Arctic Cyclones and Sea Ice in an Ensemble of CMIP6 Models

The Arctic climate system is changing rapidly. Models have estimated that by 2050 we will experience an ice-free Arctic during the summer. These large changes will have implications beyond the Arctic both through teleconnections affecting the weather in midlatitudes and through more human activities in the Arctic. Therefore, it is important to understand the Arctic climate system and the models used to make these predictions more accurate. One of the most important components to the Article climate system are cyclones. In this presentation we provide a climatology of Arctic cyclones and their relationships with the sea ice, based on an ensemble of CMIP6 models from 1985-2014. The models included are EC-Earth3, BCC-CSM2-MR, MRI-ESM2-0, MIROC6, MPI-ESM1-2-LR and MPI-ESM1-2-HR. These results are compared with ERA5 reanalysis to quantify how well the models perform compared to observations. Comparisons to observations will then allow us to better understand how reliable models are in predicting the future changes and the relationships between cyclones and sea ice. Over all the models do perform well. Average cyclone counts, cyclogenesis and lifetime of the cyclones were all comparable to the observations with ERA5. However, the models performed poorly in reproducing the intensity of the cyclones as well as the trends in cyclone characteristics and sea ice. The warm season (June November) results were observed to be less accurate than the cold season (December May) results. The models also struggled in reproducing the relationship between cyclones and sea ice, giving more emphasis on the large- scale flow than local changes with the sea ice.