CMIP6 projected trend of winter and summer variation in Arctic cyclones over the 21st century

Using the simulation results from the CMIP6 global climate models, we calculate the projected changes of different kinds of Arctic cyclones (ACs) in the twenty-first century and examine the characteristics related to the Arctic cyclones under two shared socio-economic pathways (SSP1-2.6, SSP5-8.5). There is a significant decline of ACs during winter over southern Greenland, the Barents Sea, and the Gulf of Alaska. In summer, the number of Arctic cyclones shows a significant circular decrease across most continental regions. By the end of the twenty-first century, the proportion of stronger, large-radius, and long-lifespan ACs is expected to increase, while the number of extreme Arctic cyclones will decrease in the future. However, trends in the intensity of Arctic cyclones depends on the measure of cyclone intensity used. Weaker baroclinic instability in the future is the primary reason for the decline of cyclone density in winter. In contrast, the situation in summer is more complicated. The number of Arctic cyclones in summer is influenced by factors such as the tropopause polar vortex and mid-latitude cyclones entering the Arctic, while positive anomalies in the Eady growth rate can lead to explosive cyclone development.