Land-sea thermal contrast determines the trend of Walker circulation simulated in atmospheric general circulation models

Bo Young Yim, Sang-Wook Yeh, Hwan Jin Song, Dietmar Dommenget, B. J. Sohn

Research output: Contribution to journalArticleResearchpeer-review

5 Citations (Scopus)

Abstract

Strengthening or weakening of the Walker circulation can highly influence the global weather and climate variability by altering the location and strength of tropical heating. Therefore, there is considerable interest in understanding the mechanisms that lead to the trends in the Walker circulation intensity. Conventional wisdom indicates that a strengthening or weakening of the Walker circulation is primarily controlled by inhomogeneous sea surface temperature (SST) patterns across the tropical Pacific basin. However, we show that Atmospheric Model Intercomparison Project climate model simulations with identical SST forcing have different Walker circulation trends that can be linked to differences in land surface temperatures. More prominently, stronger land-sea thermal contrast leads to increases in the precipitation in South America as well as the sea level pressure in the eastern tropical Pacific through a local circulation, resulting in a strengthening of the Walker circulation trend. This implies that correctly simulating the land temperature in atmospheric models is crucial to simulating the intensity of the Walker circulation in the present climate as well as its future change.

Original languageEnglish
Pages (from-to)5854-5862
Number of pages9
JournalGeophysical Research Letters
Volume44
Issue number11
DOIs
Publication statusPublished - 16 Jun 2017

Keywords

  • AMIP climate models
  • land-sea thermal contrast
  • sea surface temperature
  • Walker circulation

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