The relationship of monsoon onset with subsequent rainfall over India

Utilizing 40 (1941–1980) years of daily monsoon rainfall data averaged over 52, 2.5° × 2.5° latitude and longitude contiguous blocks covering the whole of India, we have investigated the relationship between monsoon onset at nine locations in India with the monsoon rainfall during the first 10, 15, 20, and 30 days of June and during the whole monsoon season. The onset is found to have a significant association only with rainfall observed during the subperiod of June, no significant correlations are found for the seasonal monsoon rainfall for any station. Interrelationships among onsets at these nine locations have also been studied. It is found that the arrival of the monsoon over the northern parts of the country has no relationship with the onset over Kerala. The relationship between the onset of the Baiu rains over 11 stations in Japan and the monsoon onset over India also has been studied by using 35 (1946–1980) years of data. Even though the onset of the Baiu over a few stations shows significant association with the monsoon onset over some stations of India, the relationship between the Baiu and monsoon onset is not very encouraging for linear predictio