Annular modes and apparent eddy feedbacks in the Southern Hemisphere
| Autor: | R. Alan Plumb, Nicholas J. Byrne, Theodore G. Shepherd, Tim Woollings |
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| Rok vydání: | 2016 |
| Předmět: |
Momentum flux
010504 meteorology & atmospheric sciences Mode (statistics) 010502 geochemistry & geophysics Atmospheric sciences 01 natural sciences Physics::Geophysics Troposphere Geophysics Middle latitudes Climatology Correlation analysis General Earth and Planetary Sciences Southern Hemisphere Physics::Atmospheric and Oceanic Physics Geology 0105 earth and related environmental sciences |
| Zdroj: | Geophysical Research Letters. 43:3897-3902 |
| ISSN: | 0094-8276 |
| DOI: | 10.1002/2016gl068851 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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