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the ENSO mode. Thus, analyzing and forecasting the Asian climate change
must consider the SSTA pattern in both the Pacific and the Indian Ocean,
namely the tropical Pacific-Indian Ocean temperature anomaly mode. For
the effect of SSTA on Indian rainfall, the PIM decreases much more Indian
rainfall than pure El Nino. The explanation that the tropical Indian Ocean
dipole is the cause of the weakening of the relation between ENSO and
Indian precipitation in recent years may be not true. Other factors may
be more important. The numerical simulation obtains generally the same
results as the observational study. It proves that the PIM has important
effect on Asian climate, which differs from ENSO mode. Therefore, to
provide better scientific explanation for short-term climate prediction, the
tropical Pacific-Indian Ocean temperature anomaly mode and its influence
should be considered and investigated.
Furthermore, the characteristics of the Asian climate systems related to
the Pacific-Indian Ocean temperature anomaly mode are investigated. The
positive phase of the tropical Pacific-Indian Ocean temperature anomaly
mode (positive SSTAs in the western Indian Ocean and eastern Pacific-
negative SSTAs in the eastern Indian Ocean — western Pacific) is favorable
for weaker Indian monsoon and eastern Asian summer monsoon, stronger
South China Sea monsoon, a weaker South Asia high with southeastwards
shift, a stronger subtropical high in the western Pacific with westwards
move. The precipitation in southeast China coastal region and from the
Changjiang-Huaihe River Basin to Sichuan Province increases, and the
rainfall in North China and Northeast China decreases. The rainfall in
India also decreases. The negative phase (reverse SSTAs of the positive
phase) makes the southwest monsoon stronger over the western Indian
Ocean and weaker over the India peninsula and the eastern Indian Ocean.
It contributes to a stronger eastern Asian summer monsoon, weaker South
China Sea monsoon, a stronger South Asia high with northwestwards shift,
and a weaker subtropical high in the western Pacific with eastwards move.
Less rainfall in Southeast China and more rainfall in the southwestern and
northern China and to the south of Changjiang River is obtained. The
precipitation in India increases.
Acknowledgments
This work was supported by the National Key Basic Research and
Development Project of China (Grant no. 2004CB18300), and the
Innovation Key Program of the Chinese Academy of Sciences (Grant
no. ZKCX2-SW-226).
