All-India Monsoon Rainfall Index at LDEO/IRI Climate Data Library

An all-India summer monsoon rainfall series for the instrumental period of 1844-1991 has been constructed using a progressively increasing station density to 1870, and one that is fixed thereafter at a uniformly distributed 36 stations. The statistical scheme accounts for the increasing variance contributed to the all-India series by the increasing number of stations during the period 1844-1870. An interesting outcome of this study is that a reliable estimate of summer monsoon rainfall over India can be obtained using only 36 observations.