Persistent Model Biases in the CMIP6 Representation of Stratospheric Polar Vortex Variability

Sudden stratospheric warmings (SSWs) can have major impact on surface wintertime weather, especially at mid-high latitudes. We do not yet a complete understanding of why some these events influence our weather more than others, but one factor may be the dynamical nature SSW; whether it involves split or displacement polar vortex, and way to explore this is through comprehensive climate models. Here, we analyze dynamics SSWs within models from sixth Coupled Model Intercomparison Project (CMIP6). All CMIP6 simulate degree, although find persistent bias in relative underrepresentation vortex events. When comparing with CMIP5 models, large biases persist despite significant model improvements resolution representing atmospheric processes. show that simulated frequency strongly related climatological lower eddy heat flux. The frequency, other hand, flux, both geometry (aspect ratio) zonal winds. This suggests those positive winds inhibit propagation wavenumber 2 planetary waves troposphere, which are associated Our results suggest how future development address longstanding biases.