Stratospheric sudden warmings and slowly propagating zonal-mean zonal windanomalies

Citation
K. Kodera et al., Stratospheric sudden warmings and slowly propagating zonal-mean zonal windanomalies, J GEO RES-A, 105(D10), 2000, pp. 12351-12359
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Volume
105
Issue
D10
Year of publication
2000
Pages
12351 - 12359
Database
ISI
SICI code
Abstract
The relationship between stratospheric sudden warming (SSWs) and slowly pro pagating zonal wind anomalies during the northern hemisphere cold season (N ovember to March) is investigated using two leading empirical orthogonal fu nctions (EOFs) of 15-day mean zonal-mean zonal wind. Poleward and downward propagation of the zonal-mean zonal wind anomalies can be translated as rot ation of state vector in a plane spanned by the two EOFs. Major SSWs occur in phase with the slowly propagating zonal wind anomalies, which implies a "conditioning" of the atmosphere by the slowly varying state. Movement of t he state vector suggests quasi-periodicity of the order of 4 months, althou gh generally only one cycle is achieved during a major warming winter, This characteristic feature can be compared to the stratospheric vacillation cy cle in a mechanistic model. It is also shown that changes in the tropospher ic planetary waves associated with the slowly propagating zonal wind anomal ies coincide with changes in the Arctic Oscillation.