Hemispheric Asymmetries in the Quasibiennial Oscillation Signature on the Mid- to High-Latitude Circulation of the Stratosphere



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Peña Ortiz, C. and García Herrera, Ricardo and Ribera, P. and Calvo Fernández, Natalia (2008) Hemispheric Asymmetries in the Quasibiennial Oscillation Signature on the Mid- to High-Latitude Circulation of the Stratosphere. Annals of the New York Academy of Sciences, 1146 . pp. 32-49. ISSN 0077-8923

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The quasibiennial oscillation (QBO) dominates the variability of the equatorial stratosphere and also affects the circulation and temperature of the extratropical region. In this paper we review previous work showing that the mid- to high-latitude circulation is weaker (stronger) when QBO easterlies (westerlies) dominate in the low equatorial stratosphere. The accepted explanation for the extratropical QBO signature is based on the QBO modulation of upward propagating planetary Rossby waves. This mechanism is consistent with the strong seasonality observed in the extratropical QBO. The largest QBO signature in the northern extratropical stratosphere occurs during winter when the dominating westerly wind allows the penetration of planetary waves in the northern stratosphere. However, during the southern winter, planetary waves do not disrupt the southern stratospheric vortex and the largest QBO signature is found during the late spring (November). To further illustrate these mechanisms, we analyze the QBO signature on the mid- to high-latitude circulation of the stratosphere using data from the ERA-40 reanalysis. The extratropical signature in both hemispheres is evaluated as a function of the latitude-height structure of the zonal wind in the tropical region in order to determine how the extratropical response depends on the vertical phase structure of the tropical QBO. We also analyze the QBO impact on planetary wave activity in order to determine how this modulation can explain the observed extratropical QBO signal.

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© 2008 New York Academy of Sciences. European Meteorology Society Annual Meeting (7º. 2007. El Escorial, Spain). European Conference on Applications of Meteorology (8º. 2007. El Escorial, Spain)

Uncontrolled Keywords:Interannual variability; General-circulation; QBO; Reanalysis; Model; Troposphere; Ozone; Waves; Solar; Cycle
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
Sciences > Physics > Atmospheric physics
ID Code:25590
Deposited On:29 May 2014 08:18
Last Modified:10 Dec 2018 15:05

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