1. Introduction
Indian summer monsoon variability needs further
introspection. The southwest monsoon accounting
for more than 75% of the annual rainfall impacts
the economy. However, the monsoon rainfall
shows considerable interannual variability. This
makes it a complex phenomenon with dependence
on the regional circulation as well as global circulation.
Periodic variation of south-west monsoon
and seasonal rainfall forecasting are of key concern
to meteorologists (Normand, 1953; Jagannathan,
1960; Rao, 1965; Rao, 1976; Singh, 1994). Rainfall
anomalies are not uniform over the country
despite regular variations in monsoon. According
to an analysis by Subbramayya (1968), there
is a negative correlation in rainfall between the
northeastern and west central part of India, but this
analysis does not indicate the variance explained
by different rainfall patterns.