Characteristics of E3SMv2’s stratospheric circulation
The paper sheds light on the physical characteristics of E3SMv2’s circulation in the stratosphere which is typically not analyzed via E3SM’s standard diagnostic packages (with the exception of the Quasi-Biennial Oscillation in the tropics). In particular, we utilize the E3SMv2 historical CMIP6 simulations and pay particular attention to the representation of E3SM’s general circulation, residual circulation and Brewer-Dobson circulation, stratospheric water vapor, the zonal wind patterns including the tropical QBO and polar Sudden Stratospheric Warmings (SSWs), and the tracer transport in the stratosphere. We also compare the E3SMv2 circulation to observations, ERA5 reanalysis data, and other CMIP6 models like NCAR’s WACCM to put the results into context. It is found that E3SMv2 exhibits strong stratospheric biases that were also already present in E3SMv1. Since the stratospheric circulation impacts the predictability and trustworthiness of E3SM’s tropospheric climate, these biases should be more widely discussed, analyzed, and remedied in future E3SM versions. The research is highly relevant for E3SM, but was conducted with funding from the Sandia Grand Challenge LDRD project: CLimate impact: Determining Etiology thRough pAthways (CLDERA).