Impacts of Atmospheric Cloud Radiative Effects on Annular Mode Persistence

Annular mode persistence is important for mid-latitude weather predictability, and holds potential implications for the climate change response of the mid-latitudes. Previous work on annular modes has mostly focused on dry dynamics, and the influence of clouds on annular mode persistence has barely been studied. We use an idealized atmospheric model to investigate how the annular mode's autocorrelation is impacted by atmospheric cloud radiative effects (ACRE) which are coupled with annular mode variability. The model does not explicitly simulate clouds, but represents ACRE as an imposed diabatic heating whose sign and magnitude depends on the annular mode index. We also test the sensitivity of our results to the amplitude of the imposed heating, and conduct the same experiment with an alternative model setup that exhibits propagating variability. These results deepen our understanding of the controls on annular mode persistence and provide potentially useful criteria for evaluating how mid-latitude clouds are simulated in comprehensive climate models.