Investigation of Sudden Stratospheric Warming (SSW) Events Between 1980 and 2100

Highlights: What are the main findings? High-top CMIP5 models systematically underestimate the energetic intensity MPS (Main Phase Strength) and spatial extent TEA (Threshold Exceedance Area) of SSW events by 61% to 82% compared to ERA5 reanalysis. A ‘teleconnection gap’ is identified where models successfully represent tropical stratospheric variability (10° N) but fail to effectively transmit this momentum forcing to the polar vortex (60° N). What are the implications of the main findings? The CMIP5 models fail to accurately represent the sensitivity of the T_s-U_h relationship and polar vortex responses. This suggests that current climate projections may be insufficient to predict anomalies of the stratospheric thermal budget and climate change. The urgent improvement of the CMIP models’ vertical and horizontal resolutions for future climate studies is found to be critical for accurately prediction of SSW events and Arctic vortex development. Furthermore, the re-analyzed datasets should be enhanced using remote sensing observations to better represent wave–mean flow interactions in the upper troposphere and stratosphere. The main objective of this work is to characterize Sudden Stratospheric Warming (SSW) conditions and their impact on local weather forecasting and climate change, using SSW definition criteria. The SSWs strongly affect Arctic vortex structure and midlatitude weather conditions. This work evaluates the frequency, amplitude, and dynamical–thermal characteristics of SSWs under historical and Representative Concentration Pathway (RCP) 4.5 scenarios, focusing on stratospheric air temperature (T_s) and zonal wind speed (U_h) at the 10° N and 60° N latitudes. The fifth-generation ECMWF atmospheric reanalysis (ERA5) is employed as the reference dataset. Simulations of five Coupled Model Intercomparison Project Phase 5 (CMIP5) models, represented by M1 to M5, are analyzed. The primary group of models included 1) the Australian Community Climate and Earth-System Simulator, version 1.3 (ACCESS1-3, M1), 2) the Hadley Center Global Environmental Model, version 2—Carbon Cycle (HadGEM2-CC, M2), and 3) the Max Planck Institute Earth System Model—Medium Resolution (MPI-ESM-MR, M3). The analysis period covers SSW events related to the Quasi-Biennial Oscillation (QBO) in the Northern Hemisphere (NH) from 1980 to 2100. The key findings indicate that while M1, M2, and M3 simulate SSW occurrence correctly for the 21st century, they exhibit significant systematic deficiencies in capturing the structural dynamics of SSW events. Specifically, the M1, M2, and M3 models underestimate the polar stratospheric temperature amplitude (T_amp) by approximately 75–80% and zonal wind amplitude (U_amp) by more than 60% compared to the ERA5 analysis. Furthermore, ERA5 exhibits a strong negative correlation (R ≈ −0.8) between U_h and T_s that is not estimated accurately using the present models. The importance of the horizontal resolution of the models and wave–mean flow interactions in determining SSW intensity and occurrence is also found to be a critical metric. Results suggest that SSW definition criteria affect Arctic and midlatitude weather system prediction at a rate of 61–82%. It is concluded that the primary configurations of CMIP5 models for accurately capturing the dynamical structure and evolution of QBO–SSW interactions are needed, and that they affect future projections of SSW events.