Annular modes and apparent eddy feedbacks in the Southern Hemisphere
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Plumb_Annular modes.pdf
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586.49 KB
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Author(s)
Byrne, Nicholas J.
Shepherd, Theodore G.
Woollings, Tim
Plumb, R. Alan
Date Issued
April 2016
Journal
Geophysical Research Letters
Publisher
American Geophysical Union (AGU)
Citation
Byrne, Nicholas J. et al. “Annular Modes and Apparent Eddy Feedbacks in the Southern Hemisphere.” Geophysical Research Letters 43.8 (2016): 3897–3902.
Version
Final published version
Abstract
Lagged correlation analysis is often used to infer intraseasonal dynamical effects but is known to be affected by nonstationarity. We highlight a pronounced quasi 2 year peak in the anomalous zonal wind and eddy momentum flux convergence power spectra in the Southern Hemisphere, which is prima facie evidence for nonstationarity. We then investigate the consequences of this nonstationarity for the Southern Annular Mode and for eddy momentum flux convergence. We argue that positive lagged correlations previously attributed to the existence of an eddy feedback are more plausibly attributed to nonstationary interannual variability external to any potential feedback process in the midlatitude troposphere. The
findings have implications for the diagnosis of feedbacks in both models and reanalysis data as well as for understanding the mechanisms underlying variations in the zonal wind.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Creative Commons Attribution-NonCommercial-NoDerivs License
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1002/2016GL068851
