Monsoon watchers are scanning the Indian Ocean for any sign that could potentially reduce the impact on seasonal rains from a raging El Nino away in the equatorial Pacific.

A few models have suggested that the Indian Ocean may be priming for a positive dipole event which can save the monsoon from being totally run over in this manner.

The Indian Ocean Dipole (IOD) mimics El Nino-La Nina phenomena in the country’s backyard. When the western basin of the ocean warms up relative to the east, it sets up a positive dipole event, and vice versa.

Sufficient convection A positive dipole event has been found to hold the monsoon in good in the face of a vicious El Nino, as was on show in 1997.

Positive dipole events on a trot from 2006, 2007 and 2008 – all non-El Nino years – too had delivered normal to slightly above rainfall for the country.

What it does is to ensure sufficient convection (cloud-building and rain) in the west Indian Ocean to make up for loss suffered otherwise during an El Nino year.

What the Japanese national forecaster Jamstec, which closely monitors Indian Ocean weather along with the Australian Bureau of Meteorology, has to say becomes significant in this context.

In the latest update, Jamstec has detected ‘basin-wide warming’ of the Indian Ocean. This means neutral dipole conditions for the time being.

Late evolution It goes on to state that the basin is expected to change into a positive IOD event in late summer and autumn.

“This evolution is rather late compared to the canonical IOD and we expect the El Nino influence may be more prominent during the summer.” This would goes to suggest that the positive IOD would materialise too late in the day for the Indian monsoon.

The Australian Bureau said that the IOD is currently neutral, with a majority of the Indian Ocean being warmer than average.

“Of the five international models that monitor the IOD, three suggest a positive IOD event is likely later in the year,” it said, more or less agreeing with the outlook of Jamstec.

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