Cooling of the wintertime Arctic stratosphere induced by the western Pacific teleconnection pattern

Abstract

A composite analysis for extreme positive events of the Western Pacific (WP) teleconnection pattern with blocking flow configurations observed over the subpolar Far East shows that such an event in winter can trigger a persistent cold period in the polar stratosphere and, if it occurs in fall or early winter, it augments the possibility of the formation of polar stratospheric clouds. The stratospheric cooling occurs in conjunction with the weakening of upper‐tropospheric planetary waves and their upward propagation into the stratosphere soon after the peak time of the WP pattern. Synoptically, this weakening of the upper‐tropospheric planetary waves is manifested as westward evolution of a developing blocking high into the climatological‐mean pressure trough over the subpolar Far East. This study thus presents a unique case where a blocking high can induce cooling in the polar stratosphere rather than warming.