The response of ENSO teleconnections to future dynamical and thermal changes

Future climate change will lead to both dynamical and thermal changes to the atmosphere, and these changes will affect the transmission and impact of ENSO-related teleconnections. As the dynamical atmospheric changes are a response to the radiatively-forced temperature changes, it is difficult to separate these effects. In this study we use a novel nudging technique to separately apply the future thermal and dynamical changes from CMIP6 models to the ECHAM6 atmospheric model.

First there is a training stage where the atmospheric model is nudged to a chosen future climate, and the nudging tendencies are recorded. In the second stage the nudging tendencies for temperature and winds can be applied individually or together to replicate different aspects of the future climate. During the second stage the nudging tendencies are independent of the current model state. This means that idealised ENSO SST experiments can be performed within the constructed future climates, and the model can respond to those perturbations. The study focuses on the how ENSO teleconnections, particularly relating the northern hemisphere polar vortex, will respond to future thermal and dynamical changes.