Distinguishable tropospheric-stratospheric coupled dynamical processes for SSW

Abstract

Among events characterized by single polar vortex moving to a low latitude region prior to sudden stratospheric warming (SSW), some are divided into two pieces of polar vortex while others retain one vortex after SSW. Based on the different vortex evolution patterns, we confirm that the significant difference in observed zonal wind over the high-latitude lower stratosphere is preceded. This can be attributed to the differences in the tropospheric geopotential height distribution in the North Atlantic region resulting in distinct tropospheric-stratospheric dynamical processes: In the growth stage of the former SSW event, the negative NAO phase is dominant and stronger westerly-wind deceleration is observed in the high-latitude lower stratosphere than the later SSW event. This is also confirmed in the model. It suggests that the teleconnection pattern in the North Atlantic region can be a possible precursor to distinguish SSW specific events.