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Japanese researchers/scientists have admitted that the Indian monsoon is undergoing an ‘uncharacteristic’ turnaround.
And they attribute it to a backyard phenomenon called Indian Ocean Dipole (IOD) that nearly mimics the El Nino-La Nina event in the east equatorial Pacific.
TWO PHASES
The IOD has positive and negative phases; the former aids the Indian monsoon thanks to raised surface temperatures of the south-west Indian Ocean.
This warmth in turn helps evaporation and convection (cloud-building).
The seasonal south-westerly monsoon winds push clouds into the land to rain it down all over.
The scenario is exactly reversed in the negative phase, which drives the rains out of the country, leading to a deficient monsoon.
The Japanese scientists had warned from February onwards that a negative IOD could build this year, which could harm Indian monsoon prospects this year.
“But in a very uncharacteristic turnaround, the negative IOD has been terminated and replaced by a positive IOD,” said Tokyo-based Toshio Yamagata, Director, Application Laboratory, Jamstec (Japan Agency for Marine-Earth Science and Technology), and Swadhin Behera, Team Leader, RIGC (Regional Institute for Global Change) under Jamstec.
Yamagata had led a team of researchers who discovered the IOD phenomenon years ago and is considered to be among the most authentic word on the subject.
RARE SHIFT
“This turnaround has helped to alleviate the monsoon deficits experienced earlier in June-July,” the Japanese scientists wrote to Business Line on Tuesday.
“Such quick shift from negative to positive IOD is very rare and it was so rapid that the dynamical (enabling) conditions could not be captured by most predictions.”
The El Nino is also seen to have weakened, which gives even a better outlook for the remaining part of the Indian monsoon in September, the scientists said.
“We hope the seasonal rainfall for the whole monsoon season might not be as bad as we had anticipated earlier in the season,” they added.
The IOD had sprung up a surprise last when a positive phase evolved on a trot for three years from 2006 with favourable impact on the Indian monsoon.
> vinson.kurian@thehindu.co.in
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