The vertical connection of the quasi-biennial oscillation- modulated 11 year solar cycle signature in geopotential height and planetary waves during Northern Hemisphere early winter
Cnossen, Ingrid; Lu, Hua. 2011 The vertical connection of the quasi-biennial oscillation- modulated 11 year solar cycle signature in geopotential height and planetary waves during Northern Hemisphere early winter. Journal of Geophysical Research, 116 (D13), D13101. 15, pp. 10.1029/2010JD015427Before downloading, please read NORA policies.
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We analyzed observational geopotential height data to provide some new insights on the 11 year solar cycle signal in the Northern Hemisphere early winter and its modulation by the quasi-biennial oscillation (QBO). The signals are strongest in the upper stratosphere. When the QBO is in its easterly phase (QBOe), it appears to move gradually eastward and poleward, resulting in a predominantly positive signal over the pole, with a weaker vertically connected negative signal over the Icelandic Low. When the QBO is in its westerly phase (QBOw), the polar stratospheric signal is mainly negative and appears connected to a negative anomaly in the troposphere over the Aleutian Low. A spectral analysis of the stratospheric response in planetary waves showed a reduction of wave number 2 power under QBOe and an enhancement of wave number 3 under QBOw. These responses are characterized by an overall increase/decrease in wave activity at middle to high latitudes rather than a latitudinal shift of wave activity. There is no clear stratosphere-troposphere connection under QBOe, but under QBOw, there is a vertically coherent increase in wave power at wave numbers 1–3 with a period of 5.6–6.9 days. We suggest that the differences in response under QBOe and QBOw can be explained through differences in initial vortex strength, resulting in either a stronger influence from the low-latitude upper stratosphere (QBOe) or from the troposphere (QBOw) on the polar stratosphere.
|Item Type:||Publication - Article|
|Digital Object Identifier (DOI):||10.1029/2010JD015427|
|Programmes:||BAS Programmes > Polar Science for Planet Earth (2009 - ) > Climate|
|NORA Subject Terms:||Atmospheric Sciences|
|Date made live:||12 Jul 2011 10:13|
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