%0 Journal Article
%A Charlton-Perez, Andrew J.
%A Baldwin, Mark P.
%A Birner, Thomas
%A Black, Robert X.
%A Butler, Amy H.
%A Calvo Fernández, Natalia
%A Davis, Nicholas A.
%A Gerber, Edwin P.
%A Gillett, Nathan
%A Hardiman, Steven
%A Kim, Junsu
%A Krüger, Kirstin
%A Lee, Yun-Young
%A Manzini, Elisa
%A McDaniel, Brent A.
%A Polvani, Lorenzo
%A Reichler, Thomas
%A Shaw, Tiffany A.
%A Sigmond, Michael
%A Son, Seok-Woo
%A Toohey, Matthew
%A Wilcox, Laura
%A Yoden, Shigeo
%A Christiansen, Bo
%A Lott, François
%A Shindell, Drew
%A Yukimoto, Seiji
%A Watanabe, Shingo
%T On the lack of stratospheric dynamical variability in low-top versions of the CMIP5 models
%D 2013
%@ 2169-897X
%U https://hdl.handle.net/20.500.14352/33554
%X We describe the main differences in simulations of stratospheric climate and variability by models within the fifth Coupled Model Intercomparison Project (CMIP5) that have a model top above the stratopause and relatively fine stratospheric vertical resolution (high-top), and those that have a model top below the stratopause (low-top). Although the simulation of mean stratospheric climate by the two model ensembles is similar, the low-top model ensemble has very weak stratospheric variability on daily and interannual time scales. The frequency of major sudden stratospheric warming events is strongly underestimated by the low-top models with less than half the frequency of events observed in the reanalysis data and high-top models. The lack of stratospheric variability in the low-top models affects their stratosphere-troposphere coupling, resulting in short-lived anomalies in the Northern Annular Mode, which do not produce long-lasting tropospheric impacts, as seen in observations. The lack of stratospheric variability, however, does not appear to have any impact on the ability of the low-top models to reproduce past stratospheric temperature trends. We find little improvement in the simulation of decadal variability for the high-top models compared to the low-top, which is likely related to the fact that neither ensemble produces a realistic dynamical response to volcanic eruptions.
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