The Impact of Oceanic Feedbacks on Stratosphere-Troposphere Coupling in
an Idealised Model
Abstract
Stratospheric temperature perturbations (STPs) caused by e.g. variations
in stratospheric ozone, are an important driver of changes in
tropospheric dynamics, particularly pertinent to the long-term climate
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, idealised 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 positive/negative feedback after ~100-200
years, whilst the AS model showed few significant changes, compared to
the A model. Changes in tropical ocean heat content were responsible,
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 Ocean region. Validation with higher-resolution and more
realistic models is necessary.