Dependence of sudden stratospheric warming type‐transition on preceding North Atlantic Oscillation conditions

Abstract Most sudden stratospheric warming (SSW) events initiate with their centers being displaced from the pole. Some retain their displaced form until termination but some split into two vortices during their course. Here, we show that existence of a transition during the course of the SSW life c...

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Bibliographic Details
Published in:Atmospheric Science Letters
Main Authors: Hyesun Choi, Wookap Choi, Seong‐Joong Kim, Baek‐Min Kim
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2020
Subjects:
North Atlantic oscillation
precursor
sudden stratospheric warming
tropospheric‐stratospheric dynamical processes
type‐transition
Meteorology. Climatology
QC851-999
North Atlantic
Online Access:https://doi.org/10.1002/asl.953
https://doaj.org/article/ed2a58f2c2914f9288b21cba83f761b5
Description
Summary:Abstract Most sudden stratospheric warming (SSW) events initiate with their centers being displaced from the pole. Some retain their displaced form until termination but some split into two vortices during their course. Here, we show that existence of a transition during the course of the SSW life cycle can be attributable to the condition of North Atlantic Oscillation (NAO) preceding before onset: Positive NAO favors SSW of displacement type with no transition while negative NAO favors the displacement–split type. We show that, in positive NAO precondition, vertical flux of wave activity immediately before onset is mostly contributed only by wavenumber 1 component, which contrasts with the relatively stronger contribution of wavenumber 2 in negative NAO precondition. Whole Atmosphere Community Climate Model (WACCM) simulation results are also consistent with the observational findings. Therefore, NAO can be regarded as a useful precursor for determining the type of forthcoming SSW events.

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