1. Rainfall pattern indicate that during flood year
the rainfall amount increases almost over all
states of the country. During drought year the
rainfall amount decreases over the entire
country but significant reduction is noticed
over central parts of the country and the west
coast.
2. The Substantial amount of rainfall in the
monsoon season is due to large-scale spatial
and temporal oscillations in the position and
intensity of the monsoon trough itself.
3. The variability of monsoon rainfall from flood
to normal to drought years depends upon the
number of depression/low-pressure area which
form over the North Bay and move Inland.
4. The coefficient of variation (C.V.) increases
during the drought year but during flood and
normal years no significant change in the
variability pattern in noticed.
5. The controlling factor of the variability of the
summer monsoon rainfall appears depression/
low-pressure area in the Bay of Bengal.
6. On examination of rainfall amount during
flood and drought year it is observed that the
rainfall amount increases significantly over the
country during flood year and decreases during
the drought year. The controlling area remains
over Orissa and adjoining Madhya Pradesh
(M.P.) and some parts of U.P. and Bihar. This is
mainly due to depression/low-pressure area
which form over the Bay and move inland.
7. It has been found from the Empirical Ortho-
gonal Function (EOF) analysis that in normal,
flood and drought year of monsoon rainfall,
some typical synoptic patterns such as mon-
soon depression/lows occurs, but lows play
more important role as compared to monsoon
depression. From EOF analysis one can under-
stand better spatial and temporal pattern of
southwest monsoon rainfall.