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Title: Are Sudden Stratospheric Warmings Preceded by Anomalous Tropospheric Wave Activity?
A combination of 240 years of output from a state-of-the-art chemistry–climate model and a twentieth-century reanalysis product is used to investigate to what extent sudden stratospheric warmings are preceded by anomalous tropospheric wave activity. To this end we study the fate of lower tropospheric wave events (LTWEs) and their interaction with the stratospheric mean flow. These LTWEs are contrasted with sudden stratospheric deceleration events (SSDs), which are similar to sudden stratospheric warmings but place more emphasis on the explosive dynamical nature of such events. Reanalysis and model output provide very similar statistics: Around one-third of the identified SSDs are preceded by wave events in the lower troposphere, while two-thirds of the SSDs are not preceded by a tropospheric wave event. In addition, only 20% of all anomalous tropospheric wave events are followed by an SSD in the stratosphere. This constitutes statistically robust evidence that the anomalous amplification of wave activity in the stratosphere that drives SSDs is not necessarily due to an anomalous amplification of the waves in the source region (i.e., the lower troposphere). The results suggest that the dynamics in the lowermost stratosphere and the vortex geometry are essential, and should be carefully analyzed in the search for more » precursors of SSDs. « less
Authors:
; ;
Award ID(s):
1643167
Publication Date:
NSF-PAR ID:
10157501
Journal Name:
Journal of Climate
Volume:
32
Issue:
21
Page Range or eLocation-ID:
7173 to 7189
ISSN:
0894-8755
Sponsoring Org:
National Science Foundation
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