Observational Evidence of Distinguishable Weather Patterns for Three Types of Sudden Stratospheric Warming During Northern Winter

Hyesun Choi,Baek-Min Kim,Seong-Joong Kim,Joo-Hong Kim

doi:10.3389/feart.2021.625868

Abstract

Sudden stratospheric warming (SSW) events often lead to a cold surface air temperature anomaly over the extratropical regions. In this study, we propose, through observational evidence, that the types of SSW determine the severity of the cold anomaly. Based on the three-type classification of SSW, it is found that the surface air temperature drops notably over central to eastern North America following an SSW-type transition, especially from displacement to split. Note, however, that the differences in mean surface air temperature anomalies between SSW types are not statistically significant, even though after SSW-type transition from displacement to split, surface air temperature anomalies are colder than the other two types. The development of an anomalous tropospheric ridge in the North Pacific Arctic sector, associated with the difference in the vertical and zonal propagation of planetary waves, characterizes the post-warming period of the displacement–split type. After the occurrence of the displacement–split type transition of SSW events, upward propagation of planetary waves of zonal wavenumber 1 is suppressed, whereas planetary waves of zonal wavenumber 2 increase in the troposphere. Accompanying the ridge in the North Pacific, a trough developed downstream over North America that carries cold polar air therein. The results in this study are relevant for the subseasonal time scale, within 20 days after an SSW occurrence.

Highlights

There is increasing evidence that weak polar vortex states can account for cold winters over midlatitudes (Cellitti et al, 2006; Kolstad et al, 2010; Park et al, 2011; Kim et al, 2014; Kidston et al, 2015; Kretschmer et al, 2018a, Kretschmer et al, 2018b)
Observational evidence for features in weather patterns based on the three types of stratospheric warmings (SSWs) events is provided through a composite analysis using reanalysis data
The surface temperature over North America becomes rapidly cold after the occurrence of DS-type SSW events

Summary

INTRODUCTION

There is increasing evidence that weak polar vortex states can account for cold winters over midlatitudes (Cellitti et al, 2006; Kolstad et al, 2010; Park et al, 2011; Kim et al, 2014; Kidston et al, 2015; Kretschmer et al, 2018a, Kretschmer et al, 2018b). Choi et al (2019) found that the three SSW types display different characteristics in upward-propagating wave activity and a tropospheric height field during the prewarming period They showed that the results based on the traditional two-type classification (Charlton and Polvani, 2007) could weaken the distinct features between DS and SS types, and suggested that DS-type SSW events should be objectively defined to improve the understanding of SSW-related phenomena. In their extended study, differences in tropospheric precursor patterns over the North Atlantic between DD- and DS-type SSW were identified (Choi et al, 2020).

RESULTS

SUMMARY

DATA AVAILABILITY STATEMENT