Based on the ERA5 daily reanalysis data from 1979 to 2019, the self-organizing mapping (SOM) analysis is performed to objectively classify tropospheric polar vortex over the northern hemisphere in winter, analyze the temporal variation characteristics of the polar vortex weather pattern, and reveal its causes of the long-term variation. Results are shown as follows: (1) According to the center position of the polar vortex, it can be divided into circumpolar type, dipole type, Eurasian type and North American type, in which the circumpolar and dipole types are the dominant circulation types. The circumpolar and dipole types show a significant decreasing and increasing trend respectively, with obvious interannual and interdecadal variability. (2) The long-term decrease of the circumpolar type and the long-term increase of the dipole type are mainly due to the rapid warming of the Arctic region, which leads to the continuous reduction of the meridional temperature gradient and the weakening of baroclinicity between the middle and high latitudes of the northern hemisphere. The weakening of the circumpolar westerly circulation weakens the strength of the polar vortex in the northern hemisphere, which makes it very easily to split. Then, based on the data of the pre-industrial control simulation (piControl) and the simulation forced by a 1% /yr CO2 increase (1pctCO2) with Ocean-Atmosphere Coupled Model (CESM2) for the Coupled Model Intercomparison Project Phase 6 (CMIP6), SOM is also used to further explore the relationship between the long-term variability of circumpolar and dipole type and global warming. It is found that the circumpolar and dipole types are still the dominant circulation types in piControl and 1pctCO2. The circumpolar and dipole types have no significant variability trend in piControl, but show a significant decreasing and increasing trend respectively in 1pctCO2, which further verifies that the long-term variabilities of two polar vortex weather patterns under observation are closely related to global warming.