INDIAN-SUMMER MONSOON RAINFALL AND 200-MBAR MERIDIONAL WIND INDEX - APPLICATION FOR LONG-RANGE PREDICTION

Verma and Kamte (1980) and Joseph et al. (1981) identified the association between Indian monsoon rainfall and 200-mbar meridional wind index for the month of May, and indicated its potential for prediction of the seasonal rainfall. A detailed investigation has been made of this relationship between the monsoon rainfall over India and the meridional wind index (arithmetic average of 200-mbar meridional wind component for May at Bombay, Delhi, Madras, Nagpur, and Srinagar) based on the data for the period 1964-1988. The relationship between all-India monsoon (June-September) rainfall (R) and the wind index (Vm) is negative (correlation coefficient = -0.72) and is significant at the 0.1 per cent level and the regression equation based on this data, for the period 1964-1988, is R = 86.98 - 2.44 Vm. The stability and consistency of the relationship between rainfall and the wind index have been examined over sliding widths of 15 and 21 years, and the relationship is found to be significant at the 1 per cent level for all windows of 21-year widths. The meridional wind index shows a good potential in the long-range prediction scheme of the Indian monsoon rainfall, along with other parameters.