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The Antarctic stratospheric sudden warming of 2002: A self‐tuned resonance?
Author(s) -
Esler J. G.,
Polvani L. M.,
Scott R. K.
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl026034
Subject(s) - forcing (mathematics) , stratosphere , vortex , resonance (particle physics) , amplitude , physics , atmospheric sciences , sudden stratospheric warming , nonlinear system , computational physics , climatology , geology , polar vortex , meteorology , atomic physics , optics , quantum mechanics
The extraordinary Antarctic stratospheric warming event of 2002 was characterized by a remarkable vertical structure, with the vortex observed to divide at upper levels in the stratosphere but not at lower levels: such ‘partially’ split vortex events are relatively rare. A simple, yet fully three‐dimensional, model is constructed to investigate the dynamics of this unique event. Planetary waves are excited on the model vortex edge by a lower boundary forcing characterized by two parameters: an amplitude h F and a frequency ω F , measured relative to a stationary frame. For realistic forcing amplitudes, a partial vortex split resembling that observed during the 2002 event is found only within a specific, narrow band of forcing frequencies. Exploiting the relative simplicity of our model, these frequencies are shown to be those causing a ‘self‐tuning’ resonant excitation of the gravest linear mode, during which nonlinear feedback causes an initially off‐resonant forcing to approach resonance.