The leading mode of rainfall variability over the Indochina exhibited by the EOF
analysis and it accounts 42.6% of the total variance.
The spatial pattern of the first EOF mode
(EOF1) exhibits large variation of rainfall over the southern part of the Indochina and the
central part of the Vietnam, which quite similar to the climatic mean pattern of the rainfall
(Fig. 2), and that agrees with the large contribution of the first mode to the total variance. The
corresponding principal component time series of the leading mode (PC1) shows interannual
variation (Fig. 3). Both of spatial EOF1 and corresponding time series PC1 suggest that when
the magnitude of PC1 increasing in positive, the rainfall over the positive area identified by
EOF1 (the southern part of the Indochina and the central part of the Vietnam) would more
increase than that of the rainfall in the main land of the Indochina. On the other hand, the
decreasing of PC1 value in negative direction means the rainfall over the southern part of the
Indochina and the central part of the Vietnam would more decrease than that of the rainfall in
the main land of the Indochina.