Uncertainty in the response of sudden stratospheric warmings and stratosphere- troposphere coupling to quadrupled CO2 concentrations in CMIP6 models
- 1Universidad Complutense de Madrid, Facultad de CC. Fisicas, Física de la Tierra y Astrofísica, Madrid, Spain (bayarzag@ucm.es)
- 2Department of Meteorology, Univ. of Reading, UK
- 3Cooperative Institute for Environmental Sciences (CIRES)/National Oceanic and Atmospheric Administration (NOAA) Chemical Sciences Division, USA
- 4Department of Earth and Atmospheric Sciences, Cornell University, USA
- 5Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, USA
- 6Columbia University, USA
- 7Met Office Hadley Centre, Exeter, UK.
- 8Courant Institute of Mathematical Sciences, New York University, USA
- 9NCAS-Climate, Department of Physics, University of Oxford, UK
- 10Deutsches Zentrum für Luft-und Raumfahrt (DLR), Oberpfaffenhofen, Germany
- 11Atmospheric and Oceanic Sciences Program, Princeton University, USA
- 12Laboratoire de Météorologie Dynamique, Ecole Normale Supérieure, France
- 13Max-Planck-Institut für Meteorologie, Germany
- 14Meteorological Research Institute, Japan
- 15NASA Goddard Institute for Space Studies, USA
- 16Centre National de Recherches Météorologiques (CNRM), Université de Toulouse, Météo- France, CNRS, Toulouse, France
- 17Canadian Centre for Climate Modelling and Analysis Environment and Climate Change, Canada
- 18Department of Earth Science, Aichi University of Education, Kariya, Japan
- 19Marchuk Institute of Numerical Mathematics, Russia
- *A full list of authors appears at the end of the abstract
Major sudden stratospheric warmings (SSWs), vortex formation and final breakdown dates are key highlight points of the stratospheric polar vortex. These phenomena are relevant for stratosphere-troposphere coupling, which explains the interest in understanding their future changes. However, up to now, there is not a clear consensus on which projected changes to the polar vortex are robust, particularly in the Northern Hemisphere, possibly due to short data record or relatively moderate CO2 forcing. The new simulations performed under the Coupled Model Intercomparison Project, Phase 6, together with the long daily data requirements of the DynVarMIP project in preindustrial and quadrupled CO2 (4xCO2 ) forcing simulations provide a new opportunity to revisit this topic by overcoming the limitations mentioned above.
In this study, we analyze this new model output to document the change, if any, in the frequency of SSWs under 4xCO2 forcing. Our analysis reveals a large disagreement across the models as to the sign of this change, even though most models show a statistically significant change. The models, however, are in good agreement as to the impact of SSWs over the North Atlantic: there is no indication of a change under 4xCO2 forcing. Over the Pacific, however, the change is more uncertain. Finally, the models show robust changes to the seasonal cycle in the stratosphere. Specifically, we find a longer duration of the stratospheric polar vortex, and thus a longer season of stratosphere-troposphere coupling.
B. Ayarzagüena1 , A. J. Charlton-Perez2 , A. H. Butler3 , P. Hitchcock4 , I. R. Simpson5 , L. M. Polvani6 , N. Butchart 7, E. P. Gerber8 , L. Gray 9, B. Hassler10, P. Lin11, F. Lott12, E. Manzini13, R. Mizuta14, C. Orbe15, S. Osprey9 , D. Saint-Martin16, M. Sigmond17, M. Taguchi18, E. M. Volodin19, S. Watanabe20
How to cite: Ayarzagüena, B., Charlton-Pérez, A. J., Butler, A. H., Hitchcock, P., Simpson, I. R., Polvani, L. M., Butchart, N., Gerber, E. P., Gray, L., Hassler, B., Lin, P., Lott, F., Manzini, E., Mizuta, R., Orbe, C., Osprey, S., Saint-Martin, D., Sigmond, M., Taguchi, M., and Volodin, E. and the DynVarMIP-SSW: Uncertainty in the response of sudden stratospheric warmings and stratosphere- troposphere coupling to quadrupled CO2 concentrations in CMIP6 models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11839, https://doi.org/10.5194/egusphere-egu2020-11839, 2020.
