A coupled ocean-atmosphere instability of relevance to the seasonal cycle

Chang Ping Chang, S. G. Philander

Research output: Contribution to journalArticlepeer-review

96 Scopus citations


Recent observational studies have suggested that interactions between the atmosphere and the ocean play an important role in the pronounced annual cycle of the eastern equatorial Pacific and Atlantic Oceans. The key to this atmosphere-ocean interaction is a positive feedback between the surface winds and the local SST gradients in the cold tongue/ITCZ complex region, which leads to an instability in the coupled system. By means of linear instability analyses and numerical model experiments, such an instability mechanisms is explored in a simple coupled ocean-atmosphere system. The instability analysis yields a family of antisymmetric and symmetric unstable SST modes. The antisymmetric mode has the most rapid growth rate. The most unstable antisymmetric mode occurs at zero wavenumber and has zero frequency. The symmetric SST mode, although its growth rate is smaller, has a structure at annual period that appears to resemble the observed westward propagating feature in the annual cycle of near-equatorial zonal wind and SST. -Authors

Original languageEnglish (US)
Pages (from-to)3627-3648
Number of pages22
JournalJournal of the Atmospheric Sciences
Issue number24
StatePublished - 1994

All Science Journal Classification (ASJC) codes

  • Atmospheric Science


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