Something old, something new, much of it borrowed....interactions of the atmospheric chemistry system

Euro-Atlantic Weather Regimes are robust features of reanalysis datasets. Based on integrations of the ECMWF model made during the Athena project, we show that Euro-Atlantic weather regimes are well simulated with models run at NWP resolution, but not at typical CMIP resolution. We also show that models with stochastic parametrisation have improved performance in simulating regime structures. These results have implications for assessing the reliability of CMIP resolution models in being able to simulate regional patterns of climate change.