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Review-article

Meteorol. Zeitschrift, N.F. 3, 259-266 (Oktober 1994)
© by Gebrüder Borntraeger 1994
0941-2948/94/0003-0259

The 10-12-year atmospheric oscillation

H. van Loon and K. Labitzke, Berlin


We dedicate this paper to the memory of Walter Orr Roberts,
in Gratitude for his interest and encouragement of our work.

Summary

This paper summarizes the results of work which is based on the discovery by [TTO Abb. 1a] Labitzke (1982,1987) of a 10-12-year oscillation in the arctic stratospheric temperature. The oscillation modulates the extratropical effect of the Quasi-Biennial Oscillation in winter and is in phase with the 11-year sunspot cycle. Labitzke's original papers dealt only with the north polar stratospheric temperature in winter, but we have expanded the investigation to cover the whole year and most of the Northern Hemisphere.

In months other than January, February and March, it is not necessary to group the data according to the phase of the QBO to find the solar signal. The [TTO Abb. 2] signal appears as a basic, consistent pattern in the correlation between stratospheric geopotential heights and the solar cycle in which the highest correlations are south of about 45° N with a distinct maximum over the western, ocean-covered part of the hemisphere. The variation of the stratospheric heights on the 10-12-year scale are - in the area of high correlations with the solar cycle - associated with temperature changes on the same time scale in the middle and upper troposphere. Preliminary work suggests that the interannual variation of the tropical and subtropical vertical motions [TTO Abb. 1b] contains a component on the 10-12-year scale; but a mechanism which connects the solar and tropospheric-stratospheric oscillations on the 10-12-year scale has not yet been found.

In January and February the correlations of a full time series of stratospheric quantities with the sun are smallest, although the basic pattern is the same as during the rest of the year. The small size of the correlation is due to the fact that they are of [TTO Abb. 7] opposite sign in the east and west years of the Quasi-Biennial Oscillation. The correlation pattern in the east years is the same as in the ten other months of the year; in the west years the opposite sign is related to the fact that those major midwinter breakdowns of the stratospheric westerly (cyclonic) vortex which take place in the west years, have so far happened only in maxima of the 11-year sunspot cycle.


References

Labitzke, K., 1987: Sunspots, the QBO, and the stratospheric temperature in the north polar region. -- Geophys. Res. Lett., 14, 535-537.
Labitzke, K., H. van Loon, 1992: Association between the 11-year solar cycle and the atmosphere. Part V: Summer. -- J. Clim. 5, 240-251.
Labitzke, K., H. van Loon, 1994: Connection between the troposphere and stratosphere on a decadal scale. -- Tellus 46A, 275-286.




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