Influence of the 11-year solar cycle on the effects of the equatorial quasi-biennial oscillation, manifesting in the extratropical northern atmosphere |
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| Authors: | S A Sitnov |
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| Institution: | (1) A. M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, Pyzhevsky 3, 119017 Moscow, Russia |
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| Abstract: | Using the longest and most reliable ozonesonde data sets grouped for four regions (Japan, Europe, as well as temperate and
polar latitudes of Canada) the comparative analysis of regional responses of ozone, temperature, horizontal wind, tropopause
and surface pressure on the equatorial quasi-biennial oscillation (QBO effects), manifesting in opposite phases of the 11-year
solar cycle (11-yr SC) was carried out. The impact of solar cycle is found to be the strongest at the Canadian Arctic, near
one of two climatological centres of polar vortex, where in solar maximum conditions the QBO signals in ozone and temperature
have much larger amplitudes, embrace greater range of heights, and are maximized much higher than those in solar minimum conditions.
The strengthening of the temperature QBO effect during solar maxima can explain why correlation between the 11-yr SC and polar
winter stratospheric temperature is reversed in the opposite QBO phases. At the border of polar vortex the 11-yr SC also modulates
the QBO effect in zonal wind, strengthening the quasi-biennial modulation of polar vortex during solar maxima that is associated
with strong negative correlation between stratospheric QBO signals in zonal wind and temperature. Above Japan the QBO effects
of ozone, temperature, and zonal wind, manifesting in solar maxima reveal the downward phase dynamics, reminding similar feature
of the zonal wind in the equatorial stratosphere. Above Europe, the QBO effects in solar maxima reveal more similarity with
those above Japan, while in solar minima with the effects obtained at the Canadian middle-latitude stations. It is revealed
that the 11-yr SC influences regional QBO effects in tropopause height, tropopause temperature and surface pressure. The influence
most distinctly manifest itself in tropopause characteristics above Japan. The results of the accompanying analysis of the
QBO reference time series testify that in the period of 1965–2006 above 50-hPa level the duration of the QBO cycle in solar
maxima is 1–3 months longer than in solar minima. The differences are more distinct at higher levels, but they are diminished
with lengthening of the period. |
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| Keywords: | Quasi-biennial oscillation QBO 11-year solar cycle Regional QBO effects Vertical structure of the QBO effects |
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