The Impact of Oceanic Feedbacks on Stratosphere-Troposphere Coupling in an Idealized Model

Stratospheric temperature perturbations (STPs) caused by for example, variations in stratospheric ozone, are an important driver of changes in tropospheric dynamics, particularly pertinent to the long-term climatic evolution of the Southern Hemisphere. However, the impact of ocean feedbacks on this interaction has not been fully examined. To study it, positive STPs were applied in three otherwise identical, idealized model configurations –atmosphere-only (A), atmosphere + slab-ocean (AS), and fully-coupled atmosphere-ocean (AO)–and the resulting atmospheric changes compared. In the AO model, changes in the tropics (extratropics) experienced a poleward-expansion (shift) and positive (negative) feedback after ∼100–200 years, whilst the AS model showed atmospheric and sea surface temperature changes that did not resemble those seen in the AO model. In the AO model, changes in tropical ocean heat content were responsible for the atmospheric changes, attributable to changes in the Ekman transport. These results indicate that full atmosphere-ocean coupling should be accounted for when studying the long-term (100+ years) tropospheric response to STPs in the Southern Hemisphere. Validation with higher-resolution and more realistic models is necessary.