A possible role for unstable coupled waves affected by resonance between Kelvin waves and seasonal warming in the development of the strong 1997-1998 El Niño

T. Toyoda, S. Masuda, N. Sugiura, T. Mochizuki, H. Igarashi, M. Kamachi, Y. Ishikawa, T. Awaji

研究成果: Contribution to journalArticle査読

10 被引用数 (Scopus)

抄録

Time-varying air-sea coupled processes in the central to eastern equatorial Pacific associated with strong El Niño development during the 1997-1998 period are examined using a newly developed reanalysis dataset obtained from four-dimensional variational ocean-atmosphere coupled data assimilation experiments. The time series of this data field exhibits realistic features of El Niño evolution. Our analysis indicates that resonance between eastward-propagating oceanic downwelling Kelvin waves and the seasonal rise of sea-surface temperature (SST) in the central to eastern equatorial Pacific generates relatively persistent high SST conditions accompanied by a deeper thermocline and more relaxed easterly winds than usual. The surface condition resulting from the wave-seasonal SST resonance represents a preconditioned state that leads to an enhancement in incident downwelling Kelvin waves to levels sufficient to induce large-amplitude unstable coupled waves in the central to eastern equatorial region. Heat balance estimates using our reanalysis dataset suggest that the unstable coupled waves are categorized within the intermediate regime of coupled Kelvin and Rossby waves and have the potential to grow rapidly. We argue that the seasonal resonance and the unstable coupled waves should play crucial roles in the development of the largest historical El Niño event, which was recorded between late 1997 and early 1998.

本文言語英語
ページ(範囲)495-512
ページ数18
ジャーナルDeep-Sea Research Part I: Oceanographic Research Papers
56
4
DOI
出版ステータス出版済み - 4 2009
外部発表はい

All Science Journal Classification (ASJC) codes

  • 海洋学
  • 水圏科学

フィンガープリント

「A possible role for unstable coupled waves affected by resonance between Kelvin waves and seasonal warming in the development of the strong 1997-1998 El Niño」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル