The main results found in this study may be summarized as follows. In our EOF analysis of rainfall over Thailand during the period 1971-2010 the most dominant mode, accounting for 21.6% of the total variance, had a spatial pattern with the same sign (positive) over almost all of Thailand. Consequently, when the PC was positive there was more rainfall than normal and when the PC was negative there was less rainfall than normal almost everywhere. An exception to this general result occurs in the south at latitudes below 9°N.
The rainfall variability during boreal winter (December to February) over the
Indochina peninsula was exhibited by the EOF technique. The leading mode of the variability
accounts 42.6% of the total variance, and shows the interannual variation. Its spatial
distribution presents large rainfall variation over the southern part over the Indochina and the
central part of Vietnam, whereas its temporal variation shows the correlation to the SST
anomalies, particularly in the Pacific Ocean.