Quasi-biennial oscillation of mid-latitude stratospheric wind and its influence on European weather regimes in winter

An analysis of 31 years (1960-90) of mid-winter (January-February) stratospheric and tropospheric data at medium latitudes near 50 degrees N shows the following results: the westerly-wind speed at the stratospheric 30-hPa level is distinctly higher in the westerly phase of the tropical QBO than in its easterly phase, but this rule holds only for low and moderate solar activity, while it is suspended in years of high solar activity; as expected from theoretical predictions, the tropospheric 500-hPa ultra-long standing wave pattern is significantly different at times of high and low stratospheric wind speed; and this difference is also associated with a significant difference in the frequency distribution of the occurrence of 'continental' and 'oceanic' surface weather regimes in central Europe in mid-winter.