EGU2020-18795
https://doi.org/10.5194/egusphere-egu2020-18795
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Response of the quasi-biennial oscillation to a warming climate in global climate models

Jadwiga Richter1, Francois Lott2, and the QBOi contributors*
Jadwiga Richter and Francois Lott and the QBOi contributors
  • 1NCAR, CGD, Boulder, United States of America (jrichter@ucar.edu)
  • 2PSL Research Institute, LMD-ENS, Paris, France
  • *A full list of authors appears at the end of the abstract

We compare the response of the quasi-biennial oscillation (QBO) to a warming climate in eleven atmosphere general circulation models that performed time-slice simulations for present-day, doubled,  and  quadrupled CO2 climates.  No consistency was found among the models for the QBO period response, with the period decreasing by eight months in some models and lengthening by up to thirteen months in others in the doubled CO2  simulations.  In the quadruped CO2 simulations  a reduction in QBO period of 14 months was found in some models, whereas in several others the tropical oscillation no longer resembled the present day QBO, although could still be identified in the deseasonalized zonal mean zonal wind timeseries.  In contrast, all the models projected a decrease in the  QBO amplitude in a warmer climate with the largest relative decrease  near 60 hPa. In simulations with doubled and quadrupled CO2 the multi-model mean QBO amplitudes decreased by 36\% and 51\%, respectively. Across the  models the differences in the QBO period response were most strongly related to how the gravity wave momentum flux entering the stratosphere and tropical vertical residual velocity responded to the increases in CO2 amounts. Likewise it was found that the robust decrease in QBO amplitudes was correlated across the models to changes in vertical residual velocity, parameterized gravity wave momentum fluxes, and to some degree the resolved upward wave flux.  We argue that uncertainty in the representation of the parameterized gravity waves is the most likely cause of the spread among the eleven models in the QBO's response to climate change.

QBOi contributors:

Richter, J.H, N. Butchart, Y. Kawatani, A. C. Bushell, L. Holt, F. Serva, J. Anstey, I. R. Simpson, S. Osprey, K. Hamilton, P. Braesicke, C. Cagnazzo, C.-C. Chen, R. R. Garcia, L. J. Gray, T. Kerzenmacher, F. Lott, C. McLandress, H. Naoe, J. Scinocca, T. N. Stockdale, S. Versick, S. Watanabe, K. Yoshida, S. Yukimoto

How to cite: Richter, J. and Lott, F. and the QBOi contributors: Response of the quasi-biennial oscillation to a warming climate in global climate models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18795, https://doi.org/10.5194/egusphere-egu2020-18795, 2020

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