Annular modes and apparent eddy feedbacks in the Southern Hemisphere

Byrne, N. J., Shepherd, T. G. ORCID: https://orcid.org/0000-0002-6631-9968, Woollings, T. and Plumb, R. A. (2016) Annular modes and apparent eddy feedbacks in the Southern Hemisphere. Geophysical Research Letters, 43 (8). pp. 3897-3902. ISSN 0094-8276 doi: 10.1002/2016GL068851

Abstract/Summary

Lagged correlation analysis is often used to infer intraseasonal dynamical effects but is known to be affected by non-stationarity. We highlight a pronounced quasi-two-year peak in the anomalous zonal wind and eddy momentum flux convergence power spectra in the Southern Hemisphere, which is prima facie evidence for non-stationarity. We then investigate the consequences of this non-stationarity 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 non-stationary interannual variability external to any potential feedback process in the mid-latitude troposphere. The findings have implications for the diagnosis of feedbacks in both models and re-analysis data as well as for understanding the mechanisms underlying variations in the zonal wind.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/63813
Identification Number/DOI	10.1002/2016GL068851
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	American Geophysical Union
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