A Tilted-Trough Mechanism for AO/NAO
Abstract
The least damped mode of the linear atmospheric dynamic system with the zonal mean flow interacting with stationary waves is shown to bear much resemblance to the observed Arctic Oscillation (AO)in terms of both zonal and associated stationary wave components. This AO-like mode results from the dynamic self-organization among the components of zonal mean flow and the associated stationary waves through a so-called tilted-trough positive feedback. Namely, the anomalous AO-like sheared zonal flow generates the associated anomaly in stationary waves in such a way that the tilts of the total stationary waves are altered to reinforce the sheared zonal-flow anomaly through the anomalous momentum flux convergence. Thus the AO-like least damped mode, which can be excited by surface or other forcing, is expected to be dominant over monthly and longer time scales.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.A21C..10J
- Keywords:
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- 1620 Climate dynamics (3309);
- 3319 General circulation;
- 3362 Stratosphere/troposphere interactions;
- 3367 Theoretical modeling