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Did rains fail?

the lacklustre performance of the South West monsoon in July 2004 has left Indian weathermen in a lurch. A section of the meteorological scientific community feels that in addition to the damage it has already done to the sowing season, the deficient rains throw up a new challenge regarding the predictability of the Indian monsoon.

"There wasn't any obvious reason why rains did not realise over north-west and central India. Almost all favourable factors were present, but they failed to work in tandem,' said a senior scientist in the India Meteorological Department (imd), which forecast about 98 per cent of 29.1 centimetres of rainfall (with an error of plus or minus 9 per cent) for this July.

The sowing activity in most states in these regions, including Maharashtra, Gujarat, Rajasthan, Madhya Pradesh, Punjab, Haryana and parts of Uttar Pradesh, has suffered. The departure from the predicted quantity of rain in meteorological subdivisions in these states ranged from the manageable 17 per cent to the whopping 51 per cent (see map: Fickle rains, awry predictions). Unlike earlier years, the subdued monsoon activity in India did not translate into bountiful rains in other countries in the region. "This year it seems the lull's every where,' the imd scientist said.

As statistical regression models, which are used for forecasting monsoon since 1988, have failed repeatedly, a probable solution would be using dynamic global circulation models. Unlike the former, which use historical data for prediction, the latter use real-time ocean, wind and land data. It is here that the Indian Ocean becomes crucial, acting as a black box for making the prediction, says M Rajeevan, director for long range forecasting at imd. But J Srinivasan, professor at the Bangalore-based Indian Institute of Science, avers: "No model can predict monsoon fluctuations. I am not sure whether models that claim to have such capacity can predict for small regions like Rajasthan.'

Scientists suggest launching a major mission-mode programme to study the Indian Ocean, similar to the 15-year-long Tropical Ocean Global Atmosphere (toga) climate project spearheaded by us National Oceanic and Atmospheric Administration to unravel El Ni

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