When studying the relation between the spatial patterns and principal component, it was found that there was high rainfall (standardized PC greater than 2.0) in June 1975, August 1978, October 1983, June 1985, July 1994, September 1996, July 1997, April 1999, May 2001, July 2006 and October 2010. On the contrary, there was low rainfall (standardized PC less than −2.0) in September 1971, September 1974, August 1976, June 1977, October 1979, July 1983, July 1984, May 1987, August 1988, May 1992, October 1994, July 1998, August 1998 and October 2004 (see small circles in figure 1(b)).
in DJF the first mode show that the relation of the eigenvectors is positive over the part southern in the Gulf of Thailand. But it is negative over the southern part near by Malaysia. The values of standardized(PC’s), which have positive and negative values. It was found that there was the most positive in 1967 found that It was high rainfall in the part southern in the Gulf of Thailand. On the contrary, there was the most negative in 1990 found that, low rainfall in this area.