Science Correspondent
BANGALORE: Even as speculation is rife if India will receive normal monsoons this year or not, the India Meteorology Department (IMD) feels the country is fortunate in not having severely deficit rainfall in the past. The only extreme deficient rainfall recorded was way back in 1879, -30 per cent of the mean rainfall.
Speaking at a symposium on `Atmospheric Sciences' at the Indian Institute of Sciences here on Saturday, V. Thapliyal of IMD, New Delhi, said the department gave more importance to category monsoon forecast than quantitative forecast. ``Even normal monsoon means four to six meteorological sub-divisions in the country will receive deficient (or excess) rainfall. India is the only country in the world where seasonal rain forecast has been very accurate in the last 12 years,'' he added. He, however, did not rule out forecast going wrong at any point of time as ``forecast is forecast.''
Earlier in the day, Prof. Roddham Narasimha of National Institute of Advanced Studies, speaking on `Wavelet Analysis of Indian Rainfall' said monsoon had been relatively regular in India, never recorded below 30 per cent of the mean. Still, it was the variability of monsoon which was the central problem in climate research.
According to A. Jayaraman of the Physical Research Laboratory, Ahmedabad,significant amounts of continental aerosols radiative were mixing with surface air and was travelling thousands of kilometres over the ocean surface endangering the ozone layer. He was referring to the results from an `Aerosol radiative forcing from Indian Ocean experiment' conducted over the Arabian Sea and the tropical Indian Ocean.
According to him, the startling discovery was that aerosols were highly absorbent (due to the presence of soot) and contributed more to absorption (leading to warm atmosphere) than scattering (resulting in a cooling of the earth's surface), particularly over the coastal regions and polluted the ocean.
On the long range forecast of Indian summer monsoon rainfall, Prof. J. Srinivasan of the Centre for Atmospheric and Oceanic Sciences, IISc, said unless numerical models were available, accurate forecast was not possible. ``I am very sceptical about the accuracy of results from the various models being used,'' he added.