Abstract: Studies on extratropical cyclones under the climate warming background have attracted particular concern in recent years. Most of these researches focused on the characteristics of interannual or interdecadal variations of cyclone frequency, intensity and storm tracks. The consensus indicated that cyclone frequency by statistics has significantly decreased in mid-latitudes, but increased in high-latitudes. Storm intensity has increased in both high- and mid-latitudes during the past 50 years. The global warming might have resulted in a northward shift of storm tracks in the Northern Hemisphere. In addition, cyclone activities have good relations with tropospheric baroclinity, westerly jet, and sea surface temperature (SST) gradient.

Key words: extratropical cyclone, climate warming, baroclinic instability, NCEP/NCAR reanalysis data, sea-level pressure