Synoptic Forcing of East Asian Cold Surges

A linearized, global spectral model with eight levels was used to determine whether the nonlinear interaction between a planetary-scale wave (wavenumber four) and a rapidly growing synoptic-scale wave (wavenumber seven) could produce a northeasterly wind, characteristic of East Asian cold surges. The amplitude of the synoptic-scale wave, or generic cyclone, was produced by a nonlinear Eady model of the atmosphere that included friction. The resulting nonlinear forcing was applied to either the first law of thermodynamics, the vorticity equation, or both. The thermal forcing did not produce a significant cold surge response. The vorticity forcing produced a respectable cold surge within 48 hours. The results of this study indicate the planetary-synoptic wave interaction is a possible method for initiating East Asian cold surges. Keyword: Theses.