Equatorial signatures of the Pacific Meridional Modes

Dependence on mean climate state

Honghai Zhang, Clara Deser, Amy C Clement, Robert Tomas

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Extratropical atmospheric variability can impact tropical climate in the Pacific sector via the Pacific Meridional Modes (PMMs). The South PMM (SPMM) has a larger equatorial signature than the North PMM (NPMM) for the same amount of extratropical variability. Here we explain this interhemispheric asymmetry using an atmospheric general circulation model coupled to a slab ocean model. By imposing an anomalous interhemispheric heating gradient, we strengthen the northeasterly trades and weaken the southeasterly trades, shifting the Intertropical Convergence Zone south of the equator. As a result, the SPMM no longer influences the equatorial region while the NPMM shows strengthened linkages to the central-western equatorial Pacific. By demonstrating that background winds determine the propagation of the wind-evaporation-sea surface temperature feedback fundamental for the PMMs, we conclude that the interhemispheric asymmetry between the PMMs is largely attributed to the asymmetric mean trades in the Pacific. The results have implications for both paleoclimate studies and model development.

Original languageEnglish (US)
Pages (from-to)568-574
Number of pages7
JournalGeophysical Research Letters
Volume41
Issue number2
DOIs
StatePublished - Jan 28 2014

Fingerprint

climate
signatures
asymmetry
intertropical convergence zone
atmospheric general circulation model
paleoclimate
Atmospheric General Circulation Models
slab
sea surface temperature
evaporation
ocean models
equatorial regions
heating
equators
linkages
ocean
slabs
sectors
gradients
propagation

Keywords

  • asymmetry
  • mean climate
  • Meridional Mode
  • trade winds
  • WES feedback

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Geophysics

Cite this

Equatorial signatures of the Pacific Meridional Modes : Dependence on mean climate state. / Zhang, Honghai; Deser, Clara; Clement, Amy C; Tomas, Robert.

In: Geophysical Research Letters, Vol. 41, No. 2, 28.01.2014, p. 568-574.

Research output: Contribution to journalArticle

Zhang, Honghai ; Deser, Clara ; Clement, Amy C ; Tomas, Robert. / Equatorial signatures of the Pacific Meridional Modes : Dependence on mean climate state. In: Geophysical Research Letters. 2014 ; Vol. 41, No. 2. pp. 568-574.
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