Affiliation:
1. Department of Atmospheric and Oceanic Sciences Fudan University Shanghai China
2. The Artificial Intelligence Group Division of Frontier Research Southern Marine Laboratory Zhuhai China
3. IRDR ICoE on Risk Interconnectivity and Governance on Weather/Climate Extremes Impact and Public Health Fudan University Shanghai China
Abstract
AbstractPositive feedback between high‐frequency eddies and low‐frequency processes is believed to play an essential role in the NAO evolution. In this study, however, it is found that the previously well‐studied upscale forcing to the intraseasonal scale window is mostly limited during the phase NAO−, but almost disappears during NAO+. The maintenance of the intraseasonal NAO+ is by a strong barotropic instability of the basic flow, which has been overlooked previously. The divergence of the Reynolds stress tensor that decelerates the basic flow is found to account for this asymmetry. For NAO−, there also exist strong interactions between the basic flow and the intraseasonal component, but the energy transfer is in a dipolar form, which, if integrated over space, contributes insignificantly as a whole. These new findings from a dynamics viewpoint shed insight deeper into NAO, a climate mode playing a key role in the Northern Hemisphere warming.
Funder
National Natural Science Foundation of China
Publisher
American Geophysical Union (AGU)
Subject
General Earth and Planetary Sciences,Geophysics
Cited by
1 articles.
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