Interannual Variation of the East Asian Cold Surge Activity

The occurrence frequency of the east Asian cold surge exhibits an interannual variation in concert with the El Niño–Southern Oscillation (ENSO) cycle. That is, the cold surge occurs more (less) frequently during warm (cold) ENSO winters. Because the cold surge high–low dipoles are coupled with the upper-level synoptic short waves, any mechanism modulating the activity of these waves would affect the cold surge activity. The streamfunction budget analysis in the short-wave regime indicates that the development of the cold surge short-wave train over east Asia and the northwest Pacific is modulated by the North Pacific ENSO short-wave train. Due to the coupling between the upper-level cold surge short-wave train and the surface cold surge dipole, it is inferred from this streamfunction budget analysis that the interannual variation of the cold surge occurrence frequency is a result of this modulation.