days and an outlook for the next two days. From the monsoon season this year on, it would issue forecasts for one week and an outlook for the following one week.

Notes regarding the possibilities of changes in monsoon activity – from active phase to break phase or from break phase to active phase would form part of these advisories.

Scientists at IMD have been working on forecasts on active and break phases for the past three years. The forecasts would be primary based on a phenomenon called Madden Julian Oscillation (MJO).

The MJO is an equatorial travelling pattern of anomalous rainfall that is planetary in scale. The MJO is characterized by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian Ocean and Pacific Ocean.

The anomalous rainfall is usually first evident over the western Indian Ocean, and remains evident as it propagates over the very warm ocean waters of the western and central tropical Pacific.

This pattern of tropical rainfall then generally becomes very nondescript as it moves over the cooler ocean waters of the eastern Pacific but reappears over the tropical Atlantic and Indian Ocean.

The wet phase of enhanced convection and precipitation is followed by a dry phase where thunderstorm activity is suppressed. Each cycle lasts approximately 30-60 days.

Speaking at a plenary session at the on-going 97th annual session of the Indian Science Congress, Dr. Nayak also disclosed that recent studies have indicated that sea level in Indian Ocean has risen by as much 9 mm between 2004-09.

Describing it as ``not an unusual phenomenon’’ considering that a sea level raise of 3 mm per year has been observed in Pacific and Atlantic Oceans between 1993-2003, he said it could be due to several reasons, including the December 2004 Tsunami.

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