Investigation of Stratospheric Precursor for the East Asian Cold Surge Using the Potential Vorticity Inversion Technique

Abstract

The downward influence of stratospheric potential vorticity (PV) on the cold surge occurrence over East Asia was examined. Strong negative PV anomalies in the upper stratosphere and the rising of geopotential height in the upper troposphere about one week ahead of the cold surge occurrence were suggested as precursory perturbations triggering the development of the cold surge, which is dynamically validated by the piecewise potential vorticity inversion technique. When the inversion is applied to the stratospheric PV anomalies, geopotential and temperature anomalies balanced to the stratospheric PV were remarkably well reproduced in both amplitude and penetrating depth as in the observations. Although the PV anomalies are mostly confined to the stratosphere, our results confirm that its downward influences are sufficiently strong such that associated tropospheric anomalies with the stratospheric PV are capable of triggering the cold surge occurrence within the given mechanism.