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Vinson Kurian

THIRUVANANTHAPURAM, Aug. 16

INDIA is too far away from the direct zone of impact of El Nino and therefore only some of these periodic weather systems are powerful enough to adversely affect the country's monsoon rainfall.

On the other hand, Indonesia and north Australia are in the direct zone of influence and have borne the brunt of most of the El Ninos leading to extensive droughts in these regions.

Stating this to Business Line, Dr P.V. Joseph, former Director of India Meteorological Departmentsaid the most recent episode of a strong El Nino during 1997 had caused devastating droughts and forest fires in Indonesia, but did not adversely impact the Indian monsoon.

``We are yet to understand a lot more about a possible El Nino-monsoon relationship. It is found that El Ninos grow in strength mainly during June-September and reach maximum intensity by December-January,'' Dr Joseph said.

Scientists have started to think of the role of drought monsoons of India in the growth of the El Nino warming of the equatorial central and east Pacific Ocean.

As is now scientifically established, the abnormal warming of the Pacific during El Nino changes the atmospheric pressure on either side of that ocean, a phenomenon known as the Southern Oscillation. It was only in the late Sixties that a causal link between El Nino and the Southern Oscillation was established.

The two phenomena are now jointly referred to as the El-Nino Southern Oscillation (ENSO). Although a statistical correlation between the ENSO and the outcome of the Indian monsoon has been found, a clear causal link between the two has yet to be established.

Moreover, even the statistical correlation between the two has broken down in recent years. So much so, although the strongest El Nino of the 20th century occurred in 1997, the monsoon that year was slightly above normal.

``We have fairly good records about monsoon rains of India since 1871. Good data on El Ninos of this period also exist. About half of the strong El Ninos of this period were accompanied by droughts in the Indian monsoon,'' says Dr Joseph.

In India we define a drought in all-India rainfall when the deficit is ten per cent or more. The strong El Ninos of this period were in the years 1871, 1877, 1884, 1891, 1899, 1911, 1918, 1925, 1932, 1941, 1957, 1972, 1982 and 1997. Of these years, the country had droughts during 1877, 1899, 1911, 1918, 1941, 1972 and 1982. Rainfall deficiencies in these years ranged from 15 per cent to 29 per cent.

The years 1884 and 1997 had above normal monsoon rainfall. As for the remaining years, rains were below normal, but were not low enough to be called drought years.

Moderate El Ninos have droughts associated with them in less than half the number of years. In recent decades, the moderate El Ninos of 1987, 1965 and 1951 were associated with droughts, but those of 1994, 1991, 1976, 1953, 1943 and 1939 not associated with droughts, Dr Joseph said.

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