The Hindu Business Line : Models say El Nino conditions may reverse from Feb

Latest updates on the warming trend in the equatorial Pacific indicate that there is 95 per cent probability that El Nino conditions may persist through the December-January-February 2006/07.

However, there are signs that the warming process may have already started to weaken, and could well start reversing through February-March-April 2007.

The International Research Institute (IRI) for Climate and Society at Columbia University says that, as of mid-December, sea surface temperatures (SSTs) remain over 1.0 deg C above average throughout much of the equatorial Pacific, even exceeding 1.5 deg C in the central and eastern equatorial Pacific.

The probability of maintaining El Nino conditions through December-January-February 2006/07 is approximately 95 per cent. But this is the maximum level they can hope to sustain. The IRI model sets back the probability to 93 per cent and progressively lower during the succeeding quarters.

WEAKENING SIGNALS

Significantly, the Australian Bureau of Meteorology (BoM) has observed that most computer models are nearly unanimous in predicting the decay of El Nino conditions in the first half of 2007.

In its update on December 21, the BoM said that there are a few signs that the event may have already started to weaken. For one, the Southern Oscillation Index (SOI) has only been `weakly negative' for more than a month.

The SOI measures the difference in air pressure between Darwin and Tahiti and compares it with the seasonal normal. Negative SOI is frequently seen with El Nino ocean conditions.

Also, the trade winds in the western and central Pacific have strengthened to near-normal values in December, and sub-surface temperatures show a weakening of east-Pacific warmth and a strengthening cool signal extending from the west.

WINTER RAINS

Meanwhile, seasonal forecasts put out by IRI suggest that India is poised to get `above normal' rainfall over a crucially important geography during December-January-February 2006/07, signalling better prospects for standing seasonal crops.

Among the regions expected to receive "up to 35- to 40 per cent above normal" rainfall are the wheat-growing belt of Punjab, Haryana, Uttar Pradesh, the entire northeast, Bihar, Jharkhand, Chhattisgarh, West Bengal, coastal Orissa, south coastal Andhra Pradesh, coastal and south interior Karnataka and Kerala.

This is expected to result from the expected but delayed warming of the Bay of Bengal, but in what are telltale signs associated with EL Nino, would leave the entire Southeast Asia, the Philippines and Indonesia high and dry.

Along with India, the wet climes are seen extending to large parts of China during this period.

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