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Motivation for this study:

Is there another reason for Winter Stratospheric Warmings? N. Kilifarska and P.Mukhtarov Geophysical Institute, Bulgarian Academy of Sciences. Motivation for this study:

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Motivation for this study:

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  1. Is there another reason for Winter Stratospheric Warmings?N. Kilifarska and P.MukhtarovGeophysical Institute, Bulgarian Academy of Sciences • Motivation for this study: • Holton-Tan relation between the phase of QBO and winter time average polar temperature is not applied for Solar Maximum conditions • Is Southern Hemisphere major stratospheric warming in September 2002 exception of the rule? Data • 38 years monthly average data for NH temperature from FUB • Ap index(describing all irregular disturbances in geomagnetic field caused by solar particle radiation) and QBO time series 1.) Polar stratosphere is warmer at solar max comparing to solar min conditions for both - East and West phase of equatorial stratospheric winds 2.) During years with High Sol. Act. correlation between polar T and East QBO is weakened and even reversed [Labitzke&Van Loon, 1988; Naito&Hirota, 1997] Fig. 1 Jan-Feb T differences between solar max and min from FBU data ? Possibly there is another mechanism warming polar stratosphere, especially at Solar Max.? Fig.3 Cross-correlation between T and geomagnetic Ap index (1-st row), T and QBO (2-nd) row; left two panels for years with high solar activity, east (1-st column) and west phase of QBO (2-nd) column; right 2 panels - the same for low solar activity years. Conclusions: Geomagnetic activity can alter Holton-Tan mechanism in explanation the Middle and Low Stratosphere Warming at Solar Max condition (for both - East and West QBO), )as well as for West QBO.& Solar Min.

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