The equatorial stratospheric semiannual oscillation and time-mean winds in QBOi models

A. K. Smith, L. A. Holt, R. R. Garcia, J. A. Anstey, F. Serva, N. Butchart, S. Osprey, A. C. Bushell, Y. Kawatani, Y. H. Kim, F. Lott, P. Braesicke, C. Cagnazzo, C. C. Chen, H. Y. Chun, L. Gray, T. Kerzenmacher, H. Naoe, J. Richter, S. VersickV. Schenzinger, S. Watanabe, K. Yoshida

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12 Citations (Scopus)


The Quasi-Biennial Oscillation initiative (QBOi) is a model intercomparison programme that specifically targets simulation of the QBO in current global climate models. Eleven of the models or model versions that participated in a QBOi intercomparison study have upper boundaries in or above the mesosphere and therefore simulate the region where the stratopause semiannual oscillation (SAO) is the dominant mode of variability of zonal winds in the tropical upper stratosphere. Comparisons of the SAO simulations in these models are presented here. These show that the model simulations of the amplitudes and phases of the SAO in zonal-mean zonal wind near the stratopause agree well with the information derived from available observations. However, most of the models simulate time-average zonal winds that are more westward than determined from observations, in some cases by several tens of m·s–1. Validation of wave activity in the models is hampered by the limited observations of tropical waves in the upper stratosphere but suggests a deficit of eastward forcing either by large-scale waves, such as Kelvin waves, or by gravity waves.

Original languageEnglish
Pages (from-to)1593-1609
Number of pages17
JournalQuarterly Journal of the Royal Meteorological Society
Issue number744
Publication statusPublished - 2022 Apr 1

Bibliographical note

Funding Information:
The National Center for Atmospheric Research is sponsored by the National Science Foundation. We thank the model groups that participated in QBOi for performing the simulations and providing output for analysis. The authors also acknowledge support for early career researchers from the World Climate Research Programme core project Stratosphere‐troposphere Processes And their Role in Climate. The QBOi archive was hosted by the Centre for Environmental Data Analysis (CEDA), UK. L. Holt was supported by NASA's Atmospheric Composition Modeling and Analysis Program (ACMAP) Grant No. 80NSSC18K0069, and NASA's Modeling, Analysis and Prediction (MAP) programme Grant No. 80NSSC17K0169. C. Cagnazzo and F. Serva have been supported by the Copernicus Climate Change Service, funded by the EU and implemented by ECMWF. Y. H. Kim was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF‐2015R1C1A1A02036449). F. Lott, L. Gray, S. Watanabe and S. Osprey acknowledge support from the JPI‐Climate/Belmont Forum project GOTHAM (ANR‐15‐JCLI‐0004‐01, NE/P006779/1). P. Braesicke, T. Kerzenmacher and S. Versick acknowledge support by the state of Baden‐Württemberg through bwHPC. Y. Kawatani was supported by Japan Society for Promotion of Science (JSPS) KAKENHI Grant Numbers JP15KK0178, JP16H04052, JP17K18816 and JP18H01286. A. K. Smith acknowledges comments from and discussion with W. J. Randel, I. R. Simpson and T.J. Dunkerton.

Publisher Copyright:
© 2019 Royal Meteorological Society.

All Science Journal Classification (ASJC) codes

  • Atmospheric Science


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