Indian Ocean capacitor effect on Indo-Western pacific climate during the summer following El Niño

Shang Ping Xie, Kaiming Hu, Jan Hafner, Hiroki Tokinaga, Yan Du, Gang Huang, Takeaki Sampe

研究成果: ジャーナルへの寄稿学術誌査読

1339 被引用数 (Scopus)

抄録

Significant climate anomalies persist through the summer (June-August) after El Niño dissipates in spring over the equatorial Pacific. They include the tropical Indian Ocean (TIO) sea surface temperature (SST) warming, increased tropical tropospheric temperature, an anomalous anticyclone over the subtropical northwest Pacific, and increased mei-yu-baiu rainfall over East Asia. The cause of these lingering El Niño effects during summer is investigated using observations and an atmospheric general circulation model (GCM). The results herein indicate that the TIO warming acts like a capacitor anchoring atmospheric anomalies over the Indo-western Pacific Oceans. It causes tropospheric temperature to increase by a moistadiabatic adjustment in deep convection, emanating a baroclinic Kelvin wave into the Pacific. In the northwest Pacific, this equatorial Kelvin wave induces northeasterly surface wind anomalies, and the resultant divergence in the subtropics triggers suppressed convection and the anomalous anticyclone. The GCM results support this Kelvin wave-induced Ekman divergence mechanism. In response to a prescribed SST increase over the TIO, the model simulates the Kelvin wave with low pressure on the equator as well as suppressed convection and the anomalous anticyclone over the subtropical northwest Pacific. An additional experiment further indicates that the north Indian Ocean warming is most important for the Kelvin wave and northwest Pacific anticyclone, a result corroborated by observations. These results have important implications for the predictability of Indo-western Pacific summer climate: the spatial distribution and magnitude of the TIO warming, rather than simply whether there is an El Niño in the preceding winter, affect summer climate anomalies over the Indo-western Pacific and East Asia.

本文言語英語
ページ(範囲)730-747
ページ数18
ジャーナルJournal of Climate
22
3
DOI
出版ステータス出版済み - 2月 1 2009
外部発表はい

!!!All Science Journal Classification (ASJC) codes

  • 大気科学

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