India on the cusp of 30-year cycle of good monsoons

The bountiful southwest monsoon so far in 2016, which has been the best in the past few years, has many deeper implications apart from marking a change in pattern.

If meteorologists are to be believed, the 'above normal' rains so far this year, could also signal a reversal of a regime of decreasing seasonal trend, which began about 30 years ago.

However, this does not mean that all southwest monsoons henceforth would be normal or 'above normal'. What it does mean is that the probability of India getting more number of years with normal monsoon for the next three decades increases, based on 30-year monsoon variability. The reversal of cycle was also highlighted by a D S Pai, deputy director General of Climatology at India Meteorological Department (IMD), during his annual forecast a while back.

This could have huge implications for agriculture, food prices, supply and overall economic growth of the country.

Confirming this, the Director General of IMD K J Ramesh said studies show that India is moving from a regime of deficit rainfall to one of normal rainfall years in the immediate future, and probably 'above normal' rainfall in the medium and long terms.

"We can hope to get more number of years with good rainfall than those with poor rainfall in the next 30 years," Ramesh told Business Standard.

Studies conducted by meteorologists show that the monsoon epoch alternates after every three to four decades between less and more frequent weak monsoon over India. The first such epoch started around 1921 and lasted till 1964, followed by another epoch from 1965-1987. The third epoch is measured from 1987 and is expected to end around 2016-17.

In the immediate future, the La Niña weather phenomenon, which causes good rains, might spill over to the next monsoon as well, unless there is a significant weather anomaly that will be known at least six months before the actual event.

La Niña, the opposite of El Niño, is associated with cooler than average sea surface temperatures in the central and eastern tropical Pacific Ocean and is known to be the cause of bountiful rains over the Indian subcontinent.

The La Niña is expected to start from August 2016 and it usually stays on for 18 to 24 months. This means the southwest monsoon next year could also be normal.

"We have developed systems and equipment to monitor those changes, as any significant anomaly will be first reflected in the oceans," Ramesh said.

He said the IMD recently sent robots to study oceans and this will help in accurately analysing weather patterns and let the department know if the La Niña is diminishing beforehand.

India already studies ocean weather patterns through 'argos' (tools for collecting oceanographic measurements and their geographical location) and the robots would supplement those efforts.

The Indian government recently entered into a collaboration with the University of East Anglia in the UK on an £8-million monsoon project, wherein scientists from both countries will study the Bay of Bengal with the help of underwater robots.

The robots will monitor the conditions that influence the monsoon, and will help forecast its arrival and progress more accurately.