Why the properties of El Niño changed during the late 1970s

B. Wang, S. I. An

Research output: Contribution to journalArticle

113 Citations (Scopus)

Abstract

Following the abrupt North Pacific climate shift in the mid-1970s, the period, amplitude, spatial structure, and temporal evolution of the El Niño notably changed. Theory is needed to explain why the coherent changes in several El Niño characteristics are nearly synchronized with the decadal climate shift. While the decadal variation in the equatorial thermocline could potentially change El Niño behavior, observation indicates that from the pre-shift (1961 - 1975) to the post-shift (1981 - 1995) period the change of equatorial eastern Pacific thermocline is insignificant. Our numerical experiments with a coupled atmosphere-ocean model illustrate that the observed changes in ENSO properties may be attributed to decadal changes in the surface winds and associated ocean surface layer dynamics without changes in the mean thermocline. A theoretical analysis is presented to elucidate the mechanisms by which the decadal variations in winds and upwelling modify the structure and propagation of the El Niño and amplify and prolong the El Niño-La Nina cycle.

Original languageEnglish
Pages (from-to)3709-3712
Number of pages4
JournalGeophysical Research Letters
Volume28
Issue number19
DOIs
Publication statusPublished - 2001 Oct 1

Fingerprint

thermocline
thermoclines
decadal variation
shift
climate
La Nina
temporal evolution
surface wind
ocean models
El Nino-Southern Oscillation
ocean surface
surface layer
sea surface
upwelling
upwelling water
surface layers
atmosphere
ocean
atmospheres
cycles

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

Cite this

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abstract = "Following the abrupt North Pacific climate shift in the mid-1970s, the period, amplitude, spatial structure, and temporal evolution of the El Ni{\~n}o notably changed. Theory is needed to explain why the coherent changes in several El Ni{\~n}o characteristics are nearly synchronized with the decadal climate shift. While the decadal variation in the equatorial thermocline could potentially change El Ni{\~n}o behavior, observation indicates that from the pre-shift (1961 - 1975) to the post-shift (1981 - 1995) period the change of equatorial eastern Pacific thermocline is insignificant. Our numerical experiments with a coupled atmosphere-ocean model illustrate that the observed changes in ENSO properties may be attributed to decadal changes in the surface winds and associated ocean surface layer dynamics without changes in the mean thermocline. A theoretical analysis is presented to elucidate the mechanisms by which the decadal variations in winds and upwelling modify the structure and propagation of the El Ni{\~n}o and amplify and prolong the El Ni{\~n}o-La Nina cycle.",
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Why the properties of El Niño changed during the late 1970s. / Wang, B.; An, S. I.

In: Geophysical Research Letters, Vol. 28, No. 19, 01.10.2001, p. 3709-3712.

Research output: Contribution to journalArticle

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