Causes of Enhanced SST Variability over the Equatorial Atlantic and Its Relationship to the Atlantic Zonal Mode in CMIP5

TitleCauses of Enhanced SST Variability over the Equatorial Atlantic and Its Relationship to the Atlantic Zonal Mode in CMIP5
Publication TypeJournal Article
Year of Publication2017
AuthorsYang Y., Xie SP, Wu L.X, Kosaka Y, Li J.P
JournalJournal of Climate
Volume30
Pagination6171-6182
Date Published2017/08
Type of ArticleArticle
ISBN Number0894-8755
Accession NumberWOS:000406040200007
Keywordsatmosphere; Climatology; events; interannual variability; meridional mode; Meteorology & Atmospheric Sciences; ocean; pacific; system; tropical atlantic
Abstract

A spurious band of enhanced sea surface temperature (SST) variance (SBEV) is identified over the northern equatorial Atlantic in the Geophysical Fluid Dynamics Laboratory (GFDL) Climate Model, version 2.1. The SBEV is especially pronounced in boreal spring owing to the combined effect of both anomalous atmospheric thermal forcing and oceanic vertical upwelling. The SBEV is a common bias in phase 5 of the Coupled Model Intercomparison Project (CMIP5), found in 14 out of 23 models. The SBEV in CMIP5 is associated with the atmospheric thermal forcing and the oceanic vertical upwelling, similar to GFDL CM2.1. While the tropical North Atlantic variability is only weakly correlated with the Atlantic zonal mode (AZM) in observations, the SBEV in CMIP5 produces conditions that drive and intensify the AZM variability via triggering the Bjerknes feedback. This partially explains why AZM is strong in some CMIP5 models even though the equatorial cold tongue and easterly trades are biased low.

DOI10.1175/jcli-d-16-0866.1
Student Publication: 
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