The Structure and Energetics of Midlatitude Disturbances Accompanying Cold-Air Outbreaks over East Asia

Abstract

The onset dates for 11 individual cold-air outbreaks over the East Asian seaboard during the Winter Monsoon Experiment (1 December 1978–28 February 1979) are used for constructing composite synoptic charts. The three-dimensional structure and energetics of disturbances with time males shorter than ∼5 days are distinguished from the corresponding properties of more slowly varying fluctuations by using time-filtering techniques. It is seen that the high-frequency disturbances accompanying the cold surges experience systematic structural changes as they migrate along a well-defined storm track from East Asia to the Gulf of Alaska. The typical life cycle of such extratropical storms is characterized by a barolinic growth phase coinciding with the polar outbreaks, and a decay phase in which barotropic processes play an active role. The propagation of low-frequency fluctuations is oriented toward lower latitudes, with new vorticity centers developing downstream and equatorward of the primary disturbanc... Abstract The onset dates for 11 individual cold-air outbreaks over the East Asian seaboard during the Winter Monsoon Experiment (1 December 1978–28 February 1979) are used for constructing composite synoptic charts. The three-dimensional structure and energetics of disturbances with time males shorter than ∼5 days are distinguished from the corresponding properties of more slowly varying fluctuations by using time-filtering techniques. It is seen that the high-frequency disturbances accompanying the cold surges experience systematic structural changes as they migrate along a well-defined storm track from East Asia to the Gulf of Alaska. The typical life cycle of such extratropical storms is characterized by a barolinic growth phase coinciding with the polar outbreaks, and a decay phase in which barotropic processes play an active role. The propagation of low-frequency fluctuations is oriented toward lower latitudes, with new vorticity centers developing downstream and equatorward of the primary disturbanc...