The Hindu Business Line : Experts see early onset of monsoon

The strong La Nina in the equatorial Pacific is predicted to last longer than thought and would favour an early onset of the southwest monsoon this year, according to researchers at the Japanese Agency for Marine-Earth Science and Technology (Jamstec).

Real-time prediction results prepared by Dr Jing-Jia Luo at the Frontier Research Centre for Global Change (FRCGC) under Jamstec suggest that the La Nina may linger until the spring of 2009.

THROWBACK TO 1988

Prof Toshio Yamagata, Leader Researcher at the FRCGC, informed Business Line that the present conditions in the Pacific are comparable to those of 1988. The La Nina which evolved in the autumn of 1986 had strengthened in 1988 and continued until the spring of 1989. India suffered from heavy rains during the La Nina of 1988.

The latest edition of the La Nina will favour an early onset of Indian summer monsoon and the seasonal rainfall is expected to be above normal. “The present La Nina evolved from 2007, and as per our model prediction, is expected to continue until spring of 2009,” Prof Yamagata said.

NEGATIVE IOD

However, the favourable condition might be diminished to some extent by the evolution of a negative Indian Ocean Dipole (IOD) in the last part of the monsoon season, according to Dr Swadhin Behera, Sub-leader, Climate Variations Research Program, at the FRCGC. Prof Yamagata and Dr Behera are members of the pioneering team that discovered the IOD phenomenon, represented in a seesawing of sea-surface temperatures in the western Indian Ocean and the sea around Indonesian archipelago.

TYPHOON MARCH

A positive IOD, when combined with a La Nina, drives up monsoon performance, as was the case in the year 2007 season. India’s west coast and the central provinces came in for a battering from monsoon disturbances (low’s and depressions) emerging from the Bay of Bengal, but the northwestern region ended with a deficit.

Prof Yamagata also expects a large number of typhoons to hit East Asia as was the case in 1988. About 31 cyclones were generated in the 1988 north Pacific cyclone seasons.

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