Abstract
The analysis of the long-term fluctuation of monthly rainfall (1951-1973) revealed that the year-to-year variability of the rainfall in and around Java is large in the "east monsoon" (dry) season and relatively small in the "west monsoon" (rainy) season. The empirical orthogonal function analysis of the anomaly rainfall showed that the quasi-biennial oscillation (QBO) is dominant over the whole of Java with the large variance (29.4% of the total variance), and that a large variability in the "east monsoon" season is mostly explained by this component. The second component (6.2% of the total variance) represents the variation in the "west monsoon" season with a contrastive spatial pattern between the Java Sea side and the Indian Ocean side of the island. It was also confirmed that the first component (the QBO mode) in the anomaly rainfall is closely connected with the QBO in the surface pressure field over Australasia through the eastern south Pacific and the second component is associated with the north- (or south-) ward shift of the winter monsoon circulation system in the Northern Hemisphere. In addition, the relations between these two modes and the "southern oscillation" are briefly discussed.
