Effects of large-scale changes in environmental factors on the genesis of Arctic extreme cyclones

The Arctic cyclone is an active weather system in the Arctic, and the Arctic extreme cyclone (AEC) strongly influences polar weather. Thus, many studies have focused on the activity of AEC and its relationship with large-scale circulation in the Arctic. In this study, Arctic cyclones were detected using the ERA5 Reanalysis data from 1979 to 2020, and the AECs of cold and warm semesters were defined using the 5th percentile of sea level pressure. An Arctic cyclone genesis index, GPI(Arctic), is established by using the least square fitting of absolute vorticity, omega, wind shear, and long-wave radiation with Eady growth rate. Our findings show that wind shear and long-wave radiation strongly influence AECs. In the cold semester, the high value of GPI(Arctic) mainly occurs in the south of Greenland, while in the warm semester, the high value of GPI(Arctic) also occurs in northeast Eurasia. The results of the multi-model integration of CMIP6 show that more AECs will be formed in the Arctic in the future (2021-2050), and their seasonal contrast will be stronger in northeast Eurasia.

Automated summary

This study detected Arctic cyclones using ERA5 Reanalysis data and defined extreme Arctic cyclones (AECs) based on sea level pressure. A mathematic model revealed that wind shear and long-wave radiation have significant influences on AECs. The multi-model integration of CMIP6 predicted that more AECs will form in the Arctic in the future, with a stronger seasonal contrast in northeast Eurasia.