For a better understanding of the mid-1970sā shift in storm track activity and mean flow-transient eddy interaction, further investigation is made by analyzing local barotropic and baroclinic energetics. The variability of storm track activity is well correlated with the Pacific Decadal Oscillation and North Atlantic Oscillation prior to the early 1980s, but this relationship has disappeared afterward and a significant linkage between the PST and AST activity has also been decoupled. Finally, interdecadal change has been also noted in the relationship between the PST and AST activities and between the storm track activity and climate indices. Third, during recent decade, the PST intensity has been enhanced in early spring whereas the AST intensity has been weakened in midwinter.
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Second, the PST activity in midwinter underwent decadal change from a weak regime in the early 1980s to a strong regime in the late 1980s. First, the most remarkable transition in the North Pacific storm track (PST) and the North Atlantic storm track (AST) activities during the boreal cold season (from November to March) occurred around early-to-mid 1970s with the characteristics of global intensification that has been noticed in previous studies.
![storm over the pacific 1960 storm over the pacific 1960](https://www.listchallenges.com/f/lists/856df58b-d720-4ae7-8946-ac0832f0b4ae.jpg)
Analysis of NCEP-NCAR I reanalysis data of 1948ā2009 and ECMWF ERA-40 reanalysis data of 1958ā2001 reveals several significant interdecadal changes in the storm track activity and mean flow-transient eddy interaction in the extratropics of Northern Hemisphere.