Sensitivity of tropical intraseasonal variability to the pattern of climate warming

TitleSensitivity of tropical intraseasonal variability to the pattern of climate warming
Publication TypeJournal Article
Year of Publication2013
AuthorsMaloney ED, Xie SP
JournalJournal of Advances in Modeling Earth Systems
Volume5
Pagination32-47
Date Published2013/03
Type of ArticleArticle
ISBN Number1942-2466
Accession NumberWOS:000317833300003
Keywordsarakawa-schubert; atmosphere; boundary-layer winds; budget; convection; el-nino; general-circulation models; madden-julian oscillation; model; pacific; static energy; temperature
Abstract

An aquaplanet general circulation model is used to assess the sensitivity of intraseasonal variability to the pattern of sea surface temperature (SST) warming. Three warming patterns are used. Projected SST warming at the end of the 21st century from the Geophysical Fluid Dynamics Laboratory Climate Model 2.1 is one pattern, and zonally symmetric and globally uniform versions of this warming perturbation that have the same global mean SST change are the other two. Changes in intraseasonal variability are sensitive to the pattern of SST warming, with significant decreases in Madden-Julian oscillation (MJO)-timescale precipitation and wind variability for a zonally symmetric warming, and significant increases in MJO precipitation amplitude for a globally uniform warming. The amplitude of the wind variability change does not scale directly with precipitation, but is instead mediated by increased tropical dry static stability associated with SST warming. The patterned SST simulations have a zonal mean SST warming that maximizes on the equator, which fosters increased equatorial boundary layer convergence and also increases equatorial SST relative to the rest of the tropics. Both factors support increased convection, reflected in reduced gross moist stability (GMS). Mean precipitation is decreased and GMS is increased in the off-equatorial Eastern Hemisphere near 10 degrees S in the patterned warming simulations, where the strongest MJO-related intraseasonal precipitation variability is preferred in both the model and observations. It is argued that future changes in MJO activity may be sensitive to the pattern of SST warming, although these results should not be interpreted as a prediction of how MJO activity will change in future climate.

DOI10.1029/2012ms000171
Short TitleJ. Adv. Model. Earth Syst.
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