Evaluation of the impact of the Atlantic Ocean on the atmospheric circulation using the EC-Earth3-ESM-1 model

The Atlantic Ocean plays a crucial role in regulating regional and global climate variability, particularly as the Atlantic meridional overturning circulation (AMOC) is weakening and on course to reach a critical tipping point in a rapidly warming climate. As a key tipping component of the climate system, the AMOC influences other Atlantic climate phenomena, e.g. the Atlantic Multidecadal Oscillation (AMO), and impacts global atmospheric circulation through air-sea interaction. Therefore, it is essential that the global Earth system models correctly capture or represent these interactions. This study aims to assess the impact of Atlantic climate phenomena on atmospheric circulation, based on historical and pre-industrial experiments conducted using the newly developed EC-Earth3-ESM-1 model under the framework of the EU project OptimESM. We focus particularly on evaluating the interaction between AMOC, AMO, and prominent large-scale atmospheric circulation patterns (e.g. the North Atlantic Oscillation (NAO), Hadley, and Walker circulation) using Empirical Orthogonal Function (EOF) and maximum covariance analysis methods. Our first results show that the EC-Earth3-ESM-1 model can reasonably capture the spatiotemporal relationship between the atmospheric circulation modes and AMOC/AMO compared to observation/reanalysis datasets. Additionally, we also investigate potential atmospheric circulation mode changes due to increasing CO2 concentration using idealized experiments. More detailed analyses will be further explored in this study.