@inbook{c6fc518276a647969b5f6bfbd847c9ae,
title = "Two different regimes of anomalous walker circulation over the Indian and pacific oceans before and after the late 1970s",
abstract = "Using the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data aided by a coupled ocean-atmosphere model, we investigated two different regimes of anomalous Walker circulation system over the Pacific and Indian Oceans before and after a climate shift, which occurred in the late 1970s. During the period before the climate shift, an upper-level velocity potential anomaly systematically moves eastward from the tropical Indian Ocean to the warm pool region of the western Pacific during the growth phase of El Ni{\~n}o-Southern Oscillation (ENSO). In the meantime, the activities of South Asian and Australian summer monsoon systems are directly affected by the evolution of the anomalous Walker circulation. During the period after the climate shift, in contrast, an upperlevel velocity potential anomaly in the vicinity of the Philippine Sea and maritime continent is observed to expand westward into the northern Indian Ocean and South Asia during the decay phase of ENSO. This feature is identified with a major precursory signal of an anomalous South Asian summer monsoon in the preceding spring. The model captures a systematic eastward propagation similar to that observed prior to the late 1970s, but fails to reproduce the westward extension of the velocity potential anomaly observed to prevail after the late 1970s. The model results suggest that the cross-basin connection between the two oceans is a prerequisite for the turnabout of ENSO prior to the climate shift, in terms of the occurrence of westerly wind bursts.",
author = "Ryuichi Kawamura and Hiromitsu Aruga and Tomonori Matsuura and Satoshi Iizuka",
note = "Funding Information: Acknowledgments. Comments by two anonymous reviewers were extremely helpful. The authors would like to thank James Carton for a careful reading of the revised version of this paper. This research was supported by the research project {"}R&D of hydrological modeling and water resources system{"} of JST/CREST, and by the research project {"}Refinement of global and regional water cycle{"}, and Grants-in-Aids (14540406) of the Japanese Ministry of Education, Sports, Culture, Science and Technology. Publisher Copyright: {\textcopyright} 2004 by the American Geophysical Union.",
year = "2004",
doi = "10.1029/147GM20",
language = "English",
isbn = "9780875904122",
series = "Geophysical Monograph Series",
publisher = "Blackwell Publishing Ltd.",
pages = "365--377",
editor = "S.P. Xie and J.A. Carton and C. Wang",
booktitle = "Earth?s Climate",
}